Incidental Findings Associated with Magnetic Resonance Imaging of the Hand and Wrist.

Objectives: To identify the prevalence of incidentalomas and incidental findings in symptomatic patients undergoing MRI of the hand or wrist.

Methods: This retrospective cross-sectional study included all children and adults who completed MRI of the hand or wrist over a 14-year period in a single UK tertiary centre. An incidental finding was any abnormality (structural or signal-based), suspected injury or disease-process that was not already established or suspected. Incidentalomas were defined as incidental findings requiring further investigation or treatment. Marginal standardisation was used to explore relationships between prognostic factors and outcomes.

Results: Overall, 490 out of 2138 (22.9%) scans contained one or more incidental anomalies and 67 (3.1%) had at least one incidentaloma. The risk of incidentalomas doubled (RR: 1.93, 95% CI: [1.01, 3.70]) when reported by a trainee and reviewed by a consultant compared to a consultant alone; increased by 12% (RR: 1.12, 95% CI: [0.98, 1.28]) per additional decade of life; and were less likely (RR: 0.34, 95% CI: [0.12, 0.94]) when contrast was used. 3 incidentalomas were found to be malignant (3.3%).

Conclusions: The risk of incidentalomas and incidental findings in MRI of the hand and wrist is lower than solid organs. Our data may be used to inform patients about the risks of imaging and allow health services to plan the capacity and capability to deal with such events.

Advances in knowledge: One in four hand or wrist MRIs yields an incidental finding and out of these, around one in seven required further action.