三維心臟超音波模型之定位方法

目前的醫學影像技術中，如CT、SPECT、PET與MRI等，雖然有較高的影像品質，但因為其所需儀器設備昂貴或呈像耗時較久，使用上有其不便之處；相較於此，超音波影像提供了即時性的觀察與便於使用，且儀器設備也較為廉價，使得超音波掃瞄成為目前十分重要的一項診療工具。在某些診療中，醫師還是需要以想像力將分散開來的二維切面圖組成完整的三維立體影像，進而對病患做進一步正確的診斷。而本論文著重於尋找二維超音波影像與建立好的三維心臟模型之間的關聯，研發由二維切片於三維模型之定位方法。其步驟包含調整心臟模型大小、模型切片與腔室輪廓比對。建立好的心臟模型之中存在主軸分量資訊，我們利用這些資訊，以主軸分量分析方法來對心臟做旋轉，並透過需要的縮放倍數來調整模型大小。針對調整大小後的心臟模型做一連串的切面，建立起一座切面資料庫，每一個切面在心臟模型的位置皆被紀錄。這些切面將與心臟模型相交形成白點圍成的輪廓，這些輪廓將代表切面，投影到平面上作為比對的資料庫。在比對過程中，將每個模型切面與輸入的超音波影像做比較，依照定位演算法，我們可以計算出最相近的切面並完成定位工作。此實驗結果顯示此定位方法有不錯的比對成功率，除了某些輸入影像會指向正確切面的鄰近切面而有些許偏差。

關鍵字

心臟；超音波；三維模型；定位；輪廓縮放；輪廓比較；心室

並列摘要

Because of the great expense and time consumption of image data acquisition for medical equipments such as CT, SPECT, PET, and MRI, ultrasonic imaging is superior in its advantage of real-time probing and friendliness of use, which made it one of the most important diagnostic tools for clinical purposes. In some diagnostic routines, physicians need to build up a 3D model by imagination from all the 2D cross-sectional images for further diagnosis. In this thesis, we focus on the relationship between 2D ultrasound images and 3D cardiac model and develop a series of process to carry out the orientation of 2D sectors in a 3D cardiac model, including model resizing, model slicing, and contour comparing. Each slice from the model is compared with an input ultrasound image, and by using the orientation algorithm, we can calculate the best matching couple to achieve the orientation work. The experimental results show that almost every number of input images matches the number of slice from the model, except some mismatches occur when the orientation may shift to a neighbor slice.

並列關鍵字

cardiac ； ultrasound ； 3D model ； orientation ； contour resizing ； contour comparing ； ventricle

參考文獻

[1] Nelson TR, Downey DB, Pretorius DH, Fenster A, “Three-Dimensional Ultrasound imaging” Philadelphia: Lippincott Williams & Wilkins, 1999.

[2] Jacqueline Nerney Welch, Jeremy A. Johnson, Michael R. Bax, Rana Badr and Ramin Shahidi., “A real-time freehand 3D ultrasound system for image-guided surgery,” IEEE Ultrasonics Symposium, 2000.

[3] J.Kuo, B.Z Atkins, O.T. von Ramm, “Left ventricle function analysis with real-time three-dimensional ultrasound,” Proceedings of the Second Joint EMBS/BMES Conference, 1105-1106, 2002

[4] Ning Lin, Welchuan Yu, and James S. Duncan, “Combinative multi-scale level set framework for echocardiographic image segmentation,” Lecture Notes In Computer Science; Vol.2488, Proceedings of the 5th international conference on medical image computing and computer-assisted intervention – part I, 682-689, 2002.

[5] A. Mishra, P. K.Dutta, and M. K. Ghosh, “A GA based approach for boundary detection of left ventricle with echocardiographic image sequences,” Image Vis. Comput., vol. 21, 967-976, 2003.

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三維心臟超音波模型之定位方法

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