85Sr scintimetry in ankylosing spondylitis

Strontium 85 step-scan scintimetry of the sacroiliac joints and spine was performed in 19 patients with established or suspected ankylosing spondylitis two weeks after intravenous injection of 100 microcuries of strontium nitrate Sr 85. In completely ankylosed sacroiliac joints and spine, scintimetry values were normal, indicating the disease was clinically arrested. Localized high uptake was observed in several patients, corresponding with areas of complaint. Tomograms of these areas demonstrated destructive changes of vertebral bodies. Uptake of strontium 85 was high in cases with early roentgenographic changes of the sacroiliac joints and minimal spinal involvement. Observations were similar in two patients in whom ankylosing spondylitis was suspected clinically. This indicated new bone formation, suggesting activity of the disease not yet seen on roentgenograms. The method is potentially valuable for establishing early diagnosis when used in conjunction with conventional clinical and radiologic techniques.