磁共振扩散加权成像在鉴别新陈腔隙性脑白质梗死中的价值

目的分析新陈腔隙性脑白质梗死的T2WI、扩散加权成像(DWI)信号特点，比较两种梗死的病灶与脑白质、病灶与脑脊液对比度及表观扩散系数(ADC)，评价DWI在鉴别新陈腔隙性脑白质梗死方面的作用。方法急性期腔隙性脑白质梗死患者27例，选择43例陈旧腔隙性脑白质梗死患者作对照。测量病灶、正常脑白质、脑脊液信号强度，计算病灶与脑白质、病灶与脑脊液的对比度。测量病灶、正常脑组织、脑脊液的ADC值并比较。结果(1)急性脑白质腔隙性梗死DWI呈高信号，ADC图呈等或低信号。DWI的病灶与脑白质、病灶与脑脊液对比度均优于T2WI。(2)陈旧脑白质腔隙性梗死DWI呈等信号，ADC图呈高信号。DWI的病灶与脑白质对比度不如T2WI。(3)DWI图像上，急性腔隙性脑白质梗死病灶与脑白质、病灶与脑脊液对比度明显高于陈旧病灶，ADC则明显低于陈旧病灶，有助于区分新陈腔隙性梗死。结论DWI的检查时间短，诊断和鉴别意义大，建议在可能的情况下，将DWI作为急性卒中样发作患者的常规检查序列。     

Clinical lacunar syndromes as predictors of lacunar infarcts. A comparison of acute clinical lacunar syndromes and findings on diffusion-weighted MRI

OBJECTIVES: To evaluate if patients with acute lacunar syndromes have acute lacunar infarcts or other types of cerebral lesions on diffusion-weighted MRI. METHODS: Patients with acute lacunar syndromes underwent echo-planar diffusion MRI of the brain within 3 days after stroke onset. Localization and size of lesions with hyperintense signal were determined, compared with clinical characteristics and with findings on follow-up T2-weighted MRI. RESULTS: Twenty-three patients participated in the study. Thirteen patients had pure motor stroke, 1 pure sensory stroke, 8 sensorimotor stroke, and 1 ataxic hemiparesis. Twenty-two patients had at least one lesion with increased signal on diffusion-weighted MR images. These acute lesions were in the internal capsule/ basal ganglia/thalamus in 13 patients, subcortical white matter in 5 patients, brainstem in 2 patients, cortex (multiple small lesions) in 1 patient, and cortex + basal ganglia in 1 patient. The median volume of the lesions was 0.6 ml on the initial examination and on follow-up, of 17 patients after 1 to 5 months, 0.5 ml. CONCLUSIONS: Almost all patients with acute ischemic lacunar syndromes have acute lesions on echo-planar diffusion-weighted MRI within 3 days after stroke onset. These lesions are mostly small and subcortical, compatible with lacunar infarcts caused by single penetrating artery occlusion, but in a minor proportion of patients (2 of 23 in our study) a cortical involvement is found.     

磁共振梯度回波T2*加权成像诊断家族性多发性脑海绵状血管畸形的价值

目的 探讨磁共振梯度回波T2*加权成像(GRE T2*-WI)诊断家族性多发性脑海绵状血管畸形(FCCM)的价值.方法 对FCCM患者的2个家系26名成员进行颅脑CT、常规MRI(T1WI、T2WI、T2FLAIR、DWI及SE)及GRE T2*-WI检查.结果 GRE T2*-WI检查发现FCCM患者12例,均为多发病灶,平均检出病灶23个,病灶主要位于基底节区,其次为皮质-皮质下、丘脑、小脑和脑干.病灶呈特异的高低混杂信号,周边围有一圈黑色低信号环,极具特征性.常规MRI检出脑内病灶数目(平均病灶数5～17个)、疑诊或确诊为FCCM患者的例数(平均例数3～9例),由多至少依次为SE、DWI、T2FLAIR、T1WI和T2WI,均较GRE T2*-WI少.而颅脑CT仅对病灶较大、合并有钙化或出血的3例患者疑诊为脑海绵状血管畸形.结论与CT和常规MRI相比,GRE T2*-WI可以更清楚地显示脑海绵状血管畸形病灶,为诊断提供更可靠的依据.     

弥散加权成像在超急性期脑梗死诊断中的应用

目的 将磁共振弥散加权成像（DWI）与常规MR技术作对比。评价DWI对超急性期脑梗死诊断的准确性和敏感性。方法 对52例超急性期，急性期，亚急性期，慢性期的患者行DWI，快速自旋回波T2WI，FLAIR及3DTOF法磁共振血管成像检查。对所有病例的病变部位均按神经解剖进行准确定位并与患者的症状，体征相联系。结果 超急性期和急性期脑梗死在DWI图像上表现为高信号，在表观弥散系数（ADC）图上表现为低信号，ADC值低于对侧相应的区域。在超急性期和急性期，病灶的ADC值显著下降,rADC值也明显下降。平均下降约59.12%。而在慢性期ADC值明显升高，甚至较正常组织还高，平均升高达20.3%。结论 DWI对6h症状起病的急性卒中的诊断明显高于传统MRI，DWI可以在超急期发现缺血病灶，早于常规T2WI及FLAR序列图像。DWI对脑梗死的早期诊断及评价起重要的作用。     

Yield of diffusion-weighted MRI for detection of potentially relevant findings in stroke patients

OBJECTIVE: To determine whether diffusion-weighted imaging (DWI) could identify potentially clinically relevant findings in patients presenting more than 6 hours after stroke onset when compared with conventional MRI. METHODS: MRI with both conventional (T2 and proton density images) and echoplanar imaging (DWI and apparent diffusion coefficient maps) was performed 6 to 48 hours after symptom onset (mean, 27 hours) in 40 consecutive patients with acute stroke. All acute lesions were identified first on conventional images, then on DWI, by a neuroradiologist who was provided with the suspected lesion location, based on a neurologist's examination before imaging. Abnormalities were rated as potentially clinically relevant if they were detected only on DWI and 1) confirmed the acute symptomatic lesion to be in a different vascular territory than suspected clinically, 2) revealed multiple lesions in different vascular territories suggestive of a proximal source of embolism, or 3) clarified that a lesion, thought to be acute on conventional imaging, was not acute. RESULTS: The initial clinical impression of lesion localization was incorrect in 12 patients (30%). Clinically significant findings were detected by DWI alone in 19 patients (48%). DWI demonstrated the symptomatic lesion in a different vascular territory than suspected clinically or by conventional MRI in 7 patients (18%) and showed acute lesions in multiple vascular distributions in 5 patients (13%). In 8 patients (20%), DWI clarified that lesions thought to be acute on conventional MRI were actually old. CONCLUSION: In patients imaged 6 to 48 hours after stroke onset, DWI frequently provided potentially clinically relevant findings that were not apparent on conventional MRI.     

A standardized MRI stroke protocol: comparison with CT in hyperacute intracerebral hemorrhage

BACKGROUND AND PURPOSE: Diagnostic imaging in hyperacute ischemic stroke has been revolutionized by the introduction of diffusion- and perfusion-weighted MRI (DWI and PWI). CT, however, is still needed to exclude intracerebral hemorrhage (ICH). The purpose of our study was to determine the diagnostic accuracy of a standardized, multimodal MRI (mMRI) stroke protocol in the qualitative and quantitative assessment of hyperacute ICH (<6 hours). METHODS: We investigated 9 patients with hyperacute ICH with CT followed immediately by a standardized mMRI stroke protocol (DWI, PWI [T2*-WI], FLAIR, T2-WI, and MRA). The time interval between MRI and symptom onset ranged from 3 hours to 5 hours 45 minutes. We analyzed and compared the size of the hematoma on CT and all mMRI images by semiautomatic volumetry. RESULTS: ICH was unambiguously identified on the basis of all mMRI sequences. With increasing susceptibility effect (T2*-WI), the ICH, appearing as an area of hyperintensity with central signal loss, became qualitatively most evident. Regarding quantitation, T2*-WI overestimated (median and mean difference, 18.9%/17.8%; SD final sigma=24.4%) and DWI correlated best (median and mean difference, 3.97%/-4.36%; SD final sigma=37. 42%) with hematoma size on CT. CONCLUSIONS: Multimodal stroke MRI is as reliable as CT in the assessment of hyperacute ICH. Therefore, additional CT is no longer necessary to rule out ICH in hyperacute stroke. The use of mMRI alone in the diagnostic workup of a hyperacute stroke patient saves time and costs while rendering all the critical information needed to initiate an optimal treatment.     

Clinical utility of diffusion-weighted magnetic resonance imaging in the assessment of ischemic stroke

Diffusion-weighted imaging (DWI) detects small changes in water diffusion that occur in ischemic brain. This study evaluated the clinical usefulness of a phase-navigated spin-echo DWI sequence compared with T2-weighted magnetic resonance imaging (T2W MRI) in patients with cerebral ischemia and assessed apparent diffusion coefficient (ADC) and T2-weighted imaging (T2WI) changes over time. ADC values and T2 ratios of image intensity were measured from the region of ischemia and from the corresponding contralateral brain region. The clinical histories of patients with DWI scans obtained over the course of 1 year were reviewed to ascertain whether DWI aided in clinical diagnosis or management. Of 103 scans obtained a mean of 10.4 days after symptom onset, DWI detected six lesions not seen on T2WI and discriminated two new infarcts from old lesions. DWI was most useful within 48 hours of the ictus. The evolution of ADC values and T2 ratios was evaluated in 26 cases with known symptom onset times. ADC values were low at less than 1 week after stroke onset and became elevated at chronic time points. T2 ratios were near normal acutely, increasing thereafter. DWI was superior to T2W MRI in detecting acute stroke, whereas both techniques assisted in determining lesion age.     

Scattered brain infarct pattern on diffusion-weighted magnetic resonance imaging in patients with acute ischemic stroke

BACKGROUND AND PURPOSE: Infarct patterns on brain imaging contribute to the etiologic classification of ischemic stroke. However, the association of specific subtypes of infarcts and etiologic mechanisms is often weak, and acute lesions are frequently missed on initial computed tomography (CT). Diffusion-weighted imaging (DWI) is superior in visualizing acute ischemic lesions as compared to CT and conventional magnetic resonance imaging (MRI). In our prospective study, we addressed the question whether a distinct pattern of infarction on DWI is associated with infarct etiology and clinical outcome. METHODS: Sixty-two patients with clinical signs of acute ischemic stroke and negative acute CT upon admission underwent DWI within 10 days after the ictus. Neurological status was documented using the NIH stroke scale. A scattered lesion pattern was defined by at least 2 separate hyperintense DWI lesions within the territory of one of the major cerebral arteries. Ischemic lesions were defined as acute if the region was demarcated strongly hyperintense in all DW images, and if the apparent diffusion coefficient was below normal. RESULTS: In 32 patients, DWI revealed a scattered lesion pattern, while in 30 patients a single acute lesion was detected. In patients with scattered lesions, potential arterial or cardiac embolic sources were detected in 26 patients (81.3%), as compared to 5 patients (16.6%) in the group with single lesions (chi(2) test, p < 0.0001). The neurological status of patients with scattered lesions improved significantly more than among patients with single lesions (Mann-Whitney test, p < 0.0003). CONCLUSION: A scattered lesion pattern on DWI in patients with acute brain infarction and negative initial CT scan is associated with an embolic etiology and may indicate a favorable clinical outcome.     

Multiple acute infarcts in the posterior circulation.

OBJECTIVE--to evaluate clinical, radiological, and prognostic features of patients with multiple acute infarcts in remote arterial territories of the posterior circulation. DESIGN--Data analysis from a prospective acute stroke registry in a community based primary care centre using a standard protocol including MRI and MRA. RESULTS--In three and a half years, 27 of the 236 patients (11%) with posterior circulation stroke had multiple acute infarcts in the posterior circulation as shown by gadolinium enhancement on MRI. Eighteen patients had multiple infratentorial and supratentorial infarcts including the cerebellum and posterior cerebral artery territory, with coexisting brainstem involvement in seven patients. Fourteen patients had a rostral basilar artery syndrome and cerebellar signs; four patients had a visual field defect with cerebellar signs. Causes were vertebral (six) or basilar (four) artery atheromatosis, and cardioembolism (four). Seven patients had multiple acute infarcts in the posterior circulation of the cerebellum and lower brainstem. Brainstem and cerebellar signs were found in most patients (five); aetiologies were small vessel disease (four), cardioembolism (one), and vertebral artery dissection (one). Two patients with large artery atheromatosis had multiple acute infarcts in the posterior circulation in the brainstem and posterior cerebral artery territory. One month after stroke more than 25% of the patients were dependent or had died. There was no difference in the outcome between the three groups, and recovery was linked to the size of infarcts rather than to a high number of infarcts. CONCLUSIONS--multiple acute infarcts in the posterior circulation usually involve the cerebellum. Simultaneous brainstem and posterior cerebral artery territory infarcts sparing the cerebellum are uncommon. They can be suspected clinically before neuroimaging, mainly when supratentorial and infratentorial infarcts coexist. This may be important, because different patterns of infarction are associated with different causes of stroke.     

Wall characteristics and mechanisms of ischaemic stroke in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study

Objective:: To evaluate the characteristics of atherosclerotic middle cerebral artery (MCA) stenosis by high-resolution magnetic resonance imaging (HR-MRI) and determine the relationship between wall characteristics and infarction patterns.

Methods:: Thirty-six patients with acute ischaemic stroke due to MCA stenosis underwent diffusion-weighted magnetic resonance imaging (DWI) and HR MRI. Wall characteristics of MCA, including irregular surface, superior location, T2-hyperintense of plaques and positive remodelling (PR), were analysed. Characteristics of acute infarct on DWI were categorised according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone or perforating artery territory infarcts). The relationship between wall characteristics and infarction patterns was evaluated.

Results:: PR was observed in 20 patients, irregular surface plaque in 18 patients, superior location of plaques in 14 patients and T2-hyperintense foci in 13 patients. Seventeen patients had multiple acute cerebral infarcts and 13 showed single acute cerebral infarcts. Border zone infarcts were the most common (76.5%) among multiple acute infarcts. Penetrating artery infarcts (PAI) accounted for 76.9% of all single infarcts. Multiple infarcts were more frequently observed in patients with PR (P = 0.007) or plaque surface irregularity (P = 0.035). Single infarcts, especially PAI, were more prevalent in patients with superior plaque (P = 0.030). No statistically significant differences were observed between multiple and single infarcts in patients with T2-hyperintense lesions (P?=?0.638).

Conclusions:: PR or irregular surface plaques were associated with artery-to-artery embolism. Superior location of plaques was associated with PAI. HR-MRI provides insights into intracranial atherosclerosis in vivo, predictive of infarction patterns.     

Significance of acute multiple brain infarction on diffusion-weighted imaging

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) is superior to conventional MRI in identification of small new ischemic lesions and discrimination of recent infarcts from old ones. Thus, this technique is useful in the detection of acute multiple brain infarcts (AMBI). We sought to determine the frequency and the topographical and etiologic patterns of AMBI detected on DWI. METHODS: We studied 329 consecutive ischemic stroke patients who underwent DWI and MRI/MR angiography within 4 days of stroke onset. AMBI was defined as noncontiguous high signal intensities on DWI in >1 vascular territory. Stroke mechanism was determined according to the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). RESULTS: We detected AMBI in 95 patients (28.9%). AMBI in anterior circulation was found in 62 cases: in 1 hemisphere in 42 (group A) and in bilateral hemispheres in 20 (group B). Twenty-two patients had AMBI in the posterior circulation (group C) and 11 in both anterior and posterior circulations (group D). The most frequent cause of stroke was large-artery atherosclerosis in groups A (33/42), B (9/20), and C (15/22) (P=0.02) and cardioembolism in group D (6/11) (P=0.02). Elevated fibrinogen or hematocrit was significantly associated with group B (P=0.01). In 9 patients in groups B and D, anatomic variations of anterior or posterior cerebral arteries or patent posterior communicating artery contributed to AMBI. CONCLUSIONS: Different topographical patterns of AMBI are associated with different vascular pathologies and stroke mechanisms. Hemorheologic abnormality or vascular anatomic variations may be contributing factors in the pathogenesis of AMBI in bilateral cerebral hemispheres or in both anterior and posterior circulations.     

缺血性卒中患者脑微出血的相关因素分析

目的 探讨缺血性卒中患者发牛脑微出血(CMBs)的相关因素. 方法 对85例急性缺血性卒中患者进行磁共振检查,其中包括梯度回波T2加权成像(GE-T2~*WI),并对患者的临床资料和影像学特点进行分析. 结果 26例(30.6%)患者中共检出CMBs 124个,每位患者的CMBs数目在1～16个之间.CMBs在基底节丘脑区和皮质一皮质下区分布较多,在幕下区较少见.发生在脑十的CMBs可有相关症状及体征.CMBs数目与年龄、腔隙性梗死数目及白质疏松程度评分有相关性(r=0.243,P=0.025;r=337,P=0.002;r=0.438,P=0.000).CMBs在GE-T2~*WI上显影良好,部分CMBs可在自旋叫波(SE)T2WI及DWI序列上显影. 结论 CMBs是脑微小血管病变标志,主要预测因素有高龄、多发腔隙性梗塞和白质疏松.     

Lack of evidence of acute ischemic tissue change in transient global amnesia on single-shot echo-planar diffusion-weighted MRI.

BACKGROUND AND PURPOSE: There is uncertainty concerning the etiology of transient global amnesia (TGA). Previous CT and MRI studies have indicated that permanent structural abnormality is rare in TGA. Diffusion-weighted (DW) MRI is very sensitive to early ischemic parenchymal changes and has recently demonstrated embolic infarction in the posterior cerebral artery territory in 2 TGA patients. We report the findings of DW MRI in 8 patients in acute stages of TGA. METHODS: Conventional and echo-planar DW MRI was performed in 2 patients in the active phase and 6 patients in the recovery phase (1 to 8 hours after cessation of anterograde memory dysfunction) of spontaneously occurring TGA. RESULTS: None of the patients showed signs of hyperintensity on DW images or hypointensity on quantitative apparent diffusion coefficient (ADC) maps to suggest regional decreases of water mobility or acute T2 changes on transverse or coronal slices. CONCLUSIONS: We were unable to detect ADC or acute T2 changes with echo-planar DW MRI in patients with TGA, which suggests that mechanisms other than ischemic infarction may cause TGA. We did not identify spreading depression-associated changes of the ADC. Further refinement of MRI sequences may be necessary to detect subtle or transient signal change in brain parenchyma.     

Hematological disorders related cerebral infarctions are mostly multifocal

Hematological disorders (HD) have been estimated to implicate approximately 1% of patients with arterial ischemic stroke. However, previously published studies are mostly retrospective or based on case reports or small series in selected young patients. We herein prospectively included consecutive patients with MRI-confirmed cerebral arterial infarctions among individuals admitted in our stroke unit during a 32 month period to determine the clinical and neuroradiological features of ischemic stroke due to HD. Patients with both HD and other identified sources of stroke were excluded. Among patients who were admitted for suspected stroke, 590 had diffusion-weighted MRI confirmed acute arterial infarcts. Cause of the cerebral infarction was HD in 13 patients (2.2%): myeloproliferative disorders (n=4), multiple myeloma (1), lymphoma (1), chronic lymphocytic leukemia (1), disseminated intravascular coagulation (2), thrombotic thrombocytopenic purpura (1), antiphospholipid antibody syndrome (2) and homozygous Q506 factor V mutation associated with lupus anticoagulant (1). The HD were previously known in 6 patients. The only significant difference between the groups of patients with or without HD was the prevalence of multiple acute infarcts in different vascular territories, detected in 53.8% of patients with HD versus 7.8% of patients without HD (mostly due to atherosclerosis, small vessel disease or cardioembolism) (p<0.0001; Fisher exact test). Initial treatment in stroke unit included anticoagulation, steroids, chemotherapy, phlebotomy or plasmatic exchanges, according to etiology. Rankin score at six months was ≤2 in 8 patients. A large spectrum of hematological diseases can be associated with cerebral infarction. In the etiologic work up, HD should be particularly looked for in patients with multifocal acute infarcts to adapt specific therapeutic management.     

Advantages of adding diffusion-weighted magnetic resonance imaging to conventional magnetic resonance imaging for evaluating acute stroke

BACKGROUND: Accurate localization of acute ischemic lesions in patients with an acute stroke may aid in understanding the etiology of their stroke and may improve the management of these patients. OBJECTIVE: To determine the yield of adding diffusion-weighted magnetic resonance imaging (DWI) to a conventional magnetic resonance imaging (MRI) protocol for acute stroke. DESIGN: A prospective cohort study. SETTING: A referral center. PATIENTS AND METHODS: Fifty-two patients with a clinical diagnosis of acute stroke who presented within 48 hours after symptom onset were included. An MRI scan was obtained within 48 hours after symptom onset. A neuroradiologist (A.M.N.) and a stroke neurologist (G.W.A.) independently identified suspected acute ischemic lesions on MRI sequences in the following order: (1) T2-weighted and proton density-weighted images, (2) fluid-attenuated inversion recovery images, and (3) diffusion-weighted images and apparent diffusion coefficient maps. MAIN OUTCOME MEASURES: Diagnostic yield and interrater reliability for the identification of acute lesions, and confidence and conspicuity ratings of acute lesions for different MRI sequences. RESULTS: Conventional MRI correctly identified at least one acute lesion in 71% (34/48) to 80% (39/49) of patients who had an acute stroke; with the addition of DWI, this percentage increased to 94% (46/49) (P<.001). Conventional MRI showed only moderate sensitivity (50%-60%) and specificity (49%-69%) compared with a "criterion standard." Based on the diffusion-weighted sequence, interrater reliability for identifying acute lesions was moderate for conventional MRI (kappa = 0.5-0.6) and good for DWI (kappa = 0.8). The observers' confidence with which lesions were rated as acute and the lesion conspicuity was significantly (P<.01) higher for DWI than for conventional MRI. CONCLUSION: During the first 48 hours after symptom onset, the addition of DWI to conventional MRI improves the accuracy of identifying acute ischemic brain lesions in patients who experienced a stroke.     

Mechanisms of acute cerebral infarctions in patients with middle cerebral artery stenosis: a diffusion-weighted imaging and microemboli monitoring study

Although most therapeutic efforts and experimental stroke models focus on the concept of complete occlusion of the middle cerebral artery as a result of embolism from the carotid artery or cardiac chamber, relatively little is known about the stroke mechanism of intrinsic middle cerebral artery stenosis. Differences in stroke pathophysiology may require different strategies for prevention and treatment. We prospectively studied 30 consecutive acute ischemic stroke patients with middle cerebral artery stenosis detected by transcranial Doppler and magnetic resonance angiography. Patients underwent microembolic signal monitoring by transcranial Doppler and diffusion-weighted magnetic resonance imaging. Characteristics of acute infarct on diffusion-weighted magnetic resonance imaging were categorized according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone, or perforating artery territory infarcts). The data of microembolic signals and diffusion-weighted magnetic resonance imaging were assessed blindly and independently by separate observers. Diffusion-weighted magnetic resonance imaging showed that 15 patients (50%) had single acute cerebral infarcts and 15 patients had multiple acute cerebral infarcts. Among patients with multiple acute infarcts, unilateral, deep, chainlike border zone infarcts were the most common pattern (11 patients, 73%), and for single infarcts, penetrating artery infarcts were the most common (10 patients, 67%). Microembolic signals were detected in 10 patients (33%). The median number of microembolic signals per 30 minutes was 15 (range, 3-102). Microembolic signals were found in 9 patients with multiple infarcts and in 1 patient with a single infarct (p = 0.002, chi(2)). The number of microembolic signals predicted the number of acute infarcts on diffusion-weighted magnetic resonance imaging (linear regression, adjusted R(2) =0.475, p < 0.001). Common stroke mechanisms in patients with middle cerebral artery stenosis are the occlusion of a single penetrating artery to produce a small subcortical lacuna-like infarct and an artery-to-artery embolism with impaired clearance of emboli that produces multiple small cerebral infarcts, especially along the border zone region.     

Cerebral microbleeds and white matter changes in patients hospitalized with lacunar infarcts

Abstract. Microbleeds (MBs) detected by gradient-echo T2*-weighted MRI (GRE-T2*),white matter changes and lacunar infarcts may be regarded as manifestations of microangiopathy. The establishment of a quantitative relationship among them would further strengthen this hypothesis. We aimed to investigate the frequency and the number of MBs in patients hospitalized with lacunar infarcts and their quantitative relationship with the severity of white matter changes (WMC) and the number of old lacunar infarcts. We performed a hospital-based survey of patients with acute lacunar infarct. Eighty-two consecutive Chinese patients with acute lacunar infarcts on diffusion-weighted imaging were recruited in 2002. The number of MBs, number of old lacunar infarcts on T2-weighted imaging and the severity of WMC on MRI on admission were recorded. MBs were detected in 22 (27%) patients. The number of MBs ranged from 1 to 42 (mean 6.59, median 3). Advancing age and previous transient ischemic attacks or cerebrovascular accidents (TIA/CVA) were more common in patients with MBs than those without. There were significant correlations among the number of MBs, extent of WMC and number of lacunar infarcts: lacunar infarcts and MBs (r = 0.297, p = 0.007); lacunar infarct and WMC (r = 0.331, p = 0.002); WMC and MBs (r = 0.522, p < 0.0001). In conclusion, linear associations exist among MBs, WMC and lacunar infarcts. Our results suggest that all three may have a shared pathogenesis such as advanced microangiopathy.     

Silent MRI infarcts and the risk of future stroke: the cardiovascular health study

BACKGROUND: Silent infarcts are commonly discovered on cranial MRI in the elderly. OBJECTIVE: To examine the association between risk of stroke and presence of silent infarcts, alone and in combination with other stroke risk factors. METHODS: Participants (3,324) in the Cardiovascular Health Study (CHS) without a history of stroke underwent cranial MRI scans between 1992 and 1994. Silent infarcts were defined as focal lesions greater than 3 mm that were hyperintense on T2 images and, if subcortical, hypointense on T1 images. Incident strokes were identified and classified over an average follow-up of 4 years. The authors evaluated the risk of subsequent symptomatic stroke and how it was modified by other potential stroke risk factors among those with silent infarcts. RESULTS: Approximately 28% of CHS participants had evidence of silent infarcts (n = 923). The incidence of stroke was 18.7 per 1,000 person-years in those with silent infarcts (n = 67) compared with 9.5 per 1,000 person-years in the absence of silent infarcts. The adjusted relative risk of incident stroke increased with multiple (more than one) silent infarcts (hazard ratio 1.9 [1.2 to 2.8]). Higher values of diastolic and systolic blood pressure, common and internal carotid wall thickness, and the presence of atrial fibrillation were associated with an increased risk of strokes in those with silent infarcts (n = 53 strokes). CONCLUSION: The presence of silent cerebral infarcts on MRI is an independent predictor of the risk of symptomatic stroke over a 4-year follow- up in older individuals without a clinical history of stroke.     

Fast magnetic resonance diffusion-weighted imaging of acute human stroke.

Rapid MRI of the molecular diffusion of water demonstrated cerebral infarcts in 32 patients. We studied these patients at various times following the onset of ischemic symptoms and found that diffusion-weighted imaging revealed the infarcts sooner than conventional T2-weighted spin-echo imaging did; four hyperacute infarcts were shown only by diffusion-weighted imaging. Acute infarcts had lower apparent diffusion coefficients (ADCs) than noninfarcted regions did. This relative difference in ADC reached a nadir in the first 24 hours and rose progressively thereafter. Chronic infarcts showed a relative increase in diffusion and were readily distinguishable from acute infarcts. The technique takes less than 2 minutes to apply using a standard 1.5-tesla scanner in the clinical setting. Diffusion-weighted imaging has the potential to play a role in improving the early anatomic diagnosis of stroke and therefore in the development and implementation of early stroke interventions.     

Bilateral multiple border zone infarctions after massive bleeding: report of two cases]

We present two patients who developed bilateral border zone brain infarctions after massive bleeding. Patient 1 was a 46-year old woman who developed bilateral visual disturbance and left hand monoparesis after excessive menstruation with severe anemia. Diffusion-weighted MRI of brain showed multiple border zone infarcts bilaterally in cerebral and cerebellar hemispheres while brain MRA was normal. Patient 2 was a 67-year old man who developed disturbance of consciousness and right hemiplegia after upper gastrointestinal tract bleeding. Diffusion-weighted MRI of brain showed bilateral multiple border zone infarcts in cerebral hemispheres, although he had asymptomatic occlusion of the left internal carotid artery. The bilateral multiple border zone infarcts are one of the key findings suggesting the presence of anemic hypoxia as a result of global brain hypoperfusion caused by massive blood loss.