Semiquantitative software SPECT analysis in aneurysmal subarachnoid hemorrhage-related vasospasm.

BACKGROUND: Cerebral vasospasm is a major cause of morbidity and mortality among patients after subarachnoid hemorrhage (SAH) from ruptured intracranial aneurysms. Patients are often monitored using transcranial Doppler (TCD) ultrasound and single photon emission computed tomography (SPECT) techniques. Historically SPECT has been evaluated qualitatively, though quantitative analysis software is now used to evaluate other cerebral pathologies.

OBJECTIVE: Our aim was to evaluate the utility of semiquantitative SPECT using Hermes brain registration and analysis software (BRASS) relative to TCD ultrasound and qualitative SPECT interpretation within a cohort of patients, all with cerebral vasospasm as measured by digital subtraction angiography.

METHODS: Retrospective analysis of 32 nonconsecutive patients, admitted for aneurysmal SAH examining perfusion deficits in terms of anterior, middle, and posterior vascular distributions using both TCD ultrasonography and brain perfusion SPECT studies.

RESULTS: McNemar analysis of accuracy between modalities showed a better overall performance trend for qualitative SPECT versus BRASS SPECT (Fisher exact = 0.99) and a statistically significant better performance of qualitative SPECT versus TCD in measuring anterior cerebral artery vasospasm (Fisher exact = 0.035). BRASS SPECT, however, performed better than qualitative SPECT in diagnosing posterior circulation vasospasm (Fisher exact = 0.180 vs. 0.358) and had greater specificity in determining anterior circulation vasospasm (71 vs. 57%).

CONCLUSION: BRASS SPECT is a useful method for evaluating cerebral perfusion and needs further optimization, particularly as it pertains to establishing semiquantitative cerebral perfusion parameters. It can serve as an adjunct to traditional SPECT evaluation of SAH particularly in determining subtle changes in the perfusion of the anterior and posterior arterial distributions.