肺動脈高壓是一種血管增生和重塑的疾病。它會導致肺動脈血管的阻力上升並且使得右心室衰
竭。本研究主要是利用磁振相位對比影像的技術取得人體肺動脈內真實的血流情況來分析血液
動力學和肺動脈高壓之間的關係, 並且探討健康的肺動脈和肺動脈高壓之間的差異。流場型態、
壓力分佈、平均剪應力和震盪剪應力在此研究被用來探討正常和病變間的差異。除了上述這些
現象之外, 我們也計算了正常和病變在肺動脈中的血流量和windkessel volume。
根據所得的分析結果, 肺動脈高壓的流場型態比健康的肺動脈來的混亂。藉由觀察壓力分
佈, 可以看到在肺動脈高壓的左右肺動脈在心臟收縮期間, 出口處的壓力會比其入口處高, 這
種情形會使得血液不容易流入肺部內。另外, 健康肺動脈的平均剪應力值都比病變得來的高, 而
且在肺動脈高壓的案例中, 可以發現在低平均剪應力區域會有高震盪剪應力的情形發生。這種低
平均剪應力和高震盪剪應力的血液動力學型態會使得管壁上的內皮細胞分泌出血管收縮的物質,
造成管壁開始增生。從血流量的分析中, 發現病變案例的左肺動脈血流量都比右肺動脈少,而且
將左右肺動脈的血流量相加後的值都比主肺動脈中的量還要少, 不像正常的肺動脈, 左右肺動
脈的血流量合跟主肺動脈是相近的。也因為這個原因, 可以發現肺動脈高壓案例的windkessel
volume 值都比正常的案例大很多。

Pulmonary arterial hypertension (PAH) is a disease of the pulmonary arteries (PA) that is
characterized by vascular proliferation and remodeling. It results in a progressive increase
in pulmonary vascular resistance (PVR) and right ventricular failure. The study aims to
analyze the relationship between hemodynamics and PAH and investigates the difference
of hemodynamics between the healthy PA and PAH to find out pathogenesis of PAH.
Phase Contrast Magnetic Resonance Imagining (PC-MRI) technology is used to get in
vivo blood flows in PA of 3 healthy volunteers and 5 patients with PAH. Flow patterns,
pressure distribution, average shear stress (ASS), oscillatory shear index (OSI), blood flow
rate and windkessel volume are measured in PA.
According the analyzed results, the flow patterns in PAH are more complex than that
in normal. Pressure distributions in right pulmonary artery (RPA) and left pulmonary
artery (LPA) of PAH do not decrease but increase along the flow direction during systole.
Hence, there are adverse pressure gradients in RPA and LPA of PAH cases so that the
blood does not flow into lungs easily. ASS in LPA and RPA of normal cases are higher
than those in PAH cases. Besides, there are regions adjacent to the arterial walls with high
OSI and also low ASS in PAH cases. Low ASS and high OSI may cause the endothelial
cells (ECs) to release the vasoconstrictor substances and consequently the vessel may be
remodeled. It is also found that the blood flow rates in LPA of PAH cases are lower than those in RPA. The sum of blood flow rates in LPA and RPA of PAH cases are lower than
the blood flow rate in MPA. The cross-section of MPA in PAH cases increase from systole
to diastole. Hence, the windkessel volume is significantly increased in PAH cases.

[1] Eddahibi, S., Guignabert, C., Barlier-Mur, A.M. et al., 2006, Cross talk between
endothelial and smooth muscle cells in pulmonary hypertension critical role for
serotonin-induced smooth muscle hyperplasia. Circulation 113, 1857-1864.
[2] Humbert, M., Morrell, N.W., Archer, S.L. et al., 2004, Cellular and molecular pathobiology
of pulmonary arterial hypertension. Journal of the American College of Cardiology
43, 13S-24S.
[3] Chin, K.M., Rubin, L.J., 2008, Pulmonary arterial hypertension. Journal of the
American College of Cardiology 51, 1527-1538.
[4] Blaise, G., Langleben, D., 2003, Plumonary arterail hypertension. Pathophysiology
and anesthetic approach. Anesthesiology 99, 1415-1432.
[5] Topper, J.N., Gimbrone, M.A. Jr, 1999, Blood flow and vascular gene expression:
fluid shear stress as a modulator of endothelial phenotype. Molecular Medicine Today
5, 40-46.
[6] Fisher, A.B., Chien, S., Barakat, A.I., Nerem, R.M., 2001, Endothelial cellular response
to altered shear stress. American Journal of Physiology - Lung Cellular and
Molecular Physiology 281, L529-533.
[7] Li, Y.S., Haga, J.H., Chien, S., 2005, Molecular basis of the effects of shear stress on
vascular endothelial cells. Journal of Biomechanics 38, 1949-1971.
[8] Chien, S., 2007, Mechanotransduction and endothelial cell homeostasis: the wisdom
of the cell. American Journal of Physiology - Heart and Circulatory Physiology 292,
H1209-H1224.
[9] Malek, A.M., Alper, S.L., Izumo, S., 1999, Hemodynamic shear stress and its role in
atherosclerosis. Journal of the American Medical Association 282, 2035-2042.
[10] Chatzizisis, Y.S., Coskun, A.U., Jonas, M., Edelman, E.R., Feldman, C.L. and
Stone, P.H., 2007, Role of endothelial shear stress in the natural history of coronary
atherosclerosis and vascular remodeling. Journal of the American College of
Cardiology 49, 2379-2393.
[11] Chiu, J.J., Usami, S., Chien, S., 2009, Vascular endothelial responses to altered shear
stress: pathologic implications for atherosclerosis. Annals of medicine 41, 19-28.
[12] Peir’o, C., Redondo, J., Rodriguez-Martinez, A., Marin, J., S’anchez-Ferrer, C.F.,
1995, Influence of endothelium on cultured vascular smooth muscle cell proliferation.
Hypertension 25, 748-751.
[13] Veyssier-Belot, C., Cacoub, P., 1999, Role of endothelial and smooth muscle cells in
the physiopathology and treatment management of pulmonary hypertension. Cardiovascular
Research 44, 274-282.
[14] Gatehouse, P.D., Keegan, J., Crowe, L.A., Masood, S., Mohiaddin, R.H., Kreitner,
K.F., Firmon, D.N., 2005, Applications of phase contrast flow and velocity imaging
in cardiovascular MRI. European Radiology 15, 2172-2184.
[15] Harloff, A., Albrecht, F., Spreer, J., Stalder, A.F., Bock, J. et al., 2009, 3D blood
flow characteristics in the carotid artery bifurcation assessed by flow-sensitive 4D
MRI at 3T. Magnetic Resonance in Medicine 61, 65-74.
[16] Kvitting, J.P., Ebbers, T., Wigstr‥om, L., Engvall, J., Olin, C.L., Bolger, A.F.,
2004, Flow patterns in the aortic root and the aorta studied with time-resolved,
3-Dimensional, phase-contrast magnetic resonance imaging: implications for aortic
valve 　sparing surgery. The Journal of Thoracic and Cardiovascular Surgery 127,
1062-1607.
[17] Wu, M.T., Huang, Y.L., Hsieh, K.S., Huang, J.T., Peng, N.J., Pan, J.Y., Huang, J.S.
and Yang, T.L., 2007, Influence of pulmonary regurgitation inequality on differential
perfusion of the lungs in Tetralogy of Fallot after repair: a phase contrast magnetic
resonance imaging and perfusion scintigraphy study. Journal of the American College
of Cardiology 49, 1880-1886.
[18] Morgan, V.L., Roselli, R.J., Lorenz, C.H., 1998, Normal three dimensional pulmonary
artery flow determined by phase contrast magnetic resonance imaging. Annals of
Biomedical Engineering 26, 557-566.
[19] Mousseaux, E.M., Tasu, J.P., Jolivet, O., Simonneau, G., Bittoun, J., Gaux, J.C.,
1999, Pulmonary arterial resistance: noninvasive measurement with indexes of pulmonary
flow estimated at velocity-encoded MR imaging-preliminary experience. Radiology
212, 896-902.
[20] Sanz, J.S., Kuschnir, P., Rius, T., Salgero, R., Sulica, R., Einstein, A.J., Dellegrottaglie,
S., Fuster, V., Rajagopalan, S., Poon, M., 2007, Pulmonary arterial hypertension
noninvasive detection with phase-contrast MR imaging. Radiology 243, 70-79.
[21] Friman, O., Hennemuth, A., Harloff, A., Bock, J., Markl, M. and Peitgen, H.O.,
2010, Probabilistic 4D blood flow mapping. Lecture Notes in Computer Science 13,
416-423.
[22] Yamashita, S., Isoda, H., Hirano, M., Takeda, H., Inagawa, S., Takehara, Y., Alley,
M.T., Markl, M., Pelc, N.J., Sakahara, H., 2007, Visualization of hemodynamics
in intracranial arteries using time-resolved three-dimensional phase-contrast MRI.
Journal of Magnetic Resonance Imaging 25, 473-478.
[23] Xavier, M., Walker, P.M., Boichot, C., Cochet, A., Steinmetz, E., Legrand, L.,
Brunotte, F., 2007, Dynamic 4D blood flow representation in the aorta and analysis
from cine-MRI in patients. Computers in Cardiology 34, 375-378.
[24] Stalder, A.F., Russe, M.F., Frydrychowicz, A., Bock, J., Hennig, J., Markl, M., 2008,
Quantitative 2D and 3D phase contrast MRI: optimized analysis of blood flow and
vessel wall parameters. Magnetic Resonance in Medicine 60, 1218-1231.
[25] Frydrychowicz, A., Stalder, A.F., Russe, M.F., Bock, J., Bauer, S., Harloff, A.,
Berger, A., Langer, M., Henning, J., Markl, M., 2009, Three-dimensional analysis
of segmental wall shear stress in the aorta by flow-sensitive four-dimensional-MRI.
Journal of Magnetic Resonance Imaging 30, 77-84.
[26] Harloff, A., NuBaumer, A., Bauer, S., Stalde, A.F., Frydrychowicz, A., Weller, C.,
Hennig, J., Markl, M., 2010. In vivo assessment of wall shear stress in the atherosclerotic
aorta using flow-sensitive 4D MRI. Magnetic Resonance in Medicine 63, 1529-
1536.
[27] Tyszka, J.M., Laidlaw, D.H., Asa, J.W., Silverman, J.M., Zhu, M., 2000, Threedimensional,
time-resolved (4D) relative pressure mapping using magnetic resonance
imaging. Journal of Magnetic Resonance Imaging 12, 321-329.
[28] Pedley, T.J., 1980, The fluid mechanics of large blood vessels. Cambridge University
Press. Cambridge, U.K., ISBN 0521226260.
[29] Berger, S.A. and Jou, L.D., 2000, Flows in stenotic vessels. Annual Reviews of Fluid
Mechanics 32, 347-382.
[30] Knight, J., Olgac, U., Saur, S.C., Poulikakos, D., Jr, W.M., Cattin, P.C., Alkadhi,
H. and Kurtcuoglu, V., 2010, Choosing the optimal wall shear parameter for the
prediction of plaque location - a patient-specific computational study in human right
coronary arteries. Atherosclerosis 210, 578-581.
[31] Ku, D.N., Giddens, D.P., Zarins, C.K., Glagov, S., 1985, Pulsatile flow and atherosclerosis
in the human carotid bifurcation. Positive correlation between plaque location
and low oscillating shear stress. Journal of the American Heart Association 5, 293-
302.
[32] Peng, H.H., Chung, H.W., Yu, H.Y., Tseng, W.Y., 2005, Useful indices to evaluate
pulmonary windkessel volume and resistance in patients with pulmonary hypertension
using MR phase contrast imaging. Proceedings of the International Society for
Magnetic Resonance in Medicine, 1732, Miami.