Influence of the selected range and location of L1 vertebral interest region on CT values in middle-aged and elderly people

English Keywords:Bone mineral density  CT value  Three-dimensional reconstruction  Osteoporosis

English Abstract:

  【Abstract】 Objectives: To analyze the differences in CT values between different sizes and locations of region of interest(ROI) in L1 vertebral body of middle-aged and elderly populations. Methods: A total of 55 patients undergone lumbar spine CT scan and dual-energy X-ray absorptiometry(DXA) examination in our hospital from July 2019 to July 2021 were collected, including 19 males and 36 females, aged 45-85 years(66.5±9.7 years) old. The CT image data and bone mineral density(BMD) of L1 vertebral body measured by DXA were collected. The L1 vertebral body was reconstructed, and the ROI with an area of 50mm2, 200mm2, and 400mm2 in the middle of the coronal, sagittal, and cross-sectional trisections were selected to measure the CT values. The cancellous bone in L1 vertebral body was reconstructed and measured in CT values. The intraclass correlation coefficient was used to evaluate the consistency of CT value measurement. The patients were divided according to the area and location of ROI, and the CT values were compared by two-way analysis of variance, and multiple comparisons were further carried out on the CT values of ROI of different parts of the same area and different areas of the same site. The results of multiple comparisons were observed, and the average CT value of the ROI group with statistically different results under the same conditions was compared with the CT value of cancellous bone, and its correlation with L1 BMD measured with DXA was analyzed. Results: The CT value measurements showed reliable intraobserver and interobserver consistency[intraclass correlation coefficient(ICC)＞0.8, P＜0.001]. The interaction effect of the selected area and location of ROI on CT values was significant(F=3.28, P＜0.05). In terms of ROI of one same site with different areas, there were significant differences in CT values in the ROI between 50mm2, 200mm2 and 400mm2 of 3 cross-sectional sections, 3 coronal sections and the left and right 1/3 of the sagittal plane(P＜0.05); There was a significant difference in CT values in the ROI between 200mm2 and 400mm2(P＜0.05); In the middle 1/3 of the sagittal plane, the CT values of 50/200/400mm2 were significantly different from each other(P＜0.05). In terms of ROI with same area in different sites, for 50mm2 ROI, there was no significant difference between the CT values of the 3 sections in the transverse/sagittal plane and the anterior 1/3 of the coronal plane(P＞0.05), and there were significant differences between the 3 sections of the transverse/sagittal plane, the anterior 1/3 of the coronal plane and the middle and posterior 1/3 of the coronal plane(P＜0.05); For 200mm2 ROI, there was no significant difference between the 3 parts of the transverse plane, the anterior 1/3 of the coronal plane, and the left and right 1/3 of the sagittal plane(P＞0.05), and there were significant differences between the 3 sections of the transverse plane, the anterior 1/3 of the coronal plane, the left and right 1/3 of the sagittal plane and the middle and posterior 1/3 of the coronal plane and the midle 1/3 of the sagittal plane(P＜0.05); For 400mm2 ROI, there was no significant difference between the upper and lower 1/3 of the transverse plane, the middle and right 1/3 of the sagittal plane, and the front 1/3 of the coronal plane(P＞0.05), there was no significant difference between the 3 parts of the transverse plane and the middle and right 1/3 of the sagittal plane(P＞0.05), there was no significant difference between the middle and posterior 1/3 of the coronal plane and the middle 1/3 of the sagittal plane(P＞0.05). The CT values of the middle and posterior 1/3 of the coronal plane, the middle 1/3 of the sagittal plane and the anterior 1/3 of the coronal plane, the middle and right 1/3 of the sagittal plane, and the 3 parts of transverse plane were significantly different from each other(P＜0.05), and there was a significant difference in CT values between the middle 1/3 of the transverse plane and the anterior 1/3 of the coronal plane(P＜0.05). According to the differences, there was no significant difference between the CT values of the anterior part of the 50mm2 vertebral body and the cancellous bone of L1 vertebral body(P＞0.05). There was no significant correlation between the CT values of the anterior 50mm2 vertebral body and the BMD of L1 vertebral body measured by DXA. Conclusions: The location and area of ROI in L1 vertebral body can affect the CT value measurement results in middle-aged and elderly people. The CT values can reflect the BMD of cancellous bone more accurately when the ROI is 50mm2 in the transverse plane, sagittal plane and the anterior 1/3 of the coronal plane.