Prevalence of Incidental Extraspinal Findings on MR Imaging of the Lumbar Spine in Adults: A Systematic Review and Meta-analysis.

Background: Low back pain is common worldwide. MR imaging may identify extraspinal findings that are not related to the proposed clinical question. The prevalence of extraspinal incidental findings and their clinical significance has not been well-established.

Purpose: This review aimed to evaluate the prevalence of extraspinal findings on MR imaging of the lumbar spine in adults and the prevalence of clinically significant incidental findings.

Data Sources: A systematic search of MEDLINE and EMBASE was performed, including studies published before June 14, 2023.

Study Selection: Studies presenting a prevalence of extraspinal findings in patients 16 years of age or older were included.

Data Analysis: A random effects meta-analysis was used to generate composite prevalence measures of extraspinal findings, patients with extraspinal findings, and clinically significant findings.

Data Synthesis: Sixteen studies were included in this meta-analysis, with a total of 19,593 patients and 6,006 extraspinal incidental findings. The overall prevalence of extraspinal findings was 19.9% (95% CI, 11.1%-30.7%). Overall, 26.7% of patients had an extraspinal finding identified (95% CI, 14.8%-40.6%). The most common subgroup of extraspinal findings was genitourinary findings in males (27.1%; 95% CI, 25.6%-28.8%). Data from 8 studies demonstrated the prevalence of clinically significant findings at 5.4% (95% CI, 3.2%-8.1%).

Limitations: Retrospective populations with small numbers of participants in clinically relevant subgroups may result in heterogeneity and imprecision within composite outcome measures.

Conclusions: Extraspinal findings are common, detected in more than one-quarter of patients. Five percent of findings are clinically significant and may require further action.