The PRECISION trial, MRI-Targeted vs Standard Biopsy in Prostate Cancer Diagnosis: (The PRECISION Trial) demonstrated the superiority of targeted biopsy compared to systematic sampling (38% vs. 26%). It also showed that targeted biopsies decreased the detection of clinically insignificant cancer2.
The AUA white paper is a consensus statement that recommends mpMRI and targeted biopsy following prior negative biopsy and continued clinical suspicion for PIRADS 3-5 lesions3. It is important to make sure that the mpMRI be of high quality and that PIRADS version 2 is used for reporting.
The utilization of mpMRI has been growing steadily through recent years. This includes the use of mpMRI prior to biopsy (rise from 7 to 83 per 1000 biopsies)4, as seen in Figure 1. However, mpMRI at the time of biopsy was not associated with a higher likelihood of prostate cancer diagnosis compared to systematic biopsy.
There is still significant interobserver variability with sustained variation in PIRADS distribution. Analyses have shown that PIRADS score (p<0.0001) and radiologist (p=0.042) were independently associated with cancer detection (figure 2)5.
Prostate MRI should be performed according to specific technical specifications6 (Table 1), and it is critical that the interpretation should be performed using the standardized PIRADS system. The currently available data support the use of mpMRI in:
- Men with prior negative prostate biopsy and continued suspicion of prostate cancer
- There is a clear recommendation to perform an MRI before undergoing a biopsy in men with no prior biopsy
Figure 1 –Unadjusted and Age-specific rates of MRI-guided biopsy4:
Figure 2 – Radiologist Variation in detecting clinically significant prostate cancer5:
MRI appears to accurately identify an “index lesion” with accuracy dependent upon the definition of grade and lesion size/volume. The MRI tumor volume has been shown to underestimate the histologic tumor volume by approximately 20-30%, and it also influences the margin estimates (Table 2).
Table 1 – MRI parameters, technical specifications and updated PIRADS scoring system6:
Table 2 – MRI underestimation of histologic tumor volumes:
Dr. Wysock continued his talk, providing some future directions. There are currently studies underway to assess the role of prostate MRI earlier in the diagnostic pathway, evaluating the role of mpMRI as a screening tool. There also studies assessing the use of bi-parametric vs. multi-parametric MRI. A recent systematic review and meta-analysis demonstrated no difference in pooled diagnostic estimates between bi-parametric and multi-parametric MRI7. There is also emerging data on the use of high-resolution ultrasound, improving the sonographic signal and potential to incorporate with MRI8.
Other future directions include the use of next-generation imaging (PET, PET/CT, PET/MRI) with and without mpMRI. There are also new radiolabels being investigated, including those targeting prostate cancer-specific targets such as prostate-specific membrane antigen (PSMA) and F-18-Fluciclovine (Axumin®).
Dr. Wysock concluded his talk by stating that prostate imaging has advanced to allow for improved disease localization within the prostate, continuing to enhance prostate cancer diagnosis and treatment. Future opportunities include the implementation of MRI screening and/or the use of bi-parametric MRI instead, high-resolution ultrasound, and molecular imaging.
Presented by: Dr. James Wysock, MD, MSc. Urologic Oncologist, NYU Langone Health, New York, New York, United States.
Written by: Hanan Goldberg, MD, MSc, Assistant Professor, Urology Department, SUNY Upstate Medical University, Syracuse, NY, USA, @GoldbergHanan at the 2020 Society of Urologic Oncology Annual Meeting – December 2-5, 2020 – Washington, DC
1. Ahmed, H. U., El-Shater Bosaily, A., Brown, L. C. et al. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. Lancet, 389:815, 201
2. Kasivisvanathan, V., Rannikko, A. S., Borghi, M. et al. MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis. N Engl J Med, 378: 1767, 2018
3. Samir Taneja MAB, H. Ballentine Carter, Michal s. Coockson. AUA/OPTIMAL TECHNOIQUES OF PROSTATE BIOPSY AND SPECIMEN HANDLING.
4. Kim SP, Karnes RJ, Mwangi R, et al. Contemporary Trends in Magnetic Resonance Imaging at the Time of Prostate Biopsy: Results from a Large Private Insurance Database. European urology focus 2019.
5. Sonn GA, Fan RE, Ghanouni P, et al. Prostate Magnetic Resonance Imaging Interpretation Varies Substantially Across Radiologists. European urology focus 2019; 5(4): 592-9.
6. Bjurlin MA, Carroll PR, Eggener S, et al. Update of the Standard Operating Procedure on the Use of Multiparametric Magnetic Resonance Imaging for the Diagnosis, Staging and Management of Prostate Cancer. The Journal of urology 2020; 203(4): 706-12.
7. Bass EJ, Pantovic A, Connor M, et al. A systematic review and meta-analysis of the diagnostic accuracy of biparametric prostate MRI for prostate cancer in men at risk. Prostate cancer and prostatic diseases 2020.
8. Abouassaly R, Klein EA, El-Shefai A, Stephenson A. Impact of using 29 MHz high-resolution micro-ultrasound in real-time targeting of transrectal prostate biopsies: initial experience. World journal of urology 2020; 38(5): 1201-6.