Quantification of intervertebral disc degeneration using dual-energy computed tomography collagen maps: a comparative study with MRI Pfirrmann grading

Abstract

To determine the correlation between quantitative HU values derived from DECT collagen maps and the MRI-based Pfirrmann grade. We retrospectively reviewed IVDs in patients who underwent both spinal DECT and MRI within one year. CT scans were acquired using single-source DECT at 80 and 135-kVp with automatic exposure control. Three readers scored IVDs according to Pfirrmann et al. on T2-weighted MRI images. Quantitative evaluation involved placing three standardized regions of interest in each IVD in DECT-based cMaps; in corresponding 135-kVp DECT scans and MRI images. Mean density measurements of AF and NP were compared with PF-grades using linear mixed model analysis. We included 339 IVDs of 97 patients [mean age 59.1 years]; (53 women [mean age 63.5 years] and 44 men [mean age 53.8 years]). cMap analysis revealed a significant difference of AF and NP collagen and chondroitin density between PF-grade I and V(AF: MD = − 31.1HU (95% CI − 59.5 to − 2.7), p = 0.032;NP:MD = − 37.8HU (95% CI − 73.6 to − 2.0), p = 0.038). 135-kVp DECT showed no IVD density reduction corresponding to PF-grades. MRI showed significant reduction of signal intensities in AF and NP with increasing PF-grades. IVD collagen and chondroitin density declined with increasing PF-grade in DECT-based cMaps, suggesting DECT-based cMaps as an additional tool for IVD classification.