THE ROLE OF CT IN THE DIAGNOSIS OF SACRO-ILIITIS

Objective. Ankylosing spondylitis is a progressive, debilitating disea se in which early diagnosis and early treatment can improve the progno sis. Radiographic confirmation is essential for diagnosis but conventi onal radiography has not proved useful, particularly in the early cour se of the disease. The aims of this study were to correlate the findin gs at conventional radiography with those at CT, and to correlate the duration of clinical symptoms with the radiological findings. Material and Methods. Forty patients with clinical sacro-iliitis and 13 contro ls were evaluated by means of conventional radiography and CT. Results : Conventional radiography was positive in 10/40 patients and CT in 30 /40 patients. Conventional radiography was positive in only 2/14 patie nts with a symptom duration of less than 2 years while CT was positive in 10/14 such patients. Conclusion. The study demonstrated a consider ably higher sensitivity in CT than in conventional radiography in dete cting the subtle changes necessary for the radiological diagnosis of s acro-iliitis, particularly in cases of short duration. CT allows an ea rly start to be made in treatment with a consequently improved prognos is. The use of conventional radiography cannot be recommended because its low sensitivity delays diagnosis in many instances.