Background:

Computed Tomography Hounsfield Unit is an alternative tool to the dual energy x-ray absorptiometry scan T-score to quantify the bone quality. DEXA scan can overestimate the bone mineral density. We studied the correlation of the vertebral mid-axial and mid-sagittal HU to the T-score.

Methods:

We retrospectively reviewed the electronic medical records of patients who underwent dual energy x-ray absorptiometry and computed tomography scans within one year. Age, gender, mid-axial and mid-sagittal Hounsfield unit, and T-score were collected and statistically analyzed.

Results:

We identified 100 patients with computed tomography of the L1-L4. There were 80 female and 20 male patients. The average age is 60.25 years (± 12.54). Nineteen patients were diagnosed with degenerative spine disease. There were 56 patients with a normal T-score, 33 with osteopenia, and 11 with osteoporosis. The average HU for the mid-sagittal view was 163 (± 59) for L1, 159 (± 62) for L2, 151 (± 59) for L3, and 150 (± 62) for L4. The mid-axial and mid-sagittal HU were positively correlated to the DEXA T-score (p < .001). The HU was 177 (95% CI: 160 to 194) for normal T-scores, 132 (120 to 143) for T-scores indicating osteopenia, and 106 (88 to 124) for T-scores indicating osteoporosis (p < .001). Post-hoc analysis showed no difference between osteopenia and osteoporosis (p = .46).

Conclusion:

Mid-sagittal HU is positively correlated to the T-score, similar to the mid-axial HU. Therefore, it can be used to acquire a general overview of the bone quality before spinal instrumentation.