Incidental Findings On Neuroimaging for Asymptomatic Children with Autism Spectrum Disorders

Background:  Incidental findings (IF) on head neuroimaging have been frequently reported in adults and children, and more commonly in children with neurologic or neurobehavioral disorders such as autism spectrum disorders (ASD).   However, there is little data available about IF in children and adolescents with and without ASD who are asymptomatic and who have agreed to participate in magnetic resonance imaging (MRI) studies. 

Objectives:  Report the prevalence and describe characteristics of IF in a population of neurologically asymptomatic children with idiopathic ASD and typically developing controls who have volunteered for imaging studies.

Methods:  We reviewed consecutive structural head MRI studies of neurologically asymptomatic children ( 6 – 16 years) , with and without ASD, who consented to participate in ongoing functional MRI (fMRI) studies at the Center for Autism Research (CAR) of The Children’s Hospital of Philadelphia between January 3, 2012 and September 30, 2012.  All imaging was obtained on a Siemens Verio 3T scanner, with a 32 channel head coil. Studies were reviewed by 1 of 8 board certified neuroradiologists, blinded to case status and without systematic case assignment.  Final reports were reviewed by 2 study team authors (blinded to case status) to determine whether IFs required further follow-up. 

IFs were divided into categories – BBIF (brain based, such as pineal cyst, ventricular enlargement, others) and NNIF (non-neurologic, such as sinus abnormalities with inflammatory changes, others), and SIF (significant IF, where intervention such as notification of family and primary care provider or other subspecialist was indicated).

Results:  Reports of 116 subjects were reviewed, N=76 ASD (92% male, average age 10.0 + 2.3 years), N=40 typically developing controls (TDC) (80% male, average age 10.5 + 3.0). 

The prevalence of any IF for ASD was 22% (N=17), with BBIF 12% (N=9) and NNIF 11% (N=8).  Less than half (45%, N=4) of BBIF were SIF, and no NNIF were SIF.  TDC prevalence of any IF was 40% (N=16); BBIF frequency 25% (N=10) and NNIF 15% (N=6).  The frequency of SIF was BBIF 13%, NNIF 3%.  For all SIF the family and primary care provider (PCP) were notified to arrange follow-up. 

BBSIF included arachnoid cyst, cerebellar abnormalities (Chiari I malformation, low lying tonsils, cerebellar ectopia), vascular anomaly (hypoplastic right vertebral artery, old perfusion injury, dilation left carotid).  NNSIF included intervention for severe sinusitis.  Of all the subjects, 6% had SIFs.

Conclusions:  We report higher rates of incidental findings than previous studies, which may be related to superior imaging resolution or increased attention to findings. Our sample is a neurologically asymptomatic group of children with ASDs and typical development who volunteered for participation in fMRI studies at CAR.   Overall prevalence of incidental findings was 28% (N=33).  In subjects with an IF, less than one quarter (7% of all study participants) notification of caregivers was deemed appropriate.  This confirms other reports suggesting the need of specific clinical management protocol(s) to assess the significance (and reportability) of incidental findings.