Validation of IMPROD biparametric MRI in men with clinically suspected prostate cancer: A prospective multi-institutional trial

Abstract

Background Magnetic resonance imaging (MRI) combined with targeted biopsy (TB) is increasingly used in men with clinically suspected prostate cancer (PCa), but the long acquisition times, high costs, and inter-center/reader variability of routine multiparametric prostate MRI limit its wider adoption. Methods and findings The aim was to validate a previously developed unique MRI acquisition and reporting protocol, IMPROD biparametric MRI (bpMRI) (NCT01864135), in men with a clinical suspicion of PCa in a multi-institutional trial (NCT02241122). IMPROD bpMRI has average acquisition time of 15 minutes (no endorectal coil, no intravenous contrast use) and consists of T2-weighted imaging and 3 separate diffusion-weighed imaging acquisitions. Between February 1, 2015, and March 31, 2017, 364 men with a clinical suspicion of PCa were enrolled at 4 institutions in Finland. Men with an equivocal to high suspicion (IMPROD bpMRI Likert score 3–5) of PCa had 2 TBs of up to 2 lesions followed by a systematic biopsy (SB). Men with a low to very low suspicion (IMPROD bpMRI Likert score 1–2) had only SB. All data and protocols are freely available. The primary outcome of the trial was diagnostic accuracy—including overall accuracy, sensitivity, specificity, negative predictive value (NPV), and positive predictive value—of IMPROD bpMRI for clinically significant PCa (SPCa), which was defined as a Gleason score ≥ 3 + 4 (Gleason grade group 2 or higher). In total, 338 (338/364, 93%) prospectively enrolled men completed the trial. The accuracy and NPV of IMPROD bpMRI for SPCa were 70% (113/161) and 95% (71/75) (95% CI 87%–98%), respectively. Restricting the biopsy to men with equivocal to highly suspicious IMPROD bpMRI findings would have resulted in a 22% (75/338) reduction in the number of men undergoing biopsy while missing 4 (3%, 4/146) men with SPCa. The main limitation is uncertainty about the true PCa prevalence in the study cohort, since some of the men may have PCa despite having negative biopsy findings. Conclusions IMPROD bpMRI demonstrated a high NPV for SPCa in men with a clinical suspicion of PCa in this prospective multi-institutional clinical trial. Trial registration ClinicalTrials.gov NCT02241122 .

Evaluation of Multiparametric MRI of the Prostate: Impact of Standardized Examination Protocols and the Endorectal Coil

“…Regarding time and cost-effectiveness, the use of biparametric MRI (bpMRI) consists of T2 weighted images and DWI, was discussed [15]. First studies proved the use of bpMRI on therapy naïve patients [16] [17]. The use of the endorectal coil in the diagnosis of prostate cancer is still unclear.…”

Reply to Joshua S. Jue and Mahmoud Alameddine’s Letter to the Editor re: Juha Knaapila, Ivan Jambor, Ileana Montoya Perez, et al. Prebiopsy IMPROD Biparametric Magnetic Resonance Imaging Combined with Prostate-Specific Antigen Density in the Diagnosis of Prostate Cancer: An External Validation Study. Eur Urol Oncol 2020;3:648–656

“…In their study, Jue et al [1] used transrectal ultrasound (TRUS)-guided extended template biopsy with a minimum of ten cores. By contrast, in our analysis and the analyses by Boesen et al [2][3][4], magnetic resonance imaging (MRI)-targeted TRUS-guided biopsy in combination with systematic 10-12-core biopsy was used. Any direct comparison of results between these studies would need to consider the biopsy findings from only the systematic biopsies.…”

“…Our study [6] is based on retrospective analyses of registered prospective clinical trials (IMPROD and MULTI-IMPROD) for which the inclusion criteria were PSA 2.5 ng/ ml and/or abnormal findings on digital rectal examination [3,4]. The retrospective analyses by Boesen et al [2,7] included men enrolled with the inclusion criteria of PSA 4 ng/ml and/or an abnormal finding on digital rectal examination.…”

Editorial for “Prostate Cancer Risk Stratification in Men With a Clinical Suspicion of Prostate Cancer Using a Unique Biparametric MRI and Expression of 11 Genes in Apparently Benign Tissue: Evaluation Using Machine‐Learning Techniques”

“…In this issue of JMRI, Perez et al builds on previous work from studies in the Multi‐IMROved prostate cancer Diagnosis (Multi‐IMPROD) trial . This multi‐institutional trial, conducted in Finland, applies an abbreviated bpMRI protocol in the assessment of PCa.…”

“…This multi‐institutional trial, conducted in Finland, applies an abbreviated bpMRI protocol in the assessment of PCa. The MRI protocol consists of two T 2 ‐weighted sequences and three separate diffusion‐weighted imaging acquisitions with an average scan time of 15 minutes . Similar to PI‐RADS, the trial implements its own reporting scheme, using custom‐designed Likert scores ranging from the unlikely (score 1) to the likely (score 5) presence of csPCa.…”