Introducing their recent study, Freitag et al. 1 state that ''two questions remain unanswered for quantitative 82Rb-PET: (1) which are the normal values of sMBF and rMBF? And (2) which quantitative parameter is the most accurate to allow for a precise diagnosis of CAD (sMBF or myocardial flow reserve [MFR])?''To get an answer, they performed a study of 357 patients that underwent 82Rb-PET/CT and integrated coronary CT angiography (CCTA). Based on the finding in CCTA, the patients were classified as (a) normal (no stenosis, N = 153), (b) with non-obstructive coronary artery disease (CAD) (\ 50%, N = 99), and (c) with obstructive CAD (C 50%, N = 105). Not surprisingly, the global stress myocardial blood flow (sMBF) (and myocardial flow reserve, MFR) were higher 3.61 ± 0.71 mLÁminÁg (3.08 ± 0.84) in normal patients than in patients with obstructive CAD 3.04 ± 0.77 mLÁminÁg (2.68 ± 0.79). Yet they turned out to be not different compared to patients with nonobstructive CAD (3.43 ± 0.69 mLÁminÁg and 2.99 ± 0.82). Also, sMBF was more accurate than MFR in identifying both ischemia and severe ischemia. The authors conclude that the provided ''normal quantitative values''-3.5 mLÁgÁmin-which they called the ''optimal threshold,'' can help rule out myocardial ischemia. Also, they suggest that a resting scan could be omitted in patients with sMBF values.We will not hover over the question of favoring sMBF over MFR: the same has been shown for 15O-Reprint requests: