TC-99M-MDP SCINTIGRAPHY IN ANKYLOSING-SPONDYLITIS

Technetium-99m-MDP bone scintigrams in 11 patients with ankylosing spo ndylitis were reviewed. Increased activity in sacroiliac joints was pr esent in five of 11 cases, all of whom had symptoms of less than 5 yea rs duration. Patients with longstanding disease had normal or low sacr oiliac joint activity. In the spine, appearances included diffuse symm etrical, unifocal or multifocal asymmetrical increased uptake involvin g the costovertebral, costotransverse and facet joints as well as the spinous processes. In advanced disease with extensive ankylosis, the l umbar spine was featureless on scintigraphy, except for focal increase d activity at the site of previous fracture in one patient. Of six ava ilable views of the sternum, increased uptake was present in five at t he manubriosternal joint and five at the sternoclavicular joints. Incr eased -peripheral uptake was mainly in the hips and knees in advanced cases. Plain radiographic changes correlated poorly with scintigraphic changes, scintigraphy detecting considerably more lesions than radiog raphy. Awareness of the scintigraphic appearances of ankylosing spondy litis may lead to diagnosis before the development of radiographic cha nges and avoid confusion with other pathology. Clinical indications fo r bone scintigraphy in ankylosing spondylitis are suggested.