心血管系统的生理流动虚拟现实
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摘要
血流动力学因素被认为与动脉粥样硬化等动脉疾病的发生和发展有着密切的关系。为了更好的了解人体心血管系统的生理和病理行为，必须深入研究动脉内的血流动力学问题。在动脉疾病的外科手术中，同样需要考虑血流动力学因素，以避免出现动脉粥样硬化等危险性的血流动力学因素。目前，对于心血管疾病病灶性部位的血流动力学的研究已经取得了大量的研究成果，但并未形成方便、快捷的集成化系统来提高血流动力学的分析效率，以利于血流动力学的临床应用，如心血管疾病的外科手术规划等。
本课题基于通用的有限元分析软件ANSYS，开发了一套用于动脉粥样硬化病灶性部位血流动力学分析的集成化软件系统VRCF（Virtual Reality of Cardiovascular Flow）。该软件系统通过友好的图形化用户界面（GUI）将CAD建模、医学图像的三维重建、血流动力学数值模拟、流动可视化等技术有机地结合在一起，为动脉粥样硬化病灶性部位的血流动力学分析提供了一个方便快捷的软件环境。该系统具有良好的数据管理系统、便捷的操作界面以及可选择的环境变量设置，其最终目的是应用于心血管疾病的外科手术规划，优化手术方案。
VRCF的大多数功能模块是基于ANSYS的二次开发实现的，因此本课题深入讨论了利用ANSYS二次开发来实现心血管系统血流动力学分析的过程。通过ANSYS的APDL流程化分析功能的开发，实现了血流动力学分析的流程化、自动化。通过ANSYS的UIDL功能的开发，将VRCF系统嵌入ANSYS的操作界面中，使其成为ANSYS的一个有机组成部分，并使得整个系统在一个良好的图形化用户界面的环境下运行。
作为VRCF系统应用的实例，应用VRCF系统对腹主动脉的血流动力学进
行了分析。结果表明：沿着肾下腹主动脉的后壁，血流速度比较低，并且在心脏收缩末期以及整个舒张期，在该区域出现了回流区；该回流区的壁面剪应力数值较低，并且壁面剪应力是交变的。因此，动脉粥样硬化疾病在该区域处发生的可能性非常大。
本课题最后就VRCF的一个重要组成部分——医学图像处理系统，开展了部分研究工作，为完善VRCF系统作了一些尝试性的工作。完成了三维重建中的图像边缘检测，并且在VRCF中为三维重建预留了接口，以期进一步完善该软件系统。
Hemodynamics is closely related to the origin and development of atherosclerotic disease. In order to understand physiological and pathological behavior of human's cardiovascular system more deeply, it is necessary to research the hemodynamics in aorta. It is also necessary to take hemodynamic factors into surgical operations to prevent the dangerous hemodynamics for atherosclerosis. Nowadays, there have been a good many hemodynamic researches for atherosclerotic disease at some focal areas, but convenient and effective integrated system for hemodynamics analysis that is clinically relative has not been available.
Based on the powerful FEM (finite element method) software ANSYS, VRCF (Virtual Reality of Cardiovascular Flow), an integrated set of software tools, is developed to research the hemodynamics at atherosclerotic focal areas. By a good graphic user interface (GUI), VRCF combines CAD modeling and 3D reconstruction of medical image, numerical simulation and flow visualization techniques to provide a convenient software environment for hemodynamics analysis. VRCF owns perfect data arrangement system, good GUI and optional environment set for path. The ultimate aim of VRCF is to provide a platform for surgical planning based on hemodynamics analysis.
Many functions of VRCF are realized based on senior development of ANSYS. So, subsequently the process of how to realize hemodynamics simulation of cardiovascular system by senior development of ANSYS is discussed. By the APDL function of ANSYS, VRCF can analyze hemodynamics conveniently and automatically. By the UIDL function of ANSYS, VRCF is embedded in the graphic
user interface of ANSYS to be a part of ANSYS and to run whole system under a good GUI environment.
As a clinical application of VRCF, the abdominal aorta is taken into consideration, and the hemodynamics of abdominal aorta is deeply analyzed. The conclusions is drawn that along the posterior wall in the infrarenal abdominal aorta, the flow velocity is low and a flow recirculation region is present in late systole and throughout diastole; At this recirculation region the shear stresses are low and oscillate; The atherosclerotic lesion appears at this region with high probability-of-occurrence.
At last, medical image processing system, the important part of VRCF, is partly developed. The edge detection of medical image has been achieved, and the tentative work for 3D reconstruction has been done to help improve VRCF.
本课题基于通用的有限元分析软件ANSYS，开发了一套用于动脉粥样硬化病灶性部位血流动力学分析的集成化软件系统VRCF（Virtual Reality of Cardiovascular Flow）。该软件系统通过友好的图形化用户界面（GUI）将CAD建模、医学图像的三维重建、血流动力学数值模拟、流动可视化等技术有机地结合在一起，为动脉粥样硬化病灶性部位的血流动力学分析提供了一个方便快捷的软件环境。该系统具有良好的数据管理系统、便捷的操作界面以及可选择的环境变量设置，其最终目的是应用于心血管疾病的外科手术规划，优化手术方案。
VRCF的大多数功能模块是基于ANSYS的二次开发实现的，因此本课题深入讨论了利用ANSYS二次开发来实现心血管系统血流动力学分析的过程。通过ANSYS的APDL流程化分析功能的开发，实现了血流动力学分析的流程化、自动化。通过ANSYS的UIDL功能的开发，将VRCF系统嵌入ANSYS的操作界面中，使其成为ANSYS的一个有机组成部分，并使得整个系统在一个良好的图形化用户界面的环境下运行。
作为VRCF系统应用的实例，应用VRCF系统对腹主动脉的血流动力学进
行了分析。结果表明：沿着肾下腹主动脉的后壁，血流速度比较低，并且在心脏收缩末期以及整个舒张期，在该区域出现了回流区；该回流区的壁面剪应力数值较低，并且壁面剪应力是交变的。因此，动脉粥样硬化疾病在该区域处发生的可能性非常大。
本课题最后就VRCF的一个重要组成部分——医学图像处理系统，开展了部分研究工作，为完善VRCF系统作了一些尝试性的工作。完成了三维重建中的图像边缘检测，并且在VRCF中为三维重建预留了接口，以期进一步完善该软件系统。
Hemodynamics is closely related to the origin and development of atherosclerotic disease. In order to understand physiological and pathological behavior of human's cardiovascular system more deeply, it is necessary to research the hemodynamics in aorta. It is also necessary to take hemodynamic factors into surgical operations to prevent the dangerous hemodynamics for atherosclerosis. Nowadays, there have been a good many hemodynamic researches for atherosclerotic disease at some focal areas, but convenient and effective integrated system for hemodynamics analysis that is clinically relative has not been available.
Based on the powerful FEM (finite element method) software ANSYS, VRCF (Virtual Reality of Cardiovascular Flow), an integrated set of software tools, is developed to research the hemodynamics at atherosclerotic focal areas. By a good graphic user interface (GUI), VRCF combines CAD modeling and 3D reconstruction of medical image, numerical simulation and flow visualization techniques to provide a convenient software environment for hemodynamics analysis. VRCF owns perfect data arrangement system, good GUI and optional environment set for path. The ultimate aim of VRCF is to provide a platform for surgical planning based on hemodynamics analysis.
Many functions of VRCF are realized based on senior development of ANSYS. So, subsequently the process of how to realize hemodynamics simulation of cardiovascular system by senior development of ANSYS is discussed. By the APDL function of ANSYS, VRCF can analyze hemodynamics conveniently and automatically. By the UIDL function of ANSYS, VRCF is embedded in the graphic
user interface of ANSYS to be a part of ANSYS and to run whole system under a good GUI environment.
As a clinical application of VRCF, the abdominal aorta is taken into consideration, and the hemodynamics of abdominal aorta is deeply analyzed. The conclusions is drawn that along the posterior wall in the infrarenal abdominal aorta, the flow velocity is low and a flow recirculation region is present in late systole and throughout diastole; At this recirculation region the shear stresses are low and oscillate; The atherosclerotic lesion appears at this region with high probability-of-occurrence.
At last, medical image processing system, the important part of VRCF, is partly developed. The edge detection of medical image has been achieved, and the tentative work for 3D reconstruction has been done to help improve VRCF.
引文
1 Malek A M, Alper S L, Izumo S. Hemodynamic shear stress and its role in atherosclerosis. JAMA, 1999, 282: 2035-2042
2 Fry D L. Acute vascular endothelial changes associated with increased blood velocity gradients. Circulation Research, 1968, 22: 165-197
3 Caro C G, Pedley R J, Schroter R C. The mechanics of the circulation. New York: Oxford University Press, 1978
4 Ku D N. Blood flow in arteries. Annual Review of Fluid mechanics, 1997, 29: 399-434
5 Lei M, Kleinstreuer C, Truskey G A. Numerical investigation and prediction of atherogenic sites in branching arteries. ASME J Biomech Eng, 1995, 117:350-357
6 Taylor C A, Hughes T J, Zarins C K. Finite element modeling of blood flow in arteries. Computer Methods in Applied Mechanics and Engineering, 1998, 158:156-196
7 Davies P F. Flow-mediated endothelial mechanotransduction. Physiol Rev, 1995, 75: 519-560
8 Malek A M, Izumo S. Control of endothelial cell gene expression by flow. Journal of Biomechanics, 1995, 28: 1515-1528
9 Gimbrone M A. Vascular endothelium: an integrator of pathophysiologic simuli in atherosclerosis. American Journal of cardiol, 1995, 75: 67-70
10 Traub O, Berk B C. Laminar shear stress: mechanism by which endothelial cells transduce an atheroprotective force. Arterioscler Thromb Vasc Bio, 1998,18: 677-685
11 Nerem R M, Alexander R W, Chappell D C. The study of the influence of flow on vascular endothelial biology. J Med Sci, 1998, 316: 169-175
12 Chien S, Li S, Shyy Y J. Effects of mechanical forces on signal transduction and gene expression in endothelial cells. Hypertension, 1998, 31: 162-169
13 Chiu J J, Wang D L, Chien S. Effects of disturbed flow on endothelial cells. ASME J Biomech Eng, 1998, 120: 2-8
14 Weinbaum S, Chien S. Lipid transport aspects of atherogenesis. ASME J Biomech Eng, 1993, 115:602-610
15 Chien S, Lee M M, Laufer L S. Effects of oscillatory mechanical disturbance on macromolecular uptake by arterial wall. Arteriosclerosis, 1981, 1:326-336
16 McDonald D A. Blood flow in arteries. Baltimore: Williams &Wilkins, 1974
17 Nichols W W, O'Rurke M F. McDonald's blood flow in arteries. Philadelphia: Lea & Febiger, 1988
18 Long Q, Xu X Y, Collins M W. Magnetic resonance image processing and structured grid generation of a human abdominal bifurcation. Computer Method and Programs in Biomedicine, 1998, 56: 249-259
19 Long Q, Xu X Y, Collins M W. The combination of magnetic resonance angiography and computational fluid dynamics: a critical review. Critical Reviews in Biomedical Engineering, 1998, 26: 227-274
20 Milner J S, Moore J A, Rutt B K. Hemodynamics of human carotid artery bifurcations: computational studies with models reconstructured from magnetic resonance imaging of normal subjects. Journal of Vascular Surgery, 1998, 28: 143-156
Moore J A, Steinman D A, Holdsworth D W. Accuracy of computational hemodynamics in complex arterial geometries reconstructed from magnetic
21 resonance imaging. Annals of Biomedical Engineering, 1999, 27: 32-41
22 David A S. Imag-based modeling in realistic arterial geometries. Annals of Biomedical Engineering, 2002, 30(4): 483-497
23 Tayor C A, Draney M T, Ku J P. Predictive medicine: computational techniques in therapertic decision making. Computer aided surgery, 1999, 4(5): 231-247
24 Huang H K. PACS: Picture archiving and communication systems in biomedical imaging. New York: VCH publishers Inc, 1996
25 Zhao S Z, Xu X Y, Hughes A D. Blood flow and vessel mechanics in a physiologically realistic model of a human carotid arterial bifurcation. Journal of Biomechanics, 2000, 33: 975-984.
26 ANSYS Inc. APDL使用手册. ANSYS Inc, 2000
27 ANSYS Inc. UIDL programmer's guide. ANSYS Inc, 2000
28 Glagov S, Rowley D A, Kohut R I. Atherosclerosis of human aorta and its coronary and renal arteries. Arch. Pathol, 1991, 72: 82-95
29 Friedman M H, Hutchins G M, Bargeron B C. Correlation between intimal thickness and fluid shear in human arteries. Atherosclerosis, 1981, 39: 425-436
30 Maier S E, Meier D, Boesiger P. Human abdominal aorta: Comparative measurements of blood flow with MR imaging and multigated Doppler. US. Radiology, 1989, 171: 487-492
31 Moore J E, Maier S E, Ku D N. Hemodynamics in the abdominal aorta: a comparison of in vivo and in vivo measurements. J. Appl. Physiol, 1994, 76: 1520-1527
32 Perktold K, Resch M, Peter R. Three-dimensional numerical analysis of pulsatile flow and wall shear stress in the carotid artery bifurcation. Biomech, 1991, 24: 409-420
33 Taylor C A, Hughes T J, Zarins C K. Computational investigations in vascular disease. Comput. Phys, 1996, 10: 224-232
34 Moore J E, Ku D N, Zarins C K. Pulsatile flow visualization in the abdominal aorta under differing physiologic conditions: Implications for increased susceptibility to atherosclerosis. J. Biomech. Eng, 1992, 114:391-397
35 Moore J E, Ku D N. Pulsatile velocity measurements in a model of the human abdominal aorta under resting conditions. Biomech. Eng, 1994, 116:337-346
36 Mostbeck G H, Dulce M C, Caputo G R. Flow pattern analysis in the abdominal aorta with velocity-encoded cine MR imaging. J. Magn. Reson. Imaging, 1993, 3: 617-623
37 Moore J E, Xu C, Glagov S. Fluid wall shear stress measurements in a model of the human abdominal aorta: Oscillatory behavior and relationship to atherosclerosis. Atherosclerosis, 1994, 110: 225-240
38 Cornhill J F, Herderick E E, Stary H C. Topography of human aortic sudanophilic lesions. Atheroscler, 1990, 15: 13-19
39 Ogden R W. Nonlinear Elastic Deformations. Chichester: Ellis Horwood, 1984
40 Sussman T, Bathe K J. A finite element formulation for nonlinear incompressible elastic and inelastic analysis. Computers and Structures, 1987, 26: 357-409
41 刘有军，方曜奇. 不可压缩流动的TG有限元解法. 大连理工大学学报，1997, 37(6): 658-662
42 Abdoulaev G, Cadeddu S, Delussu G. ViVa: The virtual vascular project. IEEE Transactions On Information Technology In Biomedicine, 1998, 2(4): 268-274
43 刘才，高贞彦，彭秀艳. 利用OpenGL实现医学图像三维表面重建. 微型电脑应用. 2000, 16(1): 57-60
James X, Horace H S, Samman N. Three-dimensional virtual-reality surgical
44 planning and soft-tissue prediction for orthognathic surgery. IEEE Transactions On Information Technology In Biomedicine, 2001, 5(2): 97-107
45 汪天富，郑昌琼，李德玉. 超声心脏图像多维重建研究进展. 生物医学工程学杂志. 2001, 18(1): 133-137
2 Fry D L. Acute vascular endothelial changes associated with increased blood velocity gradients. Circulation Research, 1968, 22: 165-197
3 Caro C G, Pedley R J, Schroter R C. The mechanics of the circulation. New York: Oxford University Press, 1978
4 Ku D N. Blood flow in arteries. Annual Review of Fluid mechanics, 1997, 29: 399-434
5 Lei M, Kleinstreuer C, Truskey G A. Numerical investigation and prediction of atherogenic sites in branching arteries. ASME J Biomech Eng, 1995, 117:350-357
6 Taylor C A, Hughes T J, Zarins C K. Finite element modeling of blood flow in arteries. Computer Methods in Applied Mechanics and Engineering, 1998, 158:156-196
7 Davies P F. Flow-mediated endothelial mechanotransduction. Physiol Rev, 1995, 75: 519-560
8 Malek A M, Izumo S. Control of endothelial cell gene expression by flow. Journal of Biomechanics, 1995, 28: 1515-1528
9 Gimbrone M A. Vascular endothelium: an integrator of pathophysiologic simuli in atherosclerosis. American Journal of cardiol, 1995, 75: 67-70
10 Traub O, Berk B C. Laminar shear stress: mechanism by which endothelial cells transduce an atheroprotective force. Arterioscler Thromb Vasc Bio, 1998,18: 677-685
11 Nerem R M, Alexander R W, Chappell D C. The study of the influence of flow on vascular endothelial biology. J Med Sci, 1998, 316: 169-175
12 Chien S, Li S, Shyy Y J. Effects of mechanical forces on signal transduction and gene expression in endothelial cells. Hypertension, 1998, 31: 162-169
13 Chiu J J, Wang D L, Chien S. Effects of disturbed flow on endothelial cells. ASME J Biomech Eng, 1998, 120: 2-8
14 Weinbaum S, Chien S. Lipid transport aspects of atherogenesis. ASME J Biomech Eng, 1993, 115:602-610
15 Chien S, Lee M M, Laufer L S. Effects of oscillatory mechanical disturbance on macromolecular uptake by arterial wall. Arteriosclerosis, 1981, 1:326-336
16 McDonald D A. Blood flow in arteries. Baltimore: Williams &Wilkins, 1974
17 Nichols W W, O'Rurke M F. McDonald's blood flow in arteries. Philadelphia: Lea & Febiger, 1988
18 Long Q, Xu X Y, Collins M W. Magnetic resonance image processing and structured grid generation of a human abdominal bifurcation. Computer Method and Programs in Biomedicine, 1998, 56: 249-259
19 Long Q, Xu X Y, Collins M W. The combination of magnetic resonance angiography and computational fluid dynamics: a critical review. Critical Reviews in Biomedical Engineering, 1998, 26: 227-274
20 Milner J S, Moore J A, Rutt B K. Hemodynamics of human carotid artery bifurcations: computational studies with models reconstructured from magnetic resonance imaging of normal subjects. Journal of Vascular Surgery, 1998, 28: 143-156
Moore J A, Steinman D A, Holdsworth D W. Accuracy of computational hemodynamics in complex arterial geometries reconstructed from magnetic
21 resonance imaging. Annals of Biomedical Engineering, 1999, 27: 32-41
22 David A S. Imag-based modeling in realistic arterial geometries. Annals of Biomedical Engineering, 2002, 30(4): 483-497
23 Tayor C A, Draney M T, Ku J P. Predictive medicine: computational techniques in therapertic decision making. Computer aided surgery, 1999, 4(5): 231-247
24 Huang H K. PACS: Picture archiving and communication systems in biomedical imaging. New York: VCH publishers Inc, 1996
25 Zhao S Z, Xu X Y, Hughes A D. Blood flow and vessel mechanics in a physiologically realistic model of a human carotid arterial bifurcation. Journal of Biomechanics, 2000, 33: 975-984.
26 ANSYS Inc. APDL使用手册. ANSYS Inc, 2000
27 ANSYS Inc. UIDL programmer's guide. ANSYS Inc, 2000
28 Glagov S, Rowley D A, Kohut R I. Atherosclerosis of human aorta and its coronary and renal arteries. Arch. Pathol, 1991, 72: 82-95
29 Friedman M H, Hutchins G M, Bargeron B C. Correlation between intimal thickness and fluid shear in human arteries. Atherosclerosis, 1981, 39: 425-436
30 Maier S E, Meier D, Boesiger P. Human abdominal aorta: Comparative measurements of blood flow with MR imaging and multigated Doppler. US. Radiology, 1989, 171: 487-492
31 Moore J E, Maier S E, Ku D N. Hemodynamics in the abdominal aorta: a comparison of in vivo and in vivo measurements. J. Appl. Physiol, 1994, 76: 1520-1527
32 Perktold K, Resch M, Peter R. Three-dimensional numerical analysis of pulsatile flow and wall shear stress in the carotid artery bifurcation. Biomech, 1991, 24: 409-420
33 Taylor C A, Hughes T J, Zarins C K. Computational investigations in vascular disease. Comput. Phys, 1996, 10: 224-232
34 Moore J E, Ku D N, Zarins C K. Pulsatile flow visualization in the abdominal aorta under differing physiologic conditions: Implications for increased susceptibility to atherosclerosis. J. Biomech. Eng, 1992, 114:391-397
35 Moore J E, Ku D N. Pulsatile velocity measurements in a model of the human abdominal aorta under resting conditions. Biomech. Eng, 1994, 116:337-346
36 Mostbeck G H, Dulce M C, Caputo G R. Flow pattern analysis in the abdominal aorta with velocity-encoded cine MR imaging. J. Magn. Reson. Imaging, 1993, 3: 617-623
37 Moore J E, Xu C, Glagov S. Fluid wall shear stress measurements in a model of the human abdominal aorta: Oscillatory behavior and relationship to atherosclerosis. Atherosclerosis, 1994, 110: 225-240
38 Cornhill J F, Herderick E E, Stary H C. Topography of human aortic sudanophilic lesions. Atheroscler, 1990, 15: 13-19
39 Ogden R W. Nonlinear Elastic Deformations. Chichester: Ellis Horwood, 1984
40 Sussman T, Bathe K J. A finite element formulation for nonlinear incompressible elastic and inelastic analysis. Computers and Structures, 1987, 26: 357-409
41 刘有军，方曜奇. 不可压缩流动的TG有限元解法. 大连理工大学学报，1997, 37(6): 658-662
42 Abdoulaev G, Cadeddu S, Delussu G. ViVa: The virtual vascular project. IEEE Transactions On Information Technology In Biomedicine, 1998, 2(4): 268-274
43 刘才，高贞彦，彭秀艳. 利用OpenGL实现医学图像三维表面重建. 微型电脑应用. 2000, 16(1): 57-60
James X, Horace H S, Samman N. Three-dimensional virtual-reality surgical
44 planning and soft-tissue prediction for orthognathic surgery. IEEE Transactions On Information Technology In Biomedicine, 2001, 5(2): 97-107
45 汪天富，郑昌琼，李德玉. 超声心脏图像多维重建研究进展. 生物医学工程学杂志. 2001, 18(1): 133-137