Learning curve in multidetector CT coronary angiography (MDCT-CA).

PURPOSE: Coronary angiography using multidetector computed tomography (MDCT-CA) is a recent technique for the nonivasive study of coronary arteries. This study assessed the diagnostic accuracy of coronary artery stenosis evaluation obtained by three readers at different levels of training or at different points of the learning curve proposed by the international guidelines. MATERIALS AND METHODS: Three radiologists in training with different levels of experience in MDCT-CA scored 50 cases at various time points of the learning curve: baseline, 4 weeks, 8 weeks and 6 months. The trainee radiologists evaluated the degree of stenosis on each coronary segment, and overall accuracy was calculated on a per-segment, pervessel and per-patient basis. RESULTS: All readers improved analysis accuracy per segment (range, 73-90%); sensitivity reached 45% per segment, 84% per vessel and 93% per patient; specificity was 99% per segment and vessel and 98% per patient. Positive and negative predictive values increased to 94% and 92%, respectively. CONCLUSIONS: Although all readers improved in diagnostic performance with growing experience with MDCT-CA, a longer training period may be necessary to achieve adequate levels of expertise in MDCT-CA to be able to perform as independent readers.

Anomalous right coronary artery origin from pulmonary artery associated with aortic stenosis, mitral regurgitation, and Vieussens' arterial ring: a very rare association and case.

We report a very rare case of anomalous origin of the right coronary artery from the pulmonary artery associated with severe aortic stenosis, severe mitral regurgitation, and Vieussens' arterial ring (VAR). Diagnosis was made accidentally during preoperative coronary angiography and confirmed by multidetector computed tomography. Surgery was performed with aortic valve replacement, mitral valve annuloplasty, right coronary artery reimplantation into the ascending aorta, and VAR resection. .

Cardiac CT to assess the risk of coronary compression in patients evaluated for percutaneous pulmonary valve implantation.

BACKGROUND: Coronary compression (CC) is a life threatening complication that can occur during percutaneous pulmonary valve implantation (PPVI). We describe our experience using cardiac CT prior to PPVI to identify patients at high CC-risk due to a close relationship between the coronary arteries and pulmonary trunk (PT). METHODS: A retrospective evaluation of candidates for PPVI who underwent CT prior to the procedure was done. Measurements of PT were performed using double oblique reconstructed images, with special attention to the stenotic tract of the PT. The analysis of coronary arteries included detection of anomalies of origin and course and assessment of their relationship with the PT, measuring the minimum distance between the coronary artery and the intended site of the future percutaneous valve implantation. RESULTS: CT analysis was performed for 52 patients. Thirty patients underwent PPVI after CT and 22 didn't. In 6/22 cases the reason not to receive a PPVI was high CC-risk detected at CT. In 6 other patients CT detected an intermediate CC-risk but the test balloon performed during angiography prior to valve placement was safe and the patients successfully underwent the procedure. None of the patients deemed as no CC-risk at CT had CC during PPVI. CONCLUSION: CT can detect patients with high and intermediate CC-risk and therefore may identify which patients are unlikely to undergo successful PPVI and those who need a careful analysis with balloon testing. CT can also rule out CC-risk identifying those patients in which balloon inflation testing could be omitted.

Classification of hemodynamically significant stenoses from dynamic CT perfusion and CTA myocardial territories.

PURPOSE: Myocardial blood flow (MBF) obtained by dynamic CT perfusion (CTP) has been recently introduced to assess hemodynamic significance of coronary stenosis in coronary artery disease. The diagnostic performance of dynamic CTP MBF is limited due to subjective interpretation of MBF maps and MBF variations caused by physiological, methodological, and technical issues. In this paper, we introduce a novel method to quantify the hypoperfused volume (HPV) in myocardial territories derived from CT angiography (CTA) to overcome the limitations of current dynamic CTP MBF analysis methods. METHODS: The diagnostic performance of HPV in classifying significant stenoses was evaluated on 22 patients (57 vessels) that underwent CTA, CTP and invasive fractional flow reserve (FFR). FFR was used as the standard of reference to determine stenosis significance. The diagnostic performance was compared to that of the mean MBF computed in regions manually annotated by an expert (MA-MBF). HPV was derived by thresholding the MBF in myocardial territories constructed from CTA by locating the closest artery. Diagnostic performance was evaluated using leave-one-case out cross-validation. Inter-observer reproducibility was assessed by performing annotations of coronary seeds (HPV) and manual regions (MA-MBF) with two users. In addition, the influence of different parameter settings on the diagnostic performance of HPV was assessed. RESULTS: Leave-one-case out cross-validation showed that HPV has an accuracy of 72% (58-83%) with sensitivity of 72% (47-90%) and specificity of 72% (58-83%). The accuracy of MA-MBF was 70% (57-82%) with a sensitivity of 50% (26-74%) and a specificity of 79% (64-91%). The Spearman correlation and the kappa statistic was (ρ = 0.94, κ = 0.86) for HPV and (ρ = 0.72, κ = 0.82) for MA-MBF. The influence of parameter settings on HPV based diagnostic performance was not significant. CONCLUSIONS: The proposed HPV accurately classifies hemodynamically significant stenoses with a level of accuracy comparable to the mean MBF in regions annotated by an expert. HPV improves inter-observer reproducibility as compared to MA-MBF by providing a more objective criterion to associate the stenotic coronary with the supplied myocardial territory.