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OBJECTIVE@#To analyze the biomechanics of cystic lesions in the mandibular body in a three-dimensional (3D) finite element model.@*METHODS@#A 3D finite element model of cystic lesion of the mandibular body was constructed based on the CT images of the mandible of a healthy adult female volunteer with normal occlusion. The size of the cyst and the residual bone wall were analyzed when the lesion area approached the stress peak under certain constraints and loading conditions.@*RESULTS@#When the size of the cyst reached 37.63 mm×11.32 mm×21.45 mm, the maximal von Mises stress in the lesion area reached 77.295 MPa, close to the yield strength of the mandible with a risk of pathological fracture. At this point, the remaining bone thickness of the buccal and lingual sides and the lower margin of the mandible in the lesion area was 1.52 mm, 0.76 mm and 1.04 mm, respectively.@*CONCLUSIONS@#Residual bone mass is an important factor to affect the risk of pathological fracture after curettage of cystic lesions. A thickness as low as 1 mm of the residual bone cortex in the cystic lesion area of the mandibular body can be used as the threshold for a clinical decision on one-stage windowing decompression combined with two- stage curettage.
Subject(s)
Adult , Female , Humans , Biomechanical Phenomena , Finite Element Analysis , Imaging, Three-Dimensional , Mandible , Stress, MechanicalABSTRACT
Objective:To analyze the value of fine needle aspiration cytology and CT perfusion imaging in differential diagnosis of benign and malignant salivary gland tumors. Methods: Perfusion CT and fine needle aspiration cytology were performed in 36 patients of salivary gland tumors(26 cases in parotid gland, 8 cases in submandibular, 1 case in sublingual gland and 1 case in pars palatalis) and perfusion parameters, including: blood flow(BF), blood volume(BV), mean transit time(MTT), permeability surface(PS). Pathological diagnosis was performed on all salivary gland tumors. Results: 13 cases of 36 patients eventually were diagnosed as malignant salivary gland tumors. The sensitivity, specificity and accordance rate for malignancy of fine needle aspiration cytology were 84.6%(11/13), 95.7%(22/23) and 91.7%(33/36), respectively. The values of BF, BV and PS of the malignant tumors were higher than those of benign tumors significantly(P<0.05). However, the MTT values showed no significant difference between benign and malignant tumors(P>0.05).The sensitivity, specificity, and accordance rate for malignancy of CT perfusion were 92.3%(12/13), 86.9%(20/23) and 88.9%(32/36), respectively. The negative cases of fine needle aspiration cytology can be correctly identified as malignant by CT perfusion imaging. Conclusion: CT perfusion imaging can provide salivary gland tumors with information of microcirculation perfusion. It contributes to the identification of benign and malignant tumors. Paralled with fine needle aspiration cytology can greatly improve the accuracy of salivary gland tumors.
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0.05).Conclusion:The CT perfusion parameters can be regarded as a surrogate marker of tumor angiogenic activity,which is a useful method in estimating the degree of angiogenesis.