In a series of 10 patients with severe traumatic brain injury FDG PET studies were carried out in an interval of 1–62 months post trauma. They revealed decreased values of glucose metabolic turnover not only in the regions visibly affected on CT and MRI, but also in distant areas of the ipsi- and contralateral hemispheres. While the global metabolism of the injured hemispheres was decreased to 73% of healthy probands, also the „unaffected“ hemispheres in patients with unilateral lesions were suppressed to 80% of control values. Focal reductions of metabolism in traumatic regions were apparent in 9 cases, reaching a level of less than 20 µmol/100g tissue/min in 7 of them. In selected homolateral regions of interest beyond the apparent traumatic lesion a decreased metabolism lower than 80% of the contralateral analogous region was found in 6 patients, predominantly in the thalamus and putamen. Surprisingly also selected regions of increased metabolism in the injured hemisphere, compared to the opposite side, were found in 4 patients. Only in 1, however, did these values surpass those of healthy volunteers. In conclusion, a decreased posttraumatic metabolic turnover is present in homolateral as well as in contralateral brain regions – in areas unaffected by trauma on morphological imaging (CT and MRI).

        Key words: cerebral glucose metabolism, brain trauma, PET, FDG, regional differences