MRI of prostate cancer at 1.5 and 3.0 T: comparison of image quality in tumor detection and staging.
OBJECTIVE
This prospective study was performed to compare the image quality, tumor delineation, and depiction of staging criteria on MRI of prostate cancer at 1.5 and 3.0 T.


METHODS
Twenty-four patients with prostate cancer underwent MRI at 1.5 T using the combined endorectal-body phased-array coil and at 3.0 T using the torso phased-array coil, among them 22 before undergoing radical prostatectomy. The prostate was imaged with T2-weighted sequences in axial and coronal orientations at both field strengths and, in addition, with an axial T1-weighted sequence at 1.5 T. Preoperative analysis of all MR images taken together was compared with the histologic findings to determine the accuracy of MRI for the local staging of prostate cancer. In a retroanalysis, the image quality, tumor delineation, and conspicuity of staging criteria were determined separately for both field strengths and compared. Statistical analysis was performed using Wilcoxon's and the McNemar tests.


RESULTS
In the preoperative analysis, MRI (at both 1.5 and 3.0 T) had an accuracy of 73% for the local staging of prostate cancer. The retroanalysis yielded significantly better results for 1.5-T MRI with the endorectal-body phased-array coil in terms of image quality (p < 0.001) and tumor delineation (p = 0.012) than for 3.0-T MRI with the torso phased-array coil. Analysis of the individual staging criteria for extracapsular disease did not reveal a superiority of either of the two field strengths in the depiction of any of the criteria.


CONCLUSIONS
Intraindividual comparison shows that image quality and delineation of prostate cancer at 1.5 T with the use of an endorectal coil in a pelvic phased-array is superior to the higher field strength of 3.0 T with a torso phased-array coil alone. As long as no endorectal coil is available for 3-T imaging, imaging at 1.5 T using the combined endorectal-body phased-array coil will continue to be the gold standard for prostate imaging.
Beyersdorff
Dirk
D
Department of Radiology, Charité, Universitätsmedizin Berlin, Schumannstrasse 20/21, Berlin 10117, Germany. dirk.beyersdorff@charite.de
Taymoorian
Kasra
K
Knösel
Thomas
T
Schnorr
Dietmar
D
Felix
Roland
R
Hamm
Bernd
B
Bruhn
Harald
H
D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
D017430:Prostate-Specific Antigen