RACER‐GRASP: Respiratory‐weighted, aortic contrast enhancement‐guided and coil‐unstreaking golden‐angle radial sparse MRI. Issue 1 (28th November 2017)

• Record Type: Journal Article
• Authors: Feng, Li; Huang, Chenchan; Shanbhogue, Krishna; Sodickson, Daniel K; Chandarana, Hersh; Otazo, Ricardo
• Is Part Of: Magnetic resonance in medicine. Volume 80:Issue 1(2018)
• Page Start: 77
• Page End: 89
• Publication Date: 2017-11-28
• Subjects: RACER‐GRASP -- coil unstreaking -- radial imaging -- streaking artifact -- free breathing -- compressed sensing -- DCE‐MRI -- liver; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.27002
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: To develop and evaluate a novel dynamic contrast‐enhanced imaging technique called RACER‐GRASP (Respiratory‐weighted, Aortic Contrast Enhancement‐guided and coil‐unstReaking Golden‐angle RAdial Sparse Parallel) MRI that extends GRASP to include automatic contrast bolus timing, respiratory motion compensation, and coil‐weighted unstreaking for improved imaging performance in liver MRI. Methods: In RACER‐GRASP, aortic contrast enhancement (ACE) guided k‐space sorting and respiratory‐weighted sparse reconstruction are performed using aortic contrast enhancement and respiratory motion signals extracted directly from the acquired data. Coil unstreaking aims to weight multicoil k‐space according to streaking artifact level calculated for each individual coil during image reconstruction, so that coil elements containing a high level of streaking artifacts contribute less to the final results. Self‐calibrating GRAPPA operator gridding was applied as a pre‐reconstruction step to reduce computational burden in the subsequent iterative reconstruction. The RACER‐GRASP technique was compared with standard GRASP reconstruction in a group of healthy volunteers and patients referred for clinical liver MR examination. Results: Compared with standard GRASP, RACER‐GRASP significantly improved overall image quality (average score: 3.25 versus 3.85) and hepatic vessel sharpness/clarity (average score: 3.58 versus 4.0), and reduced residual streaking artifact level (average score: 3.23 versus 3.94) in different contrast phases. RACER‐GRASP also enabled automatic timing of the arterial phases. Conclusions: The aortic contrast enhancement–guided sorting, respiratory motion suppression and coil unstreaking introduced by RACER‐GRASP improve upon the imaging performance of standard GRASP for free‐breathing dynamic contrast‐enhanced MRI of the liver. Magn Reson Med 80:77–89, 2018. © 2017 International Society for Magnetic Resonance in Medicine.