Diffusion-weighted magnetic resonance imaging (DW-MRI) noninvasively detects significant prostate tumors with a high probability and without contrast medium or an endorectal coil, according to a new study.

Lauren J. Bains, MD, and colleagues at the University of Bern in Switzerland prospectively studied 111 men with prostate and/or bladder cancer who underwent DW-MRI of the pelvis without an endorectal coi prior to radical prostatectomy (78 patients) or cystoprostatectomy (33 patients). based on qualitative imaging analysis, 3 independent readers blinded to clinical and pathologic data assigned a prostate cancer (PCa) suspicion grade. 

The final pathology served as the reference standard. “For study purposes only the largest tumor focus of the prostate (index lesion) was considered since it is postulated by some investigators to dictate PCa prognosis,” the researchers noted.

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Of the 111 men, 93 had PCa, which was significant in 80 cases and insignificant in 13, the investigators reported in The Journal of Urology (2014;192:737-742). The researchers defined significant PCa as any tumor with a 1 cm or greater diameter, extraprostatic extension, or a Gleason score of 7 or greater. The sensitivity and specificity of DW-MRI for detecting significant PCa was 89%–91% and 77%–81%, respectively, for the 3 readers. The median reading time was 13–18 minutes, with good interreader agreement.

“With all of these advantages DW-MRI has the potential to rapidly disseminate into clinical practice for PCa management,” the authors concluded.

It may improve patient stratification for individualized treatment options, such as by discriminating tumors requiring curative treatment from those that may benefit from expectant management, Dr. Bain’s group noted.

“To our knowledge no other study has focused on detecting significant disease based on final pathology results of entire prostates with and without preoperatively known PCa,” the authors wrote. “This design decreases the risk of reading bias common to previous studies, in which readers were aware that the study population consisted of only patients with proven PCa.”