18F-FDG uptake as a predictive factor for progressive aortic enlargement in aortic dissection.

OBJECTIVE Progressive aortic enlargement (PAE) is a critical adverse event in patients with medically treated aortic dissection (AD). However, no reliable predictor of the PAE has been established. The purpose of this study was to evaluate the value of 18F-FDG PET/CT for the prediction of PAE in patients with medically treated AD. METHODS Sixteen patients with AD who underwent optimal medical therapy were enrolled. 18F-FDG PET/CT examinations were performed in subacute phase (2 weeks-3 months) after the onset of AD. Target-to-background ratio (TBR) was measured as the maximum standardized uptake value (SUV) in the dissected aortic wall divided by blood pool SUV. The relation between TBR and occurrence of PAE (> 10 mm/year) was evaluated. RESULTS PAE was observed in four patients during the median follow-up period of 24 months. The TBR measured in the 4 patients showing PAE was significantly higher than that in the remaining 12 patients without PAE (2.44 ± 0.56 vs 1.87 ± 0.33, P = 0.025). The area under the receiver operating characteristic curve of TBR for predicting PAE was 0.82. With a threshold of 2.34, the TBR showed the sensitivity, specificity, and positive and negative predictive value of 75%, 92%, 75%, and 92%, respectively, for the prediction of PAE. CONCLUSIONS Higher 18F-FDG uptake in the dissected aortic wall as determined by TBR is associated with increased risk of PAE in patients with medically treated AD. TBR shows good specificity and negative predictive value for predicting PAE.