Figure 4.

Projection radiography (x-ray) (a) and T1-weighted coronal (b) and axial (c) magnetic resonance imaging (MRI) and ultrasonography (US) in longitudinal dorsal (d) and palmar (e) views of the 3rd distal interphalangeal joint of a patient with psoriasis-associated arthritis. An erosion was scored on x-ray (a) but not on either MRI (b,c) or US (d,e), even though small irregularities were seen. DP, distal phalanx; IP, intermediate phalanx.