Dual-Energy Computed Tomography Detection of Cardiovascular Monosodium Urate Deposits in Patients With Gout

Abstract

Importance: The prevalence of gout has increased in recent decades. Several clinical studies have demonstrated an association between gout and coronary heart disease, but direct cardiovascular imaging of monosodium urate (MSU) deposits by using dual-energy computed tomography (DECT) has not been reported to date.

Objective: To compare coronary calcium score and cardiovascular MSU deposits detected by DECT in patients with gout and controls.

Design, setting, and participants: This prospective Health Insurance Portability and Accountability Act-compliant study included patients with gout and controls who presented to a rheumatologic clinic from January 1, 2017, to November 1, 2018. All consecutive patients underwent DECT to assess coronary calcium score and MSU deposits in aorta and coronary arteries. In addition, cadavers were assessed by DECT for cardiovascular MSU deposits and verified by polarizing microscope. Analysis began in January 2017.

Main outcomes and measures: Detection rate of cardiovascular MSU deposits using DECT in patients with gout and control group patients without a previous history of gout or inflammatory rheumatic diseases.

Results: A total of 59 patients with gout (mean [SD] age, 59 [5.7] years; range, 47-89 years), 47 controls (mean [SD] age, 70 [10.4] years; range, 44-86 years), and 6 cadavers (mean [SD] age at death, 76 [17] years; range, 56-95 years) were analyzed. The frequency of cardiovascular MSU deposits was higher among patients with gout (51 [86.4%]) compared with controls (7 [14.9%]) (χ2 = 17.68, P < .001), as well as coronary MSU deposits among patients with gout (19 [32.2%]) vs controls (2 [4.3%]) (χ2 = 8.97, P = .003). Coronary calcium score was significantly higher among patients with gout (900 Agatston units [AU]; 95% CI, 589-1211) compared with controls (263 AU; 95% CI, 76-451; P = .001) and also significantly higher among 58 individuals with cardiovascular MSU deposits (950 AU; 95% CI, 639-1261) compared with 48 individuals without MSU deposits (217 AU; 95% CI, 37-397; P < .001). Among 6 cadavers, 3 showed cardiovascular MSU deposits, which were verified by polarizing light microscope.

Conclusion and relevance: Dual-energy computed tomography demonstrates cardiovascular MSU deposits, as confirmed by polarized light microscopy. Cardiovascular MSU deposits were detected by DECT significantly more often in patients with gout compared with controls and were associated with higher coronary calcium score. This new modality may be of importance in gout population being at risk from cardiovascular disease.

Figure 1.. Computed Tomography Values for Different Materials

Screenshot from Syngo dual-energy gout application shows a graphical representation of 2-material decomposition algorithm. Attenuation values at low energy (80 kVp) are plotted on the y-axis and values at high energy (140 kVp) on the x-axis. The soft tissue reference line (blue) separates materials with high atomic weight, such as calcium in cortical bone from materials with low atomic weight components, such as uric acid.

Figure 2.. Native Computed Tomography (CT) and Corresponding Dual-Energy CT (DECT) Images in 3 Patients

Patient 1: axial native coronary CT showing extensive calcified plaques in the aortic root (white arrowhead) and left anterior descending artery (LAD) (yellow arrowhead) (A) with corresponding DECT showing monosodium urate (MSU) deposits in aortic root (white arrowhead) and LAD (yellow arrowhead) (D). Patient 2: axial native CT showing calcified plaques ventral the aortic arch (arrowhead) (B) with corresponding DECT with MSU deposits (white arrowhead) close to calcified plaques and artifacts in the paraspinal shoulder musculature close to the rib (yellow arrowhead) (E). Patient 3: axial native CT with extensive calcification of the mitral valve (arrowhead) (C) with corresponding DECT showing MSU deposits close to calcified plaques of the mitral valve (white arrowhead) and artifacts in the bronchial calcifications (yellow arrowhead) (F).

Figure 3.. Polarizing Microscopic Images of Cadaver 2

Image taken from central part of aortic plaque, showing diffuse packed and patchy monosodium urate (MSU) deposits with strong negative birefringence (A) with corresponding axial dual-energy computed tomography (DECT) image showing small MSU deposit (arrowhead) in the aortic arch (D). Image taken from peripheral part of aortic plaque, showing typical needlelike appearance of MSU crystals and strong negative birefringence (B) with corresponding axial DECT image showing small MSU deposit (arrowhead) dorsomedial in the aortic arch (E). Axial native computed tomography image showing calcified plaque in the descending aorta (arrowhead) (C) with corresponding axial DECT image showing small MSU deposit (arrowhead) in the descending aorta (F).