Background

There has been increasing interest in quantitative myocardial blood flow (MBF) imaging over the last years and it is expected to become a routinely used technique in clinical practice. Positron emission tomography (PET) using [¹⁵O]H₂O is the established gold standard for quantification of MBF in vivo. A fundamental issue when performing quantitative MBF imaging is to define the limits of MBF in a clinically suitable population. The aims of the present study were to determine the limits of MBF and to determine the relationship among coronary artery disease (CAD) risk factors, gender and MBF in a predominantly symptomatic patient cohort without significant CAD.

Methods

A total of 128 patients (mean age 54 ± 10 years, 50 men) with a low to intermediate pretest likelihood of CAD were referred for noninvasive evaluation of CAD using a hybrid PET/computed tomography (PET/CT) scanner. MBF was quantified with [¹⁵O]H₂O at rest and during adenosine-induced hyperaemia. Obstructive CAD was excluded in these patients by means of invasive or CT-based coronary angiography.

Results

Global average baseline MBF values were 0.91 ± 0.34 and 1.09 ± 0.30  ml·min⁻¹·g⁻¹ (range 0.54–2.35  and 0.59–2.75 ml·min⁻¹·g⁻¹) in men and women, respectively (p < 0.01). However, no gender-dependent difference in baseline MBF was seen following correction for rate–pressure product (0.98 ± 0.45 and 1.09 ± 0.30 ml·min⁻¹·g⁻¹ in men and women, respectively; p = 0.08). Global average hyperaemic MBF values were 3.44 ± 1.20 ml·min⁻¹·g⁻¹ in the whole study population, and 2.90 ± 0.85 and 3.78 ± 1.27 ml·min⁻¹·g⁻¹ (range 1.52–5.22 and 1.72–8.15 ml·min⁻¹·g⁻¹) in men and women, respectively (p < 0.001). Multivariate analysis identified male gender, age and body mass index as having an independently negative impact on hyperaemic MBF.

Conclusion

Gender, age and body mass index substantially influence reference values and should be corrected for when interpreting hyperaemic MBF values.