Joint Imaging in Rheumatology

There are various modalities of joint imaging e.g. conventional radiography (CR), computed tomography (CT), magnetic resonance imaging (MRI), bone scintigraphy, positron emission tomography (PET), ultrasonography (US), bone densitography. CR shows only bone lesions, while CT demonstrate both bone and soft-tissue changes. MRI is the best modality at showing soft tissue contrast than CT scan and is multiplanar, but less sensitive in assessing bone lesions than CT. CONVENTIONAL RADIOGRAPHY Not only does CR establish the presence of disease, but serial films can be used to assess change or response to therapy. Bone erosions, joint space narrowing, subluxation, malalignment and ankylosis of the joints may be seen. Early bone changes are not seen in plain x-rays. Fig.1: RA: Erosions feet lateral aspect of the fifth metatarsal head (curved white arrow), Erosions of the great toe metatarsal head and medial cuneiform (black arrows). Rheumatoid Arthritis (RA) X-ray hands and feet PA view (Fig 1 & 2) will show changes in metacarpophalangeal (MCP), proximal interphalangeal (PIP), carpal joints of hands, and metatarsophalangeal (MTP) and interphalangeal joints of feet. Distal interphalangeal joints (DIP) are not involved in RA. Serial measurements of radiological progression provide substantially more information than a single X-ray. Early changes: 1. Fusiform soft tissue swelling around joint