Diffusion MRI Based 3D Stereo Visualization of Neural Tracts

• Main Authors: Chun-Yi Lo, 羅畯義
• Other Authors: Ching-Po Lin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/53754077882136540309

碩士 === 中原大學 === 醫學工程研究所 === 95 === The relationship between tumor mass and peri-tumoral structures is important for tumor excision, treatment, and estimating the tumor-infiltrated degree. Conventionally, Gadolinium(Gd)-T1WI and T2WI provide the information of tumor mass and peri-tumoral edema. Diffusion tensor MRI (DTI) has shown its feasibility in grading tumor and monitoring therapeutic effects as well as clinical outcome. Moreover, the neural fiber direction would be traced and the neuroimage would be reconstructed for showing the neural pathway thru the process of DTI. The purpose of this thesis is to develop a virtual reality (VR) system. By combining with the virtual reality (VR) technique, the information in the brain can be represented via the three- dimension stereo image, and the visualization of tumor and neural tracts can be provided for the applications of the pre-surgery trajectory plan and post-surgery evaluation. DTI was used to display the diffusion motion of water molecules in the brain. By assuming the principle diffusion direction as that of the neural tract, the neuroimage was preformed via one of the tractography algorithm, namely, the fiber assignment by continuous tracking (FACT). In this study, FA threshold was set to be 0.2, and the angular limitation was set to be 60 degrees as the criteria for the FACT algorithm for several different DTIs. By applying region of interest (ROI) selection techniques, the tumor mass and edema were respectively segmented on Gd-T1WI and T2WI, and then to build both objects by 3D reconstruction. Moreover, With the OpenGL functions, the 3D image was reconstructed via the viewpoints of two eyes, and the VR 3D stereo neuroimage was shown by stereo display system. Finally, the image of real phantom and the other which was reconstructed with OpenGL were used to evaluate the accuracy of this system. Results show that the accuracy of phantom image is 100%. However, the test average error line of OpenGL image was 0.6 which due to the color contrast of the lines and background. When the lines color of OpenGL image was set with the color of neuroimage, the accuracy is 100%, too. By the result, the accuracy of display system could be evaluated by using the phantom image. By applying to DTIs, the neuroimage was displayed in the 3D stereo mode successfully via this system. By integrating the tumor mass and edema information, the relationship among neural tracts, tumor mass and edema is much easier to realize. Moreover, the whole brain neural tracts displaying, peri-tumoral tracts or tracts through the specific area is shown by different ROI selections. In this study, a 3D VR system integrating with neuroimage and contours of tumor, and edema was developed. It helps the clinicians to understand the anatomy information of patient’s brain and then the pre-surgical planning including the surgery mode, trajectory, and tumor mass size, position determination and the post-surgical outcome can be optimized in neurosurgery.