Objective: To explore the CT features of Spondylolysis and Spondylolisthesis of Lumbar Spine.Methods:38 cases underwent thin slice scan (thickness interval: 3mm) with GE Hispeed Fx/I spiral CT.Results:(1)The CT feature of Spondylolysis: The show of defect of the pars interarticularis is a gap of low density with irregular image;(2)The primal CT features of Spondylolisthesis: Lengthened anterior posterior diameter of pinal canal?The sign of the double contour?pseudobulging disk?and neural foramen deformity.C...