However, the conventional hybrid PET-CT imaging did not improve the diagnostic accuracy of PET-measured MBF because MBF was quantified in a specific whole vascular territory instead of at a specific lesion location (vessel-specific MBF).11) In conventional hybrid PET-CT imaging, hyperemic MBF was evenly distributed throughout the whole territory irrespective of the lesion location. Therefore, only minor changes were observed after territory reassignment, and a whole-territory-based per-vessel approach may have diluted the significance of coronary stenosis. In contrast, lesion-specific hybrid PET-CT imaging can reveal real changes in hyperemic MBF and MFR based on the specific lesion. In this issue of the journal, Cho et al.12) reported the investigation of a more specific correlation of lesion location (proximal, middle, distal, or other small branches) using hybrid PET/CT imaging for improved assessment of the diagnostic accuracy of MBF parameters of anatomically significant left anterior descending (LAD) artery stenoses. Hyperemic MBF, resting MBF, and MFR were compared between LAD arteries with and without significant stenosis (≥ 70% reference diameter) in this study, and this lesion-specific measurement of myocardial perfusion using hybrid PET-CT imaging improved the diagnostic accuracy of PET-measured hyperemic MBF and MFR. The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were 71%, 68%, 74%, 65%, and 70%, respectively, for conventional hyperemic MBF (optimal cutoff = 2.15 mL/min/g), 79%, 63%, 74%, 65%, and 70%, respectively, for conventional MFR (optimal cutoff = 1.82), 83%, 74%, 80%, 78%, and 80%, respectively, for lesion-specific hyperemic MBF (optimal cutoff = 1.75 mL/min/g), and 79%, 79%, 83%, 75%, and 79%, respectively, for lesion-specific MFR (optimal cutoff = 1.86). The lesion-specific territory was confined to the LAD artery (The left main stem, left circumflex, and right coronary artery have substantial floating segments, which do not directly correlate with certain myocardial areas.), and only a few patients were included in this study. However, authors of this study attempted to overcome the limitation of conventional PET-CT imaging, and this method could play a role in the evaluation of both the myocardial status and coronary stenosis in patients with CAD. Furthermore, this method can reduce downstream investigations, such as invasive coronary angiography and changes in the treatment plan, because of a more accurate assessment of the hemodynamic state in coronary stenoses. However, the relatively high radiation dose was a major limitation of this study compared to cardiac magnetic resonance imaging without radiation exposure. In the future, advanced studies on the whole coronary artery lesion-specific MBF measured using PET-CT with decreasing radiation doses are warranted.