Faculty Bibliography

PURPOSE OF REVIEW: We review recent literature surrounding the use of prebiopsy prostate MRI and MRI-targeted biopsy in men at risk for prostate cancer. RECENT FINDINGS: Large series have strengthened the case for the use of MRI prior to prostate biopsy to maximize the detection of clinically significant disease, reduce the detection of clinically insignificant disease, and allow for tumor localization during targeted biopsy. Prebiopsy MRI followed by targeted biopsy appears to have the ability to overcome the limitations of the standard 12-core template. Use of MRI and targeted biopsy in the setting of a prior negative biopsy is supported by the literature and a recent consensus statement by the American Urological Association and the Society of Abdominal Radiology Prostate Cancer Disease-Focused Panel but is contingent upon the availability and quality of multiparametric MRI acquisition and interpretation. In men with no previous biopsy, MRI and targeted biopsy appears to increase detection of clinically significant disease compared with systematic biopsy while reducing detection of indolent disease. The addition of prostate cancer biomarkers and predictive nomograms may further enhance prebiopsy risk assessment. SUMMARY: Prostate MRI prior to biopsy may guide counseling regarding prostate cancer risk, allow for accurate tumor localization during targeted biopsy, and increase detection of clinically significant cancer while limiting detection of indolent disease. Its use prior to biopsy, in conjunction with biomarkers and predictive nomograms, may allow deferral of biopsy in select cases.

OBJECTIVE: To determine how ipsilateral (ipsi) and contralateral (contra) systematic biopsies (SB) impacts detection of clinically significant versus insignificant prostate cancer (PCa) in men with unilateral MRI lesion undergoing MRI fusion target biopsy (MRF-TB). MATERIALS AND METHODS: 211 cases with one unilateral MRI lesion were subjected to SB and MRF-TB. Biopsy tissue cores from the MRF-TB, ipsi-SB and contra-SB were analyzed separately. RESULTS: A direct relationship was observed between MRI suspicious score (SS) and detection of any cancer, Gleason 6 PCa and Gleason > 6 PCa. MRF-TB alone, MRF-TB + ipsi-SB and MRF-TB + contra-SB detected 64.1%, 89.1% and 76.1% of all PCa, respectively, 53.5%, 81.4% and 69.8% of Gleason 6 PCa, respectively, and 73.5%, 96.0% and 81.6% of Gleason >6 PCa, respectively. MRF-TB + ipsi-SB detected 96% of clinically significant PCa and avoided detection of 18.6% of clinically insignificant PCa. MRF-TB + contra-SB detected 81.6% of clinically significant PCa and avoided detection of 30.2% of clinically insignificant PCa. CONCLUSION: Our study suggests that ipsi-SB should be added to MRF-TB as detection of clinically significant PCa increases with only a modest increase in clinically insignificant PCa detection. Contra-SB in this setting may be deferred since it primarily detects clinically insignificant PCa.

Purpose To test the impact of existing Prostate Imaging Reporting and Data System (PI-RADS) version 2 (V2) decision rules, as well as of proposed adjustments to these decision rules, on detection of Gleason score (GS) 7 or greater (GS >/=7) prostate cancer. Materials and Methods Two radiologists independently provided PI-RADS V2 scores for the dominant lesion on 343 prostate magnetic resonance (MR) examinations. Diagnostic performance for GS >/=7 tumor was assessed by using MR imaging-ultrasonography fusion-targeted biopsy as the reference. The impact of existing PI-RADS V2 decision rules, as well as a series of exploratory proposed adjustments, on the frequency of GS >/=7 tumor detection, was evaluated. Results A total of 210 lesions were benign, 43 were GS 6, and 90 were GS >/=7. Lesions were GS >/=7 in 0%-4.1% of PI-RADS categories 1 and 2, 11.4%-27.1% of PI-RADS category 3, 44.4%-49.3% of PI-RADS category 4, and 72.1%-73.7% of PI-RADS category 5 lesions. PI-RADS category 4 or greater had sensitivity of 78.9%-87.8% and specificity of 75.5%-79.1 for detecting GS >/=7 tumor. The frequency of GS >/=7 tumor for existing PI-RADS V2 decision rules was 30.0%-33.3% in peripheral zone (PZ) lesions upgraded from category 3 to 4 based on dynamic contrast enhancement (DCE) score of positive; 50.0%-66.7% in transition zone (TZ) lesions upgraded from category 3 to 4 based on diffusion-weighted imaging (DWI) score of 5; and 71.7%-72.7% of lesions in both zones upgraded from category 4 to 5 based on size of 15 mm or greater. The frequency of GS >/=7 tumor for proposed adjustments to the decision rules was 30.0%-60.0% for TZ lesions upgraded from category 3 to 4 based on DWI score of 4; 33.3%-57.1% for TZ lesions upgraded from category 3 to 4 based on DCE score of positive when incorporating new criteria (unencapsulated sheetlike enhancement) for DCE score of positive in TZ; and 56.4%-61.9% for lesions in both zones upgraded from category 4 to 5 based on size of 10-14 mm. Other proposed adjustments yielded GS >/=7 tumor in less than 15% of cases for one or more readers. Conclusion Existing PI-RADS V2 decision rules exhibited reasonable performance in detecting GS >/=7 tumor. Several proposed adjustments to the criteria (in TZ, upgrading category 3 to 4 based on DWI score of 4 or modified DCE score of positive; in PZ or TZ, upgrading category 4 to 5 based on size of 10-14 mm) may also have value for this purpose. (c) RSNA, 2016 Online supplemental material is available for this article.