Wei-Hai Xu

In vivo high-resolution MR imaging of symptomatic and asymptomatic middle cerebral artery atherosclerotic stenosis

OBJECTIVE Recently, the technique of high-resolution magnetic resonance imaging (HR-MRI) has been developed to depict intracranial artery wall. We aimed to compare the vessel wall properties between symptomatic and asymptomatic atherosclerotic middle cerebral arteries (MCA) using HR-MRI. METHODS We studied 26 patients with symptomatic and 35 patients with asymptomatic MCA stenosis. Routine cranial MRI, magnetic resonance angiography and HR-MRI were performed on each patient. The cross-sectional images of MCA wall on HR-MRI were compared between the two groups. RESULTS The degree of MCA stenosis was similar between the two groups (67.9% vs 63.9%, P=0.327). On HR-MRI, eccentric plaques were observed in 26 (100%) symptomatic and 28 (80%) asymptomatic stenosis. In the remaining seven (20%) asymptomatic stenosis, only constrictive remodeling (vessel shrinkage) was observed. Compared with the asymptomatic group, symptomatic MCA stenosis had a larger wall area (P<0.001), greater remodeling ratio (P<0.001), higher prevalence of expansive remodeling (outward expansion of the vessel wall) (P=0.003) and lower prevalence of constrictive remodeling (P=0.008). CONCLUSIONS Different vessel wall properties on HR-MRI were observed between symptomatic and asymptomatic MCA stenosis. Further prospective studies are required to investigate whether HR-MRI is a helpful tool in stratifying stroke risk in patients with MCA atherosclerotic disease.

Atherosclerosis of middle cerebral artery: Evaluation with high-resolution MR imaging at 3 T

OBJECTIVE Three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) has been wildly used in the diagnosis of intracranial artery diseases, but it only shows the arterial lumen and does not delineate the vessel wall. The aim of this study was to assess whether high resolution cross sectional magnetic resonance imaging (HRMRI) could compensate the limitation of 3D TOF MRA in the atherosclerotic disease of middle cerebral artery (MCA). METHODS Fourty-eight suspected patients with atherosclerotic stenosis of MCA underwent 3D TOF MRA and HRMRI with a 3T scanner. The HRMRI was performed in 49 MCAs perpendicular to the M1 segment with T2-weighted imaging. Findings of HRMRI were compared with that of 3D MRA. RESULTS HRMRI displayed the artery wall clearly, and showed 37 abnormalities, including 20 plaques and 17 wall thickening. The inter-observer reproducibility was moderate for wall abnormalities with k=0.75 (95% CI 0.59-0.91), and excellent for plaques with k=0.91 (95% CI 0.80-1.03). 3D TOF MRA showed 34 stenoses at the M1 segment. Five normal MCAs on 3D TOF MRA had abnormal wall (3 plaques and 2 wall-thickening) on HRMRI. Two stenoses on 3D TOF MRA showed normal wall structure on HRMRI, indicating a possible negative remodeling phenomenon. CONCLUSIONS High-resolution MR imaging can clearly depict the wall structure of middle cerebral arteries. As a complementary method, HRMRI may compensate the limitation of 3D TOF MRA and help to detect atherosclerotic lesions not visualized by MRA.

Middle cerebral artery intraplaque hemorrhage: Prevalence and Clinical Relevance

Little is known about the composition of middle cerebral artery (MCA) plaques and how they relate to clinical status. Using high‐resolution magnetic resonance imaging (HR‐MRI), we aimed to examine the occurrence of high signal on T1‐weighted fat‐suppressed images (HST1) of MCA plaques, which are highly suggestive of fresh or recent intraplaque hemorrhage.

Plaque Distribution of Stenotic Middle Cerebral Artery and Its Clinical Relevance

Background and Purpose— Microanatomy studies reveal that most penetrating branches of middle cerebral artery (MCA) arise from the dorsal–superior surface of the trunk. Using high-resolution MRI, we sought to explore the plaque distribution of MCA atherosclerosis and its clinical relevance in relation to the orifices of penetrating arteries. Methods— We retrospectively analyzed the imaging and clinical data of 86 patients with atherosclerotic MCA stenosis. On high-resolution MRI, plaques were categorized based on the involvement of the superior, inferior, ventral, or dorsal MCA wall. The relationship of plaque distribution and clinical presentation was analyzed. Results— A total of 92 stenotic MCAs (40 symptomatic and 52 asymptomatic) on 828 image slices were studied. Overall, of the 251 slices with identified plaques, plaques were more frequently located at the ventral (44.8%) and inferior (31.7%) wall as compared with the superior (14.3%) and dorsal wall (9.0%; P<0.001). Symptomatic MCA stenosis had more superior (P=0.016) and less inferior (P=0.023) wall plaques than asymptomatic stenosis. Within the group of symptomatic MCA stenosis, vessels with penetrating artery infarctions had more superior (P=0.001) but less ventral (P=0.038) and inferior (P=0.024) plaques than without penetrating artery infarctions. Conclusions— MCA plaques tend to locate opposite to the orifices of penetrating arterial branches. Further studies are required to investigate whether MCA plaque distribution is an independent determinant of stroke occurrence and its subtypes.

Implementation of a Structured Guideline–Based Program for the Secondary Prevention of Ischemic Stroke in China

Background and Purpose— High rates of ischemic stroke and poor adherence to secondary prevention measures are observed in the Chinese population. Methods— We used a national, multicenter, cluster-randomized controlled trial in which 47 hospitals were randomized to either a structured care program group (n=23) or a usual care group (n=24). The structured care program consisted of a specialist-administered, guideline-recommended pharmaceutical treatment and a lifestyle modification algorithm associated with written and Internet-accessed educational material for patients for the secondary prevention of ischemic stroke. The primary efficacy outcome was the proportion of patients who adhered to the recommended measures at 12-month postdischarge. This trial is registered with ClinicalTrial.gov (NCT00664846). Results— At 12 months, 1287 (72.1%) patients in the Standard Medical Management in Secondary Prevention of Ischemic Stroke in China (SMART) group and 1430 (72%) patients in the usual care group had completed the 12-month follow-up (P=0.342). Compared with the usual care group, those in the SMART group showed higher adherence to statins (56% versus 33%; P=0.006) but no difference in adherence to antiplatelet (81% versus 75%; P=0.088), antihypertensive (67% versus 69%; P=0.661), or diabetes mellitus drugs (73% versus 67%; P=0.297). No significant difference in the composite end point (new-onset ischemic stroke, hemorrhagic stroke, acute coronary syndrome, and all-cause death) was observed (3.56% versus 3.59%; P=0.921). Conclusions— The implementation of a program to improve adherence to secondary ischemic stroke prevention efforts in China is feasible, but these programs had only a limited impact on adherence and no impact on 1-year outcomes. Further development of a structured program to reduce vascular events after stroke is needed. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00664846.

Microembolic signals predict cerebral ischaemic events in patients with moyamoya disease

Recent studies found that microembolic signals (MESs) could be detected by transcranial Doppler in patients with moyamoya disease. However, the clinical significance of MESs in moyamoya disease remains unclear. Our aim was to investigate whether the MESs could predict cerebral ischaemic events in patients with moyamoya disease.

Standard medical management in secondary prevention of ischemic stroke in China (SMART)

Background Although guidelines for secondary ischemic stroke have been developed, there is a gap between guidelines and clinic practice. Aims This study will investigate the current status of secondary ischemic stroke prevention in China, and implement a standard medical program in ischemic stroke and/or transient ischemic attack patients, and to examine the feasibility and efficacy of the program. Design This is a multicentre, parallel, randomized, open label, controlled trial to evaluate the feasibility and efficacy of a recommended guideline based program (SMART) in secondary stroke prevention. Forty-eight sites across Mainland China will participate in the trial. The number of enrolled patients in the study will be 4074. Primary outcome includes the proportion of patients adherent to eligible measures recommend by the SMART program, which is derived from current prevention guidelines for ischemic stroke, and the proportion of the patients achieving the treatment target. Secondary outcomes include new onset ischemic stroke, hemorrhagic stroke, acute coronary syndrome and all causes of death. The study has been registered on Clinicaltrials.gov (NCT00664846); to date, 3380 patients have been enrolled.

Impaired dynamic cerebral autoregulation and cerebrovascular reactivity in middle cerebral artery stenosis.

Purpose We sought to investigate the capacity of cerebral autoregulation and cerebrovascular reactivity (CVR) in patients with middle cerebral artery (MCA) stenosis. Methods Twenty-one patients with MCA stenosis diagnosed by magnetic resonance angiography and 15 healthy controls were enrolled. Cerebral autoregulation was assessed by autoregulatory parameters (rate of recovery/phase/gain) derived from transfer function from spontaneous oscillations of cerebral blood flow velocity and blood pressure. CVR was tested by a rebreathing maneuver. Results Rate of recovery, phase and CVR estimated from moderate MCA stenosis (rate of recovery  = 17.76±8.21%/s, phase  = 26.93±15.67°, and CVR  = 1.53±0.84%/mmHg, respectively) were significantly different (p<0.05) from controls (rate of recovery  = 39.62±27.99%/s, phase  = 55.66±22.10°, and CVR  = 2.18±0.80%/mmHg, respectively). Rate of recovery (r = −0.698, p<0.001), phase (r = −0.738, p<0.001)) and CVR (r = −0.690, p<0.001) were all significantly correlated with the degree of stenosis. Conclusion Cerebral autoregulation and CVR were impaired in patients with ≥ 50% MCA stenosis. The measures of both hemodynamic properties were inversely correlated with the stenotic degree.

Cardiac right‐to‐left shunt subtypes in Chinese patients with cryptogenic strokes: a multicenter case−control study

Data on the possible association between cardiac right‐to‐left shunt (RLS) and cryptogenic stroke are lacking in Asians. RLS and its subtypes in Chinese cryptogenic stroke patients were investigated.

Impaired Dynamic Cerebral Autoregulation in Moyamoya Disease

Moyamoya disease (MMD) is a cerebrovascular disease with unknown etiology, characterized by progressive stenosis of the internal carotid artery (ICA). The predominant feature of MMD is the “puff-of-smoke” vessels at the base of the brain, where the pathology of vascular network known as the dilated perforating arteries function as collateral pathways, to compensate for the reduced perfusion [1]. However, it was shown that this compensative mechanism may impair the function of arterioles and thus autoregulation [2,3], which is a protective mechanism that maintains cerebral blood flow constant despite variations in arterial blood pressure (ABP). It remains unknown from which stage this protective mechanism begins to impair and how the dysautoregulation is in association with the stages of MMD. We therefore applied a noninvasive method to investigate the autoregulation at different angiographic stages of MMD