Aortic Uptake of 18 F-NaF and 18 F-FDG and Calcification Predict the Development of Abdominal Aortic Aneurysms and Is Attenuated by Drug Therapy

Abstract

BACKGROUND: Abdominal aortic aneurysms expand over time and increase the risk of fatal ruptures. To predict expansion, the isolated assessment of 18 F-fluorodeoxyglucose (FDG) and sodium fluoride (NaF) uptake or calcification volume in aneurysms has been investigated with variability in results. We systematically evaluated whether 18 F-FDG and 18 F-NaF uptake was predictive of abdominal aortic aneurysm expansion. METHODS: Seventy-four male Sprague-Dawley rat abdominal aortic aneurysm models were imaged using positron emission tomography–computed tomography with 18 F-FDG and 18 F-NaF at 1, 2, 4, 6, and 8 weeks after CaCl 2 or saline stimulation. In the 1-week cohort (n=25), the correlation between 18 F-FDG or 18 F-NaF uptake and pathological markers was investigated. In the time course cohort (n=49), animals received either atorvastatin, losartan, aldactone, or risedronate to assess the effect of these drugs, and the relationship between aortic size and sequential 18 F-FDG and 18 F-NaF uptake or calcification volume was examined. RESULTS: In the 1-week cohort, the maximum standard unit value of 18 F-FDG and 18 F-NaF uptake correlated with CD68- (r=0.82; P =0.001) and von Kossa staining–positive areas (r=0.89; P <0.001), respectively. In the time course cohort, 18 F-FDG and 18 F-NaF uptake changed in a time-dependent manner and drugs attenuated this uptake. Specifically, 18 F-FDG showed high uptake at weeks 1 and 2, whereas a high 18 F-NaF uptake was noted throughout the study period. Atorvastatin and risedronate showed a decreased and increased aortic size, respectively. The final aortic area correlated well with 18 F-FDG and 18 F-NaF uptake and calcification volume, especially at 1 and 2 weeks ( 18 F-NaF [1 week]: r=0.61, 18 F-FDG [2 weeks]: r=0.51, calcification volume [1 week]: r=0.59; P <0.001). Multiple linear regression analysis showed that the combination of these factors predicted the final aortic size, with 18 F-NaF uptake at 1 week being the strongest predictor. CONCLUSIONS: The uptake of 18 F-NaF and 18 F-FDG and the calcification volume at appropriate times correlated with the development of abdominal aortic aneurysms, with 18 F-NaF uptake being the strongest predictor.