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。近年來有研發團隊製造人工血管，來做為實驗的平台及驗證模擬的結果，但是因為製造的人工血管模型皆為塊狀(並非中空管狀結構)、非透明、且無彈性，與實際的血管形貌還是有相當大的差距，也因此並不適當作為醫學研究或醫療訓練的模型。
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，本研究欲利用非傳統加工，製作一管壁厚度可控制之透明彈性動脈瘤模型，製程中將透過內外模具的設計、利用熔融擠製型3D列印機製作出內外模具、蒸氣表面拋光及後處理、彈性材料之澆鑄及脫模技術，最後製作出可控制血管壁厚度的全透明腦動脈瘤模型。為了讓此模型在醫生執行動脈瘤夾閉手術訓練過程中的手感能貼近真實血管動脈瘤，研究中透過機械拉伸試驗獲得最類似血管壁彈性係數的材料比例，作為澆鑄血管及動脈瘤的材料。
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的全透明血管模型，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。在驗證本研究的動脈瘤醫療模型上，第一個實驗是將染色液體(做為血液)模擬血液流速打入動脈瘤內，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。第二個實驗是將製造的動脈瘤模型，依照斷層掃描的影像，將動脈瘤固定於3D列印的頭顱內，作為訓練實習醫生如何使用動脈瘤鉗執行動脈瘤夾閉手術，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 the various 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 burst and induce strokes. To investigate the causes of vascular wall lesions and 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. In recent years, research teams have developed artificial blood vessels to serve as an experiment platform and verify simulation results. However, the artificial blood vessel models are non-transparent and blocks (not hollow tube structures), which make them quite different from actual blood vessels and unsuitable for medical research or training.
In this study, we collaborated with the Neurological Surgery Department at the Tri-Service General Hospital. 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 employed unconventional manufacturing processing to create a transparent and elastic aneurysm model with controllable vascular wall thickness. After designing the inner and outer molds, we used extrusion 3D printing to create the inner and outer molds, which was followed by vapor polishing, post-processing and the casting and demolding of the elastic material, ultimately producing a completely elastic and transparent cerebral aneurysm model with controllable vascular wall thickness. To make the feel of training for aneurysm clipping surgery more authentic, we conducted mechanical tensile tests to obtain the material proportions with elasticity closest to that of actual vascular walls and utilized the same material proportions for blood vessel and aneurysm casting.
Experiments indicated that the process developed in this study could successfully construct completely transparent, hollow, and elastic blood vessel 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 blood vessel model. 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. In our second experiment, we fixed an aneurysm model in a 3D-printed head skull based on CT scans to train interns on how to clip aneurysms using aneurysm forceps. 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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