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[Dynamic CT in the acute stage of head injury].

Dynamic computed tomography (CT) was performed on 14 patients with acute head injury. Patients were classified into three groups according to the Glasgow Coma Scale (GCS). Four patients with severe head injury (GCS 3-6) had acute subdural hematoma with diffuse cerebral swelling on the initial CT scan. Seven patients with moderate head injury (GCS 8-13) had massive acute epidural hematoma or acute subdural hematoma without diffuse cerebral swelling. Three patients with slight head injury (GCS 15) had thin acute epidural hematoma, cerebral contusion, or normal scan. Dynamic CT of the brain consisted of performing eight rapid serial scans after a bolus intravenous injection of 50 ml of contrast material. Data from these scans were analized utilizing the time-density curves of four brain regions—the arteries, gray and white matters, and the cerebral hemispheres. In patients with slight head injury, the time-density curves of these four regions on the lesional side were nearly similar to those of the opposite side. An obvious peak was observed in the artery, gray matter, and cerebral hemisphere and the peak time of these regions nearly accorded. In patients with moderate head injury, the peak time of the gray matter was slightly retarded, especially in the side ipsilateral to the acute subdural hematoma. In two cases of four head injured patients who had acute subdural hematoma with marked diffuse cerebral swelling, the time-density curves of the artery, gray matter, and cerebral hemispheres of the bilateral or lesional side were flat. In the remaining two patients, an obvious peak was observed in the artery and gray matter, but the peak time of the gray matter was greatly retarded from that of the artery. It is possible that the diffuse cerebral swelling seen on CT scans during the acute stage of head injury is due either to hyperemia or to acute cerebral edema. In the presence of diffuse cerebral swelling, the cerebral circulation of the arterioles or capillary bed may be greatly disturbed, even if the cerebral circulation of the arteries, which can be demonstrated on the dynamic CT images, is maintained.