{'fraction_non_alphanumeric': 0.0548756415317805, 'fraction_numerical': 0.04776944334780892, 'mean_word_length': 5.4974358974358974, 'pattern_counts': {'":': 0, '<': 3, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
[Effect of measurement sites on coronary computed tomography angiography-derived instantaneous wave-free ratio in the diagnosis of coronary stenosis ischemia].

Objective: To explore the influence of measurement sites on the diagnostic performance of coronary computed tomography angiography (CCTA) -derived instantaneous wave-free ratio (iFRCT) for coronary stenosis ischemia. Methods: A total of 44 patients, including 27 males and 17 females aged from 44 to 83 (59±90) years, who underwent coronary computed tomography angiography (CCTA) and invasive fractional flow reserve (FFR) in the Department of Radiology, Eastern Theater Command General Hospital from February 2009 to May 2018 were retrospectively collected. Based on CCTA images, iFRCT values at different locations (stenosis, proximal downstream of stenosis, 2 cm downstream of stenosis, 3 cm downstream of stenosis, and 4 cm downstream of stenosis) were calculated through fluid mechanics simulation. With invasive FFR≤0.80 as the reference standard, receiver operating characteristic (ROC) was used to analyze and evaluate the diagnostic performance of iFRCT in different sites. Bland-Altman and spearman correlation coefficient were used to analyze the consistency between iFRCT and invasive FFR. Intraclass correlation coefficient (ICC) and spearman correlation coefficient were used to test the repeatability of iFRCT. Results: iFRCT values at the proximal downstream of the stenosis (approximately 1 cm downstream of the stenosis) was superior to other measurement sites in the diagnosis of coronary ischemic specific stenosis. The threshold, area under the curve, sensitivity, specificity and accuracy of iFRCT at the stenosis were 0.91, 0.87 (95%CI:0.76~0.96), 82% (95%CI:48%~97%), 76% (95%CI:57%~88%) and 77% (95%CI: 63%~87%), respectively. Bland-Altman analysis showed that the mean differences between iFRCT and FFR at the proximal downstream of the stenosis was 0.07 (95%LoA: 0.06~0.09) and Spearman correlation coefficient was 0.53 (P<0.001). At the proximal downstream of the stenosis, the intraobserver ICC of iFRCT was 0.92 (95%CI: 0.85 ~0.95), the correlation coefficient was 0.85 (P<0.001); the interobserver ICC was 0.84 (95%CI: 0.60~0.94), correlation coefficient was 0.75 (P<0.001), demonstrating good repeatability between iFRCT and FFR. Conclusion: With the invasive FFR value as reference standard, iFRCT had a high diagnostic performance in detecting myocardial ischemia and the best measurement site was the proximal downstream of the stenosis.