BACKGROUND: The detection of incidental findings on children's brain MR imaging poses various practical issues because the lifelong 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 Q statistic and the I 2 statistic. DATA SYNTHESIS: Seven studies were included, reporting 5938 children (mean age, 11.3 6 2.8 years). Incidental findings were present in 16.4% (99% CI, 9.8-26.2; Q 4 117.5, I 2 4 94.9%) of healthy children, intracranial cysts being the most frequent (10.2%, 99% CI, 3.1-28.5; Q 4 306.4, I 2 4 98.0%). Nonspecific white matter hyperintensities were reported in 1.9% (99% CI, 0.2-16.8; Q 4 73.6, I 2 4 94.6%), Chiari 1 malformation was found in 0.8% (99% CI, 0.5-1.3; Q 4 7.6, I 2 4 60.5%), and intracranial neoplasms were reported in 0.2% (99% CI, 0.1-0.6; Q 4 3.4, I 2 4 12.3%). In total, the prevalence of incidental findings needing follow-up was 2.6% (99% CI, 0.5-11.7; Q 4 131.2, I 2 4 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.

Background and purpose: Mitochondrial aminoacyl-tRNA synthetases-encoded by ARS2 genes-are evolutionarily conserved enzymes that catalyse the attachment of amino acids to their cognate tRNAs, ensuring the accuracy of the mitochondrial translation process. ARS2 gene mutations are associated with a wide range of clinical presentations affecting the CNS. Methods: Two senior neuroradiologists analysed brain MRI of 25 patients (age range: 3 d-25 yrs.; 11 males; 14 females) with biallelic pathogenic variants of 11 ARS2 genes in a retrospective study conducted between 2002 and 2019.Results: Though several combinations of brain MRI anomalies were highly suggestive of specific aetiologies (DARS2, EARS2, AARS2 and RARS2 mutations), our study detected no MRI pattern common to all patients. Stroke-like lesions were associated with pathogenic SARS2 and FARS2 variants. We also report early onset cerebellar atrophy and calcifications in AARS2 mutations, early white matter involvement in RARS2 mutations, and absent involvement of thalami in EARS2 mutations. Finally, our findings show that normal brain MRI results do not exclude the presence of ARS2 mutations: 5 patients with normal MRI images were carriers of pathogenic IARS2, YARS2, and FARS2 variants.Conclusion: Our study extends the spectrum of brain MRI anomalies associated with pathogenic ARS2 variants and suggests ARS2 mutations are largely underdiagnosed

doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.