在亞洲人群包括中國人群中，顱內動脈粥樣硬化（ICAS）發病率很高，是缺血性卒中和短暫性腦缺血發作（TIA）的首要病因。然而，目前ICAS 並未被深入研究。因此我們在一系列研究中通過運用傳統及創新的神經影像學方法，來研究ICAS 的臨床及血流動力學特徵，以期促進其全面評價及危險分層。 / 既往研究發現亞洲人群和西方人群在頭頸部動脈粥樣硬化的發生和發展上存在種族差異。爲了進一步驗證這些種族差異，我們開展了一項社區研究，以探索無癥狀性顱內外動脈粥樣硬化在中國社區成年居民中的發病情況，以及二者之間的相互關係。在該研究中，我們分別採用經顱多普勒（TCD）和頸部血管超聲（CD）來評價顱內和顱外動脈的粥樣硬化。在研究納入的537 例研究對象中，我們發現顱內動脈粥樣硬化的發展優先於頸動脈粥樣硬化，而且不同階段的頸動脈粥樣硬化與顱內動脈粥樣硬化並無獨立相關關係。該結果提示，在中國人群的全身系統性粥樣硬化的過程中，顱內動脈粥樣硬化可能是一個比較早期而且相對獨立的過程，這與西方人群的情況不同。本研究結果進一步支持東西方人群在顱內外動脈粥樣硬化進程上存在的種族差異。 / 根據既往研究結果，病因為癥狀性ICAS的缺血性卒中或TIA患者卒中復發的風險很高。目前，癥狀性ICAS患者的危險分層大多基於其動脈管腔的狹窄程度。然而，管腔的解剖學狹窄程度並不一定與其血流動力學的嚴重程度成比例，而後者也可能影響相關患者的卒中復發風險。因此，我們進行了以下的一系列研究， 以評價癥狀性ICAS的血流動力學特徵，同時初步探索其在相關患者危險分層中的應用價值。 / 我們首先進行了三項研究，採用一種基於磁共振血管成像（MRA）的創新方法來評價癥狀性ICAS的血流動力學嚴重程度。基於時間飛躍法（TOF）MRA的信號對比機制，我們提出了一項名為信號強度比值（SIR）的參數來定量地評價癥狀性ICAS 的血流動力學效應；該參數代表TOF MRA 影像上經過背景信號強度校正后的ICAS 病變后和病變前的信號強度比值。在一項初步研究中，我們確定了該參數的評價和計算方法。在26例癥狀性ICAS病變中，我們發現該參數的計算操作簡便，在臨床上可行，且在同一評價者的兩次評價中具有很高的可重複性。在隨後的一項研究中，我們在102例癥狀性ICAS病變中發現該參數在兩位評價者之間具有顯著的可重複性。在第三項研究中，我們在36例具有癥狀性ICAS的缺血性卒中患者中發現SIR與患者的急性梗死灶體積顯著相關，但我們並未發現該參數與患者1年的卒中復發風險相關，可能由於該研究的樣本量過小。以上三項研究證實，SIR作為一種基於TOF MRA的評價癥狀性ICAS血流動力學嚴重程度的方法，具有可重複性及臨床可行性；而其對於相關患者危險分層的價值需要在前瞻性的較大型研究中進一步驗證。 / 在如下的另外兩項研究中，我們採用計算機流體動力學（CFD）技術對癥狀性ICAS患者的計算機斷層掃描血管成像（CTA）影像進行重建，從而評價其ICAS 病變的血流動力學特徵。首先，在一項初步研究中，我們探索了採用臨床常規CTA影像進行CFD模型重建的可行性。在10例癥狀性ICAS病變中，9例病變的CTA原始圖像成功重建為CFD模型。重建的CFD模型可以定量地反映ICAS病變的各種血流動力學特徵。該初步研究證實了基於臨床常規CTA進行CFD建模從而評價ICAS血流動力學特徵的可行性。在隨後的一項研究中，我們探索了CFD 模型反映的癥狀性ICAS 的血流動力學特徵對於相關患者卒中復發的預測價值。在32例具有70-99%管腔狹窄的癥狀性ICAS病例中，我們發現病變前後血流動力學參數的變化（包括壓力，剪切應變率及血流速度）可能預測患者的卒中復發風險。以上兩項研究證實，基於臨床常規CTA進行CFD模型重建從而定量評價癥狀性ICAS的血流動力學特徵具可行性，同時，這些血流動力學特徵可能對相關患者的卒中復發風險具有預測價值。 / 綜上所述，通過以上研究，我們進一步證實了亞洲人群和西方人群在顱內外動脈粥樣硬化的進程上存在的種族差異。更重要的是，我們的研究證實評價癥狀性ICAS病變的血流動力學特徵具有臨床意義。對於相關患者，採用以上研究中的兩種方法評價癥狀性ICAS的血流動力學特徵，可能對患者的危險分層具有潛在的指導意義。在未來的前瞻性大樣本研究中，上述方法對癥狀性ICAS患者卒中復發風險的預測價值需要進一步證實，以期促進相關的臨床決策，從而在長遠目標上降低相關患者的卒中復發風險。 / Intracranial atherosclerosis (ICAS) is of high prevalence in Asia, which is the leading cause for ischemic stroke and transient ischemic attack (TIA) in Asians, including the Chinese. However, it has not been fully appreciated or adequately investigated in relevant studies. In this thesis, we tried to delineate the hemodynamics and clinical implications of ICAS, by using several traditional and novel neuroimaging methods. / Previous studies had suggested differences in atherogenesis of intra- and extracranial arteries between Asians and Caucasians. To find further evidence, we performed a study to investigate asymptomatic ICAS and carotid atherosclerosis and their correlations in community-dwelling Chinese adults, by using transcranial Doppler and carotid duplex ultrasonography, respectively. For the 537 subjects studied, we found more advanced asymptomatic ICAS than carotid atherosclerosis, and there were no independent correlations between different stages of carotid atherosclerosis and presence of ICAS. The results suggested that atherogenesis of intracranial arteries might be a relatively independent course in systemic atherosclerosis in the Chinese population, which is unlike the case in Caucasians. By combing with previous findings, results of this study further supported the existence of racial differences in cervicocerebral atherogenesis between Asians and Caucasians. / According to previous studies, stroke patients with symptomatic ICAS are at high risk of recurrence. Currently, risk stratification of symptomatic ICAS are usually based on the percentage of luminal stenosis. However, the anatomic severity does not always proportionate to its hemodynamic significance, which may also impact on the risk of stroke recurrence in symptomatic ICAS. Therefore, we performed a series of studies as follows to evaluate the hemodynamics of symptomatic ICAS, and to assess its value in risk stratification of those with such lesions. / We first performed three studies based on time-of-flight (TOF) magnetic resonance angiography (MRA), to gauge the hemodynamic significance of symptomatic ICAS. Based on the signal contrast mechanism of TOF MRA, we developed a novel index, signal intensity ratio (SIR), representing changes of signal intensities (SI) across an ICAS on maximum intensity projections of TOF MRA, to quantify its hemodynamic significance: SIR = (mean post-stenotic SI - mean background SI) / (mean pre-stenotic SI - mean background SI). In a pilot study to establish the methodology of this index, we found it easy to perform, and highly reproducible between repetitive measurements by a same observer in 26 symptomatic ICASs. In a subsequent study, we also found this index to be substantially reproducible between measurements from two observers in 102 symptomatic ICAS lesions. In a third study, we tried to investigate the relationships between SIR of ICAS, other imaging features, and 1 year outcomes of patients with symptomatic ICAS. In the 36 patients enrolled, SIR was found to be significantly, linearly and negatively correlated to acute infarct volume on diffusion-weighted MR images. However, we did not establish a definite correlation between SIR and recurrent ischemic stroke, probably due to the small sample size. These studies suggested that SIR as evaluated on MRA was a feasible and reproducible method to gauge the hemodynamic and functional significance of ICAS. The role of this index in predicting further recurrent risks in those with symptomatic ICAS needs to be verified in future studies. / In another two studies, we applied the computational fluid dynamics (CFD) modeling technique in processing computed tomography angiography (CTA) images, to evaluate the hemodynamic characteristics of ICAS. In a pilot study, we tested the feasibility of CFD modeling of ICAS based on CTA images. Among 10 cases of symptomatic ICAS identified on CTA, the CTA source images of 9 were successfully processed to CFD models, which were able to quantitatively delineate the hemodynamic environment across the lesions. This pilot study demonstrated the feasibility of constructing CFD models of ICAS out of routinely obtained CTA source images. Then in a second study, we preliminarily explored the values of hemodynamics of ICAS revealed by such CFD models, in predicting recurrent risks in patients with symptomatic ICAS of 70-99% luminal stenosis. In the 32 cases evaluated, we found that changes of hemodynamic features across an ICAS lesion, including the changes of pressure, shear strain rate, and blood flow velocity, may be able to predict the recurrent risk in this patient subset. Therefore, it was feasible to model hemodynamics of symptomatic ICAS based on CTA images, and future prospective studies with larger sample sizes are warranted to further validate the role of CFD modeling in risk stratification of affected patients. / In conclusion, in this thesis we found further evidence to support the existence of racial differences in atherogenesis of cervicocerebral arteries between Caucasians and Asians. More importantly, we demonstrated that hemodynamics of symptomatic ICAS could be of clinical significance in characterization of such lesions. In patients with symptomatic ICAS, the two methods to evaluate hemodynamic features of ICAS as used in this thesis, may yield potential values in predicting the recurrent risk of these patients. In the near future, prospective studies enrolling more patients are warranted to further validate findings in this thesis, to embrace more reasonable and comprehensive evaluation of symptomatic ICAS, so as to facilitate decision making in clinical scenarios and patient selection in clinical studies, which in the long run may help reduce the risk of stroke recurrence in affected patients. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Leng, Xinyi. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 131-146). / Abstracts also in Chinese.

Tang, Suk Yan Amy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves [207]-[227]). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS / ABSTRACTS / TABLE OF CONTENTS / "LIST OF APPENDIX, TABLES & FIGURES" / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter 1.1 --- Cerebrovascular disease --- p.1 / Chapter 1.1.1 --- Ischemic Stroke --- p.1 / Chapter 1.1.2 --- Hemorrhagic Stroke --- p.2 / Chapter 1.2 --- Laboratory diagnosis --- p.3 / Chapter 1.2.1 --- Transcranial Doppler ultrasonography --- p.4 / Chapter 1.2.1.1 --- Normal Brain --- p.4 / Chapter 1.2.1.2 --- Intracranial Large Artery Stenosis --- p.5 / Chapter 1.3 --- Asymptomatic Intracranial Stenosis --- p.6 / Chapter CHAPTER TWO --- LITERATURE REVIEW --- p.7 / Chapter 2.1 --- Global Stroke Facts --- p.7 / Chapter 2.2 --- Stroke Studies --- p.7 / Chapter 2.2.1 --- Risk profile of stroke --- p.7 / Chapter 2.2.2 --- Stroke epidemiological study --- p.8 / Chapter 2.2.2.1 --- Incidence --- p.8 / Chapter 2.2.2.2 --- Mortality --- p.10 / Chapter 2.2.2.3 --- Increased stroke rates with increased age --- p.12 / Chapter 2.2.2.4 --- Associated disease in stroke subjects --- p.12 / Chapter 2.2.3 --- Stroke risk factors --- p.13 / Chapter 2.3 --- Stroke Impact --- p.14 / Chapter 2.3.1 --- Stroke patients --- p.14 / Chapter 2.3.2 --- Medical burden --- p.15 / Chapter 2.3.3 --- Socioeconomic burden --- p.16 / Chapter 2.4 --- Stroke Prevention --- p.17 / Chapter 2.5 --- Stroke Facts in Hong Kong --- p.19 / Chapter 2.6 --- Stroke Facts in China --- p.21 / Chapter 2.7 --- Asymptomatic Intracranial Stenosis in Asian Subjects --- p.22 / Chapter 2.7.1 --- Asymptomatic individuals --- p.22 / Chapter 2.7.2 --- Intracranial occlusive disease --- p.23 / Chapter 2.8 --- Transcranial Doppler Sonography --- p.25 / Chapter CHAPTER THREE --- AIM & OBJECTIVES OF THE RESEARCH --- p.30 / Chapter 3.1 --- Aim of the research --- p.30 / Chapter 3.2 --- Objectives of this research --- p.30 / Chapter CHAPTER FOUR --- "CLINIC-BASED CROSS-SECTIONAL SCREENING IN AN URBAN CITY 226}0ؤ HONG KONG, THE PEOPLE'S REPUBLIC OF CHINA" --- p.31 / Chapter 4.1 --- Background & Purpose --- p.31 / Chapter 4.2 --- Methods --- p.34 / Chapter 4.2.1 --- Defining the population --- p.34 / Chapter 4.2.2 --- Procedures --- p.36 / Chapter 4.2.2.1 --- Standardized TCD Report Form --- p.39 / Chapter 4.2.2.2 --- Transcranial Doppler Screening --- p.39 / Chapter 4.2.2.3 --- Data collected --- p.40 / Chapter 4.2.3 --- Defining the Risk Factors --- p.43 / Chapter 4.3 --- Statistical Analyses --- p.45 / Chapter 4.3.1 --- Research Design --- p.46 / Chapter 4.3.2 --- Descriptive Summary --- p.46 / Chapter 4.3.2.1 --- Cross-tabulated between Gender --- p.46 / Chapter 4.3.2.2 --- Cross-tabulated between Normal & Abnormal MCA status --- p.47 / Chapter 4.3.3 --- Measures for Association --- p.48 / Chapter 4.3.3.1 --- Univariate analysis --- p.48 / Chapter 4.3.3.2 --- Multivariate analysis --- p.48 / Chapter 4.3.4 --- Modeling the Risks --- p.50 / Chapter 4.3.5 --- nfluence of the number of associated risk factors on the MCA status --- p.50 / Chapter 4.4 --- Result --- p.51 / Chapter 4.4.1 --- Baseline characteristics of all screened subjects by Gender --- p.51 / Chapter 4.4.1.1 --- Age by Gender --- p.53 / Chapter 4.4.1.2 --- "Medical History of HT, DM, Hyperlipidemia, IHD, Retinopathy and Albuminuria by Gender" --- p.55 / Chapter 4.4.1.3 --- Social habit in Smoking by Gender --- p.56 / Chapter 4.4.1.4 --- Body Mass Index and Waist-to-Hip Ratio by Gender --- p.57 / Chapter 4.4.2 --- Diseased Middle Cerebral Artery --- p.61 / Chapter 4.4.3 --- Characteristics between subjects with Normal TCD result and Abnormal TCD result in the MCA status --- p.62 / Chapter 4.4.3.1 --- Age --- p.64 / Chapter 4.4.3.2 --- Gender --- p.67 / Chapter 4.4.3.3 --- "Medical History of HT, DM, Hyperlipidemia, IHD, Retinopathy and Albuminuria" --- p.67 / Chapter 4.4.3.4 --- Social habit in cigarette smoking --- p.68 / Chapter 4.4.3.5 --- Body Mass Index and Waist-to-Hip Ratio --- p.71 / Chapter 4.4.3.6 --- "Other Measurements - on Blood Pressure, Fasting Plasma Glucose, HbAlc, Lipid profiles and Fibrinogen" --- p.79 / Chapter 4.4.4 --- Unadjusted Odds Ratio --- p.84 / Chapter 4.4.4.1 --- By contingency table method --- p.84 / Chapter 4.4.4.2 --- By logistic regression model --- p.86 / Chapter 4.4.5 --- Adjusted Odds Ratio --- p.92 / Chapter 4.4.5.1 --- Entering all explanatory variables: --- p.92 / Chapter 4.4.5.2 --- Using Forward and Backward Stepwise methods with the probability for entry of 0.05 and probability for removal of 0.10: --- p.95 / Chapter 4.4.5.3 --- Applying the Model-Building Strategy: --- p.100 / Chapter 4.4.6 --- Comparing the final fitted multiple logistic regression models made by the three approaches ： --- p.103 / Chapter 4.4.7 --- Probability and Odds derived from the logistic regression model --- p.110 / Chapter 4.4.8 --- Relationship between the diseased MCA and the number of significant risk indicators that the subjects associated with..… --- p.112 / Chapter 4.4.8.1 --- Logistic regression analysis on number of risk indicators associated with the MCA status --- p.115 / Chapter 4.5 --- Discussion --- p.118 / Chapter 4.5.1 --- Research Design --- p.118 / Chapter 4.5.1.1 --- Advantage --- p.118 / Chapter 4.5.1.2 --- Disadvantage --- p.118 / Chapter 4.5.2 --- Sampling --- p.119 / Chapter 4.5.3 --- Data collected and Outcome variable classified --- p.119 / Chapter 4.5.3.1 --- Medical Record - Patients Characteristics --- p.119 / Chapter 4.5.3.2 --- Transcranial Doppler - Middle Cerebral Artery status --- p.120 / Chapter 4.5.4 --- Statistical Analyses --- p.121 / Chapter 4.5.4.1 --- Odds Ratio --- p.121 / Chapter 4.5.4.2 --- Logistic Regression Model --- p.122 / Chapter 4.5.4.3 --- Sources of Error --- p.123 / Chapter 4.5.5 --- Result --- p.125 / Chapter 4.5.5.1 --- Prevalence --- p.125 / Chapter 4.5.5.2 --- Risk indicators --- p.126 / Chapter CHAPTER FIVE --- "POPULATION-BASED CROSS-SECTIONAL SURVEY IN A RURAL VILLAGE OF HENAN, PEOPLE'S REPUBLIC OF CHINA" --- p.134 / Chapter 5.1 --- Background & Purpose --- p.134 / Chapter 5.2 --- Methods --- p.135 / Chapter 5.2.1 --- Defining the Population --- p.135 / Chapter 5.2.2 --- Procedures --- p.135 / Chapter 5.2.2.1 --- Standardized Screening Form --- p.136 / Chapter 5.2.2.2 --- Transcranial Doppler Examination --- p.137 / Chapter 5.2.3 --- Defining the Risk Factors --- p.137 / Chapter 5.3 --- Statistical Analyses --- p.140 / Chapter 5.3.1 --- Research Design --- p.141 / Chapter 5.3.2 --- Descriptive Summary --- p.141 / Chapter 5.3.2.1 --- Cross-tabulated between Gender --- p.141 / Chapter 5.3.2.2 --- Cross-tabulated between With & Without intracranial large artery stenosis --- p.142 / Chapter 5.3.3 --- Measures for Association --- p.143 / Chapter 5.3.3.1 --- Univariate analysis --- p.143 / Chapter 5.3.3.2 --- Multivariate analysis --- p.143 / Chapter 5.3.4 --- Modeling the Risks --- p.144 / Chapter 5.3.5 --- Influence of the number of associated risk factors on the prevalence of intracranial large artery stenosis --- p.144 / Chapter 5.4 --- Result --- p.145 / Chapter 5.4.1 --- Baseline characteristics of all examined villagers by Gender --- p.145 / Chapter 5.4.1.1 --- Age by Gender --- p.147 / Chapter 5.4.1.2 --- "Medical History of HT, DM and Heart disease by Gender" --- p.149 / Chapter 5.4.1.3 --- Social habit in Cigarette smoking and Alcoholic drinking by Gender --- p.149 / Chapter 5.4.1.4 --- "Family History of HT, DM, Stroke and Heart disease by Gender" --- p.149 / Chapter 5.4.1.5 --- Body Mass Index and Waist-to-Hip Ratio by Gender --- p.150 / Chapter 5.4.2 --- Distribution of the Diseased intracranial artery --- p.154 / Chapter 5.4.3 --- Characteristics between subjects with and without intracranial large artery stenosis --- p.155 / Chapter 5.4.3.1 --- Age --- p.157 / Chapter 5.4.3.2 --- Gender --- p.158 / Chapter 5.4.3.3 --- "Medical History of HT, DM and Heart disease" --- p.158 / Chapter 5.4.3.4 --- Social habit in cigarette smoking and alcohol drinking --- p.158 / Chapter 5.4.3.5 --- "Family History of HT, DM, Stroke and Heart Disease" --- p.159 / Chapter 5.4.3.6 --- Body Mass Index and Waist-to-Hip Ratio --- p.160 / Chapter 5.4.3.7 --- Other Measurements - on BP and Urine Glucose --- p.163 / Chapter 5.4.4 --- Unadjusted Odds Ratio --- p.165 / Chapter 5.4.4.1 --- By contingency table method --- p.165 / Chapter 5.4.4.2 --- By logistic regression model --- p.166 / Chapter 5.4.5 --- Adjusted Odds Ratio --- p.172 / Chapter 5.4.5.1 --- Entering all explanatory variables: --- p.172 / Chapter 5.4.5.2 --- Using the Stepwise methods available with the probability for entry is 0.05 and 0.10 for removal: --- p.175 / Chapter 5.4.5.3 --- Applying the Model-Building Strategy: --- p.180 / Chapter 5.4.6 --- Comparing the final multiple logistic regression models by the three approaches： --- p.182 / Chapter 5.4.7 --- Probability and Odds derived from the logistic regression model --- p.189 / Chapter 5.4.8 --- Relationship between the transcranial Doppler result on Intracranial large artery and the number of significant risk indicators that the subjects associated with --- p.190 / Chapter 5.4.8.1 --- Logistic Regression Model --- p.192 / Chapter 5.5 --- Discussion --- p.196 / Chapter 5.5.1 --- Research Design --- p.196 / Chapter 5.5.1.1 --- Advantage --- p.196 / Chapter 5.5.1.2 --- Disadvantage --- p.196 / Chapter 5.5.2 --- Sampling --- p.197 / Chapter 5.5.3 --- Data collected and the Outcome variable classified --- p.197 / Chapter 5.5.3.1 --- Self-Reported - Subjects Characteristics --- p.197 / Chapter 5.5.3.2 --- Transcranial Doppler - Intracranial Large Artery status --- p.198 / Chapter 5.5.4 --- Statistical Methods --- p.199 / Chapter 5.5.4.1 --- Odds Ratio --- p.199 / Chapter 5.5.4.2 --- Logistic Regression --- p.199 / Chapter 5.5.4.3 --- Sources of Error --- p.199 / Chapter 5.5.5 --- Result --- p.200 / Chapter 5.5.5.1 --- Prevalence --- p.200 / Chapter 5.5.5.2 --- Risk Indicators --- p.201 / Chapter CHAPTER SIX --- CONCLUSION --- p.204 / Chapter 6.1 --- The Clinic-based study of diseased middle cerebral artery among asymptomatic hong kong chinese --- p.204 / Chapter 6.2 --- The Population-base study of intracranial large artery stenosis among mid-aged & above chinese in rural china --- p.205 / REFERENCES / APPENDIX / Appendix I Neuroimaging - Transcranial Doppler Ultrasonography / Appendix II Statistical Methods / "Appendix III (a) Standardized TCD report form used in PWH, Hong Kong (b) Standardized Screening Form used In Yuzhou, China" / Appendix IV The ICD 9th Revision - Disease of the Circulatory System / "Appendix V Prospective Hospital-Based study in Asia, AASAP (a) Standardized Data Collection From used in AASAP" / Appendix VI Contributed in published papers

Li Huan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 285-306). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Racial differences in the distribution of cerebrovascular occlusive disease are well documented. Extracranial stenosis is more common in Caucasian while intracranial stenosis is more common in Asian, Hispanic and African-American. The prevalence of asymptomatic intracranial stenosis in middle age and elderly general population in China was about 7%. The frequency of intracranial atherosclerosis among patients with stroke and TIA is 40 to 50% in Chinese populations. Concurrent extracranial and intracranial stenoses is common in Asian, the incidence range from 10 to 39% in patients with stroke. The current population of China is 1.3 billion and it was estimated that 30% of the population will be aged 60 and above by 2050 in China. The incidence of stroke in China is 215 per 100000 which is one of the highest among the world and this burden is expected to escalate in the coming decades. However, studies of concurrent stenoses among Chinese are scarce. The aim of this precis is to present my studies that were conducted mainly among Chinese stroke patients on this particular field. The scope of the studies covers the following 4 areas: (1) Identification of Long-term prognosis of patients with concurrent stenoses; (2) Long-term prognosis of patients with concurrent stenoses and ischemic heart disease; (3) Lesion pattern and stroke mechanisms in concurrent stenoses; and (4) genetic polymorphisms of ischemic stroke patients with concurrent stenoses. The background, objectives, subjects, methods, results, and conclusions of these studies will be presented in this precis. / Man, Bik Ling. / Adviser: Lawrence K.S. Wong. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 144-184). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

Early deterioration and long-term recurrence were common after stroke or transient ischemic attach (TIA), however, it is unclear whether they were correlated with active embolization and the consequent new cerebral infarct in acute phase. By employing TCD and diffusion weighted imaging (DWI), we studied the significance of the progression of MES and infarcts during acute phase on the clinical outcomes. We found that the disappearance of MES was correlated with better improvement on day 7 of recruitment; for the long-term outcome, occurrence of exacerbating infarct tended to predict recurrent stroke. Treatment aiming to reduce MES and prevent infarct exacerbation in acute phase may improve the prognosis after stroke. / Finally, one study was performed to assess the changes of hemodynamic parameters after stenting of severe stenosis in the MCA. We aimed to investigate whether TCD can reflect the lumen changes after revascularization and detect hyperperfusion. The findings showed that the velocity of stented MCA in most patients normalized within 24 hours after procedure, but the role of TCD in detecting restenosis in long run needed to be verified; no one suffered from hyperperfusion during the period of our study. The long-term outcomes of patients with normalized velocity versus those with persistently high velocity needed to be further studied. Apart from the velocity changes, changes of the collateral flow after intervention may also be an important part of hemodynamic changes. (Abstract shortened by UMI.) / It was suggested that anti-platelet therapy can reduce the MES, but little was known about the efficacy of low molecular weight heparin (LMWH) although in theory LMWH can reduce the red fibrin-dependent thromboemboli. As a sub-analysis of Fraxiparine in Ischemic Stroke (FISS)-tris study, our study did not show advantages of LMWH in eliminating MES compared with aspirin. / Previous studies showed the accuracy of TCD in diagnosis of middle cerebral artery (MCA) stenosis was variable and the positive predictive value (PPV) was less than 50% in a recent report. One of the important reasons was that most criteria were based on the velocity-only method, ignoring other non-velocity information. Thus, we tried to establish new diagnostic criteria by means of designing an assessment form which integrated more characteristics apart from the velocity acceleration. A composite score for each MCA was calculated according to following parameters in the form: Velocity Scale (score 0-6 for peak systolic velocities<140 to ≥300cm/s), Hemodynamic Scale (score 0-5 for focal or diffuse velocity increase; score 0-6 for differences between bilateral MCA; score 17 for damping velocity), Spectrum Scale (score 0-2 for normal spectrum, turbulence and musical murmurs). Our results showed that compared with the previously reported criteria, the score calculated from the assessment form yielded much more balanced accuracy against magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). However, the composition of the assessment form was only based on personal experience and need to be further modified. Multicenter studies with large sample size are also needed to confirm the advantages of this new method. / Second, we performed three studies to investigate the relationship between the progression of MES and the short or long-term outcome and the relationship between MES and different treatments. / Hao, Qing. / Adviser: Ka Sing Wong. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3419. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 155-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.