Could Computed Tomography Hounsfield Unit Values of Lumbar Vertebrae Detect Osteoporosis?

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

This study aims to determine spinal osteoporosis in patients suffering from lumbar degenerative disease using computed tomography (CT).

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). In contrast, 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.

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.

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.