Inapparent tumor on endorectal multimodality magnetic resonance imaging of prostate: should we perform a biopsy?

To examine whether one could spare patients with a clinical suspicion of prostate cancer (PCa) but inapparent tumor on multimodality endorectal magnetic resonance imaging (e-MRI) of the prostate from undergoing prostate biopsy.

A total of 109 patients with a clinical suspicion of PCa underwent conventional and functional e-MRI of the prostate and subsequently prostate biopsy. The inclusion criteria were prostate-specific antigen level>4 ng/mL or a suspicious finding on digital rectal examination. The images were interpreted by a highly experienced radiologist and were considered negative for PCa in all cases. Regardless of the negative findings, all patients underwent an 18-core prostate biopsy. Functional e-MRI included contrast-enhanced e-MRI and diffusion-weighted imaging. The examinations were performed on a closed 1.0-T system combined with an endorectal body phased-array coil. The clinicopathologic parameters of the patients included age, prostate-specific antigen level, digital rectal examination findings, PCa detection rate, clinically significant PCa detection rate, high-grade PCa detection rate, and e-MRI specificity.

The median age of the patients was 67.4 years, and the median prostate-specific antigen level was 12.9 ng/mL. The digital rectal examination findings were positive in 42 patients (38.5%) and negative in 67 patients (61.5%). Overall, PCa was detected in 19.2% of patients, with 47.6% cases defined as clinically significant and 38.1% as high grade. Overall, the e-MRI specificity was 80.8%.

The results of our study have shown that the absence of tumor on e-MRI scans of patients with a clinical suspicion of PCa does not rule out the probability of clinically significant and high-grade PCa, making prostate biopsy mandatory for these patients as well.