Magnetization transfer imaging in the detection of injury associated with mild head trauma.

BACKGROUND AND PURPOSE Most traumatic brain injuries are classified as mild, yet in many instances cognitive deficits result. The purpose of this study was to investigate possible relationships between quantitative magnetization transfer imaging (MTI) and neurocognitive findings in a cohort of patients with mild head trauma but negative findings on conventional MR images. METHODS We examined 13 patients and 10 healthy volunteers with a standard MR protocol including fast spin-echo and gradient-echo imaging, to which was added quantitative MTI. MTI was performed with a modified gradient-echo sequence incorporating pulsed, off-resonance saturation. Both region-of-interest analysis and contour plots were obtained from the MTI data. A subgroup of nine patients was examined with a battery of neuropsychological tests, comprising 25 measures of neurocognitive ability. RESULTS The magnetization transfer ratio (MTR) in the splenium of the corpus callosum was lower in the patient group as compared with the control group, but no significant reduction in MTR was found in the pons. Individual regional MTR values were significantly reduced in two cases, and contour plot analysis revealed focal areas of abnormality in the splenium of four patients. All the patients showed impairment on at least three measures of the neuropsychological test battery, and in two cases a significant correlation was found between regional MTR values and neuropsychological performance. CONCLUSION Our results suggest that MTI and contour plot analysis may add sensitivity to the MR imaging examination of patients with traumatic brain injury.