Perfusable tissue index (PTI) is a marker of myocardial viability and requires acquisition of transmission, ¹⁵O-CO, and ¹⁵O-H₂O scans. The aim of this study was to generate parametric PTI images from a ¹⁵O-H₂O PET/CT scan without an additional ¹⁵O-CO scan.

Methods:

Data from 20 patients undergoing both ¹⁵O-H₂O and ¹⁵O-CO scans were used, assessing correlation between PTI based on ¹⁵O-CO (PTI_CO) and on fitted blood volume fractions (PTI_Vb). In addition, parametric PTI_Vb images of 10 patients undergoing ¹⁵O-H₂O PET/CT scans were generated using basis-function methods and compared with PTI_Vb obtained using nonlinear regression. Simulations were performed to study the effects of noise on PTI_Vb.

Results:

Correlation between PTI_CO and PTI_Vb was high (r² = 0.73). Parametric PTI_Vb correlated well with PTI_Vb obtained using nonlinear regression (r² = 0.91). Simulations showed low sensitivity to noise (coefficient of variation < 10% at 20% noise).

Conclusion:

Parametric PTI images can be generated from a single ¹⁵O-H₂O PET/CT scan.