31P MR spectroscopic imaging of the human prostate at 7 T: T1 relaxation times, Nuclear Overhauser Effect, and spectral characterization. Issue 3 (26th March 2014)

• Record Type: Journal Article
• Authors: Lagemaat, Miriam W.; Maas, Marnix C.; Vos, Eline K.; Bitz, Andreas K.; Orzada, Stephan; Weiland, Elisabeth; van Uden, Mark J.; Kobus, Thiele; Heerschap, Arend; Scheenen, Tom W.J.
• Is Part Of: Magnetic resonance in medicine. Volume 73:Issue 3(2015:Mar.)
• Page Start: 909
• Page End: 920
• Publication Date: 2014-03-26
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25209
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25209-sec-0001" sec-type="section"> <title>Purpose</title> <p>Optimization of phosphorus (<sup>31</sup>P) MR spectroscopic imaging (MRSI) of the human prostate at 7 T by the evaluation of <italic>T<sub>1</sub></italic> relaxation times and the Nuclear Overhauser Effect (NOE) of phosphorus‐containing metabolites.</p> </sec> <sec id="mrm25209-sec-0002" sec-type="section"> <title>Methods</title> <p>Twelve patients with prostate cancer and one healthy volunteer were scanned on a 7 T whole‐body system using a <sup>31</sup>P endorectal coil combined with an eight‐channel <sup>1</sup>H body array coil. <italic>T<sub>1</sub></italic> relaxation times were measured using progressive saturation in a two‐dimensional localization sequence. <sup>31</sup>P MRSI was performed twice: once without NOE and once with NOE using low‐power continuous wave <sup>1</sup>H irradiation to determine NOE enhancements.</p> </sec> <sec id="mrm25209-sec-0003" sec-type="section"> <title>Results</title> <p> <italic>T<sub>1</sub></italic> relaxation times of <sup>31</sup>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 <sup>31</sup>P MR spectra showed two peaks in chemical shift range of inorganic phosphate.</p> </sec> <sec id="mrm25209-sec-0004" sec-type="section"> <title>Conclusion</title> <p>Knowledge of <italic>T<sub>1</sub></italic> relaxation times and NOE enhancements enables protocol optimization for <sup>31</sup>P MRSI of the prostate at 7 T. With a strongly reduced <sup>31</sup>P flip angle (≤ 45°), a <sup>31</sup>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. <bold>Magn Reson Med 73:909–920, 2015. © 2014 Wiley Periodicals, Inc.</bold></p> </sec> </abstract>