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Background Visual and histogram-based assessments of coronary CT angiography have limited accuracy in the identification of advanced lesions. Radiomics-based machine learning (ML) could provide a more accurate tool. Purpose To compare the diagnostic performance of radiomics-based ML with that of visual and histogram-based assessment of ex vivo coronary CT angiography cross sections to identify advanced atherosclerotic lesions defined with histologic examination. Materials and Methods In this prospective study, 21 coronary arteries from seven hearts obtained from male donors (mean age, 52.3 years ± 5.3) were imaged ex vivo with coronary CT angiography between February 23, 2009, and July 31, 2010. From 95 coronary plaques, 611 histologic cross sections were coregistered with coronary CT cross sections. Lesions were considered advanced if early fibroatheroma, late fibroatheroma, or thin-cap atheroma was present. CT cross sections were classified as showing homogeneous, heterogeneous, or napkin-ring sign plaques on the basis of visual assessment. The area of low attenuation (

PURPOSE: To assess concordance and relative prognostic utility between central core laboratory and local site interpretation for significant coronary artery disease (CAD) and cardiovascular events. MATERIALS AND METHODS: In the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) trial, readers at 193 North American sites interpreted coronary computed tomographic (CT) angiography as part of the clinical evaluation of stable chest pain. Readers at a central core laboratory also interpreted CT angiography blinded to clinical data, site interpretation, and outcomes. Significant CAD was defined as stenosis greater than or equal to 50%; cardiovascular events were defined as a composite of cardiovascular death or myocardial infarction. RESULTS: In 4347 patients (51.8% women; mean age ± standard deviation, 60.4 years ± 8.2), core laboratory and site interpretations were discordant in 16% (683 of 4347), most commonly because of a finding of significant CAD by site but not by core laboratory interpretation (80%, 544 of 683). Overall, core laboratory interpretation resulted in 41% fewer patients being reported as having significant CAD (14%, 595 of 4347 vs 23%, 1000 of 4347; P < .001). Over a median follow-up period of 25 months, 1.3% (57 of 4347) sustained myocardial infarction or cardiovascular death. The C statistic for future myocardial infarction or cardiovascular death was 0.61 (95% confidence interval [CI]: 0.54, 0.68) for the core laboratory and 0.63 (95% CI: 0.56, 0.70) for the sites. CONCLUSION: Compared with interpretation by readers at 193 North American sites, standardized core laboratory interpretation classified 41% fewer patients as having significant CAD. (©) RSNA, 2017 Online supplemental material is available for this article. Clinical trial registration no. NCT01174550.

To determine the time course of enhancement patterns in the aorta and endoleaks at dynamic computed tomographic (CT) angiography as well as their effect on the endoleak detection rate in patients who have undergone abdominal aortic endovascular aneurysm repair (EVAR).This retrospective study was approved by the local ethics committee and compliant with the Declaration of Helsinki. All patients gave written informed consent for the scientific analysis of their data. Seventy-one patients (mean age, 72 years ± 8 [standard deviation]) were retrospectively included after EVAR of the abdominal aorta. All patients underwent dynamic CT angiography with 10 unidirectional scan phases, followed by a venous phase. Endoleaks were detected visually in all scan phases; the magnitude of enhancement was assessed by using region-of-interest measurements in the aorta and the detectable endoleaks. Statistical analysis was performed with the χ(2) test, the paired t test, and analysis of variance with repeated measurements.The highest mean aortic enhancement was achieved 12 seconds after the bolus-tracking threshold, and the highest mean endoleak enhancement was achieved 22 seconds after the bolus-tracking threshold. In total, 44 endoleaks were detected. The detection rates differed significantly in between the dynamic CT angiography phases (minimum, seven endoleaks at 2 seconds after the bolus-tracking threshold; maximum, 44 endoleaks at 27 seconds after the bolus-tracking threshold; P = .001). The highest detection rate was achieved when the contrast between aortic and endoleak enhancement reached its maximum.Dynamic CT angiography revealed that the peak enhancement of endoleaks is significantly different than that of the aorta and that endoleaks may not be adequately evaluated with conventional biphasic CT protocols. The use of dynamic CT angiography is associated with a significantly increased detection rate of endoleaks compared with the detection rates at the time points of conventional biphasic CT.