Oblique radiographic projection can simulate joint-space narrowing on conventional radiography (XR). (A) Metacarpophalangeal joint (MCP)-1 joint space (short arrow) appears narrowed due to oblique projection on XR. (B) Magnetic resonance imaging of the same MCP joint shows intact articular cartilage and normal joint-space width (long arrow).
Peterfy et al. Arthritis Research & Therapy 2013 15:R44 doi:10.1186/ar4202