多年來腦血管相關疾病是全世界十大死因的第二名，在不同種類的腦血管相關疾病中，腦中風是最危險的其中一種，其成因是因為顱內血管管壁病變，在血液不停的流動及衝擊下，導致動脈瘤破裂而造成中風。為了要研究血管管壁病變的原因、腦中風的成因以及探討如何預防腦中風，傳統上研究人員利用理論以及電腦模擬軟體來了解血液動力學與血管幾何形狀對於動脈瘤形成的影響。而目前在腦神經外科醫師之術前培訓上，大多是透過大體老師來讓學員們有完整的腦結構概念，以及跟隨資深醫師進入手術室學習手術過程，但是大體老師的取得不易、價格昂貴、且血管形貌和真正病患不盡相同，使得學員進入手術室真正執刀的機會也有限制。近年來有研發團隊利用3D列印技術製造人工血管，來做為實驗的平台及驗證模擬的結果，但是所列印出的管脈系統尺寸誤差大、透明度差、彈性不佳等，與實際脈管系統之結構仍有很大的差異，因此無法用於驗證模擬結果，導致研究結論不夠完善，甚至和臨床觀察的結果有相當大的落差。
本研究與三軍總醫院腦神經外科合作，由臨床主治醫師說明顱內動脈瘤手術的步驟，手術教育訓練的需求，以及目前顱內動脈瘤研究的瓶頸，經雙邊討論後，本研究欲利用3D列印、模具設計、彈性材料澆注技術，開發一專業醫療模型，可做為腦神經外科醫師訓練開顱夾除腦血管瘤手術的訓練模擬器，此醫療模型包括頭顱、腦幹、大腦軟組織、頸動脈、以及一管壁厚度可控制之中空全透明的威利氏環腦血管(Circle of Willis)脈管系統，並在幾個腦血管瘤發生機率較高的血管區段製做血管瘤，做為訓練學員的教具。
從實驗得知，本研究所開發的製程可以成功建構中空富彈性全透明且整體模型尺寸精度很高的威利氏腦動脈瘤仿生模型，這樣的技術可以延伸到製造體內其他部位的脈管系統，作為醫療研究的實際模型。在驗證本研究的威利氏腦動脈瘤仿生模型上，首先為將染色液體(做為血液)模擬血液流速打入模型內，可用來直接觀察液體在血管及動脈瘤內的流動現象，這一類的實驗往後可以延伸至研究血管的幾何形貌對於動脈瘤的形成，或是血管的幾何形貌對於動脈瘤壁上剪應力的關係。接著則是將此一的威利氏腦動脈瘤仿生模型，結合頭顱、腦幹以及腦部軟組織，以作為訓練實習醫生執行動脈瘤夾閉手術的練習模型，這一實驗將持續和三總腦神經外科合作，讓此模型能成為創新醫材、標準醫療教具。

For many years, cerebrovascular diseases have been second leading cause of death around the globe. Among all the cerebrovascular diseases, strokes are the most dangerous. They are caused by intracranial vascular wall lesions which, under the constant flow and impact of blood, result in aneurysms that may cause and induce strokes. To investigate the causes of vascular wall lesions, strokes and the means of preventing strokes, researchers conventionally used theory and computer simulations to understand the influence of hemodynamics and vascular geometry on the formation of aneurysms. At present, most of the pre-operative training of neurosurgeons is to provide students with a complete concept of brain structure through the Cadaver, and follow the senior doctor to enter the operating room to learn the surgical process, but the acquisition of the Cadaver is not easy, the price is expensive and the shape of the blood vessel is different from the real human body, so the student's chance to get a real operation in the operating room is also limited. In recent years, a research and development team has used 3D printing technology to manufacture artificial blood vessels as a platform for experiments and to verify the results of simulations. However, the listed vascular system has large dimensional errors, poor transparency, and poor elasticity. The structure of the tube system is still very different from actual vascular system, so it cannot be used to verify the simulation results, resulting in insufficient research conclusions, and even a considerable gap with the clinical observations.
In this collaborative effort with the Neurosurgery Department of the Tri-Service General Hospital under the National Defense Medical Center. A clinical physician explained the procedure of cerebral aneurysm surgery, the needs of surgical education and training, and the current obstacles in cerebral aneurysm research. Following discussion, we used the latest 3D printing, mold design, and the elastic material casting technology to develop medical models for use in training neurosurgeons in craniotomy and aneurysm clip operations. The model provides highly detailed and realistic brain stem, soft brain tissue, carotid arteries, and a hollow transparent Circle of Willis, in which the thickness of vascular walls can be controlled and aneurysms can be fabricated in multiple locations where they are likely to appear. The resulting model gives surgical trainees hands-on experience performing intricate tasks that is very similar to real-world situations.
Experiments indicated that the process developed in this study could successfully construct completely transparent, hollow, elastic and high overall model dimensional accuracy Circle of Willis bionic models. This technique can be expanded to create other vascular systems inside our body to serve as actual models for medical research. We conducted two experiments to verify the applicability of the Willis Circle bionic models. The first experiment involved the use of dyed liquid (to serve as blood) to simulate blood flow in an aneurysm. This enabled us to directly observe the flow of liquid in the blood vessels and aneurysm. Similar experiments can be used to examine the influence of vascular geometry on the formation of aneurysms or on the shear-stress relationship in vascular walls. Next, this Willis brain aneurysm bionic model, combined with the skull, brain stem and brain soft tissue, is used as an exercise model for training interns to perform aneurysm clipping surgery. We will continue to work with the Neurological Surgery Department at the Tri-Service General Hospital to turn this model into a creative medical product and a standard teaching aid in medical education.

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