Imaging of the aortic valve using fluorodeoxyglucose positron emission tomography increased valvular fluorodeoxyglucose uptake in aortic stenosis.

OBJECTIVES: Because fluorodeoxyglucose positron emission tomography (FDG-PET) imaging provides a noninvasive index of inflammation, we sought to assess whether FDG uptake in the aortic valve (AV) is increased in aortic stenosis (AS).
BACKGROUND: AS is associated with valvular inflammation.
METHODS: FDG-PET/computed tomography data were retrospectively evaluated in 84 patients (age 73 ± 9 years, 45% female), 42 patients with AS, and 42 age-matched controls. FDG uptake was determined within the AV while blinded to AS severity. Target-to-background ratio (TBR) was calculated as valvular/blood activity. Stenosis severity was established on echocardiography, and presence of AV calcification was independently assessed on computed tomography.
RESULTS: The aortic valve PET signal (TBR) was increased in AS compared with controls (median 1.53 [interquartile range (IQR): 1.42 to 1.76] vs. 1.34 [IQR: 1.20 to 1.55]; p < 0.001). Further, compared with controls, TBR was increased in mild (median 1.50 [IQR: 1.36 to 1.75]; p = 0.01) and moderate (median 1.70 [IQR: 1.52 to 1.94]; p < 0.001), but not in severe AS (median 1.49 [IQR: 1.40 to 1.54]; p = 0.08). When subjects were categorized according to AV calcification, valvular FDG uptake was increased in mildly (median 1.50 [IQR: 1.36 to 1.79]; p < 0.01) and moderately (median 1.67 [IQR: 1.50 to 1.85]; p < 0.001), but not severely calcified valves (median 1.51 [IQR: 1.38 to 1.54]; p = 0.15), compared with noncalcified valves (median 1.35 [IQR: 1.20 to 1.52]).
CONCLUSIONS: This study supports the hypothesis that AS is an inflammatory condition and suggests that inflammation may be reduced in late-stage disease. This may have important implications in the design of studies assessing the effect of therapeutic agents in modifying progression of AS.