Dual-layer spectral detector CT discography of the lumbar spine: A preliminary study

To assess the feasibility of spectral detector CT (SDCT) with axial maximum-intensity projection (MIP) reconstruction for the evaluation of lumbar CT discography. We retrospectively evaluated 44 disc levels from 18 patients who underwent CT discography on a dual-layer SDCT between May 2016 and July 2017. We compared the distribution of contrast material between conventional CT and SDCT-based iodine maps using the Jaccard index (JI) and Dice similarity coefficient (DSC). Qualitative analysis of the post-discogram features was done according to the Dallas discogram description, and changes in reading time and diagnostic confidence were analyzed. The intermethod variability between conventional CT and SDCT was good, with a mean DSC of 0.93 and a mean JI of 0.87. The mean sensitivity and positive predictive value of the SDCT-based method were 90% and 96%, respectively. The addition of SDCT-based axial MIP iodine maps increased the diagnostic confidence (p = 0.025) and reduced the reading time in both reviewers (p < 0.001). SDCT discography demonstrates the distribution of contrast medium within the disc similarly to conventional CT. Additionally, axial MIP iodine maps using SDCT allow for the fast evaluation of disc pathology with reduced reading time and can increase diagnostic confidence