In vivo 31P MR spectroscopic imaging of the human prostate at 7 T: safety and feasibility

  • 31P MR spectroscopic imaging of the human prostate provides information about phosphorylated metabolites that could be used for prostate cancer characterization. The sensitivity of a magnetic field strength of 7 T might enable 3D 31P MR spectroscopic imaging with relevant spatial resolution in a clinically acceptable measurement time. To this end, a 31P endorectal coil was developed and combined with an eight-channel 1H body-array coil to relate metabolic information to anatomical location. An extensive safety validation was performed to evaluate the specific absorption rate, the radiofrequency field distribution, and the temperature distribution of both coils. This validation consisted of detailed Finite Integration Technique simulations, confirmed by MR thermometry and Burn:x-wiley:07403194:media:MRM24175:tex2gif-stack-1 measurements in a phantom and in vivo temperature measurements. The safety studies demonstrated that the presence of the 31P endorectal coil had no influence on the specific absorption rate levels and temperature distribution of the external eight-channel 1H array coil. To stay within a 10 g averaged local specific absorption rate of 10 W/kg, a maximum time-averaged input power of 33 W for the 1H array coil was allowed. For transmitting with the 31P endorectal coil, our safety limit of less than 1°C temperature increase in vivo during a 15-min MR spectroscopic imaging experiment was reached at a time-averaged input power of 1.9 W. With this power setting, a second in vivo measurement was performed on a healthy volunteer. Using adiabatic excitation, 3D 31P MR spectroscopic imaging produced spectra from the entire prostate in 18 min with a spatial resolution of 4 cm3. The spectral resolution enabled the separate detection of phosphocholine, phosphoethanolamine, inorganic phosphate, and other metabolites that could play an important role in the characterization of prostate cancer.

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Metadaten
Author:Thiele Kobus, Andreas Bitz, Mark J. van Uden, Miram W. Lagemaat, Eva Rothgang, Stephan Orzada, Arend Heerschap, Tom W. J. Scheenen
DOI:https://doi.org/10.1002/mrm.24175
ISSN:1522-2594
Parent Title (English):Magnetic Resonance in Medicine
Publisher:Wiley-Liss
Place of publication:New York
Document Type:Article
Language:English
Year of Completion:2012
Volume:68
Issue:6
First Page:1683
Last Page:1695
Link:https://doi.org/10.1002/mrm.24175
Zugriffsart:campus
Institutes:FH Aachen / Fachbereich Elektrotechnik und Informationstechnik
collections:Verlag / Wiley-Liss