Study on bone mineral density and bone structure of lumbar vertebrae in osteoporotic elderly women with multi-slice CT

Objective: To evaluate the ability of volumetric bone mineral density (BMD) parameters of lumbar vertebrae in differentiating osteoporotic fractured from nonfractured elderly women with vQCT technique, and to compare the bony structural conditions of osteoporotic elderly women with healthy elderly women. Methods: Multi-slice CT spinal scans of L1 and L2 were acquired in 26 osteoporotic vertebral fractured elderly women (group one) and 30 nonfractured osteoporotic subjects (group two). All the retro-reconstructed images of L1 and L2 were sent to the workstation and processed by volume rendering (VR) technique to measure volumetric BMD (3D-INTGL, 3D-CORT, 3D-TRAB) and trabecular and integral BMD (2D-TRAB, 2D-INTGL) by conventional QCT technique. BMD indexes in DXA were AP-SPINE and bone mineral apparent density (BMAD) in anteroposterior position. The seven parameters between the two group s were compared. Ten healthy elderly women were selected as normal group to reformate 3D-VR images from MSCT images to analyze the bony structure and calculate the ratio of bone volume to total volume (BV/TV) in the center of L1 vertebrae, and to compare the index between the normal group and tenpatients randomly selected from the 56 osteoporotic women. Results: DXA measurements in group one: AP-SPINE and BMAD were (0.796±0.170)g/cm2 and (272.7±27.7) mg/cm3, respectively, showing no statistically significant differences comparing with (0.817±0.140) g/cm2 and (249.5 ± 26.5) mg/cm3 in group two. Volumetric BMD in group one included 2D-TRAB (70.4 ± 22.2) mg/cm3, 2D-INTGL (138.3±35.1) mg/cm3, 3D-INTGL (139.4±34.9 ) mg/cm3, 3D-CORT (133.8±26.9) mg/cm3, and 3D-TRAB (69.9 ±18.6) mg/cm3, respectively, showing statistically differences with (89.1±21.8) mg/cm3, (170.6±34.5) mg/cm3, (180.5±28.2) mg/cm3, (163.2±27.5) mg/cm3, and (83.8 ± 17.1) mg/cm3 in group two (the decrements 18%-23%). The mean value of BV/TV of L1 vertebrae was (8.12 ± 1.96)% in osteoporotic women, which was significantly lower than (39.13 ± 2.15)% of normal elderly women (P<0.01). Conclusion: Volumetric QCT parameters of lumbar vertebrae in MSCT were superior to DXA in identifying osteoporotic fractured from nonfractured elderly women. Trabecular volume of vertebrae in 3D-VR images of osteoporotic women is lower than that of healthy elderly women. (authors)