Feasibility of 100 kV Low-voltage Bone Mineral Density Measurement with Quantitative CT: Phantom and Clinical Research

To investigate the feasibility and accuracy of 100 kV low-voltage quantitative CT (QCT) for bone mineral density (BMD) measurement using the European Spine Phantom and patients. The accuracy and precision of the BMD measurements were assessed using relative measurement error (RME%), coefficient of variation (CV%), root mean square standard deviation (RMS-SD), and root mean square CV (RMS-%CV). Linear regression and Bland-Altman analyses were used to assess the agreement between 100 and 120 kV QCT-based BMD measurements. The diagnostic performance of 100 kV QCT for osteoporosis was evaluated using receiver operating characteristic curve analysis. For the ESP, the mean BMD values at 100 kV were slightly greater than those at 120 kV, mainly due to small inaccuracies remaining in the BMD calibration process. The RME% values for all vertebrae were -3.31 to 15.00% at 100 kV and -9.34 to 3.06% at 120 kV, falling within +/- 10% at 120 kV but within 0-15% at 100 kV. The CV% and RMS-%CV values decreased as the BMD increased with increasing tube voltage, while the RMS-SD exhibited a decreasing trend. For patients, linear regression and Bland-Altman analyses revealed good agreement between 120 and 100 kV (R-2 = 0.987, P < 0.001; mean error, -3.39 mg/cm(3); 95% limits of agreement, -16.49 to 9.71 mg/cm(3)). The 100 kV QCT achieved high accuracy in diagnosing osteoporosis (AUC = 0.992, P < 0.001), with a sensitivity of 99.04% and a specificity of 94.28%. 100 kV low-voltage QCT demonstrated acceptable accuracy and good reproducibility for measuring BMD, opening the possibility of 100 kV low-voltage chest CT obtained for lung cancer screening for opportunistic osteoporosis screening.