ABSTRACTBackgroundMulti‐parametric MRI (mpMRI) datasets often vary between sites due to differences in acquisition protocols.PurposeEvaluate adherence of multi‐site mpMRI dataset to minimum technical standards (MTS) of PI‐RADSv2.1.Study TypeProspective.SubjectsSix hundred patients (Age (years): ≤ 49 = 0.8%, 50–59 = 10.7%, 60–69 = 47.0%, ≥ 70 = 41.5%) with intermediate‐risk prostate cancer (PCa) imaged across 124 institutions prior to radiotherapy.Field Strength/Sequence3T, 1.5T, and 1.16T, T2‐weighted (T2w): fast spin‐echo, diffusion‐weighted imaging (DWI): single‐shot echo‐planar imaging, and dynamic contrast‐enhanced (DCE): T1‐weighted 3D fast spoiled gradient echo.AssessmentScanner vendors included Siemens, GE, Philips, Toshiba, and Hitachi. Degree of adherence to PIRADSv2.1 was determined as the proportion of datasets that met MTS. Mean and standard deviation of parameter values were calculated where applicable. Prostate imaging quality (PI‐QUAL)v2 scores were assigned by one of three observers in 491 datasets. Evaluation of DICOM metadata consistency was performed.Statistical TestsFisher's exact test to assess changes in MTS adherence over time and by field strength; Harrel's C‐index to compare MTS adherence to PI‐QUAL score. A p value of < 0.001 is considered statistically significant after Bonferroni correction.ResultsEighty‐two percent of MTS showed greater than 75% adherence. Low adherence was found in the in‐plane dimension (frequency‐encoding direction) for T2w images (57%, mean = 0.45 ± 0.16 mm) and field of view (FOV) for DW images (62%, mean = 22.67 ± 4.70 cm). Only 50% of datasets used the recommended high b value image to compute the apparent diffusion coefficient map. Adherence improved significantly over time for one T2w and two DWI parameters; the adherence of FOV improved significantly at 3T for T2w and DWI sequences. C‐index values for two T2w and two DWI parameters demonstrated a relationship between PI‐RADS MTS and PI‐QUAL score. Ten percent of anonymized datasets were stripped of some sequence information.Data ConclusionResults show promise for mpMRI standardization in characterization of PCa and identify key parameters that remain variable across datasets and institutions.Evidence Level1.Technical EfficacyStage 2.Trial RegistrationClinicalTrials.gov: NCT03367702