From the Guidelines
MRI imaging is a crucial diagnostic tool in prostate cancer management, providing detailed anatomical information that helps with detection, characterization, and staging of tumors, and should be used as an adjunct to guide baseline prostate biopsy in biopsy-naïve patients with clinically suspected prostate cancer. The use of multiparametric MRI (mpMRI) has become the standard approach for prostate evaluation, combining T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced sequences to identify suspicious lesions that may require biopsy, guide targeted biopsies for more accurate sampling, and assist in determining the extent of disease for treatment planning 1.
The PI-RADS (Prostate Imaging-Reporting and Data System) scoring system standardizes interpretation of prostate MRI findings on a 1-5 scale, with higher scores indicating greater likelihood of clinically significant cancer 1. Recent studies have shown that prebiopsy MRI is a useful adjunct for tumor localization in biopsy-naïve patients, with high-value targets (lesions with a PI-RADS score of 4 or 5) seen in 49% of patients, and 86% of these patients having positive targeted in-bore biopsies 1.
Key benefits of using MRI in prostate cancer diagnosis include:
- Improved detection of clinically significant cancers with higher sensitivity than traditional random biopsies alone
- Reduction of unnecessary biopsies and overdiagnosis of indolent disease
- Valuable information about potential disease progression without repeated invasive procedures for patients undergoing active surveillance
- Ability to visualize the prostate's zonal anatomy and detect extracapsular extension, making it particularly valuable for surgical and radiation therapy planning 1.
In terms of specific recommendations, routine MRI at 12 months using a multiparametric protocol compliant with PI-RADS version 2.1 standards is recommended for patients after focal therapy 1, and mpMRI scan should be obtained to evaluate the loco-regional extent of disease and presence of distant metastasis in patients with high-risk prostate cancer 1.
From the Research
Role of MRI in Diagnosing Prostate Cancer
- MRI plays a crucial role in the detection and staging of prostate cancer, with the introduction of functional MRI sequences 2.
- The combination of anatomical and functional MRI parameters can detect greater than 90% of significant tumors, although it is less reliable at detecting small, low-grade tumors or those in the transitional zone 3.
- MRI can improve pretreatment risk stratification, selection of patients for active surveillance, and guiding targeted biopsy, treatment planning, and follow-up after treatment 2, 4, 5.
Clinical Applications of MRI
- MRI can be used to determine which men with an elevated PSA should undergo biopsy, although it should be used with caution and only in centers with established uro-radiological expertise 3.
- MRI-directed biopsy is an exciting concept, but further evidence is required to justify its costs and complexities over standard biopsy protocols 3.
- MRI appears to be of value in planning dosimetry in men undergoing radiotherapy and in guiding selection for and monitoring on active surveillance 3, 4, 5.
Advances in MRI Technology
- Recent advancements in radiomics and artificial intelligence are being tested to potentially improve detection, assessment of aggressiveness, and provide usefulness as a prognostic marker 2.
- The use of multiparametric MRI (mpMRI) has shown promising results in diagnosis, localization, risk stratification, and staging of clinically significant prostate cancer 4, 5.
- The Prostate Imaging and Reporting Archiving Data System (PI-RADS) scoring system has been developed to standardize reporting and improve accurate interpretation of mpMRI results 5.