MRI of the arthritic small joints: comparison of extremity MRI (0.2 T) vs high-field MRI (1.5 T)

The aim of this study was to compare the diagnostic capabilities of extremi ty MRI (E-MRI) with high-field MRI in arthritic small joints, and to evalua te the patients' acceptance and perceptions of the two MR systems. One hund red three patients (group 1 = 28 patients with RA < 3 years, group 2 = 25 p atients with reactive and psoriatic arthritis and mixed connective tissue d isease, group 3 = 25 patients with rheumatoid arthritis (RA) more than 3 ye ars and group 4 = 25 patients with arthralgia) underwent dedicated E-MRI an d high-field MRI of the wrist and finger joints. Coronal short tau inversio n recovery and transversal 3D T1-weighted images before and after gadodiami de (Gd) were performed in both cases to outline the volume of the synovial membrane (Vsm) and to evaluate joints with enhancement, effusion, bone edem a, and erosions. Investigators blinded to the clinical findings evaluated t he images. Patients' compliance and acceptance of E-MRI and high-field MRT were evaluated. The median Vsm obtained on E-MRI did not differ significant ly from that obtained on high-field MRI. Vsm = 1 ml (E-MRI) and 1.1 ml (hig h-field MRI) before Gd and Vsm = 0.1 ml (E-MRI) and 0 ml (high-field MRT) a fter Gd (Wilcoxon test, p > 0.05), The difference in agreement was 8% for j oint enhancement, 2% for joint effusion, 3% for bone edema, and 4% for bone erosions. Of the patients, 64% preferred E-MRI due to more comfortable pos itioning and less claustrophobia and noise. Extremity MRI of the small arth ritic joints is comparable to high-field MRI and more readily accepted than high-field MRI by this patient group.