Abstract 4146069: ¹⁸ F-NaF and ¹⁸ F-FDG and calcification predict the development of abdominal aortic aneurysms and is attenuated by drug therapy

Background: Abdominal aortic aneurysms (AAA) expand over time and increase the risk of fatal ruptures. While large aortic diameter increases the risk of rupture, some AAA rupture at small diameters and some large aneurysms do not rupture. Therefore, identification of patients at increased risk of rapid AAA expansion and rupture is importance. 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 were predictive of AAA expansion. Methods: Seventy-four (74) male Sprague–Dawley rat AAA models were imaged using positron emission tomography-computed tomography (PET-CT) 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=0.0010) and von Kossa staining-positive areas (r=0.89, p<0.0001), 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. Although drugs suppressed 18 F-NaF and 18 F-FDG uptake, only atorvastatin significantly reduced aortic enlargement. Risedronate decreased the calcification volume; however, the aorta was significantly enlarged. 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(1week): r=0.61, 18 F-FDG(2weeks): r=0.51, calcification volume(1week): r=0.59, p<0.0001]. 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. Conclusion: The uptake of 18 F-NaF and 18 F-FDG and the calcification volume at appropriate times correlated with the development of AAAs, with 18 F-NaF uptake being the strongest predictor.