Assessment of global right ventricular function on 64-MDCT compared with MRI.

OBJECTIVE: The aim of this study was to compare ECG-gated 64-MDCT with MRI for the assessment of global right ventricular (RV) function from coronary CT angiography data. SUBJECTS AND METHODS: Thirty-eight patients (25 men, 13 women; mean age +/- SD, 55.0 +/- 8.8 years) with suspected coronary artery disease underwent contrast-enhanced 64-MDCT (64 x 0.6 mm, 120 kV, 770 mAs(eff)) and 1.5-T MRI (balanced fast-field echo; TR/TE, 3.3/1.6; flip angle, 60 degrees ; 50 phases). Double oblique short-axis MDCT and MR images were used for further analysis. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were computed from manually drawn endocardial contours of the right ventricle. For statistical analysis, repeated-measures analysis of variance and Pearson's correlation coefficients were calculated. Bland-Altman plots were computed. RESULTS: In general, RV volumes calculated from 64-MDCT agreed well with those calculated from MRI. The mean EF (+/- SD) calculated from MDCT and MRI was 51.0% +/- 7.8% and 51.4% +/- 7.3%, respectively. An excellent correlation was observed for EDV (r = 0.99), ESV (r = 0.98), SV (r = 0.98), and EF (r = 0.97). Bland-Altman plots showed no systematic variation between MDCT and MRI data. No statistically significant differences (p < or = 0.05) between the techniques were found. CONCLUSION: Although contrast injection is optimized for visualization of the coronary arteries, retrospectively ECG-gated 64-MDCT permits reliable assessment of global RV function.

Accuracy of 64-row multidetector computed tomography in detecting coronary artery disease in 134 symptomatic patients: influence of calcification.

BACKGROUND: The new 64-row multidetector computed tomography (CT)-assisted angiography can now detect coronary artery disease with shorter breath-hold time and at faster heart rates for symptomatic patients. We aim to determine if the 64-row scanner can also overcome limitations due to mild to moderate calcification. METHODS: Scheduled for conventional coronary angiography, 134 symptomatic patients underwent multidetector CT-assisted angiography within 3 months. Patients were divided into those with low or high calcium score (median score 142) by modified Agatston formula: group A calcium score <142 Agatston score (68 patients, mean age 53 years, heart rate 62 beat/min) and group B calcium score > or = 142 Agatston score (66 patients, mean age 57 years, heart rate 62 beat/min). Eleven major coronary segments were evaluated. RESULTS: In group A, 93.6% of segments were evaluable with 97.3% correlation. Segment-by-segment analyses for sensitivity, specificity, and positive and negative predictive values were 85.4%, 98.1%, 76.7%, and 99.2%, respectively. For group B, 86.9% of segments were evaluable with 90.5% correlation. Sensitivity, specificity, and positive and negative predictive values were 79.9%, 92.8%, 78.8%, and 93.5%, respectively. CONCLUSIONS: The 64-slice multidetector CT coronary angiography can reliably detect the presence of significant coronary stenosis in symptomatic patients with mild calcification, but remains limited by moderate to heavy calcification.

Use of non-invasive phase contrast magnetic resonance imaging for estimation of atrial septal defect size and morphology: a comparison with transesophageal echo.

BACKGROUND: Transesophageal echocardiography (TEE) is a trusted method of sizing atrial septal defect (ASD) prior to percutaneous closure but is invasive, uncomfortable, and may carry a small risk of morbidity and mortality. Magnetic resonance imaging (MRI) may be useful non-invasive alternative in such patients who refuse or are unable to tolerate TEE and may provide additional information on the shape of the A0SD. PURPOSE: To validate the accuracy of ASD sizing by MRI compared with TEE. METHOD: Twelve patients (mean age 30 years; range 11-60 years) scheduled for ASD closure underwent TEE, cine balanced fast field echo MRI (bFFE-MRI) in four-chamber and sagittal views and phase-contrast MRI (PC-MRI) with reconstruction using the two orthogonal planes of T2-weighted images as planning. The average of the three longest measurements for all imaging modalities was calculated for each patient. RESULTS: Mean maximum ASD length on TEE was 18.8 +/- 4.6 mm, mean length by bFFE-MRI was 20.0 +/- 5.0 mm, and mean length by PC-MRI was 18.3 +/- 3.6 mm. The TEE measurement was significantly correlated with the bFFE-MRI and PC-MRI measurements (Pearson r = 0.69, p = 0.02 and r = 0.59, p = 0.04, respectively). The mean difference between TEE and bFFE-MRI measurements was -1.2mm (95% CI: -3.7, 1.3) and between TEE and PC-MRI was 0.5 mm (95% CI: -1.9, 2.9). Bland-Altman analysis also determined general agreement between both MRI methods and TEE. The ASDs were egg-shaped in two cases, circular in 1 patient and oval in the remaining patients. CONCLUSION: ASD sizing by MRI using bFFE and phase-contrast protocols correlated well with TEE estimations. PC-MRI provided additional information on ASD shapes and proximity to adjacent structures.

Vessel density ratio: A novel approach to identify "culprit" coronary lesion by spiral computed tomography.

BACKGROUND AND OBJECTIVE: We hypothesized that a "culprit" lesion in acute coronary syndrome (ACS) should have low overall vessel lumen and plaque density on multidetector computed tomography-assisted coronary angiography (MDCTA) because of lower calcification and the presence of occlusive thrombus. However, thrombi and calcification both can themselves blur the demarcation between vessel wall and lumen. If we calculated a "vessel density ratio" (VDR) obtained by measuring the mean density of contrast-enhancement within a region of interest (ROI), which includes the vessel wall, lumen, plaque, and thrombus, and comparing that with the aortic root mean density acting as a reference point, this ratio may be more convenient, standardized, and reproducible to test the feasibility of VDR in identifying "culprit" lesions in ACS. METHODS: Sixty-four patients-21 exertional angina; 17 unstable angina/non-ST elevation myocardial infarction (NSTEMI); 26 ST elevation myocardial infarction (STEMI)-provided 188 diseased segments on conventional angiography. All underwent MDCTA within a week of angiography. ROI was mapped out from maximum intensity projections of diseased segments in planar view. RESULTS: One hundred seventy-four segments were evaluated. Patients who presented with ACS (STEMI and unstable angina/non-ST elevation myocardial infarction) had lower mean VDR compared to patients with exertional angina (0.58 vs. 0.66 vs. 0.81; P < 0.001). Culprit lesions in ACS patients also had the lowest mean VDR when compared to nonculprit lesions and lesions in patients without ACS (0.51 vs. 0.68 vs. 0.81; P < 0.001). CONCLUSIONS: VDR is a new, convenient, and standardized approach in identifying "culprit" lesions by MDCTA.