Hounsfield units in assessing bone mineral density in ankylosing spondylitis patients with cervical fracture-dislocation

Figure 1 Hounsfield unit imaging assessments. A: A 60-year-old male cervical fracture-dislocation patient with ankylosing spondylitis. Using a three-dimensional reconstruction, the middle sagittal plane was selected. Using nine reference lines, every vertebra was equally divided into 16 regions; B: The right, middle, and left sagittal planes were selected according to three reference lines.

Figure 2 Scatter plot showing the correlation between the Hounsfield units obtained from cervical vertebrae and T-values obtained from dual-energy X-ray absorptiometry of the lumbar vertebrae of 59 normal patients. A significant correlation was found (r = 0.772, r² = 0.596, P < 0.05).

Figure 3 Receiver operation characteristic curve to diagnose osteopenia and osteoporosis. A: Hounsfield unit measurement had a sensitivity of 92.2% and specificity of 87.5% with an area under the curve (AUC) of 0.931 (P < 0.05) in diagnosing osteopenia; B: Hounsfield unit measurement had a sensitivity of 80.0% and specificity of 91.7% with an AUC of 0.919 (P < 0.05) in diagnosing osteoporosis.

Figure 4 A 68-year-old man developed paralysis after a traffic accident. A: Preoperative computed tomography suggested ankylosing spondylitis combined with C2/3 fracture-dislocation; B and C: We performed a reduction with a Halo vest and an anterior combined posterior surgery; D: Postoperative bisphosphonates were used for anti-osteoporosis treatment, and cervical computed tomography was repeated at 6 mo postoperatively; E: We calculated the Hounsfield unit values of the C5 vertebra and found that the postoperative Hounsfield unit values (179.67) were significantly higher than preoperative (157.44).