Buscopan

The mpMRI protocol included standard T2-weighted imaging, diffusion-weighted imaging (DWI), and dynamic contrast enhancement (DCE), as previously reported [12] (Supplementary Table 1). Patients underwent prostate MRI using a 3-T HDx Discovery MR750 HDx scanner (GE Healthcare, Waukesha, WI, USA) with a 32-channel phased array coil. Hyoscine butylbromide (Buscopan, 20 mg/ml, Boehringer Ingelheim, Ingelheim, Germany) was administered intravenously to reduce peristaltic movement. Axial T2-weighted imaging used a slice thickness of 3 mm and a gap of 0 mm; DWI and DCE imaging were matched in the axial plane (slice thickness 3–4 mm, gap 0 mm). DWI was performed using a spin-echo echo-planar imaging pulse sequence with b values of 150, 750, 1000, 1400, and 2000 s/mm², with apparent diffusion coefficient maps automatically calculated. DCE images were acquired following a bolus injection of gadobutrol (Gadovist, Bayer Healthcare, Berlin, Germany) via a power injector at a rate of 3 ml/s (dose 0.1 mmol/kg) with temporal resolution of 7s. Lesions were characterised at baseline using a 5-point Likert scale [12] .

CT colonography preparation, colonic distention, and scan protocol were identical to the index CT colonography examination (see for detailed description Appendix I). Briefly, patients underwent a non-cathartic preparation the day before the examination and 1.5 hours prior to the examination (total of 3x50 mL of iodinated contrast agent; Telebrix Gastro, Guerbet, Aulnaysous-Bois, France) in combination with a low-fibre diet for 1 day [10 (link), 11 (link)]. Before colonic insufflation, 20 mg intravenous hyoscine butylbromide (Buscopan; Boehringer-Ingelheim, Ingelheim, Germany) was administered, after which colonic distention was achieved with automated pressure-controlled carbon dioxide insufflation (PROTOCO2L, Bracco, EZEM, Lake Success, NY, USA) through a thin, flexible rectal tube. When distension was considered sufficient via the scout image, a breath-hold supine and prone CT was performed using a 64 multi-detector-row CT scanner (Brilliance, Philips Healthcare, Best, the Netherlands; SOMATOM Sensation, Siemens Medical Solutions, Erlangen, Germany). Patients received no sedation or analgesics. Expert readers evaluated all CT colonographies within 2 weeks after the procedure. Patients were informed by phone about the results within 2 weeks after the surveillance CT colonography. Colonoscopy was done if a lesion ≥6 mm was reported.

Multiparametric MRI (mpMRI) was performed using a 3T scanner (Intera Archieva TX or Ingenia, Philips Medical Systems) with a phased-array body coil. MRI protocols are summarized in Supplementary Table 1. MRI scans consisted of T2-weighted (T2W) MRI in the axial and sagittal planes, axial DW MRI with the highest b-value of 1500 s/mm², and axial dynamic contrast-enhanced (DCE) MRI. The ADC map was generated from the DW MRI data with b-values of 0, 100, and 1000 s/mm² through a mono-exponential fit. DCE MRI was performed immediately after a bolus injection of gadopentetate dimeglumine (Magnevist, Bayer Schering Pharma) or gadobutrol (Gadovist, Bayer Schering Pharma) (dose: 0.1 mmoL/kg; rate: 2–3 mL/s) using a power injector, followed by a 20 mL saline flush. Prior to the MRI scan, 20 mg of hyoscine butylbromide (Buscopan, Boehringer Ingelheim) was administered as an intramuscular injection to reduce bowel peristalsis. However, it was not administered in patients with myasthenia gravis, glaucoma, cardiac arrhythmia, severe urinary retention, or obstructive ileus (16 patients in our study; 9 due to glaucoma and 7 due to arrhythmia). Subtraction DCE images were generated from the data pertaining to post-contrast and precontrast enhanced images, to assess the actual prostatic enhancement. All MR images were archived using PACS (PathSpeed Workstation, GE Healthcare) for image analyses.