頁籤選單縮合
題名 | Visualization of Bile Ducts From Mr Cholangiography= |
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作者 | Liu,Feng-yuan; Sun,Yung-nien; Lin,Xi-zhang; Yu,Chin-ying; Tsai,Hong-ming; Wang,Ming-shi; |
期刊 | 醫學工程 |
出版日期 | 19960600 |
卷期 | 8:3 1996.06[民85.06] |
頁次 | 頁48-53 |
分類號 | 415.11 |
語文 | eng |
關鍵詞 | MR cholangiography; Maximum intensity projection; Surface rendering; Reconstruction; |
英文摘要 | MR cholangiography is a newly developed, noninvasive imaging modality for evaluating the patients who have biliary tract diseases. Visualization with clarity and quantitative measurements of the biliary tree structure are advantageous to the differential diagnosis and treatment planning for patients. Unfortunately the images obtained by this modality are usually of low quality due to motion and other artifacts. In our research three different approaches were implemented to visualize the biliary tree. First, a fast maximum intensity projection algorithm was used as a volume rendering method to construct projections from different angles. These projections can be displayed in a cine loop with adjustable speed. It will take only 5-10 seconds to complete the projection and rendering for all viewing angles. Although one can get the sense of object rotation by this method, it's still very difficult to catch a real 3-D biliary structure due to the lack of depth cues. Second, a gradient-based surface rendering method was utilized to display the volume data. It will be need about 20-30 seconds for rendering an image of a particular viewing angle. Due to the severe artifacts and the large interslice spacing of the original data, the biliary tree seen on the rendered image seems to have a rugged surface and lack the expected smoothness. This effect is especially obvious when the viewing angle becomes more parallel to the original slice plane. Last, the tree was tracked and analyzed by using a semi-automated 3D tracking algorithm which we had proposed previously. The coordinates of the points along the medial axis of every branch are estimated by the algorithm. The radii associated with the points along the medial axes are also approximated simultaneously in the tracking process. The locations of the points along the medial axis of every branch are then smoothed by a curve fitting method with the purpose of reducing the interference of artifacts. After the tracking process, what used to be a large volume data set is now condensed to a very concise set of parameters which represents the skeletal and radius information of the biliary structure. The surface of the biliary tree can then be reconstructed and rendered from this small data set. Although this tracking and reconstruction method requires more human interaction and takes longer time, the 3-D structure of the biliary tree can be visualized very clearly. Besides, a concise representation for the biliary tree which can provide quantitative and structural information is obtained. In the future research we'll assess the errors of these methods and make them faster by improving the algorithms. |
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