What are the changes seen within the rheumatoid joint on MRI?
MRI scanning generates an image of the joint by detecting protons that have been exposed to an extremely powerful magnetic field, applied in pulses. This affects their spin in certain ways that are recorded as variations in signal on different MR sequences [1]. Spatial information is obtained using this signal and transformed by computing software into a 3D image. The great advantage of MRI over conventional radiography is that it allows depiction of inflammation as well as structural damage. Inflamed tissue, including synovium and tenosynovium, contains an infiltrate of cells as well as newly formed blood vessels. There are more mobile H+ ions (in the form of H2O) in these cells and vessels than in normal tissues, influencing the MRI signal. For example, synovitis appears on T1-weighted (T1w) images as thickened membrane (showing its anatomical features), which is high signal on T2-weighted images (T2w), indicating its high H+ content, and enhances on T1w post-contrast images, reveali
