Monosodium Urate Crystal Deposition in Coronary Artery Plaque by 128-Slice Dual-Energy Computed Tomography: An Ex Vivo Phantom and In Vivo Study.

ABSTRACT

OBJECTIVE: Monosodium uric acid (MSU) crystals may accumulate in the coronary plaque. The objective was to assess whether dual-energy computed tomography (DECT) allows for detection of MSU in coronary plaque. METHODS: Patients were examined with 128-slice DECT applying a cardiac electrocardiogram-gated and peripheral extremity protocol. Patients were divided into 3 groups gout (tophi >1 cm in peripheral joints), hyperuricemia (>6.5 mg/dL serum uric acid), and controls. The groups were matched for cardiovascular risk factors. Monosodium uric acid-positive (+) and calcified plaque were distinguished, and the coronary artery calcium score was calculated. Ex vivo phantom MSU solutions were diluted in different NaCL solutions (5%/10%/15%/20%/25%). Coronary artery models with 2 different plaque types (MSU+ and calcified) were created. RESULTS: A total of 96 patients were included (37 with gout, 33 with hyperuricemia, and 26 controls). Monosodium uric acid-positive plaques were found more often in patients with gout as compared with controls (91.9% vs 0.38%; P < 0.0001), and the number of plaques was higher (P < 0.0001). Of 102 MSU+ plaques, 26.7% were only MSU+ and 74.2% were mixed MSU+/calcified. Monosodium uric acid-positive plaque had mean 232.3 Hounsfield units (range, 213-264). Coronary artery calcium score was higher in patients with gout as compared with controls (659.1 vs 112.4 Agatston score; P < 0.001). Patients with gout had more MSU+ plaques as compared with patients with hyperuricemia (91.6% vs 2.9%; P < 0.0001), and coronary artery calcium score was higher (659.1 vs 254 Agatston score; P < 0.001), but there was no difference between patients with hyperuricemia and controls. Ex vivo phantom study MSU crystals were detected by DECT in solutions with a concentration of 15% or greater MSU and could be distinguished from calcified. CONCLUSIONS: Coronary MSU+ plaques can be detected by DECT in patients with gout.