Incremental diagnostic value of regional myocardial blood flow quantification over relative perfusion imaging with generator-produced rubidium-82 PET.

BACKGROUND: Myocardial blood flow (MBF) can be measured with positron emission tomography (PET) and its quantification should provide diagnostic information beyond that obtained through standard visual analysis. However, this possibility has not been fully studied with PET and generator-produced rubidium-82 (8²Rb). We evaluated regional MBF in segments with and without ischemia using 8²Rb PET in patients with coronary artery disease (CAD). METHODS AND RESULTS: Rest and stress 8²Rb PET and coronary angiography were performed for 12 patients with CAD. Based on angiography and relative 8²Rb perfusion images, segments were classified into 4 groups (Group A: myocardial ischemia with >70% diameter stenosis; Group B: no ischemia with stenosis; Group C: no ischemia without stenosis; Group D: ischemia without stenosis). Rest MBF was similar among the 4 groups. Groups A and B showed reduced hyperemic MBF compared with Group C (P < 0.05 vs. Group C) [Group A (n=16) 1.28 ± 0.58 ml·min⁻¹·g⁻¹; Group B (n=11) 1.72 ± 0.64 ml·min⁻¹·g⁻¹; Group C (n=9) 2.60 ± 1.09 ml·min⁻¹·g⁻¹; Group D (n=2) 2.33 ml·min⁻¹·g⁻¹]. Coronary flow reserves were inversely correlated with percent diameter stenosis (r=0.76, P < 0.0001). CONCLUSIONS: Segments with ischemia and coronary stenosis had reduced hyperemic MBF. Segments with coronary stenosis without ischemia also had reduced hyperemic MBF compared with non-stenotic segments. MBF quantification using 8²Rb PET may provide additional diagnostic information.