Incidental Brain MRI Findings in Children: A Systematic Review and Meta-Analysis.

Background: The detection of incidental findings on children's brain MR imaging poses various practical issues because the life-long implications of such findings may be profound.

Purpose: Our aim was to assess the prevalence and characteristics of incidental brain MR imaging findings in children.

Data Sources: Electronic databases (PubMed, EMBASE, and Cochrane) were searched for articles published between 1985 to July 2018, with the following search terms: "incidental," "findings," "brain," "MR imaging."

Study Selection: Inclusion criteria were the following: 1) patients younger than 21 years of age, 2) healthy children without any clinical condition, 3) MR images obtained with at least a 1.5T magnet, 4) original articles, and 5) a methodologic quality score of ≥10.

Data Analysis: Two observers independently extracted data and assessed data quality and validity. The number and type of incidental findings were pooled. Heterogeneity was assessed using the Cochran statistic and the I statistic.

Data Synthesis: Seven studies were included, reporting 5938 children (mean age, 11.3 ± 2.8 years). Incidental findings were present in 16.4% (99% CI, 9.8-26.2; Q = 117.5, I= 94.9%) of healthy children, intracranial cysts being the most frequent (10.2%, 99% CI, 3.1-28.5; Q = 306.4, I = 98.0%). Nonspecific white matter hyperintensities were reported in 1.9% (99% CI, 0.2-16.8; Q = 73.6, I = 94.6%), Chiari 1 malformation was found in 0.8% (99% CI, 0.5-1.3; Q = 7.6, I = 60.5%), and intracranial neoplasms were reported in 0.2% (99% CI, 0.1-0.6; Q = 3.4, I = 12.3%). In total, the prevalence of incidental findings needing follow-up was 2.6% (99% CI, 0.5-11.7; Q = 131.2, I = 95.4%). Incidental findings needing specific treatment were brain tumors (0.2%) and cavernomas (0.2%).

Limitations: Limitations were no age stratification or ethnicity data and variation in the design of included studies.

Conclusions: The prevalence of incidental findings is much more frequent in children than previously reported in adults, but clinically meaningfull incidental findings were present in <1 in 38 children.