Objectives: To investigate the value in clinical practice of hand magnetic resonance imaging (MRI) and whole-body bone scintigraphy in the differential diagnosis of patients with unclassified arthritis.
Methods: 41 patients with arthritis (≥2 swollen joints; >6 months’ duration), which remained unclassified despite conventional clinical, biochemical and radiographical (hands and feet) examinations, were included. Patients who fulfilled the ACR criteria for RA, or had radiographic bone erosions, were excluded. Contrast-enhanced MRI of the wrist and metacarpophalangeal joints of the most symptomatic hand and whole-body bone scintigraphy were performed. Subsequently, two rheumatologists agreed on the most likely diagnosis and patients were treated accordingly. A final diagnosis was made by another specialist review 2 years later.
Results: Tentative diagnoses after MRI and bone scintigraphy were: RA: 13, osteoarthritis: 8, other inflammatory diseases: 11, arthralgias without inflammatory or degenerative origin: 9. Two years later, 11 of 13 patients with an original tentative RA diagnosis had fulfilled the ACR criteria, while 2 were reclassified (one to psoriatic arthritis (RF-negative; +psoriasis), one to unspecific selflimiting arthritis). No patients classified as non-RA at baseline had fulfilled the ACR criteria after 2 years. Presence of MRI synovitis, MRI erosion and bone scintigraphic pattern compatible with RA showed 100% specificity for an RA diagnosis at 2 years' follow-up.
Conclusions: In arthritis patients, unclassified despite conventional clinical, biochemical and radiographic examinations, MRI and scintigraphy allowed correct classification as RA or non-RA in 39 of 41 patients, when fulfilment of ACR criteria 2 years later was considered the standard reference.
- bone scintigraphy
- magnetic resonance imaging
- rheumatoid arthritis