Although imaging results are not considered in assigning local (T) stage, multi-parametric MRI (mpMRI) of the prostate can provide important information about the extent and location of disease within the prostate, as well as anatomic information, which can influence management decisions.  MRI can localize the index lesion with moderate sensitivity (approximately 0.6) and high specificity (approximately 0.9),50, 64-74  with a large-scale meta-analysis corroborating these findings, showing a sensitivity of 57-61% and specificity of 88-96% for extraprostatic extension and seminal vesicle involvement.50 MRI has been compared with DRE for staging in single-institution studies. In one such study including 506 men who underwent clinical staging by DRE alone and then with MRI followed by surgery, MRI had a sensitivity of 51% for ≥ T3a disease as compared with 12% for DRE (p < 0.01).75 However, specificity was somewhat lower for MRI as compared with DRE (82% versus 97%; p < 0.01). Nonetheless, while there are several systems for determining the likelihood of extraprostatic extension based on MRI findings, consensus on such a definition is lacking.76-78 Most systems incorporate tumor-capsule contact length and morphologic features, such as capsular bulge. Use of higher field strength (i.e., stronger magnet, such as 3T instead of 1.5T) improves sensitivity of MRI, as does the addition of functional sequences, including diffusion-weighted imaging (DWI), dynamic contrast enhanced (DCE) imaging and magnetic resonance spectroscopic imaging (MRSI) to standard T2-weighted imaging. However, biparametric MRI, limited to T2 and diffusion-weighted phases is non-inferior to mpMRI, which adds the dynamic contrast-enhanced phase for detection of grade group 2 or higher prostate cancer. Thus, biparametric MRI is a reasonable substitute for mpMRI.79 In men choosing active surveillance, MRI should be used for targeted biopsy if available but should not replace surveillance biopsies. Additionally, MRI and targeted biopsy should be used for patient selection in focal therapy and for follow-up after treatment; however, it should be used as a complementary study and should not replace tissue sampling.  In radiotherapy, the FLAME trial demonstrated improved 5-year biochemical disease-free survival in intermediate- and high-risk patients who received a radiation ‘boost’ to MRI-visible targets in addition to whole-gland radiation compared to whole-gland treatment alone (92% versus 85%; HR: 0.45; p < 0.01).80, 81 Follow-up showed a lower probability of local failure (HR: 0.33; 95% CI: 0.14 to 0.78) and regional or distant recurrence (HR: 0.58; 95% CI: 0.35 to 0.93) in the group that received the boost.82 There was no difference between groups in toxicity. Observational studies have found comparable results.83  Regarding patients undergoing surgery, despite the accuracy with which MRI can detect index lesions, extraprostatic extension, and seminal vesicle involvement in addition to the frequency with which treatment plan is altered by MRI findings, the evidence regarding whether preoperative MRI lowers positive surgical margin rates or subsequent biochemical recurrence is mixed.84-87 A 2019 meta-analysis of 6 studies that directly compared preoperative MRI to no preoperative MRI, including 1 RCT, showed an absolute risk reduction of 5.2% in the likelihood of positive margins at final pathology in patients who had undergone preoperative MRI compared to those who had not (OR: 0.74; 95% CI: 0.63 to 0.87; p < 0.001).85 Additionally, these studies have consistently shown increased use of nerve-sparing among patients who underwent preoperative MRI, suggesting that there may also be benefits in terms of functional outcomes. In reviewing these studies, the Panel concluded that clinicians may use MRI for local staging in any risk category, not only to refine patient selection for active surveillance and to direct focal therapy, but also to guide treatment in ways that may improve oncologic and functional outcomes. It must be acknowledged, however, that access to MRI may be limited in some settings, and MRI scanner quality and radiologist expertise may influence the utility of MRI and the rate of false-positives and false-negatives.