Perfusion impairments in infantile autism on technetium-99m ethyl cysteinate dimer brain single-photon emission tomography: comparison with findings on magnetic resonance imaging

The neuro-anatomical substrate of autism has been the subject of detailed i nvestigation. Because previous studies have not demonstrated consistent and specific neuro-imaging findings in autism and most such studies have been performed in adults and school-aged children, we performed a retrospective review in young children in search of common functional and anatomical abno rmalities with brain single-photon emission tomography (SPET) using technet ium-99m ethyl cysteinate dimer (ECD) and correlative magnetic resonance ima ging (MRI). The patient population was composed of 23 children aged 28-92 m onths (mean: 54 months) who met the diagnostic criteria of autism as define d in the DSM-IV and CARS. Brain SPET was performed after intravenous inject ion of 185-370 MBq of Tc-99m-ECD using a brain-dedicated annular crystal ga mma camera. MRI was performed in all patients, including T1, T2 axial and T 1 sagittal sequences. SPET data were assessed visually. Twenty patients had abnormal SPET scans revealing focal areas of decreased perfusion. Decrease d perfusion of the cerebellar hemisphere (20/23), thalami (19/23), basal ga nglia (5/23) and posterior parietal (10/23) and temporal (7/23) areas were noted on brain SPET, By contrast all patients had normal MRI findings witho ut evidence of abnormalities of the cerebellar vermis, cerebellar hemispher e, thalami, basal ganglia or parietotemporal cortex, In conclusion, extensi ve perfusion impairments involving the cerebellum, thalami and parietal cor tex were found in this study. SPET may be more sensitive in reflecting the pathophysiology of autism than MRI. However, further studies are necessary to determine the significance of thalamic and parietal perfusion impairment in autism.