Investigation of the PSF-choice method for reduced lipid contamination in prostate MR spectroscopic imaging.
The purpose of this work was to evaluate a previously proposed approach that aims to improve the point spread function (PSF) of MR spectroscopic imaging (MRSI) to avoid corruption by lipid signal arising from neighboring voxels. Retrospective spatial filtering can be used to alter the PSF; however, this either reduces spatial resolution or requires extending the acquisition in k-space at the cost of increased imaging time. Alternatively, the method evaluated here, PSF-choice, can modify the PSF localization to reduce the contamination from adjacent lipids by conforming the signal response more closely to the desired MRSI voxel grid. This is done without increasing scan time or degrading SNR of important metabolites. PSF-choice achieves improvements in spatial localization through modifications to the radiofrequency excitation pulses. An implementation of this method is reported for MRSI of the prostate, where it is demonstrated that, in 13 of 16 pilot prostate MRSI scans, intravoxel spectral contamination from lipid was significantly reduced when using PSF-choice. Phantom studies were also performed that demonstrate, compared with MRSI with standard Fourier phase encoding, out-of-voxel signal contamination of spectra was significantly reduced in MRSI with PSF-choice.
Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA. panych@bwh.harvard.edu
Lawrence P
LP
Panych
Joseph R
JR
Roebuck
Nan-kuei
NK
Chen
Yi
Y
Tang
Bruno
B
Madore
Clare M
CM
Tempany
Robert V
RV
Mulkern
D000273:Adipose Tissue / Q000737:chemistry*; D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008055:Lipids / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D011471:Prostatic Neoplasms / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D008055:Lipids