Diffusion-weighted MR and apparent diffusion coefficient in the evaluation of severe brain injury

Purpose: To study apparent diffusion coefficient (ADC) maps in severely brain-injured patients. Material and Methods. Four deeply comatose patients with severe brain injury were investigated with single-shot, diffusion-weighted, spin-echo echoplanar imaging. The tetrahedral diffusion gradient configuration and four iterations of a set of b-values tone time of 0 mm(2)/s, and four times of 1000 mm(2)/s) were used to create isotropic ADC maps with high signal-to-noise ratio. ADC values of gray and white matter were compared among patients and 4 reference subjects. Results. One patient was diagnosed as clinically brain dead after the MR examination. The patient's ADC values of gray and white matter were significantly lower than these of 3 other brain-injured patients. In addition the ADC value of white matter was significantly lower than that of gray matter. Conclusion: The patient with fatal outcome shortly after MR examination differed significantly from other patients with severe brain injury but non-fatal outcome, with regard to ADC values in gray and white matter. This might indicate a prognostic value of ADC maps in the evaluation of traumatic brain injury.