Utility of 99mTc-human serum albumin diethylenetriamine pentaacetic acid SPECT for evaluating endoleak after endovascular abdominal aortic aneurysm repair

Abstract

OBJECTIVE. The purpose of this study was io assess the utility of 99mTe-human serum albumin diethylenetriamine pentaaeetic acid (99mTe-HSAD) SPECT in the detection of en-doleaks after endovascular abdominal aortic aneurysm repair. SUBJECTS AND METHODS. Fifteen patients (11 men, four women) with aneurysm sac expansion of 5 mm or greater after endovascular abdominal aortic aneurysm repair underwent three-phase CT, 99mTc-HSAD SPECT, and CT during aortography. Sensitivity calculations for three-phase CT and 99mTe-HSAD SPECT were performed with CT during aortography as the reference standard. The volume of each endoleak was measured with CT during aortography. Seven subjects underwent embolization with A/-butyl cyanoacrylate (NBCA)-Lipiodol (ethiodized oil, Guerbet and metallic coils. Three-phase CT and 99mTc-HSAD SPECT were repeated after embolization to assess their efficacy. RESULTS. Endoleaks were interpreted as perigraft radioisotope accumulation in 12 patients (80.0%) on 99mTc-HSAD SPECT images, in 13 patients (86.7%) on three-phase CT images, and in 15 patients (100%) on CT during aortography. The mean endoleak volume visualized with 99mTc-HSAD SPECT was 8.37 cm3 (range, 5.2-15.1 cm3), and the volume not visualized was 3.47 cm3 (2.5-4.6 cm3), a statistically significant difference (p = 0.019). In two patients, 99mTc-HSAD SPECT depicted endoleaks evident at delayed phase CT during aortography but not at three-phase CT, suggesting they were slow-filling endoleaks. Accumulation of 99mTe-HSAD corresponding to endoleaks disappeared after embolization, but CT evaluation of embolization was impeded by artifacts of NBCA-Lipiodol and metallic coils. CONCLUSION. Tecbnelium-99m-labeled HSAD SPECT proved less sensitive than three-phase CT but depicted endoleaks with volumes 5.2 cm3 or greater as perigraft radioisotope accumulation. Slow-filling endoleaks can be visualized with 99mTe-HSAD SPECT, which can be used to evaluate the efficacy of embolization.