The analysis of bone mass and microarchitecture in ovariectomized rat by dual energy X-ray absorptiometry and microCT
- VernacularTitle:比较双能X线吸收测量仪与显微CT显示不同时期去卵巢大鼠胫骨骨量和微结构的特点
- Author:
Huijie FAN
;
Ruchun DAI
;
Zhifeng SHENG
;
Lingna FANG
;
Xianping WU
;
Eryuan LIAO
- Publication Type:Journal Article
- Keywords:
X-rays;
Bone density;
Tomography,X-ray computed
- From:
Chinese Journal of Radiology
2008;42(4):419-425
- CountryChina
- Language:Chinese
-
Abstract:
Objective To observe and compare the changes of bone mass and microarchitecture in ovariectomized rat left tibia by dual energy X-ray absorptiometry(DXA)and microCT(μCT).Methods Forty seven-month-old SD rats were randomly divided into ovariectomized(OVX)and sham-operated(SHAM)groups,twenty in each group.After killed at 3 weeks and 15 weeks post-surgery,DXA scanning were performed in the left tibia in vitro.The images of left tibia were divided into seven isometric regions of interest(ROI1-7).When analysis finished,bone density(BD)of each ROI and the total bone were determined.The samples were fixed by 4% paraformaldehyde and then placed in the specimen holder filled with deionized water.The sensitive regions for bone mass changes were selected for scanning by Fluro.After scanning,the regions involving 0.4mm slice thickness and 2.5mm distance far end from tibial growth plate were selected as the ROI of cortical bone analysis.The regions selected as ROI of cancellous analysis,were involved in 1.2mm slice thickness and 0.7mm distance at the far end from tibial growth plate.After three dimension reconstruction.2D images of the maximum intensity projection and pictures of 3D microarchitecture were obtained.and BD and microarchitectural parameters were quantitatively identified.All data was statistically processed with SPSS for Windows.Results At the 3rd week,BD of ROI1 in rat left tibia in OVX(0.2346±0.0280)g/cm2 was much lower than that(0.2660±0.01990)g/cm2 in SHAM(P＜0.05).While at the 15th week,BD of ROI1(0.2527±0.0161)and ROI2(0.1862±0.0052)g/cm2 in OVX were both lower than SHAM(0.2793±0.0229)and(0.1986±0.0102)g/cm2 respectively,P＜0.01 for both).Compared wim SHAM rat[cortical area(Ct-Ar)=(0.3138±0.0621)mm2,marrow area(Ma-Ar)=(8.44±1.25)mm2,total area(T-Ar)=(8.75±1.26)mm2,moment of inertia(Mm)=(3.485±0.373)mm4],there were significant increases in Ct-Ar(0.4306±0.1308)mm2,Ma-Ar(10.31±1.98)mm2,T-Ar(10.74±2.05)mm2,and Mm(4.101±0.726)mm4 in OVX mice at the 3rd week(P＜0.05 for all).While at the 15th week,only cortical thickness(Ct-Th)(0.0235±0.0024)mm showed a decrease in OVX group(P＜0.05).In OVX group,Ct-Th(0.0235±0.0024)mm and Ct-Ar(0.2528±0.0367)mm at 15 weeks were lower than that[Ct-Th=(0.0377±0.0098)mm,Ct-Ar=(0.4306±0.1308)mm2 at 3 weeks(P＜0.01 for both)].In SHAM group,inner perimeter(In-Pm)(13.38±0.54)mm,outer perimeter(Ot-Pm)(13.59±0.56)mm and Mm(4.096±0.364)mm4 at 15 weeks were higher than that[In-Pm=(12.41±0.74)mm,Ot-Pm=(12.63±0.75)mm,Mm=(3.485±0.373)mm4 at 3 weeks(P＜0.01 for all)].OVX rats had much lower volume BD(vBD)(288.2±48.2)mg/mm3,tissue BD(tBD)(604.5±45.3)mg/mm3,bone volume fraction(BVF)(25.1±5.1)%,and trabecular mumeer(Tb-N)(6.04±2.94)mm-1(P＜0.01 for all),but higher structure model index(SMI)3.09±0.27 and trabecular separation(Tb-Sp)(0.186±0.129)mm than SHAM 2.63±0.21 and(0.078±0.038)mm respectively at the 3rd week(P＜0.01 and P＜0.05 respectively).At the 15th week,vBD(271.2±50.9)mg/mm3,BVF(21.6±5.2)%and Tb-N (3.21±1.92)mm-1 in OVX were still lower than SHAM[vBD=(389.8±77.0)mg/mm3,BVF=(30.9±6.0)%,Tb-N=(7.44±3.53)mm-1 respectively(P＜0.01 for all)],SMI 3.11±0.36 and Tb-Sp(0.370±0.215)mm in OVX were also higher than SHAM 2.58±0.36 and(0.141±0.104)mm(P＜0.01 for both),but no significant difference of tBD could be found.In OVX group.the scores of tBD(691.0±36.7)mg/mm,Tb-Th(0.040±0.009)mm,Tb-N(3.21±1.92)mm-1,Tb-Sp(0.370±0.215)mm in the 15th week were higher than that[tBD=(604.5±45.3)mg/mm,Tb-Th=(0.030±0.002)mm,Tb-N=(6.04±2.94)mm-1,Tb-Sp=(0.186±0.129)mm respectively]in the 3rd week (P＜0.05 for all),while there were no differences between the 3rd and the 15th week in SHAM group.Conclusions DXA is weak in detecting the tiny changes of BD though it is convenient and non-invasive.μCT is suitable to detect the changes of bone mass and microarchitecture.
