Iterative reconstruction of radially-sampled 31P bSSFP data using prior information from 1H MRI.
The purpose of this study is to improve direct phosphorus (31P) 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 (1H) data was evaluated. Three healthy volunteers were examined at B0=7T in order to obtain the spatial distribution of the phosphocreatine (PCr) intensities in the human calf muscle with a nominal isotropic resolution of 10mm in an acquisition time of 10min. 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 an 1H 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 featuring 31P MRI parameters. Thereby, partial volume effects as well as Gibbs ringing artifacts could be reduced. In conclusion, the iterative reconstruction of 31P bSSFP data using an 1H 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.
['Rink|Kristian|K|', 'Benkhedah|Nadia|N|', 'Berger|Moritz C|MC|', 'Gnahm|Christine|C|', 'Behl|Nicolas G R|NG|', 'Lommen|Jonathan M|JM|', 'Stahl|Vanessa|V|', 'Bachert|Peter|P|', 'Ladd|Mark E|ME|', 'Nagel|Armin M|AM|']
D000328:Adult D000465:Algorithms D005260:Female D006801:Humans D007091:Image Processing, Computer-Assisted D021621:Imaging, Three-Dimensional D007866:Leg D008279:Magnetic Resonance Imaging D018482:Muscle, Skeletal D010725:Phosphocreatine D010761:Phosphorus Radioisotopes D011522:Protons D012016:Reference Values D059629:Signal-To-Noise Ratio
Iterative reconstruction Prior knowledge (31)P MRI High-energy phosphate metabolism Radially-sampled bSSFP