This study was aiming at investigating the extent of neuronal damage in cases of traumatic brain injury (TBI) with diffuse axonal injury (DAI) using 123I-iomazenil(IMZ) SPECT and MRI. We compared the findings in 31 patients with TBI without any major focal brain lesions and 25 age-matched normal controls. Subjects underwent 123I-IMZ SPECT and MRI, and also assessment by cognitive function tests. The partial volume effect of 123I-IMZ SPECT was corrected using MRI. In the patients with TBI, decreased spatial concentration of 123I-IMZ binding was detected in the medial frontal/orbitofrontal cortex, posterior cingulate gyrus, cuneus, precuneus, and superior region of the cerebellum. ROC analysis of 123I-IMZ SPECT for the detection of neuronal injury showed a high diagnostic ability of 123I-IMZ binding density for TBI in these areas. The decreased 123I-IMZ uptake density in the cuneus and precuneus was associated with cognitive decline after the injury. In the patients with TBI, brain atrophy was detected in the frontal lobe, anterior temporal and parietal cortex, corpus callosum, and posterior part of the cerebellum. Evaluation of the neuronal integrity by 123I-IMZ SPECT and MRI provides important information for the diagnosis and pathological interpretation in cases of TBI with DAI.
Keywords: SPECT; Traumatic brain injury; imaging; iomazenil; partial volume effect.