Absolute Resting 13N-Ammonia PET Myocardial Blood Flow for Predicting Myocardial Viability and Recovery of Ventricular Function after Coronary Artery Bypass Grafting

Assessment of resting myocardial blood flow in regions of known transmural scar to confirm accuracy and precision of 3D cardiac positron emission tomography

“…%RU was lower in ROI-scar versus Seg-Scar: 43% [40–45] versus 46% [42–49], p < 0.001. As a metric of accuracy and upward bias, the upper limit threshold of rMBF in Seg-Scar was 0.44 mL/min/g which is the maximum 1SD above the mean of rMBF within TMS as has been established in the literature for a segment of TMS [ 2 , 6 , 8 , 12 ]. When ROI-Scar was analyzed, all 60 scans returned rMBF lower than 0.39 mL/min/g.…”

“…Third, rMBF within the scar (by definition) should be lower than living viable tissue. Various studies authored by Beanlands et al, Benz et al, Wang et al, and Zhang et al determined viability rMBF “thresholds” of 0.45, 0.45, 0.42, and 0.42 mL/min/g, respectively [ 2 , 10 , 12 , 33 ]. Below these thresholds, non-viable, dead myocardial scar must be present.…”

Evolving use of PET viability imaging

“…In this issue of the Journal of Nuclear Cardiology, Wang et al 15 report the diagnostic accuracy of resting myocardial blood flow (MBF) measured with dynamic 13 N-ammonia PET for identifying myocardial regions as viable and for predicting echocardiographic improvement of LV ejection fraction (C 8%) following coronary artery bypass grafting in 93 patients with CAD. Using 17 segment perfusion/metabolism ( 18 FDG) polar maps, segments were classified as normal, viable (mismatch or reverse mismatch) or scar (match).…”

Left ventricular strain analysis by positron emission tomography: Beyond myocardial perfusion

“…8 Absolute quantification of resting MBF with the use of 13 Nammonia PET has proved to be valuable in distinguishing hibernating and stunned viable myocardium from infarcted myocardium and to provide complementary practical value to regional myocardial wall thickening as assessed by CMR. 9,10 Combining peak systolic longitudinal strain with the additional information relative to post-systolic deformation provides the most informative deformation parameters to predict the transmural extent of necrosis in the early and late phases of myocardial infarction. It is worth to note that postsystolic strain, which is generally considered a marker of viability, may occur also in myocardium with transmural necrosis or scar.…”