Considering Hounsfield Units in native CT- scans for diagnosing spondylodiscitis

Abstract

Background MRI being the method of choice for radiological diagnosis of spondylodiscitis is still often delayed. The significance of native CT Scans as an alternative diagnostic tool for spondylodiscitis is poor according to the current data. Therefore, the aim of this study was to investigate, weather spondylodiscitis leads to a significant pattern of the density distribution from the affected vertebral bodies and discs measured by Hounsfield Units (HU) in native CT Scans. Methods In a retrospective study we analyzed data from 136 patients, who were treated for spondylodiscitis. Patients who provided MRI- and CT- scans of the spine were included. In axial CT planes HU from the affected intervertebral disc as well as from the affected vertebral bodies and from the unaffected adjacent intervertebral discs and vertebral bodies from the level above and below as reference were measured. Results The average measured HU of the affected disc were 26.0% less than in the not affected adjacent discs (p < 0.001). The average measured HU of the affected vertebral bodies were 33.77% higher than in the not affected adjacent vertebral body’s (p < 0.001)). The localization of the spondylodiscitis and the degree of bony destruction according to Eysel-Peters classification had no influence on these findings. Conclusion Decreased HU of the affected vertebral disc of approximate 25% and / or increased HU of the affected vertebral bodies of approximate 30% compared with adjacent vertebral discs and vertebral are indicative for spondylodiscitis even in early phase without destruction and independent of the localization.