Radiography, CT, MRI and US of a RA patient's 2nd MCP joint. (a) Radiography in anteroposterior projection. CT in (b) coronal and (c) axial planes. T1-weighted MRIin (d) coronal and (e) axial planes. US in (f) longitudinal and (g) transversal planes. Anerosion (white arrows) at the base of the 2nd proximal phalanx isvisualized on radiography (panel a), CT (panels b and c) andultrasonography (panels f and g) in both planes. This erosion was notscored on MRI. If the corresponding area on MRI (panels d and e) isreassessed, then the reader gets the impression of the presence of anerosion, with the same configuration as on CT and radiography. CT, computed tomography; MCP, metacarpophalangeal; MRI, magnetic resonance imaging; RA, rheumatoid arthritis; US, ultrasonography.