Vertebral and Femoral Bone Mineral Density (BMD) Assessment with Dual-Energy CT versus DXA Scan in Postmenopausal Females

Abstract

This study aimed to demonstrate the potential role of dual-energy CT in assessing bone mineral density (BMD) using hydroxyapatite-fat material pairing in postmenopausal women. A retrospective study was conducted on 51 postmenopausal female patients who underwent DXA and DECT examinations for other clinical reasons. DECT images were acquired with spectral imaging using a 256-slice system. These images were processed and visualized using a HAP-fat material pair. Statistical analysis was performed using the Bland-Altman method to assess the agreement between DXA and DECT HAP-fat measurements. Mean BMD, vertebral, and femoral T-scores were obtained. For vertebral analysis, the Bland-Altman plot showed an inverse correlation (R²: -0.042; RMSE: 0.690) between T-scores and DECT HAP-fat values for measurements from L1 to L4, while a good linear correlation (R²: 0.341; RMSE: 0.589) was found for measurements at the femoral neck. In conclusion, we demonstrate the enhanced importance of BMD calculation through DECT, finding a statistically significant correlation only at the femoral neck where BMD results do not seem to be influenced by the overlap of the measurements on cortical and trabecular bone. This outcome could be beneficial in the future by reducing radiation exposure for patients already undergoing follow-up for chronic conditions.

Keywords: DXA; bone mineral density; dual-energy CT; dual-energy X-ray absorptiometry; femoral neck fractures; osteoporosis; vertebral fractures.

Figure 1

DXA measurements on the lumbar vertebrae (Regione: measurement region; Area: measurement area; BMC: Bone Mineral Content; BMD: Bone Mineral Density; PR: Reference peak; AM: Age Matched).

Figure 2

DXA measurements on the femoral neck (Regione: measurement region; Area: measurement area; BMC: Bone Mineral Content; BMD: Bone Mineral Density; PR: Reference peak; AM: Age Matched).

Figure 3

DECT measurements on the lumbar vertebrae (ROI1: L4 measurement; ROI2: L3 measurement; ROI3: L2 measurement; ROI4: L1 measurement). The ROI volume was 858 mm³.

Figure 4

DECT measurements on the femoral neck (ROI5: femoral neck volume measurement). The ROI volume was 858 mm³.

Figure 5

Histogram and density plot of differences for the lumbar vertebrae.

Figure 6

Bland–Altman plot between DXA and DECT HAP–fat measurements on the lumbar vertebrae (direction of subtraction for the Y axis—DXA minus DECT; blue line shows the performance bias of the method).

Figure 7

Histogram and density plot of differences for the femoral neck.

Figure 8

Bland–Altman plot between DXA and DECT HAP–fat measurements on the femoral neck (direction of subtraction for the Y axis—DXA minus DECT; blue line shows the performance bias of the method; ULA: Upper Limit of Agreement; LLA Lower Limit of Agreement).