GADOLINIUM-DTPA ENHANCED MAGNETIC-RESONANCE-IMAGING OF BONE-CYSTS IN PATIENTS WITH RHEUMATOID-ARTHRITIS

Objectives-To examine the contents of intraosseous cysts in patients w ith rheumatoid arthritis (RA) through the signal intensity characteris tics on gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging. Methods-The hand or foot joints of nine patients with the cystic form of RA (where the initial radiological abnormality consisted of intrao sseous cysts without erosions) were imaged before and after intravenou s administration of Gd-DTPA. A 0.6 unit, T1 weighted spin echo and T2 weighted gradient echo were used to obtain images in at least two per pendicular planes. Results-Most cysts showed a low signal intensity on the non-enhanced T1 weighted (spin echo) images and a high signal int ensity on the T2 weighted (gradient echo) images, consistent with a f luid content. No cyst showed an enhancement of signal intensity on the T1 weighted images after intravenous administration of Gd-DTPA, where as synovium hyperplasia at the site of bony erosions did show an incre ased signal intensity after Gd-DTPA. Magnetic resonance imaging detect ed more cysts (as small as 2 mm) than plain films, and the cysts were located truly intraosseously. In six patients no other joint abnormali ties were identified by magnetic resonance imaging; the three other pa tients also showed, after Gd-DTPA administration, an enhanced synovium at the site of bony erosions. Conclusions-It is suggested that intrao sseous bone cysts in patients with RA do not contain hyperaemic synovi al proliferation. The bone cysts in patients with the cystic form of R A may be the only joint abnormality.