title: Iterative reconstruction of radially-sampled31P bSSFP data using prior information from1H MRI.
abstract: 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 an1H 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 featuring31P MRI parameters. Thereby, partial volume effects as well as Gibbs ringing artifacts could be reduced. In conclusion, the iterative reconstruction of31P bSSFP data using an1H 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.
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany. Electronic address: k.rink@dkfz.de.
authors.forename: Kristian
authors.initials: K
authors.lastname: Rink
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Nadia
authors.initials: N
authors.lastname: Benkhedah
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Moritz C
authors.initials: MC
authors.lastname: Berger
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Gnahm
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Nicolas G R
authors.initials: NG
authors.lastname: Behl
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Lommen
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Stahl
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Bachert
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
authors.affiliation: Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Radiology, University Hospital Erlangen, Erlangen, Germany.
authors.forename: Armin M
authors.initials: AM
authors.lastname: Nagel
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007866:Leg / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D011522:Protons; D012016:Reference Values; D059629:Signal-To-Noise Ratio
chemical_list: D010761:Phosphorus Radioisotopes; D011522:Protons; D010725:Phosphocreatine
keywords: (31)P MRI;; High-energy phosphate metabolism; Iterative reconstruction; Prior knowledge; Radially-sampled bSSFP