Abstract
OBJECTIVE: To describe the frequency and types of incidental findings on prostate MRI in a screening setting. MATERIALS AND METHODS: Prostate MRI reports from 2020 to 2024 for men aged 50-56 years were collected from three regional organised prostate cancer testing (OPT) programmes in Sweden. Incidental findings were categorised as suspicious for extra-prostatic malignancy, otherwise likely clinically relevant or of low or no clinical relevance that do not motivate contact with the screened man. Confidence intervals (CI) were calculated for proportions of scans with an incidental finding. Chi-square testing was used to test inter-regional differences of reported findings. RESULTS: At least one incidental finding was described in 119/1202 (9.9%) MRI reports. Ten reports described two incidental findings. Most (112/129, 87%) were categorised as of low or no clinical relevance, with inguinal hernia and colon diverticulosis being the most common. Proportions of these findings varied significantly (p = 0.005) between the regions: 47/355 (13%; 95% CI 10-17%), 47/539 (8.7%; 95% CI 6.5-11%) and 15/308 (5.8%; 95% CI 3.5-9.0%). Overall, 17/1202 (1.4%) of the reports described a suspected extra-prostatic malignancy or otherwise clearly clinically relevant incidental finding. Suspected extra-prostatic malignancy findings were four suspected tumours in the rectum, four suspected tumours in the bladder and two bone metastases with an unknown primary tumour. CONCLUSION: Screening prostate MRI in men in their fifties yields few incidental findings of clear clinical importance. Reporting of incidental findings of low/no clinical relevance varies between centres. Consensus-based guidelines are needed to define which types of incidental findings should be reported and notified to the screened individuals. CRITICAL RELEVANCE STATEMENT: Screening prostate MRI detects few incidental findings of clear clinical relevance. Findings of low or no clinical relevance are variably reported, which calls for consensus-based guidelines on which types of incidental findings on screening prostate MRI should be reported. KEY POINTS: No previous study has reported incidental findings on prostate MRI in a population-based screening setting. Screening prostate MRI detects few incidental findings of clear clinical relevance. Incidental findings of low or no clinical relevance are variably reported across centres. There is a need for consensus-based guidelines for which types of incidental findings on screening prostate MRI should be reported and notified to the screened individual.