Strontium 87m scanning of the sacroiliac joints in ankylosing spondylitis.

Strontium 87m scanning can provide useful information about a variety of skeletal diseases: malignant tumours (Kostamis, Constanides, Papavasiliou, Binopoulos, Sfontouris, and Malamos, 1968; Parsons Williams, Hill, Frost, and Lapham 1969; Wendeberg, and Yamamuro 1965), osteomyelitis (Bauer and Wendeberg, 1959; Gofton, 1968; Dymling and Wendeberg, 1965), osteonecrosis (Ahlback, Bauer, and Bohne, 1968; Morscher, 1970; Muheim and Bohne, 1970), and Paget's disease (Bessler, 1969). We therefore thought that scanning with 87mSr could possibly be useful in the early detection of ankylosing spondylitis (AS) and in understanding its pathology. Lovgren and Dowen (1969) described the results of 85Sr scintigraphy of sacroiliac (SI) joints in Reiter's disease, spondylarthritis, and psoriatic arthritis. We carried out this study on a larger number of patients and restricted the investigations to AS. In order to give the strontium fixation a more quantitative value, we calculated the total of all counts registered in a well-defined area. We compared the results with a control group, and investigated whether there is an increased fixation in the SI joints in patients with AS. We also sought to find a correlation between the external counting of `7mSr and several parameters that are commonly used to determine the degree and the activity of the disease: age, duration of disease, radiological stage, erythrocyte sedimentation rate, and subjective condition (Nold, Ott, and Hentschel, 1968). Finally we assessed the value of this technique as a criterion for the early detection of AS. Scintillation scanning permits the diagnosis of every change in bone metabolism at its earliest stage, whereas this change is radiologically visible only when the lesion covers more than 1 5 cm. and is already decalcified from 50 to 70 per cent. (Bauer and Ray, 1958; Bauer and Wendeberg, 1959; Charkes, 1970; Godlee, 1970). In many cases of AS the onset is early (between 10 and 20 years of age) with arthritis of the peripheral joints. Much later the disease can be diagnosed on the basis of the classic criteria. The