IDEAL-IQ联合Micro-CT定量评估兔1型糖尿病骨髓脂肪含量和骨小梁微结构相关性的研究

IDEAL-IQ combined with Micro-CT to assess the quantitative correlation of bone marrow fat content and trabecular bone microstructure in rabbit type 1 diabetes

目的 采用定量非对称回波的最小二乘估算法迭代水脂分离序列(iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence, IDEAL-IQ)联合计算机显微断层扫描(micro computed tomography, Micro-CT)技术评估兔1型糖尿病腰椎骨髓脂肪含量和骨小梁微结构相关性。材料与方法 将16只雄性日本大耳白兔随机分为糖尿病组(n=8)和对照组(n=8),糖尿病组采用四氧嘧啶造模。在造模成功后第0、4、8、12、16周通过IDEAL-IQ定量评估兔腰椎骨髓脂肪含量。在第16周采用Micro-CT及组织病理学检查对兔腰椎骨小梁微结构进行定量评估。不同时间点腰椎IDEAL-IQ脂肪分数差异比较采用重复测量方差分析;同一时间点组间脂肪分数、Micro-CT骨小梁形态计量学参数、组织病理学参数差异比较采用独立样t检验或Mann-Whitney U检验;采用Pearson相关系数评估骨髓脂肪分数与骨小梁形态计量学参数、组织病理学参数相关性。结果 糖尿病组骨髓脂肪含量随时间变化呈上升趋势,且差异存在统计学意义(P<0.05),而对照组各时间点脂肪含量差异无统计学意义(P>0.05);糖尿病组与对照组腰椎骨髓脂肪分数在第16周差异有统计学意义(59.987±4.859 vs. 51.015±8.469,P<0.05);第16周糖尿病组骨体积、总表面积、骨表面积、骨表面积总体积比、骨小梁数量均低于对照组,而骨小梁分离度高于对照组,差异有统计学意义(P<0.05);组织病理学结果显示,与对照组相比,第16周糖尿病兔腰椎骨髓脂肪细胞数量(32.875±11.051 vs. 71.667±13.125, P<0.01)增加,而骨小梁数量(11.375±1.506vs.4.333±1.211, P<0.01)与骨小梁面积(0.927±0.071vs.0.312±0.100, P<0.01)明显减少;IDEAL-IQ脂肪分数与组织病理学脂肪细胞计数呈正相关关系(r=0.539 95%CI:0.012~0.832),与骨小梁模式因子、骨小梁结构模型指数、骨小梁分离度呈轻中度正相关关系,与骨矿物质密度、总体积、骨体积、骨体积分数、总表面积、骨表面积、骨表面积体积比、骨表面积总体积比、骨小梁数量呈轻至中度负相关关系。结论 1型糖尿病腰椎骨髓脂肪含量与骨小梁微结构变化存在相关性,IDEAL-IQ联合Micro-CT的多模态定量影像技术有望为1型糖尿病提供全面的骨髓微环境评估策略。

Objective:To assess the correlation between bone marrow fat content and trabecular microstructure in the lumbar spine of type 1 diabetic rabbits using the iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence(IDEAL-IQ)in conjunction with micro computed tomography(Micro-CT).Materials and Methods:Sixteen male Japanese white rabbits were randomly divided into a diabetes group(n=8)and a control group(n=8),with the diabetes group induced with alloxan.The IDEAL-IQ quantification sequence was used to evaluate the bone marrow fat content in the lumbar spine of the rabbits at 0,4,8,12,and 16 weeks after the induction of diabetes.Micro-CT and histopathological examinations were conducted at 16 weeks to quantitatively evaluate the trabecular microstructure in the lumbar spine of the rabbits.Differences in the lumbar spine IDEAL-IQ fat fraction at different time points were compared using repeated measures analysis of variance.Differences in the fat fraction,Micro-CT trabecular morphometric parameters,and histopathological parameters between the groups at the same time point were compared using independent sample t-tests or Mann-Whitney U tests.The Pearson correlation coefficient was used to evaluate the correlation between bone marrow fat content and trabecular morphometric parameters and histopathological parameters.Results:The bone marrow fat content of the diabetes group showed an upward trend over time,and the difference was statistically significant(P<0.05),while there was no significant statistical difference in fat content at each time point in the control group(P>0.05).The fat fraction of the diabetes group was significantly higher than that of the control group at week 16(59.987±4.859 vs.51.015±8.469,P<0.05).The diabetes group had lower bone volume,tissue surface,bone surface,bone surface density,trabecular number,but higher trabecular separation than the control group,and the differences were statistically significant(P<0.05).Histopathological results showed that at week 16,compared with the control group,the number of adipocytes in the lumbar vertebral bone marrow of diabetic rabbits increased(32.875±11.051 vs.71.667±13.125,P<0.01),while the number of trabeculae(11.375±1.506 vs.4.333±1.211,P<0.01)and the trabecular area(0.927±0.071 vs.0.312±0.100,P<0.01)decreased significantly.The IDEAL-IQ fat score was positively correlated with histopathological adipocyte count(r=0.53995%CI:0.012-0.832),and was moderately positively correlated with trabecular pattern factor,structure model index,and trabecular separation.It was negatively correlated with bone mineral density,total volume,bone volume,bone volume fraction,total surface area,bone surface area,bone surface area to volume ratio,bone surface area to total volume ratio,and trabecular number,showing a mild to moderate negative correlation.Conclusions:There is a correlation between the bone marrow adipose tissue content and the microstructural changes in lumbar vertebrae in type 1 diabetes.The multimodal quantitative imaging technique combining IDEAL-IQ and Micro-CT holds promise for providing a comprehensive assessment strategy for the bone marrow microenvironment in type 1 diabetes.