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Potentially serious incidental findings on brain and body magnetic resonance imaging of apparently asymptomatic adults: systematic review and meta-analysis

BMJ 2018; 363 doi: (Published 22 November 2018) Cite this as: BMJ 2018;363:k4577
  1. Lorna M Gibson, clinical research training fellow1,
  2. Laura Paul, specialty trainee in clinical radiology2,
  3. Francesca M Chappell, medical statistician3,
  4. Malcolm Macleod, professor3,
  5. William N Whiteley, clinician scientist3,
  6. Rustam Al-Shahi Salman, professor3,
  7. Joanna M Wardlaw, professor3,
  8. Cathie L M Sudlow, professor1
  1. 1Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh BioQuarter, Edinburgh EH16 4UX, UK
  2. 2Department of Clinical Radiology, Glasgow Royal Infirmary, Glasgow, UK
  3. 3Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
  1. Correspondence to: C L M Sudlow cathie.sudlow{at}
  • Accepted 5 October 2018


Objectives To determine prevalence and types of potentially serious incidental findings on magnetic resonance imaging (MRI) in apparently asymptomatic adults, describe factors associated with potentially serious incidental findings, and summarise information on follow-up and final diagnoses.

Design Systematic review and meta-analyses.

Data sources Citation searches of relevant articles and authors’ files in Medline and Embase (from inception to 25 April 2017).

Review methods Eligible studies included prevalence and types of incidental findings detected among apparently asymptomatic adults undergoing MRI of the brain, thorax, abdomen, or brain and body. Data on study population and methods, prevalence and types of incidental findings, and final diagnoses were extracted. Pooled prevalence was estimated by random effects meta-analysis, and heterogeneity by τ2 statistics.

Main outcome measures Prevalence of potentially serious incidental findings on MRI of the brain, thorax, abdomen, and brain and body.

Results Of 5905 retrieved studies, 32 (0.5%) met the inclusion criteria (n=27 643 participants). Pooled prevalence of potentially serious incidental findings was 3.9% (95% confidence interval 0.4% to 27.1%) on brain and body MRI, 1.4% (1.0% to 2.1%) on brain MRI, 1.3% (0.2% to 8.1%) on thoracic MRI, and 1.9% (0.3% to 12.0%) on abdominal MRI. Pooled prevalence rose after including incidental findings of uncertain potential seriousness (12.8% (3.9% to 34.3%), 1.7% (1.1% to 2.6%), 3.0% (0.8% to 11.3%), and 4.5% (1.5% to 12.9%), respectively). There was generally substantial heterogeneity among included studies. About half the potentially serious incidental findings were suspected malignancies (brain, 0.6% (95% confidence interval 0.4% to 0.9%); thorax, 0.6% (0.1% to 3.1%); abdomen, 1.3% (0.2% to 9.3%); brain and body, 2.3% (0.3% to 15.4%)). There were few informative data on potential sources of between-study variation or factors associated with potentially serious incidental findings. Limited data suggested that relatively few potentially serious incidental findings had serious final diagnoses (48/234, 20.5%).

Conclusions A substantial proportion of apparently asymptomatic adults will have potentially serious incidental findings on MRI, but little is known of their health consequences. Systematic, long term follow-up studies are needed to better inform on these consequences and the implications for policies on feedback of potentially serious incidental findings.

Systematic review registration Prospero CRD42016029472.


  • Contributors: LMG designed and conducted the study; collected, managed, analysed, and interpreted data; and prepared, reviewed, and approved the manuscript. LP collected data and reviewed and approved the manuscript. MM advised on methods, interpreted data, and reviewed and approved the manuscript. FMC analysed and interpreted data; and prepared, reviewed, and approved the manuscript. WNW and RAS interpreted data, and reviewed and approved the manuscript. JMW designed and supervised the study, interpreted data, and reviewed and approved the manuscript. CLMS designed and supervised the study; interpreted data; reviewed, approved, and decided to submit the manuscript for publication; and is the guarantor. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: LMG is funded by a Wellcome Trust clinical research training fellowship (107190/Z/15/Z). None of the authors’ funding organisations contributed to the design and conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication. All authors are independent from the funders.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at (available on request from the corresponding author) and declare: support from the Wellcome Trust for the submitted work; LMG reports personal fees from UK Biobank, outside the submitted work; CLMS is chief scientist of UK Biobank; the remaining authors have no financial relationships with any organisations that might have an interest in the submitted work in the previous three years or other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: All data for this study were obtained from existing publications, and so did not need ethical approval.

  • Data sharing: The full dataset is available at with open access.

  • The lead author affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

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