Free-breathing variable flip angle balanced SSFP cardiac cine imaging with reduced SAR at 3T.

PURPOSE: To develop a free-breathing variable flip angle (VFA) balanced steady-state free precession (bSSFP) cardiac cine imaging technique with reduced specific absorption rate (SAR) at 3 Tesla. METHODS: Free-breathing VFA (FB-VFA) images in the short-axis and four-chamber views were acquired using an optimal VFA scheme, then compared with conventional breath-hold constant flip angle (BH-CFA) acquisitions. Two cardiac MRI experts used a 5-point scale to score images from healthy subjects (N = 10). The left ventricular ejection fraction, end diastolic volume (LVEDV), end systolic volume, stroke volume (LVSV), and end diastolic myocardial mass (LVEDM) were determined by manual contour analysis for BH-CFA and FB-VFA. A pilot evaluation of FB-VFA was performed in one patient with Duchenne muscular dystrophy. RESULTS: FB-VFA SAR was 25% lower than BH-CFA with similar blood-myocardium contrast. The qualitative FB-VFA score was lower than the BH-CFA for the short-axis (3.1 ± 0.5 versus 4.3 ± 0.8; P < 0.05) and the four-chamber view (3.4 ± 0.4 versus 4.6 ± 0.6; P < 0.05). The LVEDV and the LVSV were 5% and 12% larger (P < 0.05) for FB-VFA compared with BH-CFA. There was no difference in LVEDM. CONCLUSION: FB-VFA bSSFP cardiac cine imaging decreased the SAR at 3T with image quality sufficient to perform cardiac functional analysis. Magn Reson Med 76:1210-1216, 2016. © 2015 Wiley Periodicals, Inc.

High-spatial-resolution contrast-enhanced MR angiography of abdominal arteries with parallel acquisition at 3.0 T: initial experience in 32 patients.

OBJECTIVE: The objective of our study was to evaluate an isotropic high-spatial-resolution 3D contrast-enhanced MR angiography (CE-MRA) protocol with high acceleration parallel acquisition at 3.0 T for the display of the abdominal vasculature. SUBJECTS AND METHODS: Thirty-two consecutive patients (13 men, 19 women; age range, 28-88 years) with suspected abdominal arterial disease underwent abdominal 3D CE-MRA on a 3.0-T MR system, using a high-spatial-resolution (0.7 x 0.82 x 0.8 mm3) 3D gradient-refocused echo (GRE) sequence, integrated with a generalized autocalibrating partially parallel acquisitions (GRAPPA) technique with an acceleration factor of 3. Two vascular radiologists evaluated image quality and the presence and degree of arterial stenoses. Interobserver variability was calculated, using the kappa coefficient. The sensitivity and specificity of the technique were calculated and comparative analysis was performed with those of conventional catheter angiography (in eight patients) as the standard of reference. RESULTS: The abdominal arterial vasculature was visualized with diagnostic image quality in all subjects. Arterial stenoses were detected in 148 and 142 arterial segments by observer 1 and observer 2, respectively, with good interobserver agreement (kappa = 0.75; 95% confidence interval [CI]: 0.69-0.81). The sensitivity and specificity values for CE-MRA for the detection of significant (> 50%) arterial stenoses were 100% and 96% for observer 1 and 100% and 92% for observer 2, respectively. There was a significant correlation between CE-MRA and conventional angiography (R = 0.96 and 0.93 for observers 1 and 2, respectively) for the assessment of the degree of stenosis. CONCLUSION: The outlined MR angiography protocol at 3.0 T combined with parallel acquisition technique renders highly reliable and isotropic high-spatial-resolution imaging of the abdominal vasculature.