SPECT Brain Perfusion Abnormalities in Mild or Moderate Traumatic Brain Injury

Abstract

The purpose of this atlas is to present a review of the literature showing the advantages of SPECT brain perfusion imaging (BPI) in mild or moderate traumatic brain injury (TBI) over other morphologic imaging modalities such as x-ray CT or MRI. The authors also present the technical recommendations for SPECT brain perfusion currently practiced at their center. For the radiopharmaceutical of choice, a comparison between early and delayed images using Tc-99m HMPAO and Tc-99m ECD showed that 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-99m ECD. Recommendations regarding standardizing intravenous injection, the acquisition, processing parameters, and interpretation of scans using a ten grade color scale, and use of the cerebellum as the reference 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 medical history that interfered with the results of the SPECT BP were reviewed. The etiology of the trauma was in the following order of frequency: motor vehicle accidents (45%) followed by blow to the head (36%) and a fall (19%). Frequency of the symptoms was headache (60.9%), memory problems (27.6%), dizziness (26.7%), and sleep disorders (8.7%). Comparison 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 and had normal CT, 28 studies were abnormal. Focal areas of hypoperfusion were seen in 77% (176 patients, 612 lesions) of the group of 228 patients. 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%.

Long-Term Consequences of Traumatic Brain Injury: Current Status of Potential Mechanisms of Injury and Neurological Outcomes

“…4). [233][234][235][236][237][238][239][240][241] Using MRI imaging or other methodologies, evidence for depressed blood flow throughout the injured and contralateral hemisphere have been documented. Moderate reductions in chronic blood flow can augment slow, evolving injury processes or aggravate events that were initiated by the acute insult.…”

The Role of Thalamic Damage in Mild Traumatic Brain Injury

“…5 One possible explanation for this discrepancy is that, in addition to white matter, the thalamus could perhaps be another important site of injury in mTBI. 5,[7][8][9][10][11][12][13][14][15][16][17] This deep gray matter structure is often described as the central relay station of the brain because it has reciprocal projections to the entire cerebral cortex, and plays a principal role in the processing and transmission of information between sensory, motor, and associative regions. 18 These multiple functional pathways influence many global activities and therefore could potentially account for a great deal of the morbidity associated with mTBI.…”

Subcortical Hypoperfusion following Surgery For Aneurysmal Subarachnoid Haemorrhage: Implications For Cognitive Performance?

“…In this regard, it is interesting to note that in a study of SPECT brain perfusion imaging in traumatic brain injury [1] over 50% of the sites of hypoperfusion were located in the basal ganglia and thalami. However, the lack of any indication on MR imaging of major structural damage to the thalamus suggests that any direct structural damage to the thalamus would have to be subtle, and that this would in turn need to produce fairly extensive blood flow changes.…”