Biparametric MRI for Detection of Significant Prostate Cancer

Purpose Our aim is to assess whether a screening bpMRI can be used as a diagnostic non-invasive screening tool to 1) improve the diagnosis of sPCa 2) predict cancer aggressiveness 3) increase precision of biopsies and 4) reduce the number of biopsy sessions and cores.

Trial subjects Subjects are recruited at the Department of Urology, Herlev Gentofte University Hospital. Annually, approx. 1.600 men are referred to the department due to clinical suspicion of PCa. Roughly 1.100 men further proceeds to standard TRUS-bx prostate biopsies. These men are invited to participate as subjects in this study and undergo a bpMRI before biopsies, if they fulfil the inclusion criteria. All subjects provide written informed consent and can withdraw their consent at any time with no consequence in relation to their standard treatment. Intended sample size calculations (power 0•9 and 2-sided significance 0•05) were based on estimates of diagnostic accuracy (sensitivity and specificity) and detection rates by biopsy techniques (SBx and TBx) from prior mpMRI studies assuming prevalence of sPCa of 30%. Target sample size was minimum 600 patient.

Study Design This study is designed as a prospective interventional study. All enrolled patients undergo a screening bpMRI of the prostate within 1-2 weeks after inclusion and prior to biopsies. All MRI data undergo blinded evaluation according to a modified PIRADS version 2 classification from the European Society of Urogenital Radiology (ESUR) 18 by an experienced physician who register and score all suspicious lesions on a five-point scale (1- very low, 2 - low, 3 - intermediate, 4- high and 5 - very high) according to the overall probability of having significant PCa. As the bpMRI protocol does not include dynamic contrast-enhanced (DCE) imaging, scoring of lesions in the peripheral zone relied solely on DWI findings. The bpMRI is within 4-weeks followed by standard 10-core TRUS-bx performed according to current standard practice and blinded to any MRI findings. The TRUS-operator then subsequently reviews the MRI data and rapport on a dedicated workstation in the biopsy room to identify suspicious lesions presented and outlined by the radiologist. Any suspicious lesions are then targeted by additional bpMRI-guided biopsies using bpMRI-TRUS image fusion based software. BpMRI suspicion scores and biopsy results from TRUS-bx and bpMRI-bx are compared.

Furthermore, all enrolled patients are clinically followed for 5 years after the initial biopsies to detect any subsequent diagnosis of PCa, treatment recurrence or metastasis.

MRI image acquisition:

A 3T MRI-scanner (Ingenia, Philips Healthcare, the Best, the Netherlands) is used for all patients with a pelvic-phased-array coil (Philips Healthcare, Best, the Netherlands) positioned over the pelvis. Anatomical (T2W) and diffusion-weighted images (DWI) including 4 b-values (b0, b100, b800 and b2000) along with reconstruction of the corresponding apparent diffusion coefficient (ADC) map (b-values 100 and 800) are obtained from below the prostatic apex to above the seminal vesicles. A sagittal T2W luxury scout supported the axial sequences for MRI/TRUS image fusion.

Pathological evaluation A genitourinary pathologist with more than 11 yrs of dedicated experience in prostatic pathology reviews and describes all histological biopsy samples. For each PCa positive biopsy core, the location and prostatic region, the Gleason score (GS) 19 and the extent of cancer core involvement (%) are determined. Various definitions of sPCa are assessed including GS and tumor volume.