Despite the use of standardized protocols (namely PI-RADS), we can speculate that this may influence the diagnostic performance of this imaging test resulting in a worrisome high variability of mpMRI diagnostic accuracy.2,3 However, few studies investigated the variability between mpMRIs performed in non-academic vs academic centers and the importance of a central review of external mpMRI scans. In this study, we specifically aimed to assess the diagnostic benefit in terms of clinically significant PCa (csPCa) detection related to a central review of external mpMRI scans.
We retrospectively analyzed a contemporary cohort of 364 consecutive men with a positive externally performed mpMRI (PI-RADS ≥3) referred to our tertiary referral center for prostate biopsy. For 116 men (32%), according to the treating physician’s preference, we asked for a central review with a second opinion by one of our three highly experienced internal radiologists (each radiologist reported more than 500 scans). If the mpMRI report was confirmed to be suspicious, the patients proceeded to receive a prostate biopsy (targeted plus systematic). Differently, if the central second opinion did not confirm the presence of a suspicious visible lesion at mpMRI, the patient was counseled not to perform a prostate biopsy and followed using either follow-up PSA and/or mpMRI. On the other hand, all patients who did not undergo central revision proceeded to receive a prostate biopsy (targeted plus systematic). We compared the detection of csPCa between the non-central-reviewed vs central-reviewed group. We tested whether mpMRI central review was associated with the detection of csPCa at biopsy using a multivariable model accounting for potential confounders (e.g. PSA, prostate volume, PI-RADS score at the time of biopsy, and biopsy history). Moreover, we plotted the reclassification of the initial PI-RADS score after mpMRI central review.
The detection of csPCa at TBx in the non-central-reviewed vs central-reviewed group was 41 vs 63%, respectively (p = 0.001). Multivariable logistic regression analyses confirmed that a central review of external mpMRI scans represents an independent predictor of csPCa detection at TBx (odds ratio: 1.65; 95% confidence interval: 0.85–0.98, p =0.01). The central review changed the PI-RADS score in 46% of the cases with an increase and decrease of the PI-RADS score in 5 and 41% of the patients, respectively. This resulted in 45 (39%) men with initial suspicions of mpMRI that avoided prostate biopsy. The subpopulation of patients with initial PI-RADS 3 was the one in which we saw the most PI-RADS score changes following central revision. Indeed, the initial diagnosis was confirmed in only 21% of the patients, whereas 67 and 12% of the mpMRI lesions were reclassified in PI-RADS ≤2 and PI-RADS 4, respectively.
Our results undelight the presence of substantial variability and heterogeneity of the mpMRI diagnostic accuracy across different centers. This could be partially explained by the lack of implementation of standardized protocols across centers and proper training for radiologists reporting mpMRIs.2,4,5 From a clinical standpoint, our findings support the importance of mpMRI central review performed by highly experienced radiologists for scans performed in non-academic centers. This is crucial since the central review may improve the detection of csPCa at targeted biopsy, and may change the patient's clinical management reducing the number of unnecessary biopsies. This is particularly true for patients with mpMRI equivocal lesions, given their low positive predictive value and that, as suggested by our study, are overreported in non-academic centers.6 Despite novel findings, our study had some limitations. First, it is retrospective and so affected by potential selection bias. Second, the study population was quite limited. Third, only initial suspicious scans (PI-RADS ≥3) were evaluated. Finally, we had no data on the subset of patients with a non-confirmed mpMRI suspicious lesion after the central review, since these patients did not undergo prostate biopsy.
Written by: Armando Stabile, Gabriele Sorce, Francesco Pellegrino, Giorgio Gandaglia, Francesco Montorsi, Alberto Briganti
Department of Urology and Division of Experimental Oncology, URI, Urological Research Institute, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy
References:
- Stabile A, Giganti F, Rosenkrantz AB, et al. Multiparametric MRI for prostate cancer diagnosis: current status and future directions. Nat Rev Urol 2019; 17(1):41-61.
- Stabile A, Giganti F, Kasivisvanathan V, et al. Factors Influencing Variability in the Performance of Multiparametric Magnetic Resonance Imaging in Detecting Clinically Significant Prostate Cancer: A Systematic Literature Review. Eur Urol Oncol 2020; 3(2):145-167.
- Giganti F, Allen C, Emberton M, Moore CM, Kasivisvanathan V. Prostate Imaging Quality (PI-QUAL): A New Quality Control Scoring System for Multiparametric Magnetic Resonance Imaging of the Prostate from the PRECISION trial. Eur Urol Oncol 2020;3:615–9.
- Weinreb JC, Barentsz JO, Choyke PL, et al. PI-RADS Prostate Imaging - Reporting and Data System: 2015,
- Version 2. Eur Urol 2015;69:16–40. Rosenkrantz AB, Abimbola A, Anunita K, et al. The Learning Curve in Prostate MRI Interpretation: Self-Directed Learning Versus Continual Reader Feedback. AJR Am J Roentgenol 2017;208:92–100.
- Mazzone E, Stabile A, Pellegrino F, et al. Positive Predictive Value of Prostate Imaging Reporting and Data System Version 2 for the Detection of Clinically Significant Prostate Cancer: A Systematic Review and Meta-analysis. Eur Urol Oncol 2021; 4(5):697-713.