Risk of vertebral fractures: evaluation on vertebral trabecular attenuation value and hydroxyapatite concentration in patients by chest spectral CT.

OBJECTIVES: To analyze vertebral fractures risk in patients with chest scans by evaluating vertebral hydroxyapatite concentration measured on spectral CT compared to trabecular attenuation value measured on conventional CT.
METHODS: Our retrospective study reviewed CT of 216 patients. Analysis of vertebral (T11 - L1) hydroxyapatite concentration by spectral imaging and trabecular attenuation value by conventional CT imaging were performed in patients with chest CT examinations. Specificity, sensitivity, negative predictive value (NPV), and positive predictive value (PPV) were performed by using receiver operating characteristic (ROC) curves in patients with and without vertebral fractures.
RESULTS: In male patients, vertebral hydroxyapatite concentration had high area under the ROC curve (0.916), by using the optimal threshold of 72.27 mg/cm3, specificity, sensitivity, NPV, and PPV were 91.7, 80.2, 36.7, and 98.7%, respectively. In female patients, vertebral hydroxyapatite concentration also had high area under the ROC curve (0.870), by using the optimal threshold of 74.79 mg/cm3, specificity, sensitivity, NPV, and PPV were 100.0, 77.8, 47.4, and 100.0%, respectively. Area under the ROC curve was significantly different between spectral CT-measured bone hydroxyapatite concentration and conventional CT-measured attenuation value in distinguishing vertebral fractures (p = 0.007 for males; p = 0.005 for females).
CONCLUSIONS: Quantitative assessment with spectral CT may appear as higher accuracy than that of conventional CT imaging to analyze risk of vertebral fractures. Hydroxyapatite concentration measured with chest spectral CT may be used to evaluate risk of bone fractures. ADVANCES IN KNOWLEDGE: Hydroxyapatite concentration measured with chest spectral CT may be used to evaluate risk of bone fractures.