• Bart R Steensma, Mariska Luttje, Ingmar J Voogt, KlompDennis W JDWJUniversity Medical Center Utrecht, Department of Radiology, Utrecht, The Netherlands., Peter R Luijten, van den BergCornelis A TCATUniversity Medical Center Utrecht, Department of Radiotherapy, Utrecht, The Netherlands., and RaaijmakersAlexander J EAJEUniversity Medical Center Utrecht, Department of Radiology, Utrecht, The Netherlands.Eindhoven University of Technology, Department of Biomedical Engineering, Utrecht, The Netherlands..
• University Medical Center Utrecht, Department of Radiology, Utrecht, The Netherlands.
• J Magn Reson Imaging. 2019 May 1; 49 (5): 1446-1455.

BackgroundIn MRI, the signal-to-noise ratio (SNR) theoretically increases with B0 field strength. However, because of attenuation of the radiofrequency (RF) fields at 7T, it is not certain if this SNR gain can be realized for prostate imaging.Purpose/HypothesisTo investigate the SNR gain in prostate imaging at 7T as compared with 3T. It is expected that SNR will improve for prostate imaging at 7T compared with 3T.Study TypeProspective.SubjectsFour healthy volunteers and one prostate cancer patient.Field Strength/SequenceAll subjects were scanned at 3T and at 7T using optimal coil setups for both field strengths. For all volunteers, proton density-weighted images were acquired for SNR analysis and actual flip angle imaging (AFI) B 1 + | maps were acquired for correction of measured SNR values. In the patient, a T2 -weighted (T2 w) image was acquired at 3T and at 7T.AssessmentSNR was calculated in the prostate region for all volunteers. SNR was normalized for flip angle, receiver bandwidth, and voxel volume. SNR was also calculated for different sensitivity encoding (SENSE) acceleration factors.Statistical TestingSNR values are represented as the arithmetic mean of SNR values in the prostate. Estimated SNR in the T2 w image is calculated as the arithmetic mean of the signal intensity (SI) divided by the standard deviation of the SI in a specified zone. Tumor-to-tissue contrast is calculated as (SItumor +SIzone )/( SItumor -SIzone ).ResultsAn increase in SNR ranging from 1.7-fold to 2.8-fold was measured in the prostate at 7T in comparison to 3T for four volunteers. At 7T, it is possible to achieve a 4-fold SENSE acceleration in the left-right direction with similar SNR to a nonaccelerated 3T image. T2 w imaging was done at 3T and 7T in one patient, where improved tumor-to-tissue contrast was demonstrated at 7T.Data ConclusionSNR improves for prostate imaging at 7T as compared with 3T.Level Of Evidence2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1446-1455.© 2018 The Authors Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

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