Low-Field MRI, Ultrasound Demonstrate Good Responsiveness in Psoriatic Arthritis

A comparison of inflammation scores obtained using magnetic resonance imaging (MRI) and ultrasound imaging found that both modalities demonstrate good responsiveness, providing additional validation for using MRI and ultrasound as outcome measures in psoriatic arthritis (PsA), according to study results published in The Journal of Rheumatology.  

To describe and compare the performance metrics of commonly used MRI and ultrasound imaging scores, investigators conducted a substudy of The Tight Control of Psoriatic Arthritis (TICOPA; ISRCTN Registry: ISCRCTN30147736) randomized trial. The 48-week substudy, which compared standard care and tight control in early PsA, found better outcomes for tight control. The performance metrics of the outcomes of each imaging modality were evaluated and compared with the clinical data. Disease activity was measured using the Psoriatic Arthritis Disease Activity Score (PASDAS), including physician and patient global assessment of disease, dactylitis and enthesitis, tender and swollen joint counts, C-reactive protein (CRP) levels, and health-related quality of life.

Noncontrast, single-hand 0.2T MRI was assessed using the OMERACT Psoriatic Arthritis Magnetic Resonance Imaging Score (PsAMRIS) with additional global inflammation scoring. Same-hand ultrasound was scored for power Doppler, grey scale, and erosions at the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints. Matched baseline and follow-up ultrasound and MRI data and combined ultrasound, MRI, and clinical data were used for analysis; there were no data imputation.

Among the 85 patients who enrolled in the TICOPA substudy, the mean tender joint count was 11.7, the mean swollen joint count was 7.3, the mean Psoriasis Area and Severity Score skin score was 2.7, and the mean CRP was 23.9 mg/dL. In addition, 59 patients (69%) presented with polyarticular disease (≥5 joints involved). Baseline disease activity was high (mean PASDAS score, 5.1) and although there were significant within-group changes in clinical outcomes (tight control group, mean change in PASDAS score, 2.2; P <.0001 vs standard care, 1.1, P =.03), the between group differences were not significant (F=3.6, P =.06). Paired baseline and 48-week observations were available for 61 patients for MRI and 78 patients for ultrasound, with complete paired imaging and clinical data available for 50 patients.

Significant within-group changes were seen for MCP-level inflammatory PsAMRIS components: MRI global inflammation (median difference, Standardized Response Mean), 3.25 (-5.0 to 12.0), 0.68 for tight control and 1.0 (-4.5 to 17.5), 0.45 for standard care. Similar within-group changes were seen for ultrasound: 1.0 (-13.0 to 23.0), 0.45 for tight control and 3.0 (-6.0 to 21.0), 0.77 for standard care. No between group differences were seen, and no erosion progression differences were observed. Significant correlations were found between MRI and ultrasound baseline and change scores. A significant correlation was seen between baseline PsA disease activity scores and MRI global inflammation scores (Spearman’s rho for MCP, 0.46; PIP, 0.63).

Study limitations included the underpowered sample size, which precluded demonstrating differences in imaging outcomes between 2 active therapies, single-hand imaging, and a limited ability to demonstrate improvements in inflammation.

Investigators concluded, “The imaging substudy of TICOPA reported in this paper provides further validation for the use of both imaging modalities as outcome measures in this disease. The somewhat sporadic joint involvement of PsA, where only a few individual joints may be affected, makes aggregate imaging scores less responsive to change and future imaging studies should perhaps focus on polyarticular disease inclusion, or one manifestation, such as dactylitis, to demonstrate within and between group changes in response to treatment.”

Disclosure: This clinical trial was supported by Pfizer. Please see the original reference for a full list of authors’ disclosures.

Reference

Helliwell PS, Coates LC, Chew NS, et al. Comparing psoriatic arthritis low-field magnetic resonance imaging, ultrasound and clinical outcomes: data from the TICOPA trial [published online November 1, 2019]. J Rheumatol. doi:10.3899/jrheum.181385