(31) P MR spectroscopic imaging of the human prostate at 7 T: T1 relaxation times, Nuclear Overhauser Effect, and spectral characterization.

Abstract

PURPOSE:

Optimization of phosphorus ((31) P) MR spectroscopic imaging (MRSI) of the human prostate at 7 T by the evaluation of T1 relaxation times and the Nuclear Overhauser Effect (NOE) of phosphorus-containing metabolites.

METHODS:

Twelve patients with prostate cancer and one healthy volunteer were scanned on a 7 T whole-body system using a (31) P endorectal coil combined with an eight-channel (1) H body array coil. T1 relaxation times were measured using progressive saturation in a two-dimensional localization sequence. (31) P MRSI was performed twice: once without NOE and once with NOE using low-power continuous wave (1) H irradiation to determine NOE enhancements.

RESULTS:

T1 relaxation times of (31) P metabolites in the human prostate at 7 T varied between 3.0 and 8.3 s. Positive but variable NOE enhancements were measured for most metabolites. Remarkably, the (31) P MR spectra showed two peaks in chemical shift range of inorganic phosphate.

CONCLUSION:

Knowledge of T1 relaxation times and NOE enhancements enables protocol optimization for (31) P MRSI of the prostate at 7 T. With a strongly reduced (31) P flip angle (≤ 45°), a (31) P MRSI dataset with optimal signal-to-noise ratio per unit time can be obtained within 15 minutes. The NOE enhancement can improve fitting accuracy, but its variability requires further investigation.

• Authors: Miriam W Lagemaat, Marnix C Maas, Eline K Vos, Andreas K Bitz, Stephan Orzada, Elisabeth Weiland, Mark J van Uden, Thiele Kobus, Arend Heerschap, Tom W J Scheenen
• Journal: Magnetic resonance in medicine (Magn Reson Med) Vol. 73 Issue 3 Pg. 909-20 (Mar 2015) ISSN: 1522-2594 [Electronic] United States
• PMID: 24677408 (Publication Type: Journal Article)
• Copyright: © 2014 Wiley Periodicals, Inc.

Chemical References

• Phosphorus Compounds
• Phosphorus Isotopes
• Radiopharmaceuticals

Topics

• Aged
• Algorithms
• Humans
• Imaging, Three-Dimensional (methods)
• Magnetic Resonance Spectroscopy (methods)
• Male
• Middle Aged
• Molecular Imaging (methods)
• Phosphorus Compounds (metabolism)
• Phosphorus Isotopes (pharmacokinetics)
• Prostate
• Prostatic Neoplasms (metabolism, pathology)
• Radiopharmaceuticals (pharmacokinetics)
• Reproducibility of Results
• Sensitivity and Specificity
• Tissue Distribution