Diagnostic Accuracy of Electrocardiogram-Gated Thoracic Computed Tomography Angiography without Heart Rate Control for Detection of Significant Coronary Artery Stenosis in Patients with Acute Ischemic Stroke: A Comparative Study

OBJECTIVE: To compare the diagnostic performance of electrocardiogram (ECG)-gated thoracic computed tomography angiography (TCTA) without heart rate (HR) control in ischemic stroke patients with coronary CTA (CCTA) in non-stroke patients for detection of significant coronary artery stenosis. MATERIALS AND METHODS: From September 2009 through August 2014, we retrospectively enrolled 138 consecutive patients diagnosed with acute ischemic stroke who had undergone ECG-gated TCTA and conventional coronary angiography (CCA). Over the same period, we selected 167 non-stroke patients with suspected or known coronary artery disease who had undergone CCTA and CCA. With CCA as the reference standard, the diagnostic performance of TCTA and CCTA for identification of significant coronary stenosis (diameter reduction ≥ 50%) was calculated. RESULTS: There was no significant difference in baseline characteristics between TCTA (n = 132) and CCTA (n = 164), except for the higher prevalence of atrial fibrillation in the stroke group. There was significant difference (p < 0.001) between TCTA and CCTA in average HR (68 ± 12 vs. 61 ± 10 beats per minute) and image quality score (1.3 ± 0.6 vs. 1.2 ± 0.6). Significant coronary stenosis was identified in 101 (77%) patients, 179 (45%) vessels, and 293 (15%) segments of stroke patients, and in 136 (83%) patients, 259 (53%) vessels, and 404 (16%) segments of non-stroke patients. Diagnostic performance on a per-vessel and per-patient basis was similar in both TCTA and CCTA groups. There was only significant difference in area under receiver-operating characteristic curve between TCTA and CCTA groups (0.79 vs. 0.87, p < 0.001) on per-segment basis. CONCLUSION: Electrocardiogram-gated TCTA without HR control facilitates the identification of significant coronary stenosis in patients with ischemic stroke.

Virtual Non-Contrast CT Using Dual-Energy Spectral CT: Feasibility of Coronary Artery Calcium Scoring

OBJECTIVE: To evaluate the feasibility of coronary artery calcium scoring based on three virtual noncontrast-enhanced (VNC) images derived from single-source spectral dual-energy CT (DECT) as compared with true noncontrast-enhanced (TNC) images. MATERIALS AND METHODS: This prospective study was conducted with the approval of our Institutional Review Board. Ninety-seven patients underwent noncontrast CT followed by contrast-enhanced chest CT using single-source spectral DECT. Iodine eliminated VNC images were reconstructed using two kinds of 2-material decomposition algorithms (material density iodine-water pair [MDW], material density iodine-calcium pair [MDC]) and a material suppressed algorithm (material suppressed iodine [MSI]). Two readers independently quantified calcium on VNC and TNC images. The Spearman correlation coefficient test and Bland-Altman method were used for statistical analyses. RESULTS: Coronary artery calcium scores from all three VNC images showed excellent correlation with those from the TNC images (Spearman's correlation coefficient [ρ] = 0.94, 0.88, and 0.89 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Measured coronary calcium volumes from VNC images also correlated well with those from TNC images (ρ = 0.92, 0.87, and 0.91 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Among the three VNC images, coronary calcium from MDW correlated best with that from TNC. The coronary artery calcium scores and volumes were significantly lower from the VNC images than from the TNC images (p < 0.001 for all pairs). CONCLUSION: The use of VNC images from contrast-enhanced CT using dual-energy material decomposition/suppression is feasible for coronary calcium scoring. The absolute value from VNC tends to be smaller than that from TNC.

Morphological and Functional Evaluation of Quadricuspid Aortic Valves Using Cardiac Computed Tomography

OBJECTIVE: The aim of this study was to identify the morphological and functional characteristics of quadricuspid aortic valves (QAV) on cardiac computed tomography (CCT). MATERIALS AND METHODS: We retrospectively enrolled 11 patients with QAV. All patients underwent CCT and transthoracic echocardiography (TTE), and 7 patients underwent cardiovascular magnetic resonance (CMR). The presence and classification of QAV assessed by CCT was compared with that of TTE and intraoperative findings. The regurgitant orifice area (ROA) measured by CCT was compared with severity of aortic regurgitation (AR) by TTE and the regurgitant fraction (RF) by CMR. RESULTS: All of the patients had AR; 9 had pure AR, 1 had combined aortic stenosis and regurgitation, and 1 had combined subaortic stenosis and regurgitation. Two patients had a subaortic fibrotic membrane and 1 of them showed a subaortic stenosis. One QAV was misdiagnosed as tricuspid aortic valve on TTE. In accordance with the Hurwitz and Robert's classification, consensus was reached on the QAV classification between the CCT and TTE findings in 7 of 10 patients. The patients were classified as type A (n = 1), type B (n = 3), type C (n = 1), type D (n = 4), and type F (n = 2) on CCT. A very high correlation existed between ROA by CCT and RF by CMR (r = 0.99) but a good correlation existed between ROA by CCT and regurgitant severity by TTE (r = 0.62). CONCLUSION: Cardiac computed tomography provides comprehensive anatomical and functional information about the QAV.