To explore potential subclinical involvement of the axial skeleton by magnetic resonance imaging (MRI) of the sacroiliac (SI) joints and the entire spine in patients with skin psoriasis without clinical evidence of peripheral or axial inflammation.
Twenty patients with skin psoriasis but no clinical evidence of peripheral or axial inflammation and 22 healthy controls underwent standardized dermatologic and rheumatologic clinical examination and unenhanced 1.5T MRI of the SI joint and the entire spine. Two blinded readers globally assessed the presence or absence of SI joint inflammation simultaneously on T1-weighted and short tau inversion recovery MRI sequences with a confidence estimate. Bone marrow edema, fat metaplasia, erosion, and ankylosis of the SI joint, and vertebral corner inflammatory lesions and fat lesions were recorded using standardized modules. The prevalence of each lesion type was calculated in both groups, averaged across 2 readers. The number of subjects with lesions in the SI joint and spine (≥1, 2, 3, 4, or 5 lesions) as concordantly assessed by both readers was recorded.
The median duration of skin psoriasis was 23.0 years, the median age of patients was 48.5 years, and 25.0% of patients and 9.1% of healthy controls were concordantly classified by both readers as having SI joint inflammation (P = 0.23). The prevalence of bone marrow edema and structural lesions was comparable across patients and controls, both on SI joint and spine MRI.
In this controlled study, patients with skin psoriasis but no clinical arthritis or spondylitis showed limited evidence of concomitant subclinical axial involvement by SI joint and spine MRI. These findings do not support routine screening for subclinical axial inflammation in patients with longstanding skin psoriasis.