Prostate MRI is increasingly used within organised testing pathways to improve prostate cancer diagnostics while limiting overdiagnosis linked to systematic biopsy approaches. As imaging becomes part of population-based invitation programmes, extra-prostatic incidental findings raise practical and ethical questions about what to report and when to contact participants who were invited for a specific purpose. An analysis of prostate MRI reports from three regional organised prostate cancer testing programmes in Sweden reviewed incidental findings recorded between 2020 and 2024 among men aged 50–56 years. Across 1202 reports, incidental findings were uncommon and were usually considered to have low or no clinical relevance. Clear clinical importance was reported infrequently, while reporting thresholds for low-relevance findings varied between regions.
IThree Swedish Programmes and Report Classification
The reports came from organised prostate cancer testing programmes in Region Skåne, Region Västra Götaland and Region Stockholm, described as Sweden’s three most populated regions. Men were invited by letter in population-based programmes delivered by public healthcare. Men with a prostate-specific antigen value at or above 3 ng/mL were referred for prostate MRI. In Region Stockholm during 2024, an evaluation of the Stockholm3 test meant that some men with prostate-specific antigen values at or above 3 ng/mL did not undergo MRI.
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Men were identified through the national SweOPT register and the review included only each participant’s first prostate MRI recorded in the programmes during 2020–2024. Around 1000 reports were considered sufficient for analysis. Half of the scans from each region were randomly selected, resulting in 1202 MRI reports. Region Skåne and Region Västra Götaland used a structured online reporting template that included a dedicated item for incidental findings.
Incidental findings were categorised as suspicious for extra-prostatic malignancy, otherwise likely clinically relevant and requiring notification to the screened individual, or low or no clinical relevance and therefore not requiring notification. Where two incidental findings were recorded in the same report, the most severe finding determined the categorisation. One report listed prostatitis as an incidental finding but this was excluded because findings within the prostatic parenchyma were considered to fall under the prostate reporting system used for prostate MRI assessment.
Most Findings Were Classified as Low or No Clinical Relevance
At least one incidental finding was recorded in 119 of 1202 reports, corresponding to 9.9% of men. Ten men had two incidental findings, giving 129 incidental findings overall. Most incidental findings were classified as low or no clinical relevance, accounting for 112 of 129 findings, or 87%.
Inguinal hernia and sigmoid diverticula were the most common low or no clinical relevance findings, recorded 39 and 35 times, respectively. Cysts in the bladder or prostate were recorded 10 times. Other low or no clinical relevance findings were recorded 28 times, including urinary bladder diverticula, urethrocele, hydrocele, coxarthrosis, pelvic kidney and sclerotic bone lesions not suspicious for metastasis.
Regional Differences and Few Findings Requiring Notification
Reporting of low or no clinical relevance incidental findings differed significantly between regions. Region Skåne recorded such findings in 47 of 355 reports, or 13%. Region Stockholm recorded 47 of 539 reports, or 8.7%. Region Västra Götaland recorded 18 of 308 reports, or 5.8%. The inter-regional difference was statistically significant, with p = 0.005. Differences in regional or local routines, template use and individual radiologist preferences were described as potential contributors. Experience from prostate MRI reading within the Gothenburg-2 screening trial in Region Västra Götaland, where incidental finding reporting is restricted, was highlighted as a likely influence.
Incidental findings requiring notification were uncommon. In total, 17 of 1202 reports, or 1.4% of men, included an incidental finding classified as suspicious for extra-prostatic malignancy or otherwise likely clinically relevant. Ten of the 129 incidental findings were suspicious for extra-prostatic malignancy, consisting of suspected tumours in the rectum (four reports), suspected tumours in the urinary bladder (four reports) and bone metastasis (two reports) with an unknown primary tumour.
Seven incidental findings were classified as otherwise likely clinically relevant: an enlarged lymph node, a suspected bladder stone, an unknown lesion in the lesser pelvis, a ureteric stone, generally high bone marrow diffusion, a testicle in the inguinal canal and polycystic kidney disease. A testicle in the inguinal canal and polycystic kidney disease were described as findings that could already be known to participants, and malignancy risk in a non-descended testicle was described as lower in older age groups. Both were nonetheless classified as likely clinically relevant because risk was described as not negligible and polycystic kidney disease could be undiagnosed in other cases.
After the period covered, the structured MRI report template used in organised prostate cancer testing was revised in 2025 so that only incidental findings requiring clinical follow-up or an intervention were to be reported. Guidance published as an annex to organised testing recommendations in February 2025 advised reporting only clearly clinically relevant incidental findings on organised testing MRI. The stated motives included that the invitation is for prostate cancer testing rather than broad health screening, that follow-up may cause anxiety and physical harm and that widespread follow-up would create substantial healthcare workload without proven health benefit.
Across 1202 first-time prostate MRI reports from organised testing programmes in three Swedish regions between 2020 and 2024, incidental findings were recorded in 9.9% of reports and were mainly classified as low or no clinical relevance. Reporting of low-relevance findings varied significantly between regions. Findings requiring notification were rare, including suspected rectal tumours, suspected urinary bladder tumours and bone metastasis with an unknown primary tumour, alongside a small number of other findings classified as likely clinically relevant.
Source: Insights into Imaging
Image Credit: iStock
