The Study On The CT Imaging And Biomechanical Mechanism Of Head Deceleration Injury

Objective1. To study the value of injury judgment and imaging diagnosis of head deceleration injury (HDI) by analyzing the injury characteristics of HDI. In addition, a typical case of HDI would be used to reconstruction.2. Using an experimental model to further study the injury characteristics of HDI.To provide the beneficial supplementary for clinical HDI characteristics and definite pathological evidence for CT diagnosis of HDI.3. To build a 3D Chinese human head FE model based on the Chinese visible human (CVH) data set, and to study the reconstruction technique of high-quality FE model.4. To investigate the biomechanical mechanism of the occipital head impacted by accident reconstruction with FE method and provide biomechanical evidence for diagnosis and therapy of HDI.Methods1. By analyzing the conventional spiral CT imaging of head with HDI in our depatment,combined with the history of head impact and clinical data , the injury characteristics of HDI were summarized.2. Used an HDI experimental model of rabbit arising from falls, and the injury of HDI being detected with noncontrast CT and perfusion CT (PCT) approach. The detected results were compared with macroanatomy and microscopy to investigate the relations between CT findings and pathological injury.3. Successive thin-layer cross-sectional images of head were retrieved from the second CVH data set, and semi-automated segment with Photoshop CS3 software to acquire segmented data of two-dimensional (2D) head images. By using Amira 4.1 software, the segmented data were reconstructed to get head three-dimensional (3D) geometrical model of surface rendering. In Hypermesh 8.0 software, entity model reconstruction, meshing of FE and assembling of FE models have been done and a head FE model based on Chinese human was developed.4. Accident reconstruction for the HDI case was performed using LS-DYNA software, and the distribution characteristics of stress could be acquired by the numerical analysis with the FE model based on the CVH. The simulation results were compared with CT findings of case, and the biomechanical mechanism of HDI was discussed.Results and conclusions1. The traumatic condition and CT findings of HDI clinical patients, and summarized the injury characteristics of HDI were systematically analyzed. According to HDI characteristics and the history of head impact, it can help to provide the evidence for clinical rapidly, accurate judgment and therapy of head injury, and help to guide CT scanning and diagnosis of brain injury. According to HDI characteristics and CT findings, the site of impact and of the course of the traumatizing force can be deduced, and the data obtained by this procedure may theoretically provide the evidence for judgment the cause of head trauma accident.2. The course of the definite HDI traumatizing was reconstructed by using an experimental model of rabbit arising from falls, and the HDI characteristics in rabbit were as follows: scalp contusion and cranial fracture at coup site; basal fracture was more severe than cranial fracture, with more cases at the anterior or middle fossa; subdural hematoma mainly at contrecoup site; subarachnoid hemorrhage was the most frequent lesions of intracalvarium, mainly around brainstem and the ventral aspect of the brain; cerebral contusion at both coup and contrecoup site, the lesions at the site of contrecoup were more severe. The feature of pathology and CT imaging provided the beneficial supplementary for clinical HDI characteristics.3. The good corresponding relationship between pathology and CT imaging of HDI can provided the definite pathological evidence for CT diagnosis. The HDI characteristics can be satisfactorily assessed by means of combining NcCT and PCT scans. Contused areas in PCT matched pathoanatomical brain tissue breakage, bleeding, hyperemia and edema regions, which provided the experimental evidence for early and sensitive detection of cerebral contusions.4. A reconstruction methodology of FE model with complicated anatomic structure has been developed. The fist FE model based on the CVH was successfully constructed, including cerebrum, cerebellum, brainstem, cerebral falx, skull, maxillae and submaxilla. The FE model was superior to other FE model in integrality, truth and representation. The model was very helpful in the field of head biomechanical analysis simulation platform.5. The distribution characteristics of head stress were simulated by the FE analysis HDI of the occipital head impacted. As results, the Von-Mises stress was centralized in the area of skull and brain not only at the impact site but also the contrecoup site. The distribution characteristic of higher Von-Mises stress levels showed a good agreement with that of the injured region on the CT imaging, and was accorded with the injury characteristics of DHI of clinical patients and animal experiment.6. The relationship between head injury distribution and stress centralization may provide theoretical evidence for diagnosis and therapy of HDI. Accident reconstruction based on the CVH FE model may provide the technique platform for the diffusion of head stress and biomechanical analysis of head injury. Combined with the stress distribution characteristic of digitized model, the traumatizing force can be deduced, which can provide the assistant proof for accident reconstruction.