Correlation of inflammation assessed by18F-FDG PET, active mineral deposition assessed by18F-fluoride PET, and vascular calcification in atherosclerotic plaque: A dual-tracer PET/CT study

Abstract

Formation and progression of atherosclerotic plaque is a dynamic and complex process involving various pathophysiologic steps including inflammation and calcification. The purpose of this study was to compare macrophage activity as determined by 18F-FDG PET and ongoing mineral deposition as measured by 18F-sodium fluoride PET in atherosclerotic plaque and to correlate these findings with calcified plaque burden as assessed by CT. Methods: Forty-five patients were examined by whole-body 18F-FDG PET, 18F-sodium fluoride PET, and CT. Tracer uptake in various arterial segments was analyzed both qualitatively and semiquantitatively by measuring the blood-pool-corrected standardized uptake value (target-to-background ratio [TBR]). The pattern of tracer uptake in atherosclerotic lesions was compared after color-coded multistudy image fusion of PET and CT studies. The Fisher exact test and the Spearman correlation coefficient rs were used for statistical analysis of image-based results and cardiovascular risk factors. Intra- and interrater reproducibility were evaluated using the Cohen κ. Results: 18F-sodium fluoride uptake was observed at 105 sites in 27 (60%) of the 45 study patients, and mean TBR was 2.3 ± 0.7. 18F-FDG uptake was seen at 124 sites in 34 (75.6%) patients, and mean TBR was 1.5 ± 0.3. Calcified atherosclerotic lesions were observed at 503 sites in 34 (75.6%) patients. Eighty-one (77.1%) of the 105 lesions with marked 18F-sodium fluoride uptake and only 18 (14.5%) of the 124 lesions with 18F-FDG accumulation were colocalized with arterial calcification. Coincident uptake of both 18F-sodium fluoride and 18F-FDG was observed in only 14 (6.5%) of the 215 arterial lesions with radiotracer accumulation. Conclusion: PET/ CT with 18F-FDG and 18F-sodium fluoride may allow evaluation of distinct pathophysiologic processes in atherosclerotic lesions and might provide information on the complex interactions involved in formation and progression of atherosclerotic plaque. Copyright © 2011 by the Society of Nuclear Medicine, Inc.