Venous Phase Timing Does Not Predict SPECT Results During Balloon Test Occlusion of the Internal Carotid Artery

INTRODUCTION: The purpose of this study is to evaluate the role of venous phase timing when compared with technetium-99m Single Photon Emission Computed Tomography (SPECT) during angiographic balloon test occlusion of the internal carotid artery (ICA) and subsequent sacrifice of the ICA. METHODS: Fifty-six patients underwent formal balloon test occlusion from April 2008 to February 2014 at our institution. Venous phase timing was calculated for each patient. SPECT imaging for each patient was interpreted by the nuclear medicine radiologist. Statistical analysis on the 3 groups (No Hypoperfusion, Mild Hypoperfusion, Moderate/Severe Hypoperfusion) was calculated using analysis of variance. RESULTS: Twenty-six patients showed no hypoperfusion during SPECT. The average delay of venous phase for these patients was 0.65 seconds. Eight of the 26 patients went on to have vessel sacrifice, with none showing evidence of infarction at the time of discharge. Six patients showed evidence of mild hypoperfusion on SPECT. None of these patients went on to have vessel sacrifice. The average venous delay was 0.5 seconds. Twenty-four patients were found to have moderate or severe hypoperfusion. The average venous delay was 1.08 seconds. Analysis of variance among the 3 groups demonstrated no significant difference (P = 0.22). CONCLUSION: Our study demonstrated no correlation between venous phase timing and SPECT. Future studies comparing multiple tests with patients who have had vessel occlusion are necessary to determine the best adjunctive measures to predict delayed ischemia following carotid occlusion.