Surface Image of Herniated Disc on Three-Dimensional CT

ABSTRACT

PURPOSE: To evaluate surface configuration of herniated disc on three-dimensional CT. MATERIALS AND METHODS: Three dimensional surface images reconstructed from CT scans(1mm thick) of 24 surgically confirmed herniated discs in 23 patients were revieved. Disc surface was classified into peripheral and central zones in contact with consecutive peripheral ring and central endplate. Surface irregularity was categorized into two types(local andgeneral). The incidence, size, and extent of local irregularity were observed. General irregularity incidence and severity ranges in 4 grades, and peripheral width were evaluated. The findings were correlated with discography. RESULTS: Local irregularity compatible with anulus tear in discography was shown in all. It was large(13/24) andmainly peripheral tract extending to disc margin in protrusion(3/5) and sequestration(5/7), and cleft encompassing central zone to disc margin in extrusion(9/12). General irregularity was predominantly grade 3(15/22) and was shown in all except in 2 puotrusions. peripheral width was 0.56 of central radius. CONCLUSION: Extrusion inherniated disc shows characteristic cleft encompassing central zone to disc margin whereas sequestration or protrusion displays tract extending from peripheral zone to disc margin. Thus, three dimensional surface imagingmay aid the diagnosis, follow-up, prediction, and treatment of herniated disc.