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標題: 以立體血管顯像術重建三維血管模型
Using Stereoscopic Magnetic Resonance Angiography to Reconstruct Blood Vessels
作者: 黃世輝
關鍵字: 醫學影像;立體血管影像
出版社: 電機工程學系

There are two approaches to acquire an image of MRA(Magnetic Resonance Angiography) which is an imaging technique to show the blood vessels but suppress signals from all the other tissues.One is projecting the 3-D vessels onto 2-D plane.The other is to directly obtain the complete 3-D information.The advantage of 3-D MRA is that we can view the data from arbitrary direction.However,the scan time is usually very long for 3-D MRA.Due to the scan time is limited,we could use 2-D MRA only and the depth of information is sacrificed.In this thesis,we research how to recover the depth information by reconstructing 3-D vessels image from two projective MRA images.
Stereoscopic angiography utilizes two images by projecting blood vessels onto 2-D plane in two angles to reconstruct 3-D vessel image. For DSA, the pixel value is the integration of the attenuation value in the path of the X-ray. We can use this property to derive the shape of the vessels by solving the integrals. On the other hands, there are many imaging parameters in MRA(such as T1 , T2 and proton density). Therefore, it is difficult to obtain the relation between the shape of the vessels and the pixel intensity. For this reason, we attempt to reconstruct the shape of the vessels by geometry.
In the thesis, eighty images of MRA were used to demonstrate the capability of our algorithm. From these images, we use fifty images to make two projective images. The two projections are 300 apart. Then we employ our algorithm to estimate all the ellipses and reconstruct the 3-D model of the vessels. Comparing the boundaries of the original projective images with the boundaries of the reconstructed 3-D model by proved appro-
ach, the average error is 0.844.
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