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Background: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) plays a crucial role in the optimal treatment strategy for patients with coronary heart disease. We tested the feasibility of feature extraction from MPI using a deep convolutional autoencoder (CAE) model., Methods: Eight hundred and forty-three pairs of stress and rest myocardial perfusion images were collected from consecutive patients who underwent cardiac scintigraphy in our hospital between December 2019 and February 2022. We trained a CAE model to reproduce the input paired image data, so as the encoder to output a 256-dimensional feature vector. The extracted feature vectors were further dimensionally reduced via principal component analysis (PCA) for data visualization. Content-based image retrieval (CBIR) was performed based on the cosine similarity of the feature vectors between the query and reference images. The agreement of the radiologist's finding between the query and retrieved MPI was evaluated using binary accuracy, precision, recall, and F1-score., Results: A three-dimensional scatter plot with PCA revealed that feature vectors retained clinical information such as percent summed difference score, presence of ischemia, and the location of scar reported by radiologists. When CBIR was used as a similarity-based diagnostic tool, the binary accuracy was 81.0%., Conclusion: The results indicated the utility of unsupervised feature learning for CBIR in MPI., (© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.)

Background: This study evaluated corrected relative flow reserve (RFR) derived from 13 N-ammonia positron emission tomography (PET) combined with coronary computed tomography angiography (CTA)., Methods: We analyzed 61 patients who underwent coronary CTA, 13 N-ammonia PET, and invasive coronary angiography. Triple-vessel disease were excluded. Conventional RFRs were calculated as the ratio of hyperemic myocardial blood flow (hMBF) of hypoperfusion areas to those of non-ischemic lesions. Corrected RFRs were calculated using PET and coronary CTA to adjust coronary territories to their feeding vessels. Diagnostic performance was compared to detect obstructive coronary lesions., Results: Of the 180 vessels analyzed, 50 were diagnosed as obstructive lesions (≥ 70% stenosis and/or fractional flow reserve value ≤ 0.8). The coronary flow reserve (CFR), hMBF, conventional RFR, and corrected RFR of obstructive lesions were significantly lower than those of non-obstructive lesions. In receiver operating characteristic curve analysis, these quantitative PET measurements had area under the curve of 0.67, 0.71, 0.89, and 0.92, respectively. Diagnostic performance differences between corrected and conventional RFR were not statistically significant., Conclusion: In patients with single or double vessel disease, indices of RFR, with or without coronary angiographic guidance of the reference coronary territory, are better discriminators of flow-limiting stenoses than hMBF and CFR., (© 2019. American Society of Nuclear Cardiology.)

Background: This study aimed to evaluate the diagnostic performance of coronary flow reserve (CFR), hyperemic myocardial blood flow (hMBF), and CFR ratio for detecting significant coronary artery disease (CAD) on 13 N-ammonia positron emission tomography (PET).Methods and Results:We analyzed 63 patients (mean age, 71±9 years; 43 males) with suspected CAD who underwent both pharmacological stress/rest 13 N-ammonia PET and coronary angiography. CFR and hMBF for PET were calculated automatically using quantitative PET software, and the CFR ratio was defined as the ratio of per-vessel CFR to maximum CFR in a standard 17-segment model. We compared the diagnostic performance among the 3 quantitative values. In the per-vessel analysis, 55 vessels were diagnosed as significant CAD (≥70% stenosis and/or fraction flow reserve ≤0.8). CFR, hMBF, and CFR ratio of significant CAD were significantly lower than for non-significant CAD (1.85±0.69 vs. 2.38±0.69; P<0.01, 1.67±0.54 vs. 2.19±0.52 mL·min -1 ·g -1 ; P<0.01, and 0.66±0.15 vs. 0.82±0.09; P<0.01, respectively). In the receiver-operating characteristic curve analysis, CFR, hMBF, and CFR ratio had areas under the curve of 0.71, 0.75, and 0.85 respectively, and the CFR ratio was significantly higher than CFR and hMBF (P<0.05). The sensitivity, specificity, and accuracy of the CFR ratio with an optimal cutoff value of 0.75 were 75%, 85%, and 82%, respectively., Conclusions: Clinically, the CFR ratio in 13 N-ammonia PET was more effective in detecting significant CAD.

Aims: Several studies have demonstrated that type 2 diabetes mellitus (T2DM) is associated with accelerated atherosclerosis, which results in an increased risk of coronary vascular events. However, serial changes in plaque characteristics have not been reported in vivo. We evaluated the progression of coronary atherosclerosis in patients with T2DM using an integrated backscatter intravascular ultrasound (IB-IVUS) examination., Methods and Results: Forty-two T2DM and 48 non-diabetic patients who underwent percutaneous coronary intervention were enrolled in the study. Non-culprit 20-mm length coronary lesions with mild-to-moderate stenosis were measured using a 40-MHz (motorized pullback of 0.5 mm/s) IVUS catheter. IVUS examinations were performed on one target lesion in each patient. Six months later, a follow-up IVUS examination was repeated in the same coronary segment imaged at the baseline examination. T2DM patients demonstrated a greater total plaque volume (TPV; 139 ± 53 vs. 114 ± 45 mm(3), P = 0.02) and total lipid volume (TLV; 67 ± 26 vs. 55 ± 30 mm(3), P = 0.039) at the baseline examination. The progression of TPV (8.6 ± 15.4 vs. -2.2 ± 16.0%, P < 0.01) and TLV (10.8 ± 28.8 vs. -2.5 ± 20.0%, P < 0.05) from the baseline was observed in T2DM patients, but not in non-diabetic patients. The increase in TLV was blunted in T2DM patients who achieved HbA1c levels of <6.5%., Conclusion: Accelerated plaque progression with an increase in the lipid-rich component of non-culprit plaques was observed in T2DM, despite the use of standard medical treatment. Better glycaemic control ameliorated the worsening of plaque characteristics in T2DM.

Background: Population studies have shown that increased large artery stiffness is an independent predictor of cardiovascular events. Experimental studies have shown that a stiff aorta is associated with decreased coronary blood flow. However, a link between large artery stiffness and coronary microvascular function in the clinical setting has not been demonstrated previously., Objective: To evaluate the relationship between large artery stiffness and coronary flow velocity reserve (CFVR)., Patients and Methods: 102 consecutive subjects (mean (SD) age 62 (10) years) without coronary and peripheral arterial disease were enrolled in the study. After 15 minutes' rest, measurements were obtained of brachial-ankle pulse wave velocity (baPWV), augmentation index (AIx) from a carotid pulse tracing, and transthoracic echocardiographic measures, including coronary flow velocity in the left anterior descending coronary artery. In addition, coronary flow velocity during hyperaemia was measured during an intravenous infusion of adenosine triphosphate. CFVR was defined as the ratio of hyperaemic to basal coronary velocity., Results: Subjects with decreased CFVR (< 2.5; n = 40) had significantly higher baPWV (1848 (369) cm/s vs 1548 (333) cm/s; p<0.001), greater AIx (25.3 (11.0)% vs 16.3 (20.0)%; p = 0.01) and greater pulse pressure (PP) (64 (13) mm Hg vs 54 (13) mm Hg; p<0.001) than those with normal CFVR (> or = 2.5; n = 62). Multivariate analysis showed that AIx and PP were independent predictors of CFVR (r = -0.32, p<0.001 and -0.25, p = 0.02, respectively)., Conclusions: The data suggest that large artery stiffening is linked to a reduction of CFVR, which may partially explain the higher cardiac event rate in patients with increased large artery stiffness.

A 25-year-old man with low cardiac risks underwent coronary arteriography because of chest pain at rest. His only risk factors for coronary artery disease was smoking. Both right and left coronary arteries were ectatic and the left anterior descending artery was obstructed. In the acetylcholine provocation test, the left circumflex coronary artery showed severe constriction. Thus, this patient was diagnosed as having a combination of variant angina and occlusive coronary artery disease.