Increased volume of coverage for abdominal contrast‐enhanced MR angiography with two‐dimensional autocalibrating parallel imaging: Initial experience at 3.0 Tesla

Abstract

Purpose: To assess the feasibility and the quality of abdominal three-dimensional (3D) contrast enhanced MR angiograms acquired at 3.0 Tesla (T) using a new 2D-accelerated autocalibrating parallel reconstruction method for Cartesian sampling (2D-ARC). Materials and Methods:With institutional review board approval and written informed consent, a prospective trial in 6 normal healthy volunteers and 23 patients referred for evaluation of suspected renovascular disease was performed. The volunteers underwent abdominal MRA with and without 2D-ARC acceleration. Images were evaluated independently by two blinded vascular radiologists in randomized order. Vessel conspicuity was rated on a fivepoint scale. Evaluation for significant differences between the scores for each technique was performed using a Wilcoxon signed-rank test.Results: In the series of six volunteers, no statistical significance was found between the image quality scores for 2D-ARC accelerated and nonaccelerated exams. A high proportion of the 23 clinical 2D-ARC exams were graded as diagnostic (vessel conspicuity score !2; Reader 1, 96%; Reader 2, 100%) for overall image quality.Conclusion: Subjective image quality of 2D-ARC accelerated MRA was equivalent to the conventional MRA method. However, the 2D-ARC accelerated sequence provided a 3.5-fold increase in imaging volume, complete abdominal coverage, and a 30% reduction in voxel volume, all within the same acquisition time.

High resolution navigated three‐dimensional T1‐weighted hepatobiliary MRI using gadoxetic acid optimized for 1.5 tesla

“…The navigated sequence described in this work has been implemented with an autocalibrating parallel imaging reconstruction technique, known as autocalibrating reconstruction for Cartesian acquisition (ARC), that is capable of 2D acceleration using a full 3D kernel in k -space (31,32) with effective accelerations up to 3.75 easily achievable using an 8 channel coil (32). In this work, we chose not to use parallel imaging, both to maintain high SNR performance and also to facilitate valid SNR measurements, which are known to be difficult when parallel imaging methods are used (33).…”

Renal Arteries: Isotropic, High-Spatial-Resolution, Unenhanced MR Angiography with Three-dimensional Radial Phase Contrast

“…Zero fi lling was used to interpolate resolution to 0.75 mm 2 , providing spatial resolution comparable to that of state-of-the-art renal contrast-enhanced MR angiography at 3.0 T ( 18 ). Twodimensional autocalibrating reconstruction for cartesian sampling parallel imaging was performed with the identical eight-element phased-array coil and acceleration in both section and phase directions ( 19 ), with a net acceleration factor of 3.75. The imaging duration was 30 seconds.…”

Sparse Reconstruction Techniques in Magnetic Resonance Imaging

“…Techniques including the family of parallel imaging reconstruction methods 1–4 have been successful in reducing clinical MRI scan times by factors of two or four, or even higher in some applications 5–8 . These acceleration techniques have also been used to improve image quality or reduce artifacts while maintaining scan time 9,10 . However, the scan time reduction with parallel imaging is limited, and other ways of reconstructing images from undersampled data have been explored, including sparse reconstruction methods such as compressed sensing 11–28 .…”