Can MR imaging of the prostate at 3.0-T with phased-array coil compete with a combined phased-array/endorectal coil approach at 1.5-T?

Purpose : As 3.0-T offers a higher SNR it was of interest to examine whether at 3.0-T using a phased-array coil alone a comparable depiction of the prostate could be achieved compared to imaging with a combined phased-array/endorectal coil at 1.5-T. Method and materials : 18 patients (mean 67.7±8.4 ys.) who had elevated PSA levels and histologically proven prostate cancer (T2/T3) underwent MR imaging at 3.0-T using a phased-array coil. 10 of these patients were also examined at 1.5-T using combined phased-array/endorectal coils. An imaging protocol was established at 3.0-T which included a transverse pelvic scan with a large field of view (in-plane resolution 1mm) and transverse and coronal sections of the prostate and surroundings with a small field of view (in-plane resolution 0.47–0.62mm). Pulse sequences employed included T2-weighted FSE sequences with 3mm/4mm (ETL=16) section thicknesses. Scan time per orientation was about 4min. The resulting MR images were evaluated by four independent readers who rated image quality according to depiction of anatomic detail and contrast with use of a rating scale which included the usual criteria: hypointensity and bulging of the prostate capsule, asymmetry of the neurovascular bundle, obliteration of the prostate-to-rectal angle, transcapsular tumor spread and infiltration of seminal vesicles Results : In general, T2-weighted MR images at 3.0-T showed a clear, artifact-free depiction of the prostate structure, the seminal vesicles, and the adjacent structures including rectum, bladder bottom, and neurovascular bundle. The pelvis was homogeneously displayed so that the pelvic lymph nodes were clearly visualized. These images compared favorably with those at 1.5-T which, nevertheless, also showed the well-known excellent diagnostic quality. While patients welcomed the non-use of an endorectal coil at 3.0-T, the diagnostic sensitivity and specificity was comparable to published values at 1.5-T. A significant advantage resulted from simplifying the preparation time (no placement of endorectal coil necessary) which helped to speed up the whole examination. Conclusion : The comparison revealed that well-resolved images of the prostate and pelvis can be achieved at 3.0-T that are comparable in diagnostic quality to the present gold standard at 1.5-T, but spare the patient the discomfort of an endorectal coil and save valuable time.