Monosodium urate deposition in the lumbosacral spine of patients with gout compared with non-gout controls: A dual-energy CT study.

Background: Gout is the most common cause of inflammatory arthritis in adults. Gout predominantly affects the peripheral joints, but an increasing number of published cases report gout affecting the spine. We used dual-energy CT (DECT) to assess the prevalence of monosodium urate (MSU) deposition in the spine of gout patients compared to controls, and to investigate whether gout or spinal MSU deposition is associated with low back pain.

Methods: 25 controls and 50 gout subjects (non-tophaceous and tophaceous) were enrolled. Demographics, gout history, Aberdeen back pain score, serum urate (sU), ESR and CRP were ascertained. Subjects underwent DECT of the lumbosacral spine, which was analyzed using manufacturer's default post-processing algorithm for MSU deposition as well as a maximally-specific algorithm to exclude potential artifact.

Findings: 72 subjects were analyzed (25 control, 47 gout). Gout subjects had greater BMI, serum creatinine, sU, CRP, and ESR versus controls. Using the default algorithm, MSU-coded volumes in the lumbosacral spines were significantly higher among the gout subjects vs controls (p = 0.018). 34% of gout subjects vs 4% of controls had spinal MSU-coded deposition (p = 0.0036). Applying the maximally-specific DECT post-processing algorithm, 18% of gout patients vs 0% of controls continued to demonstrate spinal MSU-coded deposition (p = 0.04). Non-tophaceous and tophaceous subjects did not differ in spinal MSU-coded deposition or sU. Gout patients had more back pain than controls.

Interpretation: A significant subpopulation of gout patients have spinal MSU-coded lesions. Default and maximally-specific MSU post-processing algorithms yielded different absolute MSU-coded volumes, but similar patterns of results. Gout patients had more back pain than controls. Spinal MSU deposition in gout patients may have implications for clinical picture and treatment.