Iterative reconstruction of radially-sampled31 P bSSFP data using prior information from1 H MRI

• Published in: Magnetic resonance imaging 2016
• Main Authors: Rink, Kristian, Benkhedah, Nadia, Berger, Moritz C, Gnahm, Christine, Behl, Nicolas G.R, Lommen, Jonathan M, Stahl, Vanessa, Bachert, Peter, Ladd, Mark E, Nagel, Armin M
• Format: Article
• Language: English
• Subjects: Radiology
• ISSN: 0730-725X
• DOI: 10.1016/j.mri.2016.11.013

Abstract The purpose of this study is to improve direct phosphorus (31 P) MR imaging. Therefore, 3D density-adapted radially-sampled balanced steady-state free precession (bSSFP) sequences were developed and an iterative approach exploiting additional anatomical information from hydrogen (1 H) data was evaluated. Three healthy volunteers were examined at B0 = 7 T in order to obtain the spatial distribution of the phosphocreatine (PCr) intensities in the human calf muscle with a nominal isotropic resolution of 10 mm in an acquisition time of 10 min. Three different bSSFP gradient schemes were investigated. The highest signal-to-noise ratio (SNR) was obtained for a scheme with two point-reflected density-adapted gradients. Furthermore, the conventional reconstruction based on a gridding algorithm was compared to an iterative method using an1 H MRI constraint in terms of a segmented binary mask, which comprises prior knowledge. The parameters of the iterative approach were optimized and evaluated by simulations featuring31 P MRI parameters. Thereby, partial volume effects as well as Gibbs ringing artifacts could be reduced. In conclusion, the iterative reconstruction of31 P bSSFP data using an1 H MRI constraint is appropriate for investigating regions where sharp tissue boundaries occur and leads to images that represent the real PCr distributions better than conventionally reconstructed images.