Chronological positron emission tomographic study of severe diffuse brain injury in the chronic stage

Cerebral blood flow and metabolism were investigated in five patients with severe diffuse brain injury in the chronic stage, using positron emission tomography (PET). Regional cerebral blood flow, regional oxygen extraction fraction, regional cerebral blood volume, regional cerebral metabolic rate for oxygen, and regional cerebral metabolic rate for glucose were measured bilaterally in the frontal, temporal, occipital, and parietal gray matter, as well as the white matter of the centrum semiovale. In 4 of 5 patients, a follow-up PET study was also performed. In three cases, below-normal regional cerebral blood flow and regional cerebral metabolic rate for oxygen values accompanied by above-normal regional oxygen extraction fraction values, as well as low metabolism, were demonstrated in the initial PET studies. In two of three cases, clinical improvements were observed, and follow-up PET data also improved. These findings suggest that chronological PET studies may be able to assess quantitatively clinical improvements in patients with diffuse brain injury.