SPECT BRAIN PERFUSION ABNORMALITIES IN MILD OR MODERATE TRAUMATIC BRAIN INJURY

The purpose of this atlas is to present a review of the literature sho wing the advantages of SPECT brain perfusion imaging (BPI) in mild or moderate traumatic brain injury (TBI) over other morphologic imaging m odalities such as x-ray CT or MRI. The authors also present the techni cal recommendations for SPECT brain perfusion currently practiced at t heir center. For the radiopharmaceutical of choice, a comparison betwe en early and delayed images using Tc-99m HMPAO and Tc-99m ECD showed t hat Tc-99m HMPAO is more stable in the brain with no washout over time . Therefore, the authors feel that Tc-99m HMPAO is preferable to Tc-99 m ECD. Recommendations regarding standardizing intravenous injection, the acquisition, processing parameters, and interpretation of scans us ing a ten grade color scale, and use of the cerebellum as the referenc e organ are presented. SPECT images of 228 patients (age range, 11 to 88; mean, 40.8 years) with mild or moderate TBI and no significant med ical history that interfered with the results of the SPECT BP were rev iewed. The etiology of the trauma was in the following order of freque ncy: motor vehicle accidents (45%) followed by blow to the head (36%) and a fall (19%). Frequency of the symptoms was headache (60.9%), memo ry problems (27.6%), dizziness (26.7%), and sleep disorders (8.7%). Co mparison between patients imaged early (<3 months) Versus those imaged delayed (>3 months) from the time of the accident, showed that early imaging detected more lesions (4.2 abnormal lesions per study compared to 2.7 in those imaged more than 3 months after the accident). Of 41 patients who had mild traumatic injury without loss of consciousness a nd had normal CT, 28 studies were abnormal. Focal areas of hypoperfusi on were seen in 77% (176 patients, 612 lesions) of the group of 228 pa tients. The sites of abnormalities were in the following order: basal ganglia and thalami, 55.2%, frontal lobes, 23.8%, temporal lobes, 13%, parietal, 3.7%, insular and occipital lobes together, 4.6%.