Objective: To investigate the incidence of microvascular myocardial ischemia in diabetic patients without obstructive coronary artery disease (CAD) and its relationship with angina. Materials and Methods: Diabetic patients and an intermediate-to-high pretest probability of CAD were prospectively enrolled. Non-diabetic patients but with an intermediate-to-high pretest probability of CAD were retrospectively included as controls. The patients underwent dynamic computed tomography-myocardial perfusion imaging (CT-MPI) and coronary computed tomography angiography (CCTA) to quantify coronary stenosis, myocardial blood flow (MBF), and extracellular volume (ECV). The proportion of patients with microvascular myocardial ischemia, defined as any myocardial segment with a mean MBF ≤ of 100 mL/min/100 mL, in patients without obstructive CAD (Coronary Artery Disease–Reporting and Data System [CAD-RADS] grade 0–2 on CCTA) was determined. Various quantitative parameters of the patients with and without diabetes without obstructive CAD were compared. Multivariable analysis was used to determine the association between microvascular myocardial ischemia and angina symptoms in diabetic patients without obstructive CAD. Results: One hundred and fifty-two diabetic patients (mean age: 59.7 ± 10.7; 77 males) and 266 non-diabetic patients (62.0 ± 12.3; 167 males) were enrolled; CCTA revealed 113 and 155 patients without obstructive CAD, respectively. For patients without obstructive CAD, the mean global MBF was significantly lower for those with diabetes than for those without (152.8 mL/min/100 mL vs. 170.4 mL/min/100 mL, P < 0.001). The mean ECV was significantly higher for diabetic patients (27.2% vs. 25.8%, P = 0.009). Among the patients without obstructive CAD, the incidence of microvascular myocardial ischemia (36.3% [41/113] vs. 10.3% [16/155], P < 0.001) and interstitial fibrosis (69.9% [79/113] vs. 33.3% [8/24], P = 0.001) were significantly higher in diabetic patients than in the controls. The presence of microvascular myocardial ischemia was independently associated with angina symptoms (adjusted odds ratio = 3.439, P = 0.037) in diabetic patients but without obstructive CAD. Conclusion Dynamic CT-MPI + CCTA revealed a high incidence of microvascular myocardial ischemia in diabetic patients without obstructive CAD. Microvascular myocardial ischemia is strongly associated with angina.

Objective:To investigate the diagnostic performance of CT-derived fractional flow reserve (CT-FFR) derived from standard images (STD), images processed by first-generation (SSF1) and second-generation (SSF2) whole-heart motion correction algorithm, respectively.Methods:Patients who underwent both coronary CT angiography (CCTA) and invasive coronary angiography (ICA) with FFR examination within 3 months in Shanghai General Hospital, Shanghai Jiao Tong Univerisity School of Medicine from January 2020 to December 2022 were screened in this retrospective study. Totally of 121 patients (134 lesions) were finally included in the study. CCTA images were reconstructed using iterative reconstruction, iterative reconstruction plus SSF1 and SSF2 algorithms. All images were divided into three groups: STD group, SSF1 group, and SSF2 group. The image quality of the CCTA images was assessed using the Likert scale, and differences between the two groups were compared using the Mann-Whitney U and Kruskal-Wallis test. The correlation and consistency between CT-FFR and FFR were evaluated using Spearman correlation coefficient and Bland-Altman plots. The diagnostic performance of CCTA and CT-FFR from three groups was compared by receiver operating characteristic (ROC) curves. The area under the curve (AUC) was compared using the DeLong test. Results:Compared to the STD group and SSF1 group, the SSF2 group showed the best performance in image quality score (median=3.7). Best correlation ( r=0.652, P<0.001) and consistency (mean difference=0.03) between CT-FFR and FFR were observed in SSF2 group. ROC analysis results revealed that, at the per-lesion level, in the diagnosis of ischemic lesions, the diagnostic performance of CT-FFR in the SSF2 group was significantly better than that of the SSF1 group (AUC=0.88 vs. 0.76, P=0.003), while no significant difference was observed between STD group and SSF1 group ( P=0.125). At the per-patient level, the SSF2 group also demonstrated the highest diagnostic performance. Conclusion:The SSF2 algorithm significantly improved CCTA image quality and enhanced its diagnostic performance for evaluating stenosis severity and CT-FFR calculations.