Diffusion-weighted magnetic resonance imaging is useful for assessing inflammatory myopathies

Introduction: Short tau inversion recovery (STIR) sequences in whole-body MRI are usually used for detecting muscle edema (ME) in inflammatory myopathies. We evaluated b-value 800 diffusion-weighted imaging (b800 DWI).Methods: Two radiologists independently and a consensus reader retrospectively reexamined 60 patients with inflammatory myopathies and 15 controls. For each participant, 78 muscles were analyzed with 3 sets of imaging acquisitions: T1-weighted (T1) turbo spin echo and STIR; T1 and DWI; and T1, STIR and DWI. Mean edema per patient was compared between sequences. Agreement was evaluated. Results: Diffusion-weighted imaging detected more ME compared with STIR (P < 0.001). Agreement between readers was better with both sequences (k = 0.94) than with b800 DWI (k = 0.89) or STIR (k = 0.84) alone. Discussion: Diffusion-weighted imaging is a valuable add-on for the study of inflammatory myopathies. Muscle Nerve 59:555–555, 2019     

Feasibility of establishing cerebral ischemia models by using aerocyst-blocking bilateral ascending pharyngeal artery of piglets Imaging assessment

BACKGROUND: The cerebral ischemia and ischemia/reperfusion animal models are used to simulate the human cerebrovascular diseases is one of the popular topics of neurological science recently. To study the pathophysiology, pathogenesis, prophylaxis and treatment of ischemic cerebrovascular diseases and to establish the ideal animal model that is the most similar to the human cerebral ischemia, are the topics that the people generally cared about. OBJECTIVE: To evaluate the effects of aerocyst-blocking bilateral ascending pharyngeal artery on the establishment of cerebral ischemia models by using digital subtraction angiography (DSA), magnetic resonance diffusion-weighted imaging (DWI) and magnetic resonance perfusion-weighted imaging (PWI). DESIGN: Repetitive measure animal experiment. SETTING: Zhongshan Hospital Affiliated to Dalian University. MATERIALS: The experiment was carried out in the Animal Laboratory (Provincial Laboratory), Zhongshan Hospital of Dalian Univeristy from January to May 2006. A total of 14 domestic piglets, of 6 months old, weighing 12–15 kg, of either gender, were selected from Animal Experimental Center, Dalian University. Multistar T.O.P digital subtraction angiography machine was provided by Siemens Company, German. METHODS: Aerocyst-blocking bilateral ascending pharyngeal artery was used to establish cerebral ischemia models. And then, Multistar T.O.P. DSA was used for imaging of cerebral vessels before blocking, during blocking and at 0.5 and 2 hours after ischemia perfusion. GE Signa 1.5 T supraconduction magnetic resonance imaging was used for DWI examination; in addition, PWI was used based on focal sites and areas. Otherwise, magnetic resonance imaging (MRI) was used to detect signal changes of T1WI and T2WI in ischemic areas. MAIN OUTCOME MEASURES: Analytic results of DSA, DWI, PWI and MRI. RESULTS: All 14 experimental piglets were involved in the final analysis. ① DSA: The blood flow of bilateral ascending pharyngeal arteries and its branch were blocked at blocking phase, which restored 0.5 and 2 hours after reperfusion. ② DWI and PWI: There were no observable abnormalities in PWI and DWI at pre-blocking. Abnormal increased signals were found on both DWI and PWI at during and post-blocking. There were reduction in ADC and rCBF and delay in rTTP at all time points except pre-blocking. ③ MRI: There were no abnormal signals observable at any time of pre- and post-blocking in T1WI and T2WI. CONCLUSION: It is feasible to establish this kind of animal experimental models, and it can simulate the ischemic state; meanwhile, the existence and extent can be showed directly by DSA, DWI, and PWI.     

DWI及SWI序列对弥漫性轴索损伤的诊断价值

目的探讨弥散加权（DWI）和磁敏感加权（SWI）序列在脑弥漫性轴索损伤（DAI）中的诊断价值。方法回顾性分析17例经临床和影像证实的急性DAI患者的MRI资料,包括常规T1WI、T2WI、液体衰减反转恢复（FLAIR）序列以及DWI和SWI序列,分别比较各序列对DAI非出血性和出血性病灶的检出数目,并分析其分布特点和信号特征。结果DAI病灶主要分布在白质、皮髓交界区、基底节、胼胝体、脑干及小脑等区域。DWI对非出血性DAI病灶的检出率最高,与其它序列的差异有统计学意义（P〈0．05）。而SWI对出血性DAI病灶的检出率最高,与其它序列的差异也均有统计学意义（P〈0．05）。结论DWI和SWI序列联合应用大大提高DAI病灶的检出率,为临床早期诊断提供更加可靠的影像学依据,应作为MRI检查DAI的常规和首选序列。     

常规磁共振与弥散性磁共振检查对多发性硬化的诊断价值

目的：比较常规磁共振（MRI）检查和弥散磁共振（MR－DWI）检查技术对判定脑内多发性硬化（MS）的价值。方法：经临床表现与实验室检查明确MS的病例有26例行MRI扫描,T1,T2加权及质子密度像,MRDWI用平面回波成像技术,将两者所见进行比较,同时使用软件进行MRI－DWI的弥散系数（apparent diffusion coefficient ADC)值及影像分析。结果：MRI扫描在T2W1像上可见明确T2高信号及高质子密度者占25／26,脑室旁白质为主占病灶总数的83％,T1W1表现为低信号者占16／26,可见急性期发作的病灶均有不同程度的强化,96．5％是多病灶的,MR－DWI示发病早期12例可见高信号,ADC值高于脑缺血但低于脑肿瘤,结论：使用多种MRI技术可以明确判定脑内白质区的MS病灶是急性期还是非急性期。同时应用MR－DWI,ADC图检查对判断病灶是脑缺血性病灶或肿瘤有较大帮助,是诊断MS等脱髓鞘疾病的有效影像学方法。     

Diagnostic benefit of high b-value computed diffusion-weighted imaging in acute brainstem infarction

Background and purposeDiffusion-weighted imaging (DWI) is a cornerstone in diagnostic of ischemic stroke. The aim of this study was to investigate the usefulness of high-b-value computed DWI (c-DWI) in comparison to standard DWI in patients with acute brainstem infarction.Materials and methods56 patients with acute brainstem infarction were retrospectively analysed by two readers. DWI was obtained with the b-values 0, 500 and 1000 s/mm² on either a 1.5 or 3 T magnetic resonance imaging (MRI) scanner. c-DWI was calculated with a monoexponential model with high b-values 2000, 3000, 4000 and 5000 s/mm². All c-DWI series with high-b-values were compared to the standard DWI sequence at b-value of 1000 s/mm² in terms of image artifacts, lesion extent and contrast.ResultsThere was no statistically significant difference between 1.5 and 3 T MRI regarding the measured ischemic lesion size. There were no statistically significant differences between the ischemic lesion sizes on DWI at b-values of 1000 s/mm² and on c-DWI at higher b-values. Overall, the contrast between the lesion and the surrounding normal areas improved with increasing b-value on the isotropic DWIs: maximum at b = 5000, followed by that at b 2000 and b 1000 s/mm², in order. The best relation between artifacts and lesion contrast was identified for b 2000 s/mm².ConclusionHigh b-value DWI derived from c-DWI has a higher visibility for ischemic brainstem lesions compared to standard DWI without additional time cost. The b-2000 image is recommended to use in clinical routine, higher b-value images lead to more imaging artifacts, which might result in misdiagnosis.     

Patterns of diffusion‐weighted magnetic resonance imaging associated with etiology improve the accuracy of prognosis after transient ischaemic attack

Objective: Diffusion‐weighted magnetic resonance imaging (DWI) is a sensitive diagnostic tool for detecting acute ischaemic lesions in patients with transient ischaemic attacks (TIAs). The additional predictive value of DWI lesion patterns is not well known. Methods: Two hundred and fifty‐four consecutive patients with TIA underwent DWI within 7 days of symptom onset. The presence and pattern of acute ischaemic lesions were related to clinical features, etiology, and stroke recurrence at seven‐ and 90‐day follow‐up. Results: Diffusion‐weighted images abnormalities were identified in 117 (46.1%) patients. The distribution of DWI lesions was cortical, 31; subcortical, 32; scattered lesions in one arterial territory (SPOT) 42; and in multiple areas, 12. SPOT were significantly associated with motor weakness, large‐artery atherosclerosis (LAA), and the cardioembolic subtype of TIA. Single cortical lesions were also associated with cardioembolism, whereas subcortical acute lesions were associated with recurrent episodes, dysarthria, and motor weakness. During follow‐up, seven patients had a stroke within 7 days (2.8%, 95% CI 2.9–6.4%), and 12 had a stroke within 3 months (4.7%%, 95% CI 2.9–6.4%). In the Cox logistic regression model, the combination of LAA and positive DWI remained as independent predictors of stroke recurrence at 90‐day follow‐up (HR 5.78, 95 CI 1.74–19.21, P = 0.004). Conclusion: According to our results, MRI, including DWI, should be considered a preferred diagnostic test when investigating patients with potential TIAs. The combination of neuroimaging and vascular information could improve prognostic accuracy in patients with TIA.     

磁共振弥散加权成像对急性脑梗死的诊断价值

目的:探讨磁共振弥散加权成像(DWI)对急性脑梗死的诊断价值.方法:对26例急性脑梗死患者(发病＜6h4例、6-24h14例、1-7d8例)进行常规MRI(T,flair,T2WI,T2flair)检查以及DWI检查,并由计算机算出表观扩散系数(ADC)图.结果:发病＜6h的4例患者常规MRI未见异常;DWI均出现高信号;ADC均为低信号.发病6h-7d的22例患者MRI T2 WI均为高/稍高信号,T1 flair均为低/稍低信号;DWI均为高信号;ADC均为低信号.结论:DWI能在超早期显示急性脑梗死的病灶,对急性脑梗死有着非常重要的诊断价值.     

Diffusion-Weighted Magnetic Resonance Imaging in the Diagnosis of Cerebral Venous Thrombosis : A Meta-Analysis

ObjectiveA role of diffusion-weighted imaging (DWI) in the diagnosis of cerebral venous thrombosis (CVT) is not wellunderstood. This study evaluates the effectiveness of DWI in the diagnosis of CVT. MethodsLiterature search was conducted in electronic databases for the identification of studies which reported the outcomes of patients subjected to DWI for CVT diagnosis. Random-effects meta-analyses were performed to achieve overall estimates of important diagnostic efficiency indices including hyperintense signal rate, the sensitivity and specificity of DWI in diagnosing CVT, and the apparent diffusion coefficient (ADC) of DWI signal areas and surrounding tissue. ResultsNineteen studies (443 patients with 856 CVTs; age 40 years [95% confidence interval (CI), 33 to 43]; 28% males [95% CI, 18 to 38]; symptom onset to DWI time 4.6 days [95% CI, 2.3 to 6.9]) were included. Hyperintense signals on DWI were detected in 40% (95% CI, 26 to 55) of the cases. The sensitivity of DWI for detecting CVT was 22% (95% CI, 11 to 34) but specificity was 98% (95% CI, 95 to 100). ADC values were quite heterogenous in DWI signal areas. However, generally the ADC values were lower in DWI signal areas than in surrounding normal areas (mean difference−0.33×10^-3 mm²/s [95% CI, −0.44 to −0.23]; p<0.00001). ConclusionDWI has a low sensitivity in detecting CVT and thus has a high risk of missing many CVT cases. However, because of its high specificity, it may have supporting and exploratory roles in CVT diagnosis.     

Optimizing the risk estimation after a transient ischaemic attack – the ABCDE⊕ score

Background and purpose: The risk of stroke after a transient ischaemic attack (TIA) can be predicted by scores incorporating age, blood pressure, clinical features, duration (ABCD‐score), and diabetes (ABCD2‐score). However, some patients have strokes despite a low predicted risk according to these scores. We designed the ABCDE+ score by adding the variables ‘etiology’ and ischaemic lesion visible on diffusion‐weighted imaging (DWI) –‘DWI‐positivity’– to the ABCD‐score. We hypothesized that this refinement increases the predictability of recurrent ischaemic events. Methods: We performed a prospective cohort study amongst all consecutive TIA patients in a university hospital emergency department. Area under the computed receiver‐operating curves (AUCs) were used to compare the predictive values of the scores with regard to the outcome stroke or recurrent TIA within 90 days. Results: Amongst 248 patients, 33 (13.3%, 95%‐CI 9.3–18.2%) had a stroke (n = 13) or a recurrent TIA (n = 20). Patients with recurrent ischaemic events more often had large‐artery atherosclerosis as the cause for TIA (46% vs. 14%, P < 0.001) and positive DWI (61% vs. 35%; P = 0.01) compared with patients without recurrent events. Patients with and those without events did not differ with regard to age, clinical symptoms, duration, blood pressure, risk factors, and stroke preventive treatment. The comparison of AUCs [95%CI] showed superiority of the ABCDE+ score (0.67[0.55–0.75]) compared to the ABCD²‐score (0.48[0.37–0.58]; P = 0.04) and a trend toward superiority compared to the ABCD‐score (0.50[0.40–0.61]; P = 0.07). Conclusion: In TIA patients, the addition of the variables ‘etiology’ and ‘DWI‐positivity’ to the ABCD‐score seems to enhance the predictability of subsequent cerebral ischaemic events.     

DWI在超急性期脑出血诊断中的临床应用研究

目的:评价磁共振弥散加权成像(DWI)对超急性期脑出血诊断的准确性。方法:对卒中样起病,发病时间在6h以内,因怀疑缺血性脑血管病急诊行头部MRI检查,按文献Schellinger描述的超急性期脑出血MRI特征初步诊断脑出血,并随即行头部CT证实。10例患者均进行DWI、ADC图和常规MRI扫描,测算不同序列血肿体积,并与头部CT进行比较。结果:10例MRI初步诊断脑出血的患者均经CT确诊为脑出血,敏感性和特异性均为100%,超急性期脑出血血肿DWI的特征性表现为高低混杂信号,磁共振T2WI?DWI和ADC图显示血肿体积均大于CT,差异有显著性(P<0.01);而T1WI与CT的血肿体积无显著差异(P>0.05)。结论:DWI对超急性期脑出血诊断准确,有重要临床应用价值。     

脑梗死磁共振弥散加权成像信号改变和近似弥散系数的时间演变规律

目的 :确定脑梗死磁共振弥散加权成像 (DWI)信号改变和近似弥散系数 (ADC)的时间演变规律。方法 :分析 10 1例脑梗死患者的 13 5次DWI资料。结果 :超急性、急性和亚急性期脑梗死DWI为高信号 ,慢性早期多数病灶仍为高信号 ,慢性晚期绝大部分病灶为等或低信号。超急性期、急性期和亚急性期脑梗死ADC下降 ,慢性早期多数病灶接近或高于正常 ,慢性晚期明显升高。结论 :脑梗死的DWI信号和ADC变化具有特征性的时间演变规律 ,结合常规MRI ,DWI可以推断脑梗死所处的时期     

Hyperacute intraventricular hemorrhage: detection and characterization, a comparison between 5 MRI sequences

We aimed to evaluate the diagnostic accuracy of MRI for detecting early intraventricular hemorrhage (IVH) (within 6 hours after hemorrhage and to describe the MR features that allow diagnosis. For this purpose, MR data of 22 patients with hyperacute intraparenchymal hemorrhage were independently rated as negative or positive for IVH by two observers, in a blind, retrospective study taking computed tomography (CT) as providing the correct diagnosis of IVH. Sensitivity, specificity, intra- and interobserver agreement were assessed. On FSE-FLAIR, EPI-GRE-T2* and DWI images, all cases of IVH were correctly rated (sensitivity of 100%). For b0 EPI images, obtained from diffusion-weighted echo planar sequences, one case of IVH was missed by one reader (sensitivity of 88%). For T1 images, one patient was incorrectly rated negative for IVH by the two readers (sensitivity of 90%). Three forms of IVH were described, including clotted hematoma, layered hemorrhage and red blood cell deposit. When CT images were obtained within a time span of less than 3 hours after MRI, volume was assessed. Volume of hemorrhage on CT correlated best with DWI images but was underestimated on EPI-GRE T2* images.     

Sporadic MM2‐thalamic + cortical Creutzfeldt‐Jakob disease: Utility of diffusion tensor imaging in the detection of cortical involvement in vivo

In sporadic Creutzfeldt‐Jakob disease (sCJD), high signal intensity in fluid attenuated inversion recovery (FLAIR) and diffusion‐weighted imaging (DWI) sequences in striatum and/or cortical regions of the brain are present in about 83% of cases, reflecting tissue damage, such as spongiform change and abnormal prion protein deposits. Novel diffusion sequences of MRI might improve the detection of CJD characteristic changes in the subset of patients in whom these alterations are absent or less evident. We report a neuropathologically confirmed case of the rare MM2 T + C subtype of sCJD, with mixed clinical and neuropathological features of MM2 thalamic and MM2 cortical subtypes, in whom the use of diffusion tensor imaging helped to identify cortical hyperintensities that could be easily overlooked with conventional DWI.     

Diffusion weighted MR imaging on a low-field open magnet. Comparison with findings at 1.5T in 18 patients with cerebral ischemia

Diffusion-weighted MR imaging (DWI) is particularly sensitive for the detection of acute stoke. Until recently, DWI was performed with EPI technology. We compared 18 patients with clinical suspicion of acute stroke on a standard 1.5T unit and an open low-field MR scanner. Eighteen patients with 20 lesions of acute stroke were studied retrospectively with DWI and ADC mapping on both systems. The technique used was a rotating fast-spin echo T2 at low-field and an EPI sequence at 1.5T. Both examinations were performed within 24 hours and analyzed by two neuroradiologists. We obtained the same results on DWI sequences on both systems, regarding high intensity lesions on DWI. Interpretation of the ADC maps proved to be difficult on low-field MR near the lateral ventricles (3/18). We experienced the same difficulty of interpretation at low and high field in the cerebellum, in the temporal fossa and in cortex situated near bone, due to susceptibility artifacts. Chronic lesions were better visualized at low than at high field. In our opinion, DWI on a low-field open MR scanner is a good technique to evaluate subacute stroke and was as reliable as when performed on a 1.5T MR system.     

Distortion correction for diffusion‐weighted MRI tractography and fMRI in the temporal lobes

Single shot echo‐planar imaging (EPI) sequences are currently the most commonly used sequences for diffusion‐weighted imaging (DWI) and functional magnetic resonance imaging (fMRI) as they allow relatively high signal to noise with rapid acquisition time. A major drawback of EPI is the substantial geometric distortion and signal loss that can occur due to magnetic field inhomogeneities close to air‐tissue boundaries. If DWI‐based tractography and fMRI are to be applied to these regions, then the distortions must be accurately corrected to achieve meaningful results. We describe robust acquisition and processing methods for correcting such distortions in spin echo (SE) EPI using a variant of the reversed direction k space traversal method with a number of novel additions. We demonstrate that dual direction k space traversal with maintained diffusion‐encoding gradient strength and direction results in correction of the great majority of eddy current‐associated distortions in DWI, in addition to those created by variations in magnetic susceptibility. We also provide examples to demonstrate that the presence of severe distortions cannot be ignored if meaningful tractography results are desired. The distortion correction routine was applied to SE‐EPI fMRI acquisitions and allowed detection of activation in the temporal lobe that had been previously found using PET but not conventional fMRI. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.     

磁共振弥散加权成像评价机械性取栓的实验研究

目的 应用磁共振弥散加权成像(DWI)技术评价机械性取栓治疗栓塞性脑梗死的疗效。 方法 40只新西兰兔颈内动脉注入血凝块栓子制备急性栓塞性脑梗死模型后按随机数字表法分为非治疗组（不做任何治疗）、6h机械取栓组、8h机械取栓组、12h机械取栓组（分别于制模成功后6h、8h、12h在DSA导引下经股动脉插管机械取栓）,每组10只,各组分别在6h、8h、12h、24h行DWI并计算各时段表观弥散系数(ADC)和梗死体积。 结果 兔脑梗死超急性期（6 h内）均在DWI上显示缺血区,表现为高信号,在T1WI、T2WI上表现为正常信号;T1WI、T2WI及DWI对急性期(24h内)脑梗死的检出率差异有统计学意义(P＜0.05)。非治疗组、12h机械取栓组在急性期内ADC值逐渐降低,梗死体积逐渐扩大,而6h、8h机械取栓组在急性期取栓后ADC值逐渐上升,梗死体积缩小。梗死后24h,与非治疗组和12h机械取栓组比较,6h和8h机械取栓组ADC值较高,梗死体积较低,差异均有统计学意义(P＜0.05)。 结论 栓塞性脑梗死早期机械性取栓效果显著,DWI是动态观察急性脑梗死治疗效果的敏感影像学手段。     

Is there a benefit of mechanical thrombectomy in patients with large stroke (DWI‐ASPECTS ≤ 5)?

Background and purpose

Whether to withhold mechanical thrombectomy when the diffusion‐weighted imaging (DWI) lesion exceeds a given volume is undetermined. Our aim was to identify markers that will help to select patients with large DWI lesions [DWI?Alberta Stroke Program Early Computed Tomography Score (DWI‐ASPECTS) ≤ 5] that may benefit from thrombectomy.

Methods

From May 2010 to November 2016, 82 acute ischaemic stroke patients with DWI‐ASPECTS ≤5 (43 men, 64.6 ± 14.4 years, National Institutes of Health Stroke Scale 18.4 ± 5.4) treated with state‐of‐the‐art mechanical thrombectomy were studied. Thrombectomy alone was performed in 28 (34%) and bridging therapy in 54 (66%) patients. Recanalization was defined as a thrombolysis in cerebral infarction score 2B‐3 and significant hemorrhagic transformation as parenchymal haematoma type 2 (European Cooperative Acute Stroke Study 3 classification). Pretreatment variables were compared between patients with a good (modified Rankin Scale 0?2) and a poor (modified Rankin Scale 3?6) neurological outcome at 3 months.

Results

Overall, 28 patients (34%) achieved good neurological outcome at 3 months. Recanalizers were significantly more likely to achieve good outcome (61% vs. 7.3%, P < 0.0001), had lower mortality (24% vs. 49%, P = 0.03) and similar rates of parenchymal haematoma type 2 (9.8% vs. 7.3%, P = 1) compared to non‐recanalizers. Regression modelling identified DWI‐ASPECTS >2 [odds ratio (OR) 6.93; 95% confidence interval (CI) 1.05–45.76, P = 0.04), glycaemia ≤6.8 mmol/l (OR 4.05; 95% CI 1.09–15.0, P = 0.03) and thrombolysis (OR 3.67; 95% CI 1.04–12.9, P = 0.04) as independent predictors of good neurological outcome.

Conclusions

In patients with DWI‐ASPECTS ≤5, two‐thirds of patients experienced good neurological outcome when recanalized by state‐of‐the‐art thrombectomy, whilst only one in 14 non‐recanalizers achieved similar outcomes. Pretreatment markers of good neurological outcomes were DWI‐ASPECTS >2, intravenous thrombolysis and glycaemia ≤6.8 mmol/l.     

核磁共振脑灌注成像及DWI联合应用在诊断早期脑梗死缺血半暗带中的临床价值

目的 探讨核磁共振脑部灌注加权成像(PWI)及脑部弥散加权成像(DWI)联合应用在诊断早期脑梗死缺血半暗带中的临床价值。方法 本研究中的受试对象均来自2016年1月-2017年4月来本院就诊的脑梗死患者,选出符合纳入标准的100例作为研究对象,并根据脑梗死发生时间分成超急性期、急性期、亚急性期和慢性期,分别观察PWI和DWI表现,以表观弥散系数(ADC)为DWI的检测评价指标,以局部脑血容量(rCBV)、局部脑血流量(rCBF)、平均通过时间(MTT)和达峰时间(TTP)为PWI的检测评价指标,并比较不同时期脑梗死的PWI和DWI表现。结果 随着脑梗死患者发病时间的延长,T₂WI显示信号随之增高,DWI信号随之降低,ADC信号随之增高。随着梗死时间延长,梗死区ADC值随之增加,健侧对应区随着梗死时间的变化,ADC值无明显变化; 在每个不同分期中健侧对应区的ADC值均高于梗死区(P均<0.05); 超急性期rCBV和rCBF值均为降低信号,MTT和TTP均为升高信号; 急性期rCBV、rCBF、MTT和TTP值在三种信号上均有表现,但rCBV和rCBF值均以降低信号为主,MTT和TTP均以升高信号为主; 亚急性期中rCBV和rCBF为正常和降低信号,其中以正常信号为主,MTT和TTP均为降低和升高信号,并以升高信号为主; 慢性期rCBV和rCBF均表现为降低信号,MTT和TTP均为降低和升高信号,并以降低信号为主; 超急性期DWIPWI均有表现,并以DWIPWI均有表现,并以DWIPWI为主; 亚急性期DWI=PWI和DWI>PWI均有表现,并以DWI=PWI为主; 慢性期均为DWI=PWI。结论 PWI联合DWI对脑梗死早期的诊断价值较高,PWI对缺血半暗带有较好的诊断,其与DWI相结合可更准确地判定缺血半暗带。     

Usefulness of MRA‐DWI mismatch in neuroendovascular therapy for acute cerebral infarction

Background: This study evaluated the usefulness of MR angiography (MRA)–diffusion‐weighted imaging (DWI) mismatch in neuroendovascular therapy over 3 h after onset of acute cerebral infarction. Methods: The subjects were 14 cases (age, 73 ± 8.4 years) who had an anterior circulation deficit on DWI/MRA on arrival and underwent neuroendovascular therapy over 3 h after onset. MRA‐DWI mismatch (MDM) (+) was defined as ‘major artery lesion (+) and diffusion‐weighted image‐Alberta Stroke Program Early CT Score (DWI‐ASPECTS) ≥6’; MDM (?) was defined as ‘major artery lesion (+) and DWI‐ASPECTS <6’. Results: Reperfusion was achieved in nine of 14 patients (64%) undergoing neuroendovascular therapy. Within the reperfusion group, in the five MDM (+) patients and the four MDM (?) patients, the outcome was a favorable clinical response in the MDM (+) group. The modified Rankin Scale (mRS) scores after 90 days were 0–2 in 3 (60%) and 3–6 in 2 (40%) of the MDM (+) group patients and 0–2 in 0 (0%) and 3–6 in 4 (100%) of the MDM (?) group patients. In the MDM (+) group, a good outcome was achieved. However, the number of cases was small, so this was not a significant difference. Within the non‐reperfusion group, in the three MDM (+) patients and the two MDM (?) patients, the mRS scores after 90 days were 0–2 in 1 (33%) and 3–6 in 2 (67%) of the MDM (+) group patients and 0–2 in 0 (0%) and 3–6 in 2 (100%) of the MDM (?) group patients. In both groups, the outcome was poor. Conclusions: With neuroendovascular therapy, a good outcome with reperfusion was achieved in the MDM (+) group compared to the MDM (?) group. This suggests that the presence or absence of MDM may be useful in determining prognosis after reperfusion.     

磁共振弥散成像在超急性缺血性脑梗死诊断中的研究

目的评价磁共振扩散加权成像（DWI）和表观扩散系数（ADC）图对超急性期脑梗死的诊断价值。方法对17例以卒中样发病6h以内、临床怀疑脑梗死的患者进行单次激发平面回波DWI和常规T2WI扫描,测定梗死灶和对侧相应部位正常脑组织的ADC值。结果DWI上表现为高信号,ADC图上表现为低信号,病灶ADC值较对侧相应区域明显下降者,诊断为脑梗死阳性,共15例,其最终临床诊断均为超急性脑梗死;阴性2例,其最终临床诊断均为短暂性脑缺血发作。DWI和ADC图诊断超急性期脑梗死的敏感性和特异性均为100％,比常规T。wI有更高的敏感性与特异性。结论DWI和ADC图对超急性期脑梗死的诊断中发挥重要作用。