陳廣新 趙東良 郭金興
摘 ?要: 探討基于CTA的個(gè)體化腦動(dòng)脈瘤的流固耦合分析,為臨床應(yīng)用提供幫助。利用真實(shí)患者的腦動(dòng)脈瘤DICOM格式影像檢查數(shù)據(jù),利用MIMICS軟件進(jìn)行三維重建血流模型、應(yīng)用3-matic軟件進(jìn)行修復(fù)、光順,應(yīng)用ANSYS ?ICEM ?CFD軟件生成流體的有限元模型,利用HYPERWORKS SimLab軟件基于流體模型構(gòu)建動(dòng)脈壁有限元模型,使用ANSYS ?FLUENT+Transient Structural進(jìn)行雙向流固耦合計(jì)算一個(gè)心動(dòng)周期的動(dòng)脈瘤血流動(dòng)力學(xué)參數(shù)。本文有限元模型的構(gòu)建方法可有效的分析動(dòng)脈瘤的血流動(dòng)力學(xué)參數(shù),為臨床提供科學(xué)的理論指導(dǎo)。
關(guān)鍵詞: 腦動(dòng)脈瘤;血流動(dòng)力學(xué);計(jì)算流體力學(xué)分析
中圖分類號(hào): TP319 ? ?文獻(xiàn)標(biāo)識(shí)碼: A ? ?DOI:10.3969/j.issn.1003-6970.2020.01.020
本文著錄格式:陳廣新,趙東良,郭金興,等. 基于CTA的個(gè)體化腦動(dòng)脈瘤的流固耦合分析及其臨床應(yīng)用[J]. 軟件,2020,41(01):97101
【Abstract】: The fluid-solid coupling analysis of individualized cerebral aneurysms based on CTA was discussed to provide help for clinical application. Using DICOM format image examination data of cerebral aneurysms of real patients, three-dimensional blood flow model reconstruction is performed by MIMICS software, repair and smoothing are performed by 3-matic software, finite element model of fluid is generated by ANSYS ICEM CFD software, finite element model of arterial wall is constructed by HYPERWORKS SimLab software based on fluid model, and bidirectional fluid-solid coupling is performed by Ansys Fluent+Transient Structure to calculate hemodynamic parameters of aneurysm in one cardiac cycle. The construction method of finite element model in this paper can effectively analyze the hemodynamic parameters of aneurysm and provide scientific theoretical guidance for clinic.
【Key words】: Cerebral aneurysm; Hemodynamics; Computational fluid dynamics analysis
0 ?引言
顱內(nèi)動(dòng)脈瘤(intracranial aneurysms,IA)是一種嚴(yán)重危害健康的腦血管疾病,普通人群發(fā)病率約為3.2%[1]。IA一旦破裂,致殘率及致死率非常高[2]。隨著醫(yī)學(xué)影像診斷技術(shù)的提高,IA大多可準(zhǔn)確診斷[3]。計(jì)算流體力學(xué)(computational fluid dynamics,CFD)對(duì)血流動(dòng)力學(xué)的研究提供了可以借鑒的方法,大大的拓寬了血流動(dòng)力學(xué)的研究途徑。血流動(dòng)力學(xué)因素包括壁面壓力、血流速度、壁面剪切應(yīng)力等被認(rèn)為是影響動(dòng)脈瘤的發(fā)生發(fā)展的重要因素。應(yīng)用計(jì)算流體力學(xué)對(duì)動(dòng)脈瘤進(jìn)行血流動(dòng)力學(xué)研究,具有可控性好、穩(wěn)定性高、計(jì)算準(zhǔn)確等優(yōu)勢(shì)。國(guó)內(nèi)外學(xué)者已經(jīng)基于CFD方法對(duì)血流動(dòng)力學(xué)進(jìn)行了大量的研究[4,5]。以往的研究偏重于流體力學(xué)分析,對(duì)動(dòng)脈瘤進(jìn)行流固耦合分析較少。本文基于個(gè)體化動(dòng)脈瘤CTA影像數(shù)據(jù),分別構(gòu)建血流、動(dòng)脈壁的有限元模型,采用雙向流固耦合計(jì)算,獲得一個(gè)心動(dòng)周期的血流動(dòng)力參數(shù),分析動(dòng)脈瘤的血流動(dòng)力學(xué)特點(diǎn),為臨床的研究提供借鑒。
1 ?材料與方法
1.1 ?圖像采集
采集牡丹江醫(yī)學(xué)院附屬紅旗醫(yī)院一名動(dòng)脈瘤患者未破裂腦動(dòng)脈瘤影像數(shù)據(jù),患者知情同意,經(jīng)醫(yī)院倫理委員會(huì)批準(zhǔn)。使用日本東芝Aquilion 64層螺旋CT行頭部CTA檢查,檢查數(shù)據(jù)以DICOM格式輸出。
1.2 ?三維模型構(gòu)建
使用MIMICS 21.0軟件手動(dòng)導(dǎo)入采集的動(dòng)脈瘤DICOM格式文件。采用閾值分割、區(qū)域增長(zhǎng)等算法,計(jì)算三維模型,獲得動(dòng)脈瘤3D模型,并經(jīng)手動(dòng)分割,保留載瘤動(dòng)脈。將獲得的3D動(dòng)脈瘤模型以stl格式導(dǎo)入正向工程軟件3-matic進(jìn)行光順、表面網(wǎng)格優(yōu)化,最終獲得包括動(dòng)脈瘤的血流3D模型(圖1)。動(dòng)脈壁的模型須依此生成。
1.3 ?有限元網(wǎng)格生成
動(dòng)脈壁網(wǎng)格:基于動(dòng)脈瘤stl格式直接生成動(dòng)脈壁網(wǎng)格。將.stl格式的動(dòng)脈瘤模型導(dǎo)入SimLab軟件(美國(guó)Altair公司有限元網(wǎng)格劃分軟件)中,生成三層的棱形網(wǎng)格結(jié)構(gòu),壁厚0.2 mm(圖2)。
動(dòng)脈瘤網(wǎng)格:應(yīng)用ANSYS ICEM CFD(美國(guó)ANSYS公司流體網(wǎng)格劃分軟件)軟件劃分動(dòng)脈瘤.stl格式模型。流體采用四面體類型、為保證計(jì)算精度邊界層5層加密(圖3)。
[8] Fatma Gulden Simsek, Young W. Kwon. Investigation of material modeling in fluid–structure interaction analysis of an idealized three-layered abdominal aorta: aneurysm initiation and fully developed aneurysms[J]. J Biol Phys, 2015, 41(2): 173-201.
[9] Paris Perdikaris, Joseph A. Insley, Leopold Grinberg, Yue Yu, Michael E. Papka, George Em. Karniadakis. Visualizing multiphysics, fluid-structure interaction phenomena in intracranial aneurysms[J]. Parallel Comput, 2016, 55: 9-16.
[10] Tianlun Qiu, Guoliang Jin, Wuqiao Bao, Haitao Lu. Intercorrelations of morphology with hemodynamics in intracranial aneurysms in computational fluid dynamics[J]. Neurosciences, 2017, 22(3): 205-212.
[11] Kristian Valen-Sendstad, Aslak W. Bergersen, Yuji Shimogonya, et.al. Real-World Variability in the Prediction of Intracranial Aneurysm Wall Shear Stress: The 2015 International Aneurysm CFD Challenge[J]. Cardiovasc Eng Technol, 2018; 9(4): 544-564.
[12] Yunling Long, Jingru Zhong, Hongyu Yu, Huagang Yan, Zhizheng Zhuo, Qianqian Meng, Xinjian Yang, Haiyun Li. A scaling aneurysm model-based approach to assessing the role of flow pattern and energy loss in aneurysm rupture prediction[J]. J Transl Med, 2015; 13: 311.
[13] Gambaruto AM, Janela J, Moura A, et al. Sensitivity of hemodynamics in a patient specific cerebral aneurysm to vascular geometry and blood rheology[J]. Math Biosci Eng, 2011, 8(2): 409-423.
[14] Cebral JR, Meng H. Counterpoint: realizing the clinical utility of computational fluid dynamics-closing the gap[J]. AJNR Am J Neuroradiol, 2012, 33(3): 396-398.
[15] Xiang J, Natarajan SK, Tremmel M, Ma D, Mocco J, Hopkins LN, Siddiqui AH, Levy EI, Meng H. Hemodynamic morphologic discriminants for intracranial aneurysm rupture[J]. Stroke J Cereb Circ, 2011, 42(1): 144-152.
[16] Lu G, Huang L, Zhang XL, Wang SZ, Hong Y, Hu Z, Geng DY. Influence of hemodynamic factors on rupture of intracranial aneurysms: patient-specific 3D mirror aneurysms model computational fluid dynamics simulation[J]. AJNR Am J Neuroradiol, 2011, 32(7): 1255-1261.
[17] Jia Lu, Shouhua Hu, Madhavan L. Raghavan. A shell- based inverse approach of stress analysis in intracranial aneurysms[J]. Ann Biomed Eng, 2013, 41(7): 1505-1515.
[18] Xu Bai-Nan, Wang Fu-Yu, Liu Lei, Zhang Xiao-Jun, Ju Hai-Yue. Hemodynamics model of fluid–solid interaction in internal carotid artery aneurysms[J]. Neurosurg Rev, 2011, 34(1): 39-47.
[19] Fatma Gulden Simsek, Young W. Kwon. Investigation of material modeling in fluid structure interaction analysis of an idealized three-layered abdominal aorta: aneurysm initiation and fully developed aneurysms[J]. J Biol Phys, 2015, 41(2): 173-201.
[20] Yue Yu, Paris Perdikaris, George Em Karniadakis. Fractional modeling of viscoelasticity in 3D cerebral arteries and aneurysms[J]. J Comput Phys, 2016, 323: 219-242.
[21] J.D. Humphrey, G.A. Holzapfel. Mechanics, Mechanobiology, and Modeling of Human Abdominal Aorta and Aneurysms[J]. J Biomech, 2012, 45(5): 805-814.
[22] Malebogo N. Ngoepe, Alejandro F. Frangi, James V. Byrne, Yiannis Ventikos. Thrombosis in Cerebral Aneurysms and the Computational Modeling Thereof: A Review Front Physiol[J]. 2018, 9: 306.
[23] Michael J Bonares, A Leonardo de Oliveira Manoel, R Loch Macdonald, Tom A Schweizer.Behavioral profile of unruptured intracranial aneurysms: a systematic review[J]. Ann Clin Transl Neurol, 2014, 1(3): 220-232.