Analysis of MRI and SPECT in patients with acute head injury.

Traumatic lesions defined by magnetic resonance (MR) imaging were divided into two groups according to findings on computed tomography (CT). This classification reflected difference in the regional cerebral blood flow (rCBF). In the contusional lesions which CT could demonstrate, rCBF varied from hyperperfusion to hypoperfusion, while it was almost always decreased in the lesions which CT could not detect. These results suggest that the former may include a mixture of brain oedema and hyperemia and the latter may imply brain oedema. MR imaging can reveal the minor oedema which CT fails to show in patients with acute head injury.