BACKGROUND:To decrease operation amount of finite element analysis and increase its clinical practice,previous studies explored the material properties and 10 kinds of material attributes were assigned,which met the requirements of finite element analysis.Moreover,it can be used to calculate bone density.OBJECTIVE:To explore a method for measurement of bone density based on three-dimensional reconstruction and finite element analysis.METHODS:A total of 11 specimens of femoral superior segment were selected.The mass of control group was firstly measured.The experimental groups were treated with thin-slice high resolution CT scan and three-dimensional reconstruction in Mimics 10.0,volume meshing in Ansys,assigned with 10,100 and 400 kinds of material attributes Mimics,exported to Ansys to calculat the volumes of the block elements of every types of material attributes.The mass and the density of the specimens was harvested according to the empirical formula concerning the gray value and the bone density.All results were treated with one-way ANOVA.RESULTS AND CONCLUSION:One-way ANOVA showed that there were no significant differences between control group and experimental groups assigned with 10,100 and 400 kinds of material attributes (P＞0.28),and there were no significantly among the experimental groups (P＞0.8).Results show that the method was able to measure the mass and the density of bone quantitatively,as well as the proportion between compact bone and cancellous bone;to assign 10 kinds of material attributes to three-dimensional model of femur could match the needs for measurements.The results can be used as an initial preparation for the unification of bone density and finite element analysis for osteoporosis.

BACKGROUND:Based on previously theoretical derivation,it thought that assignment with 10 kinds of material attributes to three-dimensional model of bone can match the needs of finite element analysis,however,whether the results is consistent with actual needs to be validated by experimental results.OBJECTIVE:Twelve specimens of femoral superior segment were used for finite element analysis,which were verified with results of biomechanical testing,to explore a reasonable method for material assignment of bone.METHODS:All 12 specimens of femoral superior segment were treated with CT scan,three-dimensional reconstruction in Mimics 10.0 and volume meshing in Ansys.The finite element analysis group was divided into 2 kinds (compact bone and cancellated bone),10,50,100,200,400 kinds of material attributes groups based on the gray value.All models were assigned with material attributes and tested in Ansys for mechanics data of nodes on surface of femoral neck.In biomechanical testing group,12 specimens of femoral superior segment were treated with compressed testing to harvest mechanics data of measuring point same as that of finite element analysis group.RESULTS AND CONCLUSION:The one-way analysis of variance showed that the differences between the biomechanical testing group and finite element analysis group of 2 kinds of material attributes had no obvious significance (P=0.082).Compared to the 10,50,100,200,400 kinds of material attributes group,the difference had no significance (P > 0.39).However,the differences between the 2 kinds of material attributes and the 10,50,100,200,400 kinds of material attributes in the finite element analysis group were obviously difference (P< 0.05),which was no difference in the 10,50,100,200,400 kinds of material attributes (P>0.9).The results demonstrated that to assign 10 kinds of material attributes to three-dimensional model of bone can match the needs of finite element analysis.

Objective To evaluate the clinical value of multi-slice spiral CT (MSCT)in the screening of coronary artery lesions in elderly patients with diabetes mellitus.Methods MSCT and coronary angiography(CAG)were performed in 136 elderly patients(68 patients with diabetes and 68 patients without diabetes).The number of diseased coronary segments and the plaque type (noncalcified,mixed and calcified)for each patient were determined.The characteristics of coronary lesions were compared between patients with and without diabetes.The sensitivity and specificity of MSCT were evaluated.Results More noncalcified and calcified plaques and few ermixed plaques were observed in patients with diabetes,compared with patients without diabetes(noncalcified plagues:10 cases or 14.7％ vs.4 cases or 5.9％;calcified plagues:47 cases or 69.1％ vs.39 cases or 57.4％)(P＜ 0.05).In addition,diabetic patients showed a significantly higher frequency of multivessel disease(P＜0.05).Furthermore,MSCT was able to clearly show stenosis and plaque type in the trunk and branches of the coronary artery,with a sensitivity of 91.0％,a specificity of 95.0％,a positive predictive value of 93％ and a negative predictive value of 96.0％.Conclusions Diabetes is associated with a higher risk of coronary artery disease.MSCT can effectively detect the characteristics of coronary artery disease in diabetic patients and is an effective,noninvasive,and safe screening method.