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  • 151.
    Andersson, David
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Holgersson, Emanuel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Optimering av ett 3D cellmanipulationssystem: Karakterisering av hur ultraljud påverkar temperatur i ett chip2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A popular method for manipulation of cells is the use of ultrasound. Since the ultrasound usually affects the temperature in its surroundings, there is an interest in characterizing the temperature change in a chip mounted on a transducer that is supplying high frequency ultrasound. If it were possible to control the temperature in the chip by only controlling the voltage being supplied to the ultrasound transducer, the energy costs would be reduced due to not needing a high energy demanding cooling system to control the temperature. By varying the amplitude of the voltage being supplied to the transducer, the temperature in the chip was observed continuously. An IR camera was used to measure the temperature during cycles of heating and cooling. The result shows that there is a certain linearity between the voltage applied to the transducer and the temperature in the chip in certain intervals of voltage. Conduction of heat energy seems to be the lead reason of temperature change in the chip. It has been shown to be possible to control the temperature with a controller as simple as a proportional one, but if a faster pace of heating is desired, then the use of a more sophisticated one should suffice.

  • 152.
    Andersson, Elin
    et al.
    KTH, School of Technology and Health (STH).
    Filipsson, Emma
    KTH, School of Technology and Health (STH).
    Upphandling av medicintekniska produkter inom sjukvården i Sverige2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since 1994, the Public Procurement Act has undergone changes aimed to improve the procurement process and promoting innovation. In order to promote innovation there are a number of government agencies that offer financial assistance, especially to small business with innovative ideas. Despite these efforts, newly established small businesses have difficulties entering the market.

    The study investigates whether changes have been made in the public procurement of medical devices with regard to price and quality prioritization. The priority criteria is presented by the contracting authority as percentage in the allocation criteria. The study is limited to in vitro diagnostic products contracting in Swedish healthcare between the years 2009 and 2015. All tenders, companies that apply for participation in procurement, were analyzed based on sales, number of employees and year of establishment with the purpose of evaluating differences between winning tenders and other tenders.

    The result shows that prioritization has been increasingly on price rather than the quality. Regarding the winning tenders the study shows that larger, more established companies dominates the market. Noteworthy is that this dominance has increased over theses last years. The increase may be due to a spiral effect that is created when winning tenders get an increased economic power. 

  • 153.
    Andersson, Evelina
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    The 2-dimensional biomechanical modeling of the loads on the spine (L5-L1) during a “Back Walkover” maneuver in gymnastics2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Injuries in the female gymnast are common and it is important to understand the biomechanical factors responsible for injury. The Back Walkover maneuver requires one of the greatest amounts of lumbar hyperextension compared to other common gymnastic maneuvers. During the Back Walkover large lateral and vertical impact forces follows on the spine. The spine and muscles around the spine have to absorb generally large forces; therefore the loads on the back and certainly on the lower back are of significant interest. Additionally, it takes a lot of strength and a vast range of motion to perform gymnastic maneuvers such as The Back Walkover. It is of interest to study mechanical loads on a female gymnast since they show higher occurrences of stress-related pathologies of the lumbar spine.

    Therefore the purpose of this project was to examine the loads on the spine during the gymnastic maneuver Back Walkover. Tests on a single female gymnast were made at the sports engineering lab at the University of Adelaide in Australia. Using the 3D-camera system; Optitrack Motion Capture System and Kistler Force Plate, positional data for two dimensions, X-direction (anterior-posterior) and Z-direction (vertical), and ground force were received. Data received were progressed into a graph, diagrams and biomechanical calculations where forces for the vertebrae L1 were calculated in vertical and horizontal direction. The received forces were compared to vertical and horizontal forces in L1 during standing position. Together with developed videos this assisted to model the loads of the spine (L1) during the gymnastic maneuver the “Back Walkover”. The study has led to a deeper knowledge for the community about the risks for female gymnasts and has widened the experience of the project participant, as the project aimed. 

  • 154.
    Andersson, Fredrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Skoglund, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Viktorsson, Jan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Ainegren, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    A Portable Douglas Bag System2015In: Congress Proceedings: ICSNS 2015 / [ed] Hakkarainen Anni, Lindinger Stefan, Linnamo Vesa, 2015, p. 59-Conference paper (Refereed)
  • 155.
    Andersson, Frida
    KTH, School of Technology and Health (STH).
    Finite Element Modeling of Skull Fractures: Material model improvements of the skull bone in theKTH FE head model2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main aim of this project was to develop a model for predicting skull fractures of a 50th percentile male, using a finite element head model developed at the Neuronics department of KTH, Royal Instituteof Technology. The skull bone is modeled as a three layered bone, where the outer and inner tables are modeled as shell elements, while the diploë is modeled by two layers of solid elements. The material model of the tables was changed from the material model MAT_PLASTIC_KINEMATIC to a material model including a damage parameter to soften the damaged material and to enable ploting of the damage of the skull bone. Due to the coarse mesh of the FE head model the material model was not allowed to include any erosion, deleting element as they reach their ultimate strain. With these requests, two materials from the LS-DYNA material library seemed appropriate: material 81,MAT_PLASTICITY_WITH_DAMAGE and material 105, MAT_DAMAGE_2.

    To evaluate these materials and adjust the input parameters a dog bone FE model was developed and tension tests were simulated with this model, equivalent to tension tests performed on equally shaped skull bone specimens. The material simulating a behavior most similar to the behavior from the tension tests turned out to be material 81. This material model was then implemented in the full FE head model for further input parameter adjustment and validation. Four different cadaver experiments were simulated, with different impacting objects: sphere, box, cylinder and flat cylinder surface, and impacted areas of the head: vertex, temporo-parietal and frontal. The forces obtained in the simulations were compared to the forces of the cadaver experiments. The fracture prediction was based on the damage parameter, which could be plotted to visualize the areas where the ultimate strain was exceeded and thereby the area most likely to be fractured. This parameter was then compared to the documented fractures from the cadaver experiments.

    The result showed that using material 81 with the input parameter EPPFR=0.05 gave the overall most accurate forces and fracture predictions. The breaking stress, σB, did not affect the fractures significantly but a reduced σB resulted in reduction of the peak forces. The thickness of the diploë did not have any significant impact on the fracture occurrence, but a thinner diploë had a reducing impact on the peak forces as well.

  • 156.
    Andersson, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Individualized mathematical modeling of neural activation in electric field2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Deep Brain Stimulation (DBS) is a treatment of movement disorders such as Parkinson's disease and essential tremor. Today it has been used in more than 80.000 patients. Electrical stimulation is administered by an implanted pulse generator through an electrode surgically placed in a target brain area specific to the treated disease. Opposed to alternative purely surgical treatment procedures, DBS is reversible and can be turned off.

    In this project, the aim is to individualise an already existing computational model of DBS, but also to look at optimisation of the treatment by developing a neuron model. It has been executed the following way. To localise the target area for the electrode, Magnetic Resonance Imaging (MRI) is used. An MRI image consists of volume elements called voxels. By analysing these voxels, it is possible to set up a coordinate system for the position of different parts of the brain. To build up an individualised model of the DBS, an MRI image is segmented into tissues of different conductivity thus resulting in a more accurate description of the electrical field around the electrode. To visualize the stimuli coverage for the medical staff, the MRI image of the target area, the electrode, and the electrical field produced by the stimuli are depicted in the same figure. From the results, we can draw the conclusion that this method works well for individualising the computational model of DBS, but it has only been used on one MRI scan so far so it needs further testing to obtain more data to compare with.

    The neuron model is a temporospatial mathematical model of a single neuron for the prediction of activation by a given electrically applied field generated by a DBS lead. The activation model is intended to be part of a patient-specific model of an already existing computational model of DBS. The model originate from a neuron model developed by Hodgkin and Huxley (HH). The original HH model only takes into account one compartment and, to make the neuron model more accurate, it is combined with a cable model. The simulation results obtained with the model have been validated against an established and widely accepted neuron model. The results correlated highly to each other with only minor differences. To see how position and orientation impact on activation, the developed HH model was tested for different pulse widths, distances from the lead, and rotations of the neuron relative to the lead. A larger pulse width makes activation more likely and so does a larger amplitude. Thicker neurons are more likely to get activated, neurons closer to the lead and also neurons perpendicular to the lead. From the results we can draw the conclusion that this method is a good way to stimulate neural activation of a single neuron. In future research, it might be possible to compare results from the neuron model with patient's response to treatment.

  • 157.
    Andersson, Ida
    et al.
    KTH, School of Technology and Health (STH).
    Falck, Josefina
    KTH, School of Technology and Health (STH).
    Förstudie för utveckling av en höj- och sänkbar pall i operationsmiljö2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 158.
    Andersson, Ida
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Hedvall, Anders
    KTH, School of Technology and Health (STH), Medical Engineering.
    Relationships Between Skin Properties and Body Water Level2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A need for a quantitative method to determine body water level has been identified by a team of Clinical Innovation Fellows at the Centre for Technology in Medicine and Health (CTMH). A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing. A possible solution is a sensor that would measure alterations in skin properties due to changes in total body water. CTMH has had an idea of such a sensor, which is evaluated in this work. At an early stage of this evaluation process, it became clear that the research regarding correlations between skin properties and body hydration level was not sufficient to warrant the initiation of a sensor development process. Therefore, the main objective of this thesis became to investigate such correlations.

    An extensive literature review is presented, from which an experiment was developed. The experiment was performed on four human test subjects and involved measurements of skin thickness and elasticity parameters, before and after a weight loss of 3.2-3.7 % due to dehydration. The results showed clear decreases in skin thickness and indications of alterations in skin distensibility as well as in the skin’s immediate elastic response to applied negative pressure. It could also be seen that skin at different body sites does not respond in the same way - calves showed more distinct results than thighs and volar forearm.

    The material provided in this thesis encourages further studies of the correlation between the mentioned properties and total body water. If a predictable correlation can be found, a sensor development process could start. A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing.

  • 159.
    Andersson, Jennie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    T2 Mapping Compared to Standard MRI Assessment: An Assessment of the Knee Cartilage on Distal Femur2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Magnetic resonance imaging (MRI) has become the most important modality for assessment of pathological changes in the knee cartilage. The assessment of the cartilage is usually made by a set of anatomical MRI images with different sequences. Newer techniques, that map various in MRI parameters, have been developed and allows changes in an earlier stage of the disease. One of these techniques is T2 mapping. The goal of this thesis was to compare this newer technique, T2 mapping, with the standard MRI assessment for assessment of articular cartilage on distal femur in the knee. The purpose was to assess the cartilage with these two different methods and analyze its outcomes.

    Eight subjects were included in this study and scanned with a 3.0 T or 1.5 T MRI machine. A specific MRI knee protocol was used for the standard MRI assessment, and a multi-echo sequence was used for the T2 mapping. The T2 map was created and analyzed in the program IntelliSpace Portal.

    Both the standard MRI assessment and the T2 map showed changes in the knee cartilage. The result showed either indication for damage cartilage or healthy cartilage. The standard assessment showed cartilage lesion in three subjects and no lesion in five subjects. The same outcomes were with the T2 mapping. However, not all results were equal. The T2 mapping also showed higher values in the trochlea area where no indications for changes were found in the standard assessment.

    This study showed similar results for both the standard assessment and the T2 map. Both methods could identify damage and is, therefore, useful for assessment of the knee cartilage. The outcomes of the different methods differ, and the assessment is therefore made in different ways. The T2 mapping can be analyzed both visual and quantitative. The outcomes were both a color map of the knee but also results in graphs and values. The standard assessment is only assessed from grayscale images. The best outcomes from the T2 mapping was when it only was changes within the cartilage and not when the cartilage lesion was adjacent to an underlying bone lesion. Based on what was examined in this work, the best result was when T2 mapping was used together with the anatomical images used in the standard assessment.

    The conclusion is that the standard assessment is necessary when it comes to make a damage assessment and perform damage marking as for Episurf. The T2 mapping is, however, an interesting method and will be more useful with more applications in the future. It is therefore exciting to keep an eye on the technology and its development.

  • 160.
    Andersson, Jonathan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Water–fat separation in magnetic resonance imaging and its application in studies of brown adipose tissue2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Virtually all the magnetic resonance imaging (MRI) signal of a human originates from water and fat molecules. By utilizing the property chemical shift the signal can be separated, creating water- and fat-only images. From these images it is possible to calculate quantitative fat fraction (FF) images, where the value of each voxel is equal to the percentage of its signal originating from fat. In papers I and II methods for water–fat signal separation are presented and evaluated.

    The method in paper I utilizes a graph-cut to separate the signal and was designed to perform well even for a low signal-to-noise ratio (SNR). The method was shown to perform as well as previous methods at high SNRs, and better at low SNRs.

    The method presented in paper II uses convolutional neural networks to perform the signal separation. The method was shown to perform similarly to a previous method using a graph-cut when provided non-undersampled input data. Furthermore, the method was shown to be able to separate the signal using undersampled data. This may allow for accelerated MRI scans in the future.

    Brown adipose tissue (BAT) is a thermogenic organ with the main purpose of expending chemical energy to prevent the body temperature from falling too low. Its energy expending capability makes it a potential target for treating overweight/obesity and metabolic dysfunctions, such as type 2 diabetes. The most well-established way of estimating the metabolic potential of BAT is through measuring glucose uptake using 18F-fludeoxyglucose (18F-FDG) positron emission tomography (PET) during cooling. This technique exposes subjects to potentially harmful ionizing radiation, and alternative methods are desired. One alternative method is measuring the BAT FF using MRI.

    In paper III the BAT FF in 7-year olds was shown to be negatively associated with blood serum levels of the bone-specific protein osteocalcin and, after correction for adiposity, thigh muscle volume. This may have implications for how BAT interacts with both bone and muscle tissue.

    In paper IV the glucose uptake of BAT during cooling of adult humans was measured using 18F-FDG PET. Additionally, their BAT FF was measured using MRI, and their skin temperature during cooling near a major BAT depot was measured using infrared thermography (IRT). It was found that both the BAT FF and the temperature measured using IRT correlated with the BAT glucose uptake, meaning these measurements could be potential alternatives to 18F-FDG PET in future studies of BAT.

  • 161.
    Andersson, Katarina
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Optimization of the Implantation Angle for a Talar Resurfacing Implant: A Finite Element Study2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs.

    This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant.

    To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft.

    A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy.

  • 162.
    Andersson, Katarina
    et al.
    KTH, School of Technology and Health (STH).
    Löfgren, Carita
    KTH, School of Technology and Health (STH).
    Partial Development of a Water Purification System Using Heat from Solar Energy, with Focus on Bangladesh2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 163.
    Andersson, Klara
    et al.
    KTH, School of Technology and Health (STH).
    Busch Paulsson, Esther
    KTH, School of Technology and Health (STH).
    Accuracy Validation of Pulse Oximeters used at Hospitals: A Cross-Sectional Study performed in Stockholm2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis had the purpose to look into the accuracy of the pulse oximeter, the experienced as well as the actual. A pulse oximeter utilizes optics to non-invasively estimate the oxygen saturation (SO2) in the blood with an indirect value (SpO2). The accuracy of the pulse oximeter and its two belonging sensors (ear and finger) was compared against the method that is considered to give the most reliable value of this parameter, i.e. arterial blood gas test (SaO2). The experienced accuracy was evaluated with the help of a questionnaire. The target group was healthcare professionals at four main hospitals in Stockholm, and further three departments were chosen at each hospital; lung, cardiology, and emergency department. Additional data was collected with help of measurements performed on patients, where readings from pulse oximeters were compared against arterial blood gas tests. Data was collected from two measurement sites on the body, the ear and the finger. Differences between SpO2 and SaO2 as well as differences between ear and finger for the same pulse oximeter were investigated. The result from the two methods indicated that the healthcare professionals were aware of existing deviations between SpO2 and SaO2, and some also had strategies to deal with them. The trend of the collected data was analyzed to draw a conclusion of the most accurate pulse oximeter according to the tests. There was not enough data collected to make any statistical conclusion, but according to the data none of the pulse oximeters fulfilled the set requirement. Differences existed when SpO2 was compared against SaO2, and also when SpO2 from the ear and finger for the same pulse oximeter were compared against each other. According to the data, one pulse oximeter was concluded to be more accurate than the others. Suggestions for future work can be to collect a bigger amount of data to be able to draw a statistical conclusion, and eventually focus on interviews to look deeper into the healthcare professionals’ strategies and workflow. 

  • 164.
    Andersson, Klara
    et al.
    KTH, School of Technology and Health (STH).
    Busch Paulsson, Esther
    KTH, School of Technology and Health (STH).
    Utvärdering av användarvänlighet hos hjälpmedel för ät-träning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mandometer® is a medical device, which assists patients with overweight and eating disorders to normalize their eating beahavior. Mandometer® has been developed by Mando Group AB and is used on Mandometer- and Mandolean Clinics in Sweden, USA and Australia in their treatment. A new version of Mandometer® has been recently developed, from generation four to generation five. It consists of a light scale and a mobile app, instead of a scale and a computer.  No previous study about the usability of the new version has been done. On behalf of Mando Group AB has such an evaluation been executed using questionnaires and conversations with both patients and healthy individuals. The results have been compiled and analyzed, and based on this a conclusion has been drawn. The usability is sufficient, but there are some deficiencies. This can be fixed by the suggested improvements and the written instruction manual. The result also shows that the development of the product is a clear improvement compared to the previous version.

  • 165.
    Andersson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Svensson, karolina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Södergren, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microfluidics for High-Pressure Analyses2018In: 12th Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland) / [ed] Samilu Fransilla, 2018, p. 8-8Conference paper (Refereed)
    Abstract [en]

    When using appropriate materials and microfabrication techniques, the small dimensionsand mechanical stability of microstructured devices allow for processes at high pressureswithout loss in safety. The largest area of applications has been demonstrated in chemistry,where extraction, synthesis and analyses often excel at high densities and high temperatures.These two parameters are accessible through high pressures. Capillary chemistry has beenused since long but, just like in low-pressure applications, there are several advantages in usingmicrofluidic platforms for control of reactions, catalysis, mixing and separation. For example,planar isothermal set-ups, large local variations in geometries, dense form factors, small deadvolumes and precisely positioned microstructures.In analytical systems, we are studying high-pressure components and microsystems forsampling, sample preparation, analyses and fractionation. We will present what drives ourresearch and development: Our experimental set-up with high-pressure pumps, high-speedcamera, sensors, valves, piston-chambers, backpressure regulators, cooling table, etc. How wehave built capability in pumping and valving by the use of stainless steel and paraffinactuation. How we are making high pressure silicon-glass and glass-glass chips with integratedelectrical thin film sensors, using printed circuit boards to ease handling of the chips andintegrating modules. A set of relevant publications are listed below.

  • 166. Andersson, Martin
    et al.
    Mattsson, Soren
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Leide-Svegborn, Sigrid
    A biokinetic and dosimetric model for ionic indium in humans2017In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 62, no 16, p. 6397-6407Article in journal (Refereed)
    Abstract [en]

    This paper reviews biokinetic data for ionic indium, and proposes a biokinetic model for systemic indium in adult humans. The development of parameter values focuses on human data and indium in the form of ionic indium(III), as indium chloride and indium arsenide. The model presented for systemic indium is defined by five different pools: plasma, bone marrow, liver, kidneys and other soft tissues. The model is based on two subsystems: one corresponding to indium bound to transferrin and one where indium is transported back to the plasma, binds to red blood cell transferrin and is then excreted through the kidneys to the urinary bladder. Absorbed doses to several organs and the effective dose are calculated for In-111- and In-113m-ions. The proposed biokinetic model is compared with previously published biokinetic indium models published by the ICRP. The absorbed doses are calculated using the ICRP/ICRU adult reference phantoms and the effective dose is estimated according to ICRP Publication 103. The effective doses for In-111 and In-113m are 0.25 mSv MBq(-1) and 0.013 mSv MBq(-1) respectively. The updated biokinetic and dosimetric models presented in this paper take into account human data and new animal data, which represent more detailed and presumably more accurate dosimetric data than that underlying previous models for indium.

  • 167.
    Andersson, Matilda
    Halmstad University, School of Business, Engineering and Science.
    Analysis of Changes in Running Technique Between a Shod and Barefoot Running Condition.2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Lately, barefoot running has become popular and there is a debate on the pros and cons of barefoot running with regards to running injuries. Many factors are causing injuries and one of the factors discussed is the fact that we run in shoes. When we run in shoes the biomechanics of the running technique may and therefore be a possible cause to injury. Aim: The aim of the study was to assess how the foot strike pattern, angle of the knee and ankle joint at time of initial contact, as well as the step length changes between a shod and barefoot running condition in habitually shod runners when running in a pace equivalent to their running pace over ten kilometers. Method: Twenty-seven healthy runners (18 male, 9 female) were included in the study. The study took place at the fitness center of Halmstad University. Subjects ran on a treadmill, in an individual pace equivalent to their running pace over ten km, both in a shod and barefoot running condition. Two-dimensional analysis of the sagittal plane kinematics of the knee joint, ankle joint and foot position to horizontal, foot strike pattern and step length was done. Participants ran for ten minutes with shoes and for five minutes barefoot. Running technique was videotaped using an Iphone 6 camera and landmarks were marked with white tape to ease the analysis. Results: Changes in foot strike pattern was observed. When running barefoot 63% of the subjects adopted a non-heel strike pattern compared to 18.5% when shod (p=0.001). Knee flexion was increased at IC for the barefoot condition, with 164°±6 relative knee angle compared to 167°±6 when shod (p=0.001). Ankle angle at IC did not show a statistical significant difference between conditions (p=0.657). When barefoot the angle was 117°±8 compared to 115°±8 when shod. Foot angle to horizontal showed a flatter foot placement at IC with a less dorsiflexed foot for the barefoot condition (-4°±8) compared to shod (-12°±8), (p=0.001). Step length was decreased for the barefoot condition (0.82m ±0.15)   compared to shod (0.85m ±0.13), (p=0.008). Conclusion: Results are consistent with previous findings that barefoot running in some cases change the running technique with a flatter foot placement, an increased knee flexion at IC and a decreased step length. However, caution must be taken when habitually shod runners transition to barefoot running in regards to the biomechanical changes that may occur. To benefit from barefoot running a non-heel strike pattern is required. Further, the running technique may be the more important factor, regardless of wearing shoes or not.

  • 168.
    Andersson, Mats
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Burdakov, Oleg
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Zikrin, Spartak
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, The Institute of Technology.
    Global search strategies for solving multilinear least-squares problems2012In: Sultan Qaboos University Journal for Science, ISSN 1027-524X, Vol. 17, no 1, p. 12-21Article in journal (Refereed)
    Abstract [en]

    The multilinear least-squares (MLLS) problem is an extension of the linear leastsquares problem. The difference is that a multilinear operator is used in place of a matrix-vector product. The MLLS is typically a large-scale problem characterized by a large number of local minimizers. It originates, for instance, from the design of filter networks. We present a global search strategy that allows for moving from one local minimizer to a better one. The efficiency of this strategy is illustrated by results of numerical experiments performed for some problems related to the design of filter networks.

  • 169.
    Andersson, Mats
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Burdakov, Oleg
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Zikrin, Spartak
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Global Search Strategies for Solving Multilinear Least-squares Problems2011Report (Other academic)
    Abstract [en]

    The multilinear least-squares (MLLS) problem is an extension of the linear least-squares problem. The difference is that a multilinearoperator is used in place of a matrix-vector product. The MLLS istypically a large-scale problem characterized by a large number of local minimizers. It originates, for instance, from the design of filter networks. We present a global search strategy that allows formoving from one local minimizer to a better one. The efficiencyof this strategy isillustrated by results of numerical experiments performed forsome problems related to the design of filter networks.

  • 170.
    Andersson, Mats
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Burdakov, Oleg
    Linköping University, Department of Mathematics, Optimization . Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Zikrin, Spartak
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    Sparsity Optimization in Design of Multidimensional Filter Networks2013Report (Other academic)
    Abstract [en]

    Filter networks is a powerful tool used for reducing the image processing time, while maintaining its reasonably high quality.They are composed of sparse sub-filters whose low sparsity ensures fast image processing.The filter network design is related to solvinga sparse optimization problem where a cardinality constraint bounds above the sparsity level.In the case of sequentially connected sub-filters, which is the simplest network structure of those considered in this paper, a cardinality-constrained multilinear least-squares (MLLS) problem is to be solved. If to disregard the cardinality constraint, the MLLS is typically a large-scale problem characterized by a large number of local minimizers. Each of the local minimizers is singular and non-isolated.The cardinality constraint makes the problem even more difficult to solve.An approach for approximately solving the cardinality-constrained MLLS problem is presented.It is then applied to solving a bi-criteria optimization problem in which both thetime and quality of image processing are optimized. The developed approach is extended to designing filter networks of a more general structure. Its efficiency is demonstrated by designing certain 2D and 3D filter networks. It is also compared with the existing approaches.

  • 171.
    Andersson, Mats
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Adaptive Spatio-temporal Filtering of 4D CT-Heart2013In: Image Analyses: Image Processing, Computer Vision, Pattern Recognition, and Graphics / [ed] Joni-Kristian Kämäräinen, Markus Koskela, Berlin Heidelberg: Springer, 2013, p. 246-255Conference paper (Refereed)
    Abstract [en]

    The aim of this project is to keep the x-ray exposure of the patient as low as reasonably achievable while improving the diagnostic image quality for the radiologist. The means to achieve these goals is to develop and evaluate an efficient adaptive filtering (denoising/image enhancement) method that fully explores true 4D image acquisition modes.

    The proposed prototype system uses a novel filter set having directional filter responses being monomials. The monomial filter concept is used both for estimation of local structure and for the anisotropic adaptive filtering. Initial tests on clinical 4D CT-heart data with ECG-gated exposure has resulted in a significant reduction of the noise level and an increased detail compared to 2D and 3D methods. Another promising feature is that the reconstruction induced streak artifacts which generally occur in low dose CT are remarkably reduced in 4D.

  • 172.
    Andersson, Mats
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Kronander, Torbjorn
    Velocity Adaptive Filtered Angiography1999Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method of imaging a blood vessel in a body using X-rays and an injectable contrast medium is described. The contrast medium is injected into the body, and signals constituted by an X-ray image sequence depicting X-ray attenuation values is recorded. The X-ray attenuated values in each spaced-time neighborhood are combined in a way that is dependent on the processed image sequence and separately established for each neighborhood, and separating, from background and vessel signals, flow signals having energy contributions mainly in an area of frequency domain bounded by surfaces corresponding to threshold velocities separately established for each neighborhood, which surfaces are shifted a specified amount along a temporal frequency axis.

  • 173.
    Andersson, Nina
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Cerebrospinal fluid infusion methods: development and validation on patients with idiopathic normal pressure hydrocephalus2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cerebrospinal fluid (CSF) infusion tests can be used to estimate the dynamic properties of the CSF system. Idiopathic normal pressure hydrocephalus (INPH) is a syndrome signified by a disturbance to the CSF system, where the cause is unknown and the diagnosis is difficult to determine. As an aid in identifying patients with INPH who will improve after shunt surgery, infusion tests are commonly used to determine the outflow conductance (Cout), or outflow resistance (Rout=1/Cout), of the CSF system. The tests are also used to determine shunt function in vivo. The general aim of this thesis was to develop and validate CSF infusion methods, to investigate the dynamics of the CSF system. The methods should be applicable to patients with INPH, to aid in the quest to further improve the diagnosis and management of this syndrome.

    An existing mathematical model describing the dynamics of the CSF system was further developed. The characteristics of the model were verified and the effect of expanding intracranial air on the intracranial pressure (ICP) was simulated. The simulations supported the recommendation to maintain sea-level pressure during air ambulance transportation of patients with suspected intracranial air.

    A recently developed infusion apparatus was evaluated, on an experimental model as well as on a patient material. The repetitiveness in estimating Cout was found to be good. A statistically significant difference was found between the repeated Cout estimations in the patient group, indicating that there might have been a small physiological change introduced during the infusion test. A parameter, ∆Cout, was proposed and evaluated. It proved to reflect the reliability of individual Cout investigations in a clinically useful way, as well as to provide easily interpreted information.

    An adaptive algorithm for assessment of Cout was developed and evaluated on a patient group. The new algorithm was shown to reduce the investigation time, from 60 minutes, by 14.3 ± 5.9 minutes (mean ± SD), p<0.01, without reducing the reliability of the estimated Cout below clinically relevant levels.

    The relationship between ICP and CSF outflow was studied in a group of patients investigated for INPH. It was found that in the range of moderate increase from baseline pressure, the assumption of a pressure independent Rout was confirmed (p=0.5). However, at larger pressure increments, the relationship had a non-linear tendency (p<0.05). This indicates that the traditional view of a pressure independent Rout might have to be questioned in the region where ICP exceeds baseline pressure too much.

    Infusion tests can be performed in different ways, where three main categories may be distinguished. The bolus infusion method was compared to the constant pressure and constant flow infusion methods, on an experimental model as well as on a patient material. When physiological pressure fluctuations were added to the model, significant differences were found in the determination of Cout in the range of clinical importance, i.e. low Cout (p<0.05). The finding was supported by the patient investigations, the difference was however not significant.

    With the application of the new methods developed in this thesis, and the increased knowledge concerning relationships between CSF dynamic parameters, the CSF infusion test was further improved with the ability to increase measurement reliability in a reduced time. This constitutes a good basis to perform a large multi-centre study with the main goal to determine the predictive value of the parameter Cout.

  • 174.
    Andersson, Olle
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Predicting Patient Length Of Stay at Time of Admission Using Machine Learning2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis investigates the possibility of using machine learning methods to predict patient length of stay at the time of admission to a clinical ward from the emergency department. The main aim of this thesis is to provide a comparative analysis of different algorithms and to suggest a suitable model that can be used in a hospital prediction software. The results show that it is possible to achieve a balanced accuracy of 0.72 at the time of admission and of 0.75 at a later stage in the process. The suggested algorithm was Random Forest which combines good accuracy with effective training time, making it suitable for on-line use in a hospital. The study shows that there is a clear potential for the use of machine learning methods for predicting length of stay, but that further improvements have to be made before adaption into the healthcare.

  • 175. Andersson, R
    et al.
    Loyd, Dan
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Pressure sensed non-invasively directly on the extra corporeal bloodline tube2001In: PROCEEDINGS OF THE 23RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-4: BUILDING NEW BRIDGES AT THE FRONTIERS OF ENGINEERING AND MEDICINE, 2001, Vol. 23, p. 3179-3181Conference paper (Refereed)
    Abstract [en]

    To clinically measure blood pressure at extra corporeal bloodlines involves a hazard due to the infection risk and a risk for thrombosis formation. The aim was to design a non-invasive pressure sensor, measuring directly on a tube section. A modified tube cross-section was used to improve sensitivity. Using the developed sensing principle, a consistent relation (r=0.999) was obtained between pressure and output signal. The output was stable and an acceptable drift within the temperature-range. The method shows great promise for applications in monitoring of the dialysis process.

  • 176.
    Andersson, Simon
    et al.
    KTH, School of Technology and Health (STH).
    Lundberg, Fabian
    KTH, School of Technology and Health (STH).
    Analys av resursbehovet per patient på akutmottagningen vid Karolinska Universitetssjukhuset Solna2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The staff of the emergency department at Karolinska Universitetssjukhuset Solna has in recent years experienced a higher workload, although the number of patients has not increased. Karolinska Universitetssjukhuset do not possess a set method to analyze the resource needs of different patient groups, and the difference between them. The project would thus give Karolinska Universitetssjukhuset a better understanding of different patients' resource needs in the form of a resource consumption model. This model was created through discussions with staff and analysis of data from Karolinska's internal data warehouse, Karda. From this a patient group distribution was created with the aim of grouping patients with similar resource needs. Time studies and surveys were conducted and compiled at the emergency department to generate important information. Analysis of the results obtained suggests that patients have, in recent years, become more ill and therefore more costly for the hospital. A resource consumption model has been created which can analyze and compare the patients' burden of care with one another by three parameters. These are priority and monitoring, period of residence and on-call salary increment. However, this model is not currently able to analyze all parameters simultaneously, only individually. In order to analyze parameters simultaneously the model and calculations would need to be revised. This could be a continuous study for further work in this specific area.  

  • 177. Andersson, T.
    et al.
    Anderson, C.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Human in vivo cutaneous microdialysis: Estimation of histamine release in cold urticaria.1995In: Acta Dermato-Venereologica, ISSN 0001-5555, E-ISSN 1651-2057, no 75, p. 343-347Article in journal (Refereed)
    Abstract [en]

    A novel bioanalytical in vivo sampling technique, cutaneous microdialysis, was used to follow the chronology of skin histamine release in 3 patients with cold urticaria and in 2 healthy volunteers. Laser Doppler perfusion imaging was used simultaneously to monitor the skin circulatory response. Microdialysis samples were collected at 10-min intervals and analysed by radioimmunoassay technique. Fifty minutes after probe insertion, the ventral forearm skin in the area of the dialysis membrane was provoked for 5-15 min with a 25 x 40 mm ice cube covered with plastic foil. In the cold urticaria patients, an up to 80-fold increase of histamine was observed, with peak levels 20-30 min after challenge. Histamine levels then fell to reach "baseline" levels within 50 min. In the healthy subjects, the histamine increase was earlier, less pronounced and of shorter duration. Cutaneous microdialysis and laser Doppler imaging offer new possibilities for the chronological multiparameter assessment of inflammatory skin disorders in vivo.

  • 178.
    Andersson, Thord
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Dept. of C4ISR, Swedish Defence Research Agency, Linköping, Sweden, .
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Geodesic registration for interactive atlas-based segmentation using learned multi-scale anatomical manifolds2018In: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 112, p. 340-345Article in journal (Refereed)
    Abstract [en]

    Atlas-based segmentation is often used to segment medical image regions. For intensity-normalized data, the quality of these segmentations is highly dependent on the similarity between the atlas and the target under the used registration method. We propose a geodesic registration method for interactive atlas-based segmentation using empirical multi-scale anatomical manifolds. The method utilizes unlabeled images together with the labeled atlases to learn empirical anatomical manifolds. These manifolds are defined on distinct scales and regions and are used to propagate the labeling information from the atlases to the target along anatomical geodesics. The resulting competing segmentations from the different manifolds are then ranked according to an image-based similarity measure. We used image volumes acquired using magnetic resonance imaging from 36 subjects. The performance of the method was evaluated using a liver segmentation task. The result was then compared to the corresponding performance of direct segmentation using Dice Index statistics. The method shows a significant improvement in liver segmentation performance between the proposed method and direct segmentation. Furthermore, the standard deviation in performance decreased significantly. Using competing complementary manifolds defined over a hierarchy of region of interests gives an additional improvement in segmentation performance compared to the single manifold segmentation.

  • 179.
    Andersson, Thord
    et al.
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Läthén, Gunnar
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lenz, Reiner
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Modified Gradient Search for Level Set Based Image Segmentation2013In: IEEE Transactions on Image Processing, ISSN 1057-7149, E-ISSN 1941-0042, Vol. 22, no 2, p. 621-630Article in journal (Refereed)
    Abstract [en]

    Level set methods are a popular way to solve the image segmentation problem. The solution contour is found by solving an optimization problem where a cost functional is minimized. Gradient descent methods are often used to solve this optimization problem since they are very easy to implement and applicable to general nonconvex functionals. They are, however, sensitive to local minima and often display slow convergence. Traditionally, cost functionals have been modified to avoid these problems. In this paper, we instead propose using two modified gradient descent methods, one using a momentum term and one based on resilient propagation. These methods are commonly used in the machine learning community. In a series of 2-D/3-D-experiments using real and synthetic data with ground truth, the modifications are shown to reduce the sensitivity for local optima and to increase the convergence rate. The parameter sensitivity is also investigated. The proposed methods are very simple modifications of the basic method, and are directly compatible with any type of level set implementation. Downloadable reference code with examples is available online.

  • 180.
    Andersson, Thord
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Karlsson, Anette
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Smedby, Örjan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Almer, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Consistent intensity inhomogeneity correction in water–fat MRI2015In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 42, no 2, p. 468-476Article in journal (Refereed)
    Abstract [en]

    PURPOSE:

    To quantitatively and qualitatively evaluate the water-signal performance of the consistent intensity inhomogeneity correction (CIIC) method to correct for intensity inhomogeneities METHODS: Water-fat volumes were acquired using 1.5 Tesla (T) and 3.0T symmetrically sampled 2-point Dixon three-dimensional MRI. Two datasets: (i) 10 muscle tissue regions of interest (ROIs) from 10 subjects acquired with both 1.5T and 3.0T whole-body MRI. (ii) Seven liver tissue ROIs from 36 patients imaged using 1.5T MRI at six time points after Gd-EOB-DTPA injection. The performance of CIIC was evaluated quantitatively by analyzing its impact on the dispersion and bias of the water image ROI intensities, and qualitatively using side-by-side image comparisons.

    RESULTS:

    CIIC significantly ( P1.5T≤2.3×10-4,P3.0T≤1.0×10-6) decreased the nonphysiological intensity variance while preserving the average intensity levels. The side-by-side comparisons showed improved intensity consistency ( Pint⁡≤10-6) while not introducing artifacts ( Part=0.024) nor changed appearances ( Papp≤10-6).

    CONCLUSION:

    CIIC improves the spatiotemporal intensity consistency in regions of a homogenous tissue type. J. Magn. Reson. Imaging 2014.

  • 181.
    Andersson, Thord
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Romu, Thobias
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Forsgren, Mikael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Smedby, Örjan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Almer, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Endocrinology.
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Self-calibrated DCE MRI using Multi Scale Adaptive Normalized Averaging (MANA)2012In: Proceedings of the annual meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2012), 2012, 2012Conference paper (Other academic)
  • 182.
    Andersson, Torbjörn
    Örebro University, School of Health and Medical Sciences.
    The development of ultrasound in radiology in Sweden2012In: Ultrasound in clinical diagnosis: from pioneering developments in Lund to global application in medicine / [ed] Bo Eklöf, Kjell Lindström, Stig Persson, Oxford: Oxford University Press, 2012, p. 121-128Chapter in book (Other academic)
  • 183. Andreassen, Björn
    et al.
    Holmberg, Rickard
    Brahme, Anders
    Janek Strååt, Sara
    Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI). Stockholm University, Faculty of Science, Department of Physics.
    PET/CT measurements and GEANT4 simulations of the inducedpositron activity from high energy scanned photon beamsManuscript (preprint) (Other academic)
  • 184.
    Andres, Bustamante
    et al.
    Tecnológico de Monterrey, MEX.
    Cheddad, Abbas
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    Rodriguez-Garcia, Alejandro
    Tecnológico de Monterrey, MEX.
    Digital Image Processing and Development of Machine Learning Models for the Discrimination of Corneal Pathology: An Experimental Model2019Conference paper (Refereed)
  • 185.
    Anette, Kniberg
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Nokto, David
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    A Benchmark of Prevalent Feature Selection Algorithms on a Diverse Set of Classification Problems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Feature selection is the process of automatically selecting important features from data. It is an essential part of machine learning, artificial intelligence, data mining, and modelling in general. There are many feature selection algorithms available and the appropriate choice can be difficult. The aim of this thesis was to compare feature selection algorithms in order to provide an experimental basis for which algorithm to choose. The first phase involved assessing which algorithms are most common in the scientific community, through a systematic literature study in the two largest reference databases: Scopus and Web of Science. The second phase involved constructing and implementing a benchmark pipeline to compare 31 algorithms’ performance on 50 data sets.The selected features were used to construct classification models and their predictive performances were compared, as well as the runtime of the selection process. The results show a small overall superiority of embedded type algorithms, especially types that involve Decision Trees. However, there is no algorithm that is significantly superior in every case. The pipeline and data from the experiments can be used by practitioners in determining which algorithms to apply to their respective problems.

  • 186.
    Angelopoulos, A.
    et al.
    -.
    Apostolakis, A.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    K 0–K̄0 mass and decay-width differences: CPLEAR evaluation1999In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 471, no 2, p. 332-338Article in journal (Refereed)
    Abstract [en]

    The CPT-violation parameters Re(δ) and Im(δ) determined recently by CPLEAR are used to evaluate the K0 mass and decay-width differences, as given by the difference between the diagonal elements of the neutral-kaon mixing matrix (M−iΓ/2). The results – GeV and GeV – are consistent with CPT invariance. The CPT invariance is also shown to hold within a few times 10−3–10−4 for many of the amplitudes describing neutral-kaon decays to different final states.

  • 187.
    Angelopoulos, Angelos
    et al.
    -.
    Apostolakis, A.
    -.
    Aslanides, E.
    -.
    Backenstoss, Gerhard
    -.
    Bargassa, P.
    -.
    Bee, C P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Physics at CPLEAR2003In: Physics Reports, Vol. 374, no 3, p. 165-270Article in journal (Refereed)
    Abstract [en]

    LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

  • 188.
    Angelopoulos, Angelos
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    K0⇋ K̄0 transitions monitored by strong interactions: a new determination of the K L–K S mass difference2001In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 503, no 1, p. 49-57Article in journal (Refereed)
    Abstract [en]

    The CPLEAR set-up (modified) has been used to determine the KL–KS mass difference by a method where neutral-kaon strangeness oscillations are monitored through kaon strong interactions, rather than semileptonic decays, thus requiring no assumptions on CPT invariance for the decay amplitudes. The result, Δm=(0.5343±0.0063stat±0.0025syst)×1010ℏ/s, provides a valuable input for CPT tests.

  • 189.
    Angelopoulos, Angelos
    et al.
    -.
    Locher, M P
    -.
    Markushin, V E
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon1999In: The European Physical Journal C-Particles and Fields, ISSN 434-6044, Vol. 10, no 1, p. 19-25Article in journal (Refereed)
    Abstract [en]

    We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on 12" style="position: relative;" tabindex="0" id="MathJax-Element-1-Frame" class="MathJax">12C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle.

  • 190.
    Angland, Erik
    et al.
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Karlsson, Henrik
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Gustafsson, Agnetha
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Pettersson, Håkan
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Luftmätningar av  inhalerat 99mTc till BMA vid ventilationsundersökningar med Technegas.2006Conference paper (Other academic)
  • 191.
    Anthony, Diana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Creating an Individualized Predictive Model of PAO2 and PACO2 Changes During Voluntary Static Apnea for Sedentary Subjects2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The primary aim of this study was to fill a gap in the literature in understanding maximal BH in untrained, non-divers by generating a predictive numerical model for PAO2 and PACO2 throughout BH. There have been little to no previous attempts at explicitly characterizing the influence of impermanent personal or environmental factors on PAO2 or PACO2 at BH breakpoint. The metabolic human consumption of O2 and production of CO2 as measured through alveolar partial pressures was observed over time during a voluntary maximum breath-hold for 18 members of the general population. The coefficient of determination was used to determine accuracy of the model in fitting participants’ BH data from this experiment. The volume of the last inhalation pre-BH, time to subjective breakpoint, and breath-to-breath calculated respiratory exchange ratio (RER) were identified as the most influential combination of key variables that improved PAO2 model fit (from R2 = 0.8591 to R2 = 0.8840). Clustering methods coupled with two sample t-tests or ANOVA were then used to identify survey responses most correlated to inter-BH similarities. These were barometric pressure, age, height, weight, resting HR, smoker/ freediver/scuba experience, and weekly frequency of engaging in physical exercise. The model was validated on testing data from an experienced free-diver, from non-rebreathing trials of a sample of the participants, and from simulated dives of 5 participants from research in the Environmental Physiology Department of Karolinska in 1994 [1]. It has been suggested that the presented model can be a valuable tool in developing safer free diving practices. Furthermore, interesting trends in continuous HR, starting PACO2 values, and O2 consumption were observed and analyzed using statistical analysis. Findings were discussed with connection to the underlying physiological principles that might explain the results obtained.

  • 192.
    Antonsson, Jacob
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Motion Tracking Using a Permanent Magnet2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this project the possibility of using a network of magnetometers sensing a permanent magnet for tracking has been investigated. Both the orientation and the position of the magnet have been considered. A dipole approximation of the magnetic field is used to develop two models. One of the models parametrizes the orientation with the magnetic moment vector, while the other parametrizes the orientation with a unit quaternion. An extended Kalman filter have been used to estimate position and orientation.

    Several calibration algorithms have been developed to calibrate for sensor errors, differences in sensor coordinate frame orientations and also for the estimation of the magnetic moment norm of a permanent magnet. The models have been tested using an optical reference system for position and orientation estimation. Initial results are ambiguous and further testing is necessary. One conclusion is that the model using the magnetic moment vector as orientation parametrization is less sensitive to the accuracy of the initial guesses of the filter recursions and also less sensitive to possible model errors.

    A mathematical result of the possibility of using a non stationary sensor network to track the magnet is also given.

  • 193.
    Antonsson, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    On optical methods for intracerebral measurements during stereotactic and functional neurosurgery: Experimental studies2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Radio frequency (RF) lesioning and deep brain stimulation (DBS) are the two prevailing surgical treatments for movement disorders within the field of stereotactic and functional neurosurgery. For RF-lesioning, a small volume of brain tissue is coagulated and knowledge of the lesion size and growth is of great importance for the safety and outcome of the procedure. This thesis deals with adapting the laser Doppler perfusion monitoring (LDPM) technique for measurements in brain tissue during RF-lesioning. The relation between LDPM signal changes and developed lesion size was investigated. LDPM measurements were evaluated both in vitro (albumin protein solution) and in vivo in the porcine brain during RF-lesioning corresponding to a bilateral thalamotomy in man. The investigated signals from the LDPI measurements can be used for following the lesioning time course and to detect if a lesion was created, both in vitro and in the animal model. For the albumin model, both the total backscattered light intensity and the perfusion signal can be used as markers for estimating the final coagulation size, while in the animal model this conclusion was not statistical verified.

    Independent on surgical method, RF-lesioning or DBS, intracerebral guidance is an important aspect within stereotactic and functional neurosurgery. To increase the accuracy and precision of reaching the correct target, different methods for intracerebral guidance exist, such as microelectrode recording and impedance methods. In this thesis, the possibility of developing an optical intracerebral guidance method has been investigated. Diffuse reflectance spectroscopy served as technology and all measurements were performed stereotactically in both porcine and human brain. Measurements of white and gray matter showed large differences, with higher reflectivity for white brain matter, both in porcine and in human brain. For the human measurements during DBS-implants, large differences between white matter and functional targets were found. Additionally, differences between native and lesioned porcine brain matter were detected. Both studies support the idea of using diffuse reflectance spectroscopy for developing an intracerebral guidance method.

  • 194.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute.
    Hjälmdahl, Magnus
    Swedish National Road and Transport Research Institute.
    Evaluation of a sleepiness warning system: a test truck study2009Report (Other academic)
    Abstract [en]

    Sleep related crashes have received increasing attention over the past decade. Driver support systems that are able to detect sleepiness and warn the driver could be a potential countermeasure to reduce sleepiness related crashes. The aim of this study was to evaluate a warning system in an experimental investigation performed in a real time car driving application. An additional aim was also to examine the suitability of using an experimental vehicle at test track for evaluation of a sleepiness warning system. The modalities used for warning was a combination of sound, vibrations in belt and spoken messages. In addition a hand worn confirmation button was used. In total 40 participants drove at a closed test track during night (00h-05h). They were instructed to sleep between 01.00 and 07.00 for two nights prior to the night of the experiment. The design of the study was a between group, with 10 participants in each group. The four different groups experienced one of the following: A: No warning - baseline; B: SENSATION warning system with an early trigger; C: SENSATION warning system with a late trigger; D: Feedback (DMS - Siemens) and warning with a late trigger. The trigger of the warnings was based on observer registrations of the driver and driver behaviour. The drivers were instructed to drive a distance of 110 kilometres. The car was a Volvo 850, equipped with sensors in order to measure driving behaviour (lateral position, speed, steering wheel angle). As sleepiness indicators blink duration was used (mean and sd), measured with EOG. After the drive the participants answered a questionnaire. The experiment focused on comprehension, usability, effectiveness, and acceptance.

  • 195.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Advantages and disadvantages of different methods to evaluate sleepiness warning systems2009Report (Other academic)
    Abstract [en]

    This is a methodological paper with the aim to discuss pros and cons related to different tools and environments when evaluating the effect of warnings given to sleepy drivers. There is no simple answer to the question which platform is most suitable. It depends on the research question asked, and it is possible that different aspects of the problem should be approached with different methods. A driving simulator has clear advantages when high control and repeatability are paramount. A simulator can also be used when the driver has to be put into a potentially dangerous scenario. How ecologically valid the results obtained from a simulator in fact are depends very much on the fidelity of the simulator. A test track study is based on real driving and should have a higher degree of ecological validity. On the other hand, the test track most often consists of an unrealistic environment. For assessing the prevalence of drowsy driving in real traffic, and in order to investigate what drivers actually do when they receive a sleepiness warning, it is absolutely necessary to study their natural behaviour when they go about their daily routines. Here field operational tests or naturalistic driving studies are most suitable. A disadvantage is the lack of control.

  • 196. Anurag,
    et al.
    Moosavi, S. R.
    Rahmani, A. -M
    Westerlund, T.
    Yang, Geng
    KTH, School of Information and Communication Technology (ICT), Industrial and Medical Electronics.
    Liljeberg, P.
    Tenhunen, H.
    Pervasive health monitoring based on internet of things: Two case studies2015In: Proceedings of the 2014 4th International Conference on Wireless Mobile Communication and Healthcare - "Transforming Healthcare Through Innovations in Mobile and Wireless Technologies", MOBIHEALTH 2014, 2015, p. 275-278Conference paper (Refereed)
    Abstract [en]

    With the continuous evolution of wireless sensor networks and Internet of Things (IoT) various aspects of life will benefit. IoT based pervasive healthcare system has potential to provide error free medical data and alerting system in critical conditions with continuous monitoring. The system will minimize the need of dedicated medical personnel for patient monitoring and help the patients to lead a normal life besides providing them with high quality medical service. In this paper, we provide the implementation of IoT-based architectures for remote health monitoring based on two popular wireless technologies, Wi-Fi and ZigBee. We analyse the two architectures with the aim of identifying their pros and cons and discuss suitability of mentioned wireless communication technologies for different healthcare application domains.

  • 197. Apostolakis, A
    et al.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    KTH, School of Engineering Sciences (SCI).
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    A determination of the CP violation parameter η+- from the decay of strangeness-tagged neutral kaons1999In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 458, no 4, p. 545-552Article in journal (Refereed)
    Abstract [en]

    LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

  • 198.
    Apostolakis, A.
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Measurement of the energy dependence of the form factor f+ in K 0 e3 decay2000In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 473, no 1, p. 186-192Article in journal (Refereed)
    Abstract [en]

    Neutral-kaon decays to πeν were analysed to determine the q2 dependence of the K0e3 electroweak form factor f+. Based on 365612 events, this form factor was found to have a linear dependence on q2 with a slope λ+=0.0245±0.0012stat±0.0022syst.

  • 199.
    Arfaoui, Yousef K.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Evaluation of a new instrument for measuring segmented radial force of SE-stents implemented in the LGF2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Endovascular surgery is a relatively new, rapidly growing, clinical technique and research area. A new endovascular tool has been developed by Endovascular Development AB, the Liungman Guidewire Fixator (LGF) that secures the distal position of a guidewire. The design of the LGF resembles a nitinol (Nickel-Titanium) stent and exerts a radial force against the blood vessel wall. It is desirable to have a well-founded understanding of all the mechanical characteristics of the product from a medical technology safety perspective.

     

    There are different methods for uniformly measure the radial force of an object, i.e. where one single total radial force represents the entire object.

    This report investigates the possibility for segmented radial force measurement by the development of a new measuring instrument. A prototype of the measuring instrument has been produced to test if the proposed method can be implemented or not.

     

    The prototype has been designed, developed and constructed to measure the radial force of individual segments of the stent. The stent segments were created using iris diaphragms and their resistance to radial change were measured using strain gauges. The concept was to measure the radial force differences between each segment with respect to the diameter of the stent. The results show a large and high intensity variation of data due to the strain gauge application. The variation is due to disturbances and flaws in the manufacturing process. On the other hand, one can see that the values for the radial forces of the segments for them different LGFs provide reasonable magnitudes. Some experiments also presents results similar to previous experiments. However, at the same time, no statistically significant conclusion can be drawn. The concept and the theory should work if the errors are changed. In summary, the proposal is to further develop the prototype and complement the experiment using finite element analysis.

  • 200.
    Arganda-Carreras, Ignacio
    et al.
    Institute Jean Pierre Bourgin, France.
    Turaga, Srinivas C.
    Howard Hughes Medical Institute, VA USA.
    Berger, Daniel P.
    Harvard University, MA 02138 USA.
    Ciresan, Dan
    Scuola University of Profess Svizzera Italiana, Switzerland.
    Giusti, Alessandro
    Scuola University of Profess Svizzera Italiana, Switzerland.
    Gambardella, Luca M.
    Scuola University of Profess Svizzera Italiana, Switzerland.
    Schmidhuber, Juergen
    Scuola University of Profess Svizzera Italiana, Switzerland.
    Laptev, Dmitry
    ETH, Switzerland.
    Dwivedi, Sarvesh
    ETH, Switzerland.
    Buhmann, Joachim M.
    ETH, Switzerland.
    Liu, Ting
    University of Utah, UT USA.
    Seyedhosseini, Mojtaba
    University of Utah, UT USA.
    Tasdizen, Tolga
    University of Utah, UT USA.
    Kamentsky, Lee
    Broad Institute, MA USA.
    Burget, Radim
    Brno University of Technology, Czech Republic.
    Uher, Vaclav
    Brno University of Technology, Czech Republic.
    Tan, Xiao
    University of New S Wales, Australia.
    Sun, Changming
    CSIRO, Australia.
    Pham, Tuan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Bas, Erhan
    Howard Hughes Medical Institute, VA USA.
    Uzunbas, Mustafa G.
    Rutgers State University, NJ 08903 USA.
    Cardona, Albert
    Howard Hughes Medical Institute, VA USA.
    Schindelin, Johannes
    University of Wisconsin, WI USA.
    Sebastian Seung, H.
    Princeton University, NJ 08544 USA; Princeton University, NJ 08544 USA.
    Crowdsourcing the creation of image segmentation algorithms for connectomics2015In: Frontiers in Neuroanatomy, ISSN 1662-5129, E-ISSN 1662-5129, Vol. 9, no 142Article in journal (Refereed)
    Abstract [en]

    To stimulate progress in automating the reconstruction of neural circuits, we organized the first international challenge on 2D segmentation of electron microscopic (EM) images of the brain. Participants submitted boundary maps predicted for a test set of images, and were scored based on their agreement with a consensus of human expert annotations. The winning team had no prior experience with EM images, and employed a convolutional network. This "deep learning" approach has since become accepted as a standard for segmentation of FM images. The challenge has continued to accept submissions, and the best so far has resulted from cooperation between two teams. The challenge has probably saturated, as algorithms cannot progress beyond limits set by ambiguities inherent in 2D scoring and the size of the test dataset. Retrospective evaluation of the challenge scoring system reveals that it was not sufficiently robust to variations in the widths of neurite borders. We propose a solution to this problem, which should be useful for a future 3D segmentation challenge.

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