To the Editor Moss et al 1 recently published a prospective, international, multicenter longitudinal cohort study of 704 patients with recent myocardial infarction (MI) that investigated whether coronary atherosclerotic plaque activity as assessed by 18 F-sodium fluoride positron emission tomography (PET) and coronary computed tomography (CT) angiography is associated with recurrent coronary events. Their findings suggest that coronary atherosclerotic plaque activity is not associated with cardiac death, nonfatal MI, or revascularization after a minimum 2-year follow-up period. This is a significant study with a large sample size that used a novel and promising marker to assess plaque activity.While this study demonstrates no effect of coronary atherosclerotic plaque activity on future coronary events, it is important to recognize the limitations of PET-CT in evaluating all aspects of plaque characteristics. 18 F-sodium fluoride PET-CT allows quantification of coronary microcalcifications to evaluate plaque activity; soft plaques lack visible calcification, which limits their detection by PET-CT, as they do not uptake radiotracers typically used in PET imaging. Soft plaque burden can be quantified via other measurement tools in different imaging modalities; for example, the SCOT-HEART study used low-attenuation plaque (LAP) as a measurement tool acquired by coronary CT angiography and found LAP plaque burden to be the strongest predictor of fatal or nonfatal MI. 2 LAP, characterized by its low density on coronary CT angiography, represents soft, lipid-rich plaques prone to rupture. Thus, not considering the additional effects of soft plaques should be stated as a limitation of PET-CT studies investigating coronary plaque progression.In addition to the evaluation of soft plaques with coronary CT angiography, the use of other PET-CT markers, eg, 18 Ffluorodeoxyglucose 68 Ga-DOTATATE, to visualize earlier stages of atherosclerosis, such as inflammation and macrophage activity, could provide additional resolution. 3,4 To fully gauge the primary end points of this study, it is important to use a variety of markers. In conclusion, the authors should be recognized for this significant and challenging study. Future research should strive to integrate multiple imaging modalities and comprehensively evaluate various plaque characteristics to improve risk prediction models and enhance patient care.