Cardiac computed tomography-derived coronary artery volume to myocardial mass

In the absence of disease impacting the coronary arteries or myocardium, there exists a linear relationship between vessel volume and myocardial mass to ensure balanced distribution of blood supply. This balance may be disturbed in diseases of either the coronary artery tree, the myocardium, or both. However, in contemporary evaluation the coronary artery anatomy and myocardium are assessed separately. Recently the coronary lumen volume to myocardial mass ratio (V/M), measured noninvasively using coronary computed tomography angiography (CTCA), has emerged as an integrated measure of myocardial blood supply and demand in vivo. This has the potential to yield new insights into diseases where this balance is altered, thus impacting clinical diagnoses and management.In this review, we outline the scientific methodology underpinning CTCA-derived measurement of V/M. We describe recent studies describing alterations in V/M across a range of cardiovascular conditions, including coronary artery disease, cardiomyopathies and coronary microvascular dysfunction. Lastly, we highlight areas of unmet research need and future directions, where V/M may further enhance our understanding of the pathophysiology of cardiovascular disease.     

Impact of scan quality on the diagnostic performance of CCTA,SPECT, and PET for diagnosing myocardial ischemia defined by fractional flow reserve

BackgroundScan quality can have a significant effect on the diagnostic performance of non-invasive imaging techniques. However, the extent of its influence has scarcely been investigated in a head-to-head manner.MethodsTwo-hundred and eight patients underwent CCTA, SPECT, and PET prior to invasive fractional flow reserve measurements. Scan quality was classified as either good, moderate, or poor.ResultsDistribution of good, moderate, and poor quality scans was; CCTA; 66%, 22%, 13%; SPECT; 52%, 38%, 9%; PET; 86%, 13%, 1%. Good quality CCTA scans possessed a higher specificity (75% vs. 31%, p = 0.001), positive predictive value (PPV, 71% vs. 51%, p = 0.050), and accuracy (80% vs. 60%, p = 0.009) compared to moderate quality scans, while sensitivity (94%) and negative predictive value (NPV, 88%) were similar to moderate and poor quality scans. Sensitivity (76%), NPV (84%), and accuracy (85%) of good quality SPECT scans was superior to those of moderate (41% p = 0.001, 56% p = 0.010, 70% p = 0.010) and poor quality (30% p = 0.003, 65% p = 0.069, 63% p = 0.038). Specificity (92%) and PPV (87%) of good quality SPECT scans did not differ from scans of diminished quality. Good quality PET scans exhibited high sensitivity (84%), specificity (86%), NPV (88%), PPV (81%) and accuracy (85%), which was comparable to scans of lesser quality. Good quality CCTA, SPECT, and PET scans demonstrated a similar diagnostic accuracy (p = 0.247).ConclusionDiagnostic performance of CCTA, and SPECT is hampered by scan quality, while the diagnostic value of PET is not affected. Good quality CCTA, SPECT, and PET scans possess a high diagnostic accuracy.     

Diagnostic concordance and discordance between angiography-based quantitative flow ratio and fractional flow reserve derived from computed tomography in complex coronary artery disease

BackgroundBoth quantitative flow ratio (QFR) and fractional flow reserve derived from computed tomography (FFR_CT) have shown significant correlations with invasive wire-based fractional flow reserve. However, the correlation between QFR and FFR_CT is not fully investigated in patients with complex coronary artery disease (CAD). The aim of this study is to investigate the correlation and agreement between QFR and FFR_CT in patients with de novo three-vessel disease and/or left main CAD.MethodsThis is a post-hoc sub-analysis of the international, multicenter, and randomized SYNTAX III REVOLUTION trial, in which both invasive coronary angiography and coronary computed tomography angiography were prospectively obtained prior to the heart team discussion. QFR was performed in an independent core laboratory and compared with FFR_CT analyzed by HeartFlow?. The correlation and agreement between QFR and FFR_CT were assessed per vessel. Furthermore, independent factors of diagnostic discordance between QFR and FFR_CT were evaluated.ResultsOut of 223 patients, 40 patients were excluded from this analysis due to the unavailability of FFR_CT and/or QFR, and a total of 469 vessels (183 patients) were analyzed. There was a strong correlation between QFR and FFR_CT (R ?= ?0.759; p ?< ?0.001), and the Bland-Altman analysis demonstrated a mean difference of ?0.005 and a standard deviation of 0.116. An independent predictor of diagnostic concordance between QFR and FFR_CT was the lesion location in right coronary artery (RCA) (odds ratio 0.395; 95% confidence interval 0.174–0.894; P ?= ?0.026).ConclusionIn patients with complex CAD, QFR and FFR_CT were strongly correlated. The location of the lesion in RCA was associated with the highest diagnostic concordance between QFR and FFR_CT.     

Optimized interpretation of fractional flow reserve derived from computed tomography: Comparison of three interpretation methods

BackgroundAn optimal system for interpreting fractional flow reserve (FFR) values derived from CT (FFRCT) is lacking. We sought to evaluate performance of three FFR_CT measurements in detecting ischemia by comparing them with invasive FFR.MethodsFor 73 vessels in 50 patients who underwent coronary CT angiography (CCTA) and FFR_CT analysis followed by invasive FFR, the greatest diameter stenosis on CCTA, FFR_CT difference between distal and proximal to the stenosis (ΔFFR_CT), FFR_CT 2 cm distal to the stenosis (lesion-specific FFR_CT), and the lowest FFR_CT in distal vessel tip were calculated. Significant obstruction (≥50% diameter stenosis) and ischemia (lesion-specific FFR_CT ≤0.80, the lowest FFR_CT ≤0.80, or ΔFFR_CT ≥0.12 based on the greatest Youden index) were compared with invasive FFR (≤0.80).ResultsForty (55%) vessels demonstrated ischemia during invasive FFR. On multivariable generalized estimating equations, ΔFFR_CT (odds ratio [OR] 10.2, p < 0.01) remained a predictor of ischemia over CCTA (OR 2.9), lesion-specific FFR_CT (OR 3.1), and the lowest FFR_CT (OR 0.9) (p > 0.05 for all). Area under the curve (AUC) of ΔFFR_CT (0.86) was higher than CCTA (0.66), lesion-specific FFR_CT (0.71), and the lowest FFR_CT (0.65) (p < 0.01 for all). Addition of each FFR_CT measure to CCTA showed improvement of AUC and significant net reclassification improvement (NRI): ΔFFR_CT (AUC 0.84, NRI 1.24); lesion-specific FFR_CT (AUC 0.77, NRI 0.83); and the lowest FFR_CT (AUC 0.76, NRI 0.59) (p < 0.01 for all).ConclusionsCompared with diameter stenosis, ΔFFR_CT, lesion-specific FFR_CT, and the lowest FFR_CT improved ischemia discrimination and reclassification, with ΔFFR_CT being superior in identifying and discriminating ischemia.     

Coronary volume to left ventricular mass ratio in patients with diabetes mellitus

BackgroundDiabetes mellitus is a major risk factor for coronary artery disease (CAD) and may provoke structural and functional changes in coronary vasculature. The coronary volume to left ventricular mass (V/M) ratio is a new anatomical parameter capable of revealing a potential physiological imbalance between coronary vasculature and myocardial mass. The aim of this study was to examine the V/M derived from coronary computed tomography angiography (CCTA) in patients with diabetes.MethodsPatients with clinically suspected CAD enrolled in the ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care) registry and known diabetic status were included. Coronary artery volume and left ventricular myocardial mass were analyzed from CCTA and the V/M ratio was calculated and compared between patients with and without diabetes.ResultsOf the 3053 patients (age 66 ?± ?10 years; 66% male) with known diabetic status, diabetes was present in 21.9%. Coronary volume was lower in patients with diabetes compared to those without diabetes (2850 ?± ?940 ?mm³ vs. 3040 ?± ?970 ?mm³, p ?< ?0.0001), whereas the myocardial mass was comparable between the 2 groups (122 ?± ?33 ?g vs. 122 ?± ?32 ?g, p ?= ?0.70). The V/M ratio was significantly lower in patients with diabetes (23.9 ?± ?6.8 ?mm³/g vs. 25.7 ?± ?7.5 ?mm³/g, p ?< ?0.0001). Among subjects with obstructive CAD (n ?= ?2191, 24.0% diabetics) and non-obstructive CAD (16.7% diabetics), the V/M ratio was significantly lower in patients with diabetes compared to those without (23.4 ?± ?6.7 ?mm³/g vs. 25.0 ?± ?7.3 ?mm³/g, p ?< ?0.0001 and 25.6 ?± ?6.9 ?mm³/g vs. 27.3 ?± ?7.6 ?mm³/g, respectively, p ?= ?0.006).ConclusionThe V/M ratio was significantly lower in patients with diabetes compared to non-diabetics, even after correcting for obstructive coronary stenosis. The clinical value of the reduced V/M ratio in diabetic patients needs further investigation.     

2019年度FFRCT研究进展

FFRCT自2013年提出后经过多年的发展现已在冠心病(CAD)诊疗中显示出重要的价值。随着CT技术及计算机算法的进步,FFRCT的诊断性能不断提高,临床适用人群也不再局限于稳定性冠心病病人。就2019年FFRCT的主要研究进展予以综述,包括如何提高成功率、探索最佳阈值以及最新临床应用。     

Ethnic differences in coronary anatomy,left ventricular mass and CT-derived fractional flow reserve

BackgroundStudies have observed higher incidence of cardiovascular mortality in South Asians (SA), and lower prevalence in East Asians (EA), compared with Caucasians. These observations are not entirely explained by ethnic differences in cardiovascular risk factors and mechanistic factors such as variations in cardiac anatomy and physiology may play a role. This study compared ethnic differences in CT-assessed left ventricular (LV) mass, coronary anatomy and non-invasive fractional flow reserve (FFRCT).MethodsThree-hundred symptomatic patients (age 59 ± 7.9, male 51%) underwent clinically-mandated CT-coronary-angiography (CTA) were matched for age, gender, BMI and diabetes (100 each ethnicity). Assessment of coronary stenosis, luminal dimensions and vessel dominance was performed by independent observers. LV mass, coronary luminal volume and FFRCT were quantified by blinded core-laboratory. A sub-analysis was performed on patients (n = 187) with normal/minimal disease (0–25% stenosis).ResultsStenosis severity was comparable across ethnic groups. EA demonstrated less left-dominant circulation (2%) compared with SA (8.2%) and Caucasians (10.1%). SA compared with EA and Caucasians demonstrated smallest indexed LV mass, coronary luminal volumes and dimensions. EA compared with Caucasians had comparable indexed LV mass, coronary luminal dimensions and highest luminal volumes. The latter was driven by higher prevalence of right-dominance including larger and longer right posterior left ventricular artery. FFR_CT in the left anterior descending artery (LAD) was lowest in SA (0.87) compared with EA (0.89; P = 0.009) and Caucasians (0.89; P < 0.001), with no difference in other vessels. All observed differences were consistent in patients with minimal disease.ConclusionThis single-centre study identified significant ethnic differences in CT-assessed LV mass, coronary anatomy and LAD FFR_CT. These hypotheses generating results may provide a mechanistic explanation for ethnic differences in cardiovascular outcomes and require validation in larger cohorts.     

Peri-coronary inflammation is associated with findings on coronary computed tomography angiography and fractional flow reserve

PurposePeri-coronary adipose tissue attenuation expressed by fat attenuation index (FAI) on coronary CT angiography (CCTA) reflects peri-coronary inflammation and is associated with cardiac mortality. We aimed to investigate the association between FAI and whole vessel and lesion plaque quantification on CCTA in stable patients with intermediate epicardial stenosis evaluated by fractional flow reserve (FFR).MethodsA total of 187 left anterior descending arteries (LAD) with intermediate stenosis who underwent FFR measurement and CCTA were studied. FAI was assessed by the crude analysis of the mean CT attenuation value of LAD on CCTA. Determinants of FAI and FFR were explored. Furthermore, the impact of combined baseline data, CCTA-derived lesion plaque assessment, whole vessel quantification, cardiac mass and FAI on discrimination efficacy for ischemia was evaluated as FFR used for a reference standard.ResultsThe mean FAI and the median FFR values were −73.0 and 0.77, respectively. Multivariate analysis revealed that male, CCTA-derived positive remodeling, lower minimum lumen area, higher target vessel total cardiac mass, and lower FFR were independent predictors of FAI. CCTA-derived two-dimensional and three-dimensional analysis and FAI were independently and significantly associated with FFR values. Net reclassification index and integrated discrimination improvement index were both significantly improved when FAI was added to the baseline model for lesions with FFR <0.75, but not for FFR≤0.80.ConclusionsFAI was associated with FFR, CCTA-derived two-dimensional and three-dimensional lumen and plaque quantification and cardiac mass in patients with intermediate lesions in LAD, indicating that comprehensive CTA assessment may provide risk-stratification.     

Trans-lesional fractional flow reserve gradient as derived from coronary CT improves patient management: ADVANCE registry

BackgroundThe role of change in fractional flow reserve derived from CT (FFR_CT) across coronary stenoses (ΔFFR_CT) in guiding downstream testing in patients with stable coronary artery disease (CAD) is unknown.ObjectivesTo investigate the incremental value of ΔFFR_CT in predicting early revascularization and improving efficiency of catheter laboratory utilization.MaterialsPatients with CAD on coronary CT angiography (CCTA) were enrolled in an international multicenter registry. Stenosis severity was assessed as per CAD-Reporting and Data System (CAD-RADS), and lesion-specific FFR_CT was measured 2 ?cm distal to stenosis. ΔFFR_CT was manually measured as the difference of FFR_CT across visible stenosis.ResultsOf 4730 patients (66 ?± ?10 years; 34% female), 42.7% underwent ICA and 24.7% underwent early revascularization. ΔFFR_CT remained an independent predictor for early revascularization (odds ratio per 0.05 increase [95% confidence interval], 1.31 [1.26–1.35]; p ?< ?0.001) after adjusting for risk factors, stenosis features, and lesion-specific FFR_CT. Among the 3 models (model 1: risk factors ?+ ?stenosis type and location ?+ ?CAD-RADS; model 2: model 1 ?+ ?FFR_CT; model 3: model 2 ?+ ?ΔFFR_CT), model 3 improved discrimination compared to model 2 (area under the curve, 0.87 [0.86–0.88] vs 0.85 [0.84–0.86]; p ?< ?0.001), with the greatest incremental value for FFR_CT 0.71–0.80. ΔFFR_CT of 0.13 was the optimal cut-off as determined by the Youden index. In patients with CAD-RADS ≥3 and lesion-specific FFR_CT ≤0.8, a diagnostic strategy incorporating ΔFFR_CT >0.13, would potentially reduce ICA by 32.2% (1638–1110, p ?< ?0.001) and improve the revascularization to ICA ratio from 65.2% to 73.1%.ConclusionsΔFFR_CT improves the discrimination of patients who underwent early revascularization compared to a standard diagnostic strategy of CCTA with FFR_CT, particularly for those with FFR_CT 0.71–0.80. ΔFFR_CT has the potential to aid decision-making for ICA referral and improve efficiency of catheter laboratory utilization.     

SPECT定量心肌血流及冠状动脉血流储备的研究进展

应用SPECT、单光子显像剂及示踪动力学技术能方便地定量心肌血流量（MBF）及冠状动脉血流储备（CFR）。特别是碲锌镉心脏专用SPECT的使用,能更快速、准确地获得定量结果。MBF、CFR的获得对冠心病诊断准确性的提高、患者的再分层及进一步预后评估具有重要意义,并且为冠状动脉微血管疾病的诊断提供客观依据。但是使用SPECT定量MBF及CFR仍存在一些不足之处尚待解决。笔者旨在对SPECT定量MBF及CFR的不同方法、初步应用结果及临床意义作一综述。     

Advanced computed tomographic anatomical and morphometric plaque analysis for prediction of fractional flow reserve in intermediate coronary lesions

Objective

To determine the application of advanced coronary computed tomography angiography (CCTA) plaque analysis for predicting invasive fractional flow reserve (FFR) in intermediate coronary lesions.

Methods

Sixty-one patients with 71 single intermediate coronary lesions (≥50–80% stenosis) on CCTA prospectively underwent coronary angiography and FFR. Advanced anatomical and morphometric plaque analysis was performed based on CCTA data set to determine optimal criteria for significant flow impairment. A significant stenosis was defined as FFR ≤ 0.80.

Results

FFR averaged 0.85 ± 0.09, and 19 lesions (27%) were functionally significant. FFR correlated with minimum lumen area (MLA) (r = 0.456, p < 0.001), minimum lumen diameter (MLD) (r = 0.326, p = 0.006), reference lumen diameter (RLD) (r = 0.245, p = 0.039), plaque burden (r = −0.313, p = 0.008), lumen area stenosis (r = −0.305, p = 0.01), lesion length (r = −0.692, p < 0.001), and plaque volume (r = −0.668, p < 0.001). There was no relationship between FFR and CCTA morphometric plaque parameters. By multivariate analysis the independent predictors of FFR were lesion length (beta = −0.581, p < 0.001), MLA (beta = 0.360, p = 0.041), and RLD (beta = −0.255, p = 0.036). The optimal cutoffs for lesion length, MLA, MLD, RLD, and lumen area stenosis were >18.5 mm, ≤3.0 mm², ≤2.1 mm, ≤3.2 mm, and >69%, respectively (max. sensitivity: 100% for MLA, max. specificity: 79% for lumen area stenosis).

Conclusions

CCTA predictors for FFR support the mathematical relationship between stenosis pressure drop and coronary flow. CCTA could prove to be a useful rule-out test for significant hemodynamic effects of intermediate coronary stenoses.     

FFR CT的技术原理、注意事项和结果解释

有创性血流储备分数（FFR）是评价冠状动脉血管生理功能的金标准。FFR_CT是基于冠状动脉CT血管成像的影像后处理技术,可用于评估特异性缺血病灶。大量证据支持FFR_CT有很高的诊断准确性,该技术正在从实验研究应用到临床人群。如何在日常临床工作中优化FFR_CT技术以实现病人利益最大化引起了广泛关注。总结FFR_CT的基本原理,对其注意事项和结果解读进行分析,以利于指导FFR_CT的临床应用。      

Physiologic evaluation of ischemia using cardiac CT: Current status of CT myocardial perfusion and CT fractional flow reserve

Cardiac CT, specifically coronary CT angiography (CTA), is an established technology which detects anatomically significant coronary artery disease with a high sensitivity and negative predictive value compared with invasive coronary angiography. However, the limited ability of CTA to determine the physiologic significance of intermediate coronary stenoses remains a shortcoming compared with other noninvasive methods such as single-photon emission CT, stress echocardiography, and stress cardiac magnetic resonance. Two methods have been investigated recently: (1) myocardial CT perfusion and (2) fractional flow reserve (FFR) computed from CT (FFRCT). Improving diagnostic accuracy by combining the anatomic aspects of coronary CTA with a physiologic assessment via CT perfusion or FFRCT may reduce the need for additional testing to evaluate for ischemia, reduce downstream costs and risks associated with an invasive procedure, and lead to improved patient outcomes. Given a rapidly expanding body of research in this field, this comparative review summarizes the present literature while contrasting the benefits, limitations, and future directions in myocardial CT perfusion and FFRCT imaging.     

Assessment of lesion-specific ischemia using fractional flow reserve (FFR) profiles derived from coronary computed tomography angiography (FFRCT) and invasive pressure measurements (FFRINV): Importance of the site of measurement and implications for patient referral for invasive coronary angiography and percutaneous coronary intervention

BackgroundFractional flow reserve (FFR)-derived from computed tomography angiography (CTA; FFRCT) and invasive FFR (FFRINV) are used to assess the need for invasive coronary angiography (ICA) and percutaneous coronary intervention (PCI). The optimal location for measuring FFR and the impact of measurement location have not been well defined.Methods930 patients (age 60.7 + 10 years, 59% male) were included in this study. Normal and diseased coronary arteries were classified into stenosis grades 0–4 in the left anterior descending artery (LAD, n = 518), left circumflex (LCX, n = 112) and right coronary artery (RCA, n = 585). FFRCT (n = 1215 arteries) and FFRINV (n = 26 LAD) profiles were developed by plotting FFR values (y-axis) versus site of measurement (x-axis: ostium, proximal, mid, distal segments). The best location to measure FFR was defined relative to the distal end of the stenosis. FFR ≤0.8 was considered positive for ischemia.ResultsIn normal and stenotic coronary arteries there are significant declines in FFRCT and FFRINV from the ostium to the distal vessel (p < 0.001), due to lesion-specific ischemia and to effects unrelated to the lesion. A reliable location (distal to the stenosis) is 10.5 mm [IQR 7.3–14.8 mm] for FFRCT and within 20–30 mm for FFRINV. Rates of positive FFR (from the distal vessel) reclassified to negative FFR (distal to the stenosis) are 61% (FFRCT) and 33% (FFRINV).ConclusionFFRCT and FFRINV values are influenced by stenosis severity and the site of measurement. FFR measurements from the distal vessel may over-estimate lesion-specific ischemia and result in unnecessary referrals for ICA and PCI.     

PET/CT冠状动脉血流储备测定在冠状动脉微血管性疾病中的研究进展

冠状动脉微血管性疾病（CMVD）是指在多种致病因素下,冠状动脉微血管结构和（或）功能异常所致的劳力性心绞痛或心肌缺血客观证据的临床综合征。CMVD在冠心病中仍有较高的发病率,部分CMVD预后不佳,对其进行早期诊断、预后评估和治疗干预均具有重要的临床意义。PET/CT定量分析能客观、准确地测量静息和负荷状态下冠状动脉血流灌注量,进而获得冠状动脉血流储备,有效地协助早期诊断CMVD,评估其预后和指导治疗。笔者就PET/CT血流储备测定在CMVD中的研究进展进行综述。     

SPECT myocardial perfusion versus fractional flow reserve for evaluation of functional ischemia: A meta analysis

Purpose

The present meta-analysis illustrates the accuracy of myocardial perfusion SPECT (MPS) to diagnose functional stenotic coronary artery disease (CAD) with fractional flow reserve (FFR) as standard reference.

Methods

All investigators screened and selected studies that compared MPS with FFR in symptomatic patients with suspected CAD. Patients and study characteristics were independently extracted by two investigators; differences were resolved by consensus.

Results

13 articles, including 1,017 patients, 699 vessels were included in the study. No significant publication bias was detected (P = 0.65). At the patient level, the summary sensitivity and specificity were 77% (95% confidence interval [CI], 70–83%) and 77% (95%CI, 67–84%) for MPS. Vessel-level pooled sensitivity was 66% (95%CI, 57–74%) and specificity was 81% (95%CI, 70–89%). The overall diagnostic performance of MPS was moderate. [The area under the summary receiver operating characteristic (sROC) curve was 0.83]. No study influenced the pooled results larger than 0.03.

Conclusions

The accuracy between FFR and MPS SPECT was moderate.     

Plaque volume,composition, and fraction versus ischemia and outcomes in patients with coronary artery disease

BackgroundThe various plaque components have been associated with ischemia and outcomes in patients with coronary artery disease (CAD). The main goal of this analysis was to test the hypothesis that, at patient level, the fraction of non-calcified plaque volume (PV) of total PV is associated with ischemia and outcomes in patients with CAD. This ratio could be a simple and clinically useful parameter, if predicting outcomes.MethodsConsecutive patients with suspected CAD undergoing coronary computed tomography angiography with selective positron emission tomography perfusion imaging were selected. Plaque components were quantitatively analyzed at patient level. The fraction of various plaque components were expressed as percentage of total PV and examined among patients with non-obstructive CAD, suspected stenosis with normal perfusion, and those with reduced myocardial perfusion. Clinical outcomes included all-cause mortality and myocardial infarction.ResultsIn total, 494 patients (age 63 ​± ​9 years, 55% male) were included. Total PV and all plaque components were significantly larger in patients with reduced myocardial perfusion compared to patients with normal perfusion and those with non-obstructive CAD. During follow-up 35 events occurred. Patients with any plaque component ​≥ ​median showed worse outcomes (log-rank p ​< ​0.001 for all). In addition, low-attenuation plaque ​≥ ​median was associated with worse outcomes independent of total PV (adjusted HR: 2.754, 95% CI: 1.022–7.0419, p ​= ​0.045). The fractions of the various plaque components were not associated with outcomes.ConclusionLarger total PV or any plaque component at patient level are associated with abnormal myocardial perfusion and adverse events. The various plaque components as fraction of total PV lack additional prognostic value.     

基于深度学习的FFRCT在可疑冠心病病人中的应用

目的 探讨基于深度学习的CT血流储备分数（FFR_CT）在可疑冠心病病人中应用的可行性,分析缺血性病变（FFR_CT≤0.80）的预测因素及对治疗决策的影响。方法 回顾性纳入因疑似冠心病行冠状动脉CT血管成像（CCTA）的病人292例,其中男187例,女105例,平均年龄（65.8±10.3）岁。利用CCTA影像将狭窄程度分为轻度 （≥25%且<50%）、中度（≥50%且<70%）和重度（≥70%且<99%）。采用基于深度学习的FFR_CT软件对病人的CCTA数据进行测量。根据FFR_CT数值范围将病人分为阳性组（FFR_CT≤0.80,102例）和阴性组（FFR_CT>0.80,190例）。2组病人的一般资料、CCTA上的血管特征及血运重建,以及基于FFR_CT与CCTA制定的治疗策略的比较采用Mann-Whitney U 检验、t检验及卡方检验。采用Logistic回归分析FFR_CT≤0.80的独立预测因素。结果 阳性组病人的年龄更大,男性更多,高血压、糖尿病和吸烟的比例均高于阴性组（均P<0.05）。阳性组较阴性组病人更多的表现为中重度狭窄（分别为80.4%和28.4%）,更多的病人行血运重建术（分别为56.8%和11.1%）,均P<0.05。74例病人（25.3%）基于FFR_CT的结果治疗决策发生改变。多因素Logsitic回归分析显示,高血压（OR=2.245）、糖尿病（OR=2.238）及中重度狭窄（OR=8.837）是FFR_CT≤0.80的独立预测因素（均P<0.05）。结论 基于深度学习的FFR_CT技术在可疑冠心病病人中的应用是可行的,高血压、糖尿病及中重度狭窄是FFR_CT≤0.80的独立预测因素,FFR_CT可能影响病人的治疗决策。     

Importance of measurement site on assessment of lesion-specific ischemia and diagnostic performance by coronary computed tomography Angiography-Derived Fractional Flow Reserve

BackgroundValues of fractional flow reserve (FFR_CT) by coronary computed tomography angiography (CTA) decline from the ostium to the terminal vessel, irrespective of stenosis severity. The purpose of this study is to determine if the site of measurement of FFR_CT impacts assessment of ischemia and its diagnostic performance relative to invasive FFR (FFR_INV).Methods1484 patients underwent FFR_CT; 1910 vessels were stratified by stenosis severity (normal; <25%, 25–50%, 50–70%, and >70% stenosis). The rates of positive FFR_CT (≤0.8) were determined by measuring FFR_CT from the terminal vessel and from distal-to-the-lesion. Reclassification rates from positive to negative FFR_CT were calculated. Diagnostic performance of FFR_CT relative to FFR_INV was evaluated in 182 vessels using linear regression, Bland Altman analysis, and receiver operating characteristic (ROC) curves.ResultsPositive FFR_CT was identified in 24.9% of vessels using terminal vessel FFR_CT and 10.1% using FFR_CT distal-to-the-lesion (p ?< ?0.001). FFR_CT obtained distal-to-the-lesion resulted in reclassification of 59.6% of positive terminal FFR_CT to negative FFR_CT. Relative to FFR_INV, there were improvements in specificity (50% to 86%, p ?< ?0.001), diagnostic accuracy (65% to 88%, p ?< ?0.001), positive predictive value (50% to 78%, p ?< ?0.001), and area-under-the-curve (AUC, 0.83 to 0.91, p ?< ?0.001) when FFR_CT was measured distal-to-the-lesion.ConclusionFFR_CT values from the terminal vessel should not be used to assess lesion-specific ischemia due to high rates of false positive results. FFR_CT measured distal-to-the-lesion improves the diagnostic performance of FFR_CT relative to FFR_INV, ensures that FFR_CT values are due to lesion-specific ischemia, and could reduce the rate of unnecessary invasive procedures.