Could Computed Tomography Hounsfield Unit Values of Lumbar Vertebrae Detect Osteoporosis

Background: Dual-energy X-ray absorptiometry (DEXA) scanning has several disadvantages determining osteoporosis especially for the degenerative spine.

Introduction: To determine spinal osteoporosis in patients suffering from lumbar degenerative disease using computed tomography (CT).

Methods: A total of 547 subjects that underwent DEXA and abdominal CT within a period of three months were examined retrospectively and separated into groups based on lumbar degenerative alteration on the CT scan. The subjects that showed degenerative severity at L1-L4, in at least two levels, were graded and placed in the degenerative group (Group D, n=350), while the other subjects constituted the control group (Group C, n=197). The Hounsfield unit (HU) of the vertebral body trabecular bone, the T-score, and bone mineral density (BMD) of L1-L4 and hips were determined from the CT images. CT-HU parameters for osteoporosis acquired from the control group were used to ascertain undiagnosed osteoporosis.

Results: The CT-HU was positively correlated with T-score and lumbar BMD for both groups (P<0.001), while the L1-L4 correlation was higher in Group C than in Group D. Based on linear regression, the T-score and CT-HU for L1-L4 osteoporosis were 129, 136, 129 and 120 HU, respectively in Group C. Undiagnosed spinal osteoporosis was greater in Group D compared to the controls (44.2% vs. 9.6%, respectively) based on the CT-HU thresholds.

Conclusion: Lumbar spine degeneration can augment BMD and T-score, resulting in the underestimation of lumbar osteoporosis. The osteoporosis threshold determined by CT-HU may be a valuable technique to determine undiagnosed spinal osteoporosis.

Keywords: Hounsfield unite (HU); Osteoporosis; T-score; bone mineral density.; computed tomography; lumbar spinal degeneration.