Abstract
BACKGROUND: Due to the low sensitivity of plain radiography, the diagnosis of early stage ankylosing spondylitis (AS) is often difficult since many patients do not meet the radiographic criteria. The objective of our study was to investigate the diagnostic value of performing multidetector computed tomography (MDCT) of the sacroiliac (SI) joint in the evaluation of AS patients. METHODS: Thirty seven patients with definite or probable AS were evaluated. Plain radiography and MDCT imaging of the pelvis were performed for evaluating the SI joints. Two radiologists analyzed the images, and they graded the sacroiliitis on a scale of 0-4 according to the modified NY criteria. The clinical variables we analyzed included the disease duration, the treatment duration, the prescribed drugs, peripheral joint involvement, enthesopathy, the functional limitations and the BASDAI. RESULTS: MDCT detected more bilateral sacroiliitis as compared to the plain radiography (86.5% vs. 75.7%, respectively), and MDCT yielded a higher grade of disease in 32.4% (right SI joint) and 24.3% (left SI joint) of the patients. More patients satisfied the modified NY criteria with using MDCT as compared with that when using the plain radiography (81.1% vs. 54.1%, respectively, p=0.002). CONCLUSIONS: Visualization of the sacroiliac joint by MDCT provided a better diagnosis of AS, and especially during the early stage of the disease.