ABSTRACT
Objective Ankylosing spondylitis (AS) can affect both the lumbar zygapophyseal joint and the centrum .This study was to compare multislice spiral CT ( MSCT) and MRI in the diagnosis of zygapophyseal joint lesions in AS patients and assess the role of zygapophyseal joint lesions in the early diagnosis of AS . Methods We retrospectively analyzed the lumbar imaging data of 41 male patients with AS .Forty-one male AS patients underwent MSCT , 18 receiving normal MRI , and the other 23 diffusion weighted imaging (DWI) and CE-T1WI-STIR in addition.Using Fisher′s Exact Test, we compared MSCT and MRI in their detection rates of a-pophyseal joint lesions and positive changes in the zygapophyseal joint and lumbar centrum .Then we analyzed the relation between the zygapophyseal joint lesions and the disease duration . Results The detection rates of zygapophyseal joint and centrum lesions were 90.2%and 58.5%on MSCT (P>0.05), and 80.5%and 46.3%on MRI (P>0.05), respectively.MSCT and MRI exhibited sig-nificant differences in the detection rate of centrum lesions (P0.05). These lesions could appear within 1 year after the onset of AS or ahead of vertebral changes . Conclusion Both MSCT and MRI can manifest zygapophyseal joint lesions , which may develop in the lumbar spine at the early stage of AS , ahead of centrum lesions .This is important for the early diagnosis of AS .