"Incomplete ring" sign: a simple method for CT detection of spondylolysis.
Multiple authors have pointed out the difficulty of detecting spondylolysis with lumbar CT. A simple method to detect spondylolysis on lumbar CT is described. Identifying one intact cortical ring for each vertebra absolutely excludes the diagnosis obviating the time-consuming need to search each image looking for positive evidence of the abnormality. If at least one intact cortical ring for each vertebra is not found, a defect in the ring at the appropriate position assures the diagnosis.
D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D013168:Spondylolisthesis / Q000000981:diagnostic imaging*; D013169:Spondylolysis / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed