Multiparametric magnetic resonance imaging of the prostate underestimates tumour volume of small visible lesions

Abstract

To assess the relationship between the volume of the index lesion (IL) measured at multiparametric magnetic resonance imaging (mpMRI; MRIvol) and at radical prostatectomy (RPvol), stratifying it according to Prostate Imaging-Reporting and Data System (PI-RADS) score. Patients and MethodsWe identified 332 men with a positive mpMRI (single lesion with PI-RADS ≥3) who underwent systematic plus targeted biopsy and subsequent RP at two tertiary referral centres between 2013 and 2018. All mpMRIs were reviewed by experienced radiologists using PI-RADS scores. The study outcome was to assess the relationship between MRIvol (based on planimetry from MRI sequence best showing tumour) and RPvol (based on tumour involved area of each RP pathology slice). To achieve this endpoint, we performed a multivariable linear regression analysis (LRA) to predict RPvol using PI-RADS, prostate-specific antigen level, prostate volume, age, digital rectal examination, Gleason score at MRI-targeted biopsy, biopsy history and time from mpMRI to RP as covariates. Non-parametric locally estimated scatterplot smoothing (LOESS) function was used to graphically explore the relationship between MRIvol and RPvol, stratifying for PI-RADS score. ResultsOverall, 24%, 49% and 27% of men had visible PI-RADS 3, 4 and 5 lesions at mpMRI. The median (interquartile range [IQR]) MRIvol and RPvol were 0.67 (0.29-1.76) mL and 1.39 (0.58-4.23) mL. At LRA, MRIvol was significantly correlated with a RPvol underestimation (slope: 2.4, 95% confidence interval [CI] 0.1-46.3). The non-parametric LOESS analysis showed a non-linear relationship between MRIvol and RPvol. Significant underestimation was reported across all volumes with the highest differences between MRIvol and RPvol in the low volume range (<2 mL), where RPvol almost doubled MRIvol. A similar effect was observed across all PI-RADS scores subgroups. ConclusionsIn the present study, mpMRI significantly underestimated the exact volume of the IL, especially for small visible lesions, regardless of PI-RADS score. This should be considered when planning tailored focal therapy approaches often delivered to men with smaller prostatic lesions.

Grade and stage misclassification in intermediate unfavorable‐risk prostate cancer radiotherapy candidates

“…21,22 Furthermore, other studies reported an underestimation of MRI regarding the true size and extend of PCa tumor. 23,24 Since the ability of MRI to improve prediction of upgrading and/or upstaging is still under debate, other clinical tools, such as PSMA PET/CT scans or biomarkers (the prostate health index, urine PCA3, 4Kscore, TMPRSS2-ERG, and ConfirmMDX) may prove of value. 25,26 Moreover, despite novel findings, these tools still have to prove their efficacy and are not currently available in the clinical practice.…”

“…Conversely, Diamand et al failed to identify added benefit from MRI findings regarding prediction of extracapsular extension and seminal vesicle invasion, according to results recorded in an external validation cohort 21,22 . Furthermore, other studies reported an underestimation of MRI regarding the true size and extend of PCa tumor 23,24 . Since the ability of MRI to improve prediction of upgrading and/or upstaging is still under debate, other clinical tools, such as PSMA PET/CT scans or biomarkers (the prostate health index, urine PCA3, 4Kscore, TMPRSS2–ERG, and ConfirmMDX) may prove of value 25,26 .…”

“…In consequence previous investigators, who examined the same concept relied on the same methodology 9 . Second, the retrospective information of the SEER database limits the amount of detail regarding certain clinical and/or pathological characteristics that may be more detailed within prospectively recorded institutional series 23,27 . For example, the SEER database does not offer information about MRI imaging.…”

Does previous prostate surgery affect multiparametric magnetic resonance imaging accuracy in detecting clinically significant prostate cancer? Results from a single institution series

“…The mpMRI images were scored and reported using the PI‐RADS version 2 16 . All patients underwent both TBx and SBx at our center according to the technique previously described 17–19 . TBx was performed using a software‐registration fusion approach and was immediately followed by additional random SBx using a sextant biopsy scheme during the same session, in accordance with the currently available guidelines 11 .…”

“…16 All patients underwent both TBx and SBx at our center according to the technique previously described. [17][18][19] TBx was performed using a softwareregistration fusion approach and was immediately followed by additional random SBx using a sextant biopsy scheme during the same session, in accordance with the currently available guidelines. 11 Biopsies were performed by experienced urologists using an 18-gauge needle and a biopsy gun providing a specimen size of 18−22 mm.…”