How may complementary magnetic resonance imaging findings facilitate the diagnosis of inflammatory hand arthritis involving the distal interphalangeal joint? A prospective cohort study.

PURPOSE: In this study, we aimed to characterize the role of magnetic resonance imaging (MRI) in making a specific diagnosis of inflammatory hand arthritis (IHA), particularly in early stages or ambiguous cases.

METHODS

Patients aged ≥18 years with suspicious IHA in at least one joint were enrolled in this single-center prospective study. Three Tesla MRI (3T-MRI) with a fine-tuned protocol was utilized, whereby differential diagnoses were made by radiologists according to the predominant involvement of synovium or synovioentheseal complex (SEC) and/or specific degenerative findings. Physical examination, laboratory findings, treatment response, and already-established classification criteria were used to reach the final diagnostic groups: psoriatic arthritis (PsA), rheumatoid arthritis (RA), erosive osteoarthritis or calcium pyrophosphate dihydrate deposition disease (EOA/CPPD), and arthritis with distal interphalangeal joint (DIPJ) involvement (ADIPI) not otherwise classified into any group. Statistical analyses mainly included pairwise comparisons of MRI findings across diagnostic groups.

RESULTS

Of 80 patients enrolled, 57 [42 women; mean age, 54 years (range, 28-79 years)] constituted the final group with eventual clinical diagnoses of 11 PsA, 14 RA, 11 EOA/CPPD, and 21 ADIPI. MRI revealed no difference between the PsA and ADIPI groups, except for nailbed enthesitis (P = 0.048, effect size: 0.416). A comparison between PsA and RA revealed that enthesitis, excluding pulley enthesitis, was more frequently observed in PsA (P = 0.033, effect size: 0.497). Periarticular soft tissue edema was also more common in PsA than RA (P = 0.042, effect size: 0.461). When the ADIPI and PsA groups were combined, enthesitis and periarticular soft tissue edema were more common than in other groups (P < 0.001).

CONCLUSION

SEC inflammation and periarticular edema on MRI strongly predict PsA, especially in patients with DIPJ arthritis who do not meet rheumatological classification criteria.

CLINICAL SIGNIFICANCE: 3T-MRI with a fine-tuned protocol enables a more accurate differential diagnosis of hand inflammatory arthritis, potentially guiding earlier and more targeted interventions.