Characteristics of CT Hounsfield Unit Values in Lumbar Vertebrae and Lumbar Pedicle – A comparative Study Based on CT Scans and Dual-Energy X-ray Absorptiometry (DEXA)

Abstract PurposesThe purpose of this study was to evaluate CT HU value in specific regions of the Lumbar Spine and investigate the correlation between their CT HU values and the corresponding bone quality index provided by Dual-Energy X-ray Absorptiometry (DEXA). MethodsA total of 32 Chinese adults with lumbar degenerative disc disease requiring diagnostic lumbar CT and DEXA at our hospital were retrospectively reviewed in this study. The HU value of medial cortical area (mHU), lateral cortical area (lHU) and trabecular area (tpHU) of the pedicle and superior part, middle part, inferior part of the vertebral body (sHU, mbHU, iHU, respectively) were measured on CT images. T score and BMD score of each vertebra were also measured by DEXA. The HU value was compared between sex groups, vertebra and the correlations of HU value with DEXA T-score, DEXA BMD-score were analyzed. ResultsIn vertebral body, the value of mHU is the lowest (p<0.001) while mbHU and iHU are not significantly different. The tpHU had the lowest HU value compared to mHU and lHu. mHU had significantly higher value than lHU at all levels (p<0.001). The value of mHU and lHU is found correlated with T-scores(p0.05). The HU values of all vertebral body regions at all lumbar levels (sHU,mbHU,iHU) correlate strongly with T-scores and BMD(r>0.6, p<0.01). ConclusionsCT HU value could be a reliable indicator for regional bone quality, especially in people with lumbar degenerative changes. The superior portion of the lumbar vertebra had the lowest bone density in comparison with other regions of the vertebra at L1-L4. In lumbar pedical, the medial lateral cortical bone area had higher bone density than the lateral cortical bone and trabecula bone area.