[11C]-PBR28 positron emission tomography signal as an… : PAIN
O), in KOA. Twenty-one KOA patients and 11 healthy controls (HC) underwent positron emission tomography/magnetic resonance imaging (PET/MRI) knee imaging with the TSPO ligand [11C]-PBR28. Standardized uptake values were extracted from regions-of-interest (ROIs) semiautomatically segmented from MRI data, and compared across groups (HC, KOA) and subgroups (unilateral/bilateral KOA symptoms), across knees (most vs least painful), and against clinical variables (eg, pain and Kellgren–Lawrence [KL] grades). Overall, KOA patients demonstrated elevated [11C]-PBR28 binding across all knee ROIs, compared with HC (all P’s < 0.005). Specifically, PET signal was significantly elevated in both knees in patients with bilateral KOA symptoms (both P's < 0.01), and in the symptomatic knee (P < 0.05), but not the asymptomatic knee (P = 0.95) of patients with unilateral KOA symptoms. Positron emission tomography signal was higher in the most vs least painful knee (P < 0.001), and the difference in pain r