Dual-Energy CT Detects Spinal Monosodium Urate in Patients With Gout

A significant percentage of patients with gout have spinal monosodium urate (MSU) lesions as detected by dual-energy computed tomography (DECT), according to study findings published in Seminars in Arthritis and Rheumatism.

The researchers used DECT to measure spinal MSU deposits in patients with nontophaceous and tophaceous gout compared with healthy control participants, and to determine the association between spinal MSU deposits and low back pain.

The study comprised 75 adult patients (25 with tophaceous gout, 25 with nontophaceous gout, and 25 controls) between the ages of 45 and 80 years. Demographic, clinical, and laboratory data were collected, including the Aberdeen low back pain score, serum urate levels, serum creatinine levels, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels. Axial scanning using DECT imaging was performed and analyzed using the manufacturer’s default calculation algorithm and a maximally-specific DECT algorithm to remove potential artifact.

In total, 72 patients completed all analyses (25 controls and 47 patients with gout). Patients with gout were more likely to have a history of kidney disease and had a higher body mass index (BMI), serum creatinine level, serum urate level, CRP level, and ESR compared with healthy controls.

Patients with gout demonstrated higher rates of MSU-coded deposition compared with controls using the manufacturer’s default algorithm (36% of patients with gout vs 4% of controls; P =.0036) and the maximally-specific algorithm (18% of patients with gout vs 0% of controls; P =.04). There was a significant correlation between MSU-coded deposition and serum urate, but not ESR or CRP.

There was no significant difference in MSU-coded deposition, low back pain, or serum urate levels between patients with tophaceous and nontophaceous gout. While patients with gout were more likely than controls to have back pain, their back pain scores did not vary based on the presence or absence of spinal MSU-coded lesions.

Limitations of the study included inconsistencies in the patient population with respect to duration of disease and the use of urate lowering therapy, the absence of conventional CT features of gout in all patients, and limited statistical power when using the maximally-specific algorithm.

The researchers concluded, “Additional studies are needed to (1) confirm that spinal MSU-coded lesions actually represent MSU; (2) determine the absolute volume of spinal MSU deposition among gout patients; (3) identify which gout patients are at risk for developing spinal MSU deposition; (4) determine the clinical impact of such MSU deposition, including its impact on total body urate burden and potential treatment resistance; and (5) determine the prevalence of frank tophaceous disease in the spine.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Toprover M, Mechlin M, Fields T, Oh C, Becce F, Pillinger MH. Monosodium urate deposition in the lumbosacral spine of patients with gout compared with non-gout controls: A dual-energy CT study. Semin Arthritis Rheum. Published online June 30, 2022. doi:10.1016/j.semarthrit.2022.152064