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To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2009.00434.x Byline: Yong You (1), Qing Hao (1), Thomas Leung (1), Vincent Mok (1), Xiangyan Chen (1), Alex Lau (1), Howan Leung (1), Ka Sing Wong (1) Keywords: Siphon ICA; TCD; stenosis Abstract: ABSTRACT BACKGROUND Transcranial Doppler (TCD) is widely applied to evaluate the intracranial large artery stenosis. We aimed to evaluate the accuracy of TCD in detecting siphon internal carotid artery (SICA) stenosis against digital subtraction angiography (DSA). METHODS A total of 145 patients with TCD and DSA performed were recruited. The SICA and other intracranial arteries were evaluated through transorbital and transtemporal acoustic window by TCD. We defined the best cutoff value for significant SICA stenosis by receiver-operating characteristic (ROC) curve analyses and calculated the sensitivity, specificity, and positive and negative predictive values (PPV and NPV). RESULTS Mean age of the patients was 65.7 years (range 28-88 years) and 75.1% (109/145) were men. The peak systolic velocity (PSV) = 120 cm/second had the largest area under the ROC curve (area under the ROC curve = .868) compared with the MFV = 70 cm/second and MFV = 80 cm/second (area under the ROC curve = .822 and .845). So the criteria for SICA stenoses were defined as PSV = 120 cm/second plus additional parameters (abnormal spectrum, circumscribed velocity changes, or side-to-side difference). Twenty-nine patients were diagnosed with SICA stenosis or occlusion on TCD. Fourteen patients had abnormal TCD findings that were not confirmed by DSA. One patient with normal TCD but DSA showed mild (40%) stenoses. Accuracy parameters for TCD were as follows: sensitivity = 96.7% (95% confidence interval [CI]= 80.9-99.8), specificity = 93.9% (95% CI = 89.9-96.4), PPV = 65.9% (95% CI = 50.0-79.1), NPV = 99.6% (95% CI = 97.2-1.0). Most false-positive patients (11 of 15 patients) had other significant intracranial large arteries lesions. CONCLUSIONS The criteria have limited but acceptable sensitivity and specificity in detecting SICA stenoses. Abnormal findings of siphon carotid on TCD require further clarification. Author Affiliation: (1)From the Departments of Medicine & Therapeutics, and Department of Diagnostic Radiology & Organ Imaging, the Chinese University of Hong Kong, Shatin, Hong Kong SAR (QH, TL, VM, XC, AL, HL, KSW); and Department of Neurology, 1st Affiliated Hospital of Nanhua University, Hengyang, Hunan Province, China (YY). Article History: Acceptance: Received August 17, 2008, and in revised form March 30, 2009. Accepted for publication May 08, 2009. Article note: Correspondence: Address correspondence to Dr. Ka Sing Wong, MD, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR. E-mail: ks-wong@cuhk.edu.hk.

To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2008.00337.x Byline: Qing Hao (1), Shan Gao (1), Thomas Wai Hong Leung (1), Ming Hui Guo (1), Yong You (1), Ka Sing Wong (1) Keywords: Transcranial Doppler; middle cerebral artery stenosis; diagnostic criteria Abstract: ABSTRACT BACKGROUND AND PURPOSE Current criteria for middle cerebral artery (MCA) stenosis by transcranial Doppler were mainly based on the flow velocity acceleration, ignoring other useful parameters. We tested the accuracy of new criteria using magnetic resonance angiography (MRA) as the confirmative method. METHODS A compositive score for each MCA was calculated according to following parameters: Velocity Scale (score 0-6 for peak systolic velocity RESULTS The median scores in normal-mild, moderate, and severe groups on MRA differed significantly (P < .001). The optimal cutoff score for CONCLUSIONS This new method was feasible and reliable and showed some advantages over the velocity-only method. Further studies using digital subtraction angiography as the gold standard are needed to ameliorate the new criteria. Author Affiliation: (1)Department of Medicine &Therapeutics, The Chinese University of Hong Kong, Hong Kong, China (QH, MHG, YY, KSW); Department of Neurology, Peking Union Medical College Hospital & CAMS, Beijing, China (SG); and Department of Neurology, 1st Affiliated Hospital, Nanhua University, Hengyang, China (YY). Article History: Acceptance: Received May 1, 2008, and in revised form September 24, 2008. Accepted for publication November 8, 2008. Article note: Correspondence: Address correspondence to Ka Sing Wong, MD, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Shatin, HKSAR, China. E-mail: ks-wong@cuhk.edu.hk.

To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2008.00339.x Byline: Qing Hao (1), Hui Meng Chang (1), Meng Cheong Wong (1), Ka Sing Wong (1), Christopher Chen (1) Abstract: ABSTRACT BACKGROUND AND PURPOSE Microemboli signal (MES) detected by transcranial Doppler (TCD) may represent ongoing embolic phenomenon and is a predictor of recurrent stroke or transient ischemic attack. We sought to study the frequency of MES in stroke patients with large artery occlusive diseases treated with low molecular weight heparin (LMWH) or aspirin. METHODS Patients participating in the Fraxiparine in Ischemic Stroke (FISS)-tris study were recruited. MES detection was performed from middle cerebral artery on the 1st, 3rd, and 7th days after randomization. The correlation between the presence of MES and the treatment was determined by the [chi].sup.2 test. RESULTS Among 47 patients, 26 were randomized to LMWH and 21 to aspirin. On day 1, MES were detected in 10 patients (7/26 on LMWH, 3/21 on aspirin; P= .475). On day 3, 12 patients had MES (7/25 on LMWH, 5/20 on aspirin; P= .821). On day 7, 11 patients had MES (6/25 on LMWH, 5/20 on aspirin; P= .938). The median of the number of MES on days 1, 3, and 7 was 4 (range 1-10), 5 (range 1-42), and 3 (range 1-33) for the LMWH group and 1 (range 1-15), 4 (range 1-10), and 2 (range 1-4) for the aspirin group. CONCLUSIONS There were no significant differences in the frequency of MES between patients with large artery occlusive disease treated with LMWH and aspirin. Author Affiliation: (1)From the Department of Medicine &Therapeutics, The Chinese University of Hong Kong, Hong Kong, China (QH, KSW); Department of Pharmacology, National University of Singapore, Singapore (CC); Department of Neurology, National Neuroscience Institute, Singapore General Hospital Campus, Singapore (HMC); and National Cancer Centre, Singapore (MCW). Article History: Acceptance: Received June 9, 2008, and in revised form October 14, 2008, Accepted for publication November 8, 2008. Article note: Correspondence: Address correspondence to Christopher Chen, FRCP, MD, Department of Pharmacology, National University of Singapore, 21 Lower Kent Ridge Road, Singapore 119077. E-mail: cplhchen@yahoo.com.sg

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2007.00158.x Byline: Xiang-yan Chen (1), Wynnie Wai Man Lam (1), Ho Keung Ng (1), Yu-hua Fan (1), Ka Sing Wong (1) Keywords: Ischemic stroke; calcification; intracranial artery; atherosclerosis; risk factors; multi-detector-row computed tomography (MDCT) Abstract: ABSTRACT BACKGROUND AND PURPOSE Calcification in cerebral arteries is understudied, although frequently observed on computed tomography of the brain (CT brain). We aimed to assess the incidence of intracranial artery calcification in ischemic stroke patients and to evaluate its correlation with ischemic stroke. METHODS Our study included ischemic stroke patients and age-gender-matched nonischemic stroke patients referred for CT brain. RESULTS One hundred and seventy-five ischemic stroke patients and 182 controls were enrolled. The highest prevalence of calcification was seen in intracranial internal carotid artery (IICA) (80.4%), and less commonly in the vertebral artery (35.6%). There was a higher prevalence of intracranial artery calcification in ischemic stroke patients than controls (92.6% vs. 76.4%, P < .001). Hypertension (OR = 2.056, 95% CI: 1.129 [proportional to] 3.745), diabetes (OR = 2.483, 95% CI: 1.233 [proportional to] 5.001), smoking (OR = 2.844, 95% CI: 1.542 [proportional to] 5.243), intracranial artery calcification (OR = 3.172, 95% CI: 1.252 [proportional to] 8.036), hyperlipidemia (OR = 6.714, 95% CI: 3.302 [proportional to] 13.650), and atrial fibrillation (OR = 7.941, 95% CI: 2.790 [proportional to] 22.599) were found to be independently associated with ischemic stroke. CONCLUSIONS We demonstrated a higher incidence of intracranial artery calcification in ischemic stroke patients. Besides traditional risk factors, intracranial artery calcification was found to be an independent risk factor of ischemic stroke. Author Affiliation: (1)Department of Anatomical & Cellular Pathology (X-YC, HKN); Department of Diagnostic Radiology & Organ Imaging (WWML); and Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR (Y-HF, KSW). Article History: Acceptance: Received January 10, 2007, and accepted for publication January 22, 2007. Article note: Correspondence: Address correspondence to K.S. Wong, MD, Department of Medicine & Therapeutics, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. E-mail: ks-wong@cuhk.edu.hk.

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2006.00048.x Byline: Xiang-Yan Chen (1), Wynnie Wai Man Lam (1), Ho Keung Ng (1), Hai-Lu Zhao (1), Ka Sing Wong (1) Keywords: Middle cerebral artery; magnetic resonance imaging; postmortem study; histology; diagnosis Abstract: ABSTRACT Background and Purpose. Magnetic resonance imaging (MRI) has been widely applied in detecting intracranial large artery stenosis, but there have been few validation studies to compare with histopathology. The aim of the postmortem study is to assess the accuracy of MRI in identifying middle cerebral artery (MCA) stenosis. Methods. We recruited, consecutively, Chinese postmortem autopsies in our hospital during 19 months. MRI was performed in the postmortem brains to scan the cross-sections of MCAs with barium expanding the artery lumen. The MCAs were then removed for histopathologic studies. With histopathology as a reference standard, the accuracy of MRI was evaluated, and the correlation between MCA stenosis identified by MRI and radiologically or histopathologically evident brain infarcts was investigated. Results. Seventy-six consecutive autopsies were recruited. The sensitivity and specificity of MRI in detecting more than 30% MCA stenosis were 38.6% and 92.2%, with a positive predictive value of 87.2% and negative predictive value of 52.2%, and the corresponding values of MRI in identifying more than 50% MCA stenosis were 57.1%, 90.8%, 50%, and 83.0%, respectively. Both more than 30% and more than 50% MCA stenosis identified by MRI were found to be associated with infarctions in the corresponding MCA territory (P= 0.001, odds ratio = 4.365, 95% CI: 1.684-11.313; and P= 0.039, odds ratio = 2.694, 95% CI: 1.139-6.377). Conclusions. Our study demonstrates the agreement between ex vivo MRI and histopathology in identifying MCA stenosis, and the correlation between the MCA stenosis identified by MRI and radiologically or histopathologically evident brain infarcts. Author Affiliation: (1)From the Department of Anatomical and Cellular Pathology (X-Y C, HKN); Department of Diagnostic Radiology and Organ Imaging (WL); and Department of Medicine and Therapeutics, Chinese University of Hong Kong, Shatin, Hong Kong SAR (H-LZ, KSW). Article History: Received January 04, 2006, and in revised form March 14, 2006. Accepted for publication March 22, 2006. Article note: Address correspondence to Ka Sing Wong, MD, Department of Medicine and Therapeutics, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. E-mail: ks-wong@cuhk.edu.hk.

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2006.00027.x Byline: Xin Wang (1), Wynnie W. M. Lam (1), Yu Hua Fan (1), Colin A. Graham (1), Timothy H. Rainer (1), Ka Sing Wong (1) Keywords: Small subcortical infarcts; stroke; embolism; MCA stenosis; diffusion-weighted imaging Abstract: ABSTRACT Background and Purpose. Small subcortical infarcts (SSI, maximum lesion diameter [less than or equal to]2.0 cm) are usually considered as infarcts caused by small vessel disease. However, SSI can also be associated with large artery occlusive disease such as middle cerebral artery (MCA) stenosis. We performed a prospective study to investigate the relationship between MCA stenosis and SSI distribution and further to investigate the mechanism of SSI caused by MCA stenosis. Methods. Magnetic resonance angiography (MRA) and diffusion-weighed MRI (DWI) of consecutive acute ischemic stroke patients with recent SSI were studied. The distribution of acute infarcts on DWI was categorized as cortical infarct (CI), border zone infarct (BI), or perforating artery infarct (PAI). Results. Totally, 93 cases were recruited, among which 12 had single SSI with MCA stenosis (group 1) and 26 patients had multiple SSI with MCA stenosis (group 2), while 55 patients without MCA stenosis had single SSI (group 3). For patients with single SSI and MCA stenosis, 6 had BI and 6 had PAI; for patients with multiple SSI and MCA stenosis, 25 had BI, 4 had PAI and 9 had CI (compared with group1: P= .001); for patients with single SSI but without MCA stenosis, 20 had BI and 35 had PAI (compared with group1: P= .58). Conclusion. Multiple acute infarcts along the border zone are the commonest pattern in small infarcts with MCA stenosis, especially among those with multiple acute infarcts. Our data suggest that hemodynamic compromise and artery-to-artery embolism may be both important factors for infarcts in patients with MCA stenosis. Author Affiliation: (1)From the Department of Medicine and Therapeutics (XW, YHF, KSW); Department of Diagnostic Radiology & Organ Imaging (WWML); Accident & Emergency Medicine Academic Unit (CAG, THR), the Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; and Department of Neurology, the Qingdao Municipal Hospital, Qingdao, China (XW). Article History: Received July 13, 2005, and in revised form November 30, 2005. Accepted for publication December 7, 2005. Article note: Address correspondence to Dr Ka Sing Wong, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong, China. E-mail: ks-wong@cuhk.edu.hk.

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2006.00030.x Byline: Jian Hui Fu (1), Chuan Zhen Lu (1), Zhen Hong (1), Qiang Dong (1), Ding Ding (1), Ka Sing Wong (1) Keywords: Acetazolamide; asymptomatic; cerebral vasomotor reactivity; white matter lesions Abstract: ABSTRACT Background and Purpose. The relationships between cerebral vasomotor reactivity (CVR) and white matter lesions (WMLs) were investigated mainly in patients with carotid stenosis. We aimed to study the relationship in asymptomatic elderly subjects without large artery occlusive disease. Methods. A total of 33 elderly individuals (mean age was 76.2 years) who were free from neurological deficit or cognitive impairment were studied. Bilateral mean blood flow velocity was measured in the middle cerebral artery using a 2-MHz pulsed transcranial Doppler (TCD) system together with intravenous administration of acetazolamide as vasodilatory stimuli. WMLs on a fluid-attenuated inversion recovery (FLAIR) sequence of MRI were classified into two categories: subcortical deep white matter hyperintensity (SDWMH) and periventricular hyperintensity (PVH). The lesions in each category were then divided into three grades (grade 0-I, grade II, grade III) according to the Fazekas scale. Results. CVR was inversely associated with the extent of SDWMH and PVH. The differences in CVR were statistically significant among different severity of WMLs: for SDWMH (70%[+ or -] 10% in grade 0-I, 60%[+ or -] 10% in grade II, and 40%[+ or -] 10% in grade III, P < .001); for PVH (80%[+ or -] 10% in grade 0-I, 60%[+ or -] 10% in grade II, and 40%[+ or -] 10% in grade III, P < .001). Conclusions. Impaired CVR is related to the extent of WMLs in asymptomatic elderly individuals without large artery stenosis. The findings in our study suggest that dysfunction of cerebral vascular autoregulation might be an important factor in the development of WMLs in the asymptomatic elderly without large artery occlusive disease. Author Affiliation: (1)From the Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China (JHF, CZL, ZH, QD, DD); Department of Medicine & Therapeutics, Chinese University of Hong Kong, Hong Kong SAR, China (KSW). Article History: Received March 31, 2005, and in revised form September 27, 2005, December 14, 2005. Accepted for publication December 17, 2005. Article note: Address correspondence to Dr Jian Hui FU, Department of Neurology, Hua Shan Hospital, Fudan University, 12 Wulumuqi Zhong Road, Shanghai 200040, China. E-mail: jianhuif@21cn.com.