磁共振DWI及PWI在急性期脑梗死中的应用

目的 评价DWI及PWI在急性期脑梗死的应用价值.方法 35例急性期脑梗死病例行DWI、PWI检查,测量并计算ADC值、rCBV值、MTT值.结果 30例急性期脑梗死DWI上均为高信号,PWI上灌注异常(P＜0.05).13例超急性期脑梗死发现缺血半暗带.结论 DWI与PWI对急性脑梗死评价更全面、正确.     

磁共振灌注成像在胰腺癌中的应用现状研究

磁共振灌注加权成像是近年来随着磁共振快速成像序列的出现而发展起来的一项功能成像技术,能够直观的反映组织、器官的血流动力学和微循环灌注情况,是影像学从形态学到功能学发展的一种体现。胰腺癌是胰腺最常见的恶性肿瘤,其临床诊断及疗效评估主要依靠影像学检查方法。本文综述了MR灌注成像的原理、意义及其在胰腺癌的术前诊断、鉴别诊断及临床治疗中的应用现状。     

Local mild hypothermia with thrombolysis for acute ischemic stroke within a 6-h window

Objective

To determine the safety and efficacy of combined local mild hypothermia and IV rtPA in treating acute ischemic stroke (AIS) patients with MRI perfusion- and diffusion-weighted imaging (PWI/DWI) mismatch within a 6-h stroke window.

Methods

AIS patients within 6 h of a minimum 20% PWI/DWI MRI mismatch were randomly assigned to 3 groups: local mild hypothermia with IV rtPA (Group A); IV rtPA (Group B); or conventional anti-platelet aggregation (Group C). Mortality and National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Scale (mRS) score and Barthel Index (BI) were used in evaluation.

Results

There were significant differences in NIHSS 24 h after treatment among the three groups (P < 0.001). Based on mRS and BI, more patients in Groups A and B showed favorable outcomes than patients in Group C (P = 0.017 and P = 0.009, respectively); however, there were no significant efficacy differences between Groups A and B. The incidence of symptomatic ICH and the mortality rates within 90 days in the 3 groups were similar. In addition, there were no significant differences in NIHSS improvement at 24 h and favorable outcomes 90 days after IV rtPA treatment between patients within 3 h and 3–6 h from symptom onset.

Conclusions

There was no benefit of combined local hypothermia/IV rtPA treatment compared to IV rtPA alone. PWI/DWI mismatching on MRI can be a selection criteria for IV rtPA treatment within a 6-h window.     

磁共振灌注成像技术在运动性失语中的价值探讨

目的研究磁共振灌注成像对运动性失语脑激活图中肿瘤内及肿瘤周边激活区阳性率显示的价值。方法 17例肿瘤患者,语言磁共振任务完成后,加做PWI检查,并在Linux系统下做Bold激活区与PWI图像的融合。PWI图中白色血管若与红色的脑激活区重叠,则认为是假阳性结果;反之,则认为是与语言相关的激活区。结果17例病人中,Ⅱ级星形胶质细胞瘤7例,Ⅲ级星形胶质细胞瘤5例,胶母细胞瘤5例。在7例Ⅱ级星形胶质细胞瘤患者的图片命名任务激活图中,位于肿瘤内及肿瘤周边的激活区共计11处,其中BOLD激活信号与CBV图中的血管影重叠的共计3处,两者不重叠的共计8处,即假阳性率26%,阳性率74%;在5例Ⅲ级星形胶质细胞瘤患者中,位于肿瘤内及肿瘤周边的激活区共计14处,其中BOLD激活信号与CBV图中的血管影重叠的共计4处,两者不重叠的共计10处,即假阳性率31%,阳性率69%;在5例胶母细胞瘤的图片命名任务激活图中,位于肿瘤内及肿瘤周边的激活区共计18处,其中BOLD激活信号与CBV图中的血管影重叠的共计7处,两者不重叠的共计11处,即假阳性率39%,阳性率61%。结论 BOLD激活信号阳性率与肿瘤级别呈负相关,结合PWI图像是判断Bold信号真实性的较特异方法。     

肾脏MR扩散与灌注加权成像的原理及其应用

磁共振（MR）扩散加权成像和灌注加权成像的原理及其在肾脏方面的基础研究和临床应用。     

通过MRI平扫增强及灌注成像扫描对颅脑肿瘤占位效应的诊断及手术治疗效果探讨

目的探讨MRI平扫增强联合灌注成像扫描对颅脑肿瘤占位的诊断及手术治疗效果。方法选取2016年5月到2018年5月我院120例疑似诊断为颅脑肿瘤占位患者,使用自身对照法,所有患者均接受MRI平扫增强(FSE)和灌注成像扫描(PWI)检查,并随访手术以及病理检查,金标准采用术后病理标准。比较两组FSE、PWI分别单一诊断与FSE联合PWI诊断的准确率、灵敏度以及特异度。结果 FSE法诊断为颅脑肿瘤占位83例(6例由术后病例诊断为阴性),阴性37例(32例由术后病例诊断为阳性),即遗漏诊断32例,错误诊断6例,PWI诊断为颅脑肿瘤占位96例(5例由术后病例诊断为阴性),阴性24例(18例由术后病例诊断为阳性),即遗漏诊断18例,错误诊断5例,FSE法联合PWI法检查显示:诊断为颅脑肿瘤占位112例(5例由术后病例诊断为阴性),阴性8例(2例由术后病例诊断为阳性),即遗漏诊断2例,错误诊断5例,通过对比单一FSE法、PWI法以及FSE法联合PWI序列法的准确率、灵敏度和特异度结果表明:FSE、PWI法单一诊断及联合诊断的特异度无统计学意义(P>0.05);FSE法联合PWI法的准确率、灵敏度均高于单一FSE法、PWI法,差异具有统计学意义(P<0.05)。结论 FSE联合PWI法应用于颅脑肿瘤占位,可提高其诊断准确率和灵敏度,具有较高的临床应用价值,值得进一步推广使用。     

Multiple spin-echo spectroscopic imaging for rapid quantitative assessment of N-acetylaspartate and lactate in acute stroke.

Monitoring the signal levels of lactate (Lac) and N-acetylaspartate (NAA) by chemical shift imaging can provide additional knowledge about tissue damage in acute stroke. Despite the need for this metabolic information, spectroscopic imaging (SI) has not been used routinely for acute stroke patients, mainly due to the long acquisition time required. The presented data demonstrate that the application of a fast multiple spin-echo (MSE) SI sequence can reduce the measurement time to 6 min (four spin echoes per echo train, 32 x 32 matrix). Quantification of Lac and NAA in terms of absolute concentrations (i.e., mmol/l) can be achieved by means of the phantom replacement approach, with correction terms for the longitudinal and transversal relaxation adapted to the multiple spin-echo sequence. In this pilot study of 10 stroke patients (symptom onset < 24 hr), metabolite concentrations obtained from MSE-SI add important information regarding tissue viability that is not provided by other sequences (e.g., diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI)). Metabolic changes extended beyond the borders of the apparent diffusion coefficient (ADC) lesion in nine of the 10 patients, showing a rise in Lac concentrations up to 18 mmol/l, while NAA levels sometimes dropped below the detection level. Considerable differences among the patients in terms of the Lac concentrations and the size of the SI-ADC mismatch were observed.     

Characterization of gadolinium-based dynamic susceptibility contrast perfusion measurements in permanent and transient MCAO models with volumetric based validation by CASL

Perfusion imaging is crucial in imaging of ischemic stroke to determine ‘tissue at risk'' for infarction. In this study we compared the volumetric quantification of the perfusion deficit in two rat middle-cerebral-artery occlusion (MCAO) models using two gadolinium-based contrast agents (P1152 (Guerbet) and Magnevist (Bayer-Schering, Pittsburgh, PA, USA)) as compared with our well established continuous arterial spin labeling (CASL) perfusion imaging technique. Animals underwent either permanent MCAO or transient MCAO with 80-min reperfusion. Imaging was performed at four different time points after MCAO. A region-of-interest (ROI) analysis of the subregions of the ischemic zone (core, penumbra, transient reversal (TR), and sustained reversal (SR)) using P1152 showed significant reduction in blood flow in the core and TR subregions relative to the penumbral and SR subregions while occluded. After reperfusion, a significant increase in blood flow was recorded at all time points after reperfusion in all regions except TR. From the ROI analysis the threshold for the penumbra was determined to be −62±11% and this value was subsequently used for quantification of the volumetric deficit. The ischemic volume as defined by dynamic susceptibility contrast (DSC), was only statistically different from the CASL-derived ischemic volume when using Magnevist at post-reperfusion time points.     

Correlation of MR perfusion-weighted imaging of prostatic cancer with tumor angiogenesis

Objective:MR perfusion-weighted imaging(PWI)has been widely applied in the research of cerebral tumor,benign and malignant musculoskeletal neoplasms and so on.The aim of this study is to explore the application of MR perfusion-weighted imaging in prostatic cancer(Pca),and evaluate the correlation of PWI features with vascular endothelial growth factor (VEGF)and microvessel density(MVD).Methods:Twenty-eight consecutive patients who were diagnosed clinically as prostatic cancer and thirty healthy volunteers were examined by PWI.MVD and VEGF were stained with immunohistochemical methods.Some parameters of PWI,including the steepest slope of signal intensity-time curve(SSmax)and the change in relaxation rate(△R2*peak)at lesions,were analyzed.Correlation analysis was used to determine the relationship between the results of PWI and that of immunohistochemistry.Results:(1)In the healthy volunteers.the steepest slope of signal intensity-time curve(SSmax)and △R2*peak of perfusion curve were;0.430±0.011,2.01±0.7 respectively;however,in the prostatic caucer,they were 57.8±5.0,3.0±0.6 respectively;with significant difference(t=4.11,3.28,P＜0.01).(2)The VEGF and MVD expression of twenty-eight Pca patients were significantly higher.Conclusion:On MR perfusion.weighted imaging,SSmax and △R2*peak Can reflect MVD and VEGF expression levels in prostatic cancer.suggesting information on tumor angiogenesis.Thus they are beneficial to the diagnosis and treatment of prostatic cancer.