磁共振扩散加权成像对急性腔隙性脑梗死的诊断价值

目的 :探讨急性腔隙性脑梗死患者的脑部磁共振扩散加权成像 (MRDWI)表现及其ADC值变化。方法 :搜集急性脑梗死病例 5 4例 ,根据MRI显示病灶的位置、形态和最大直径 ,分为急性腔隙性脑梗死组 ( 3 9例 )和急性大面积脑梗死组 ( 15例 )。选正常对照组 5例。结果 :3 9例急性腔隙性脑梗死病例均有不同程度MRDWI表现 ;其ADC值与急性大面积脑梗死组之间差异无显著性意义。结论 :MRDWI对急性腔隙性脑梗死的诊断具有很好的敏感性和特异性 ,结合ADC图和ADC值则可作出更准确的诊断     

电针对急性脑梗死的作用机制研究——对家兔脑动态CT时间-密度曲线的影响

目的:通过家兔颅脑动态CT时间-密度曲线分析,了解针刺后急性脑梗死家兔血脑屏障的改变,进一步探讨针灸治疗急性期脑梗死的机制。方法:采用家兔自体血栓栓塞,建立急性脑梗死家兔模型,电针刺激督脉经穴“百会”、“水沟”治疗,观察电针对急性脑梗死家兔脑组织血管内血流灌注和血管内血流充盈时间的影响。结果:电针能明显增加缺血区脑组织的血灌流量,降低缺血区血管内血流充盈时间。电针刺激后各组指标与模型组比较有显著性差异(P<0.01)。结论:电针对急性脑梗死家兔血脑屏障具有明显的保护和修复作用,其作用机制可能与针刺能有效改善脑部血灌流量、改变了脑组织缺血缺氧的状况、减少脑梗死发作后引起的脑水肿、从而减少对血脑屏障的破坏作用有关。     

急性脑梗塞磁共振弥散加权成像的演变特征

目的：研究临床急性脑梗塞病变在弥散加权（DW）MRI上的表现规律。材料和方法：用单次激发平面回波弥散加权MRI和MRI其他技术对47例脑梗塞患者和14例非脑梗塞患者进行了对比研究。分别测量梗塞灶ACD图、DWI和T2WI的信号强度，绘出时间-信号强度图。分别在DWI和T2WI上测量梗塞面积．比较两者的关系。结果：急性脑梗塞发病后局部ACD逐渐降低．至12h达到峰值．以后逐渐升高。弥散加权MRI对急性脑梗塞病变非常敏感和特异，发病3h内T2WI为阴性，DW－MRI全部显示了梗塞灶；发病24h内T2WI所显示的梗塞灶面积明显小于DWI。发病7天内梗塞灶在DWI上与正常脑信号比均＞2．0．非脑梗塞病变均＜2．0。结论：急性脑梗塞病变在DW．MRI上有特征性演变规律，DW．MRI能快速、敏感、准确地诊断急性脑梗塞     

Diffusion and magnetization transfer MRI of brain infarct, infection, and tumor in children

The purpose of this study was to determine the efficacy of diffusion-weighted imaging (DWI) and magnetization transfer imaging (MTI) in the differential diagnosis of brain infarct, infection, hamartoma, and tumor in 106 children. The apparent diffusion coefficients (ADCs) and magnetization transfer ratios (MTRs) of the lesions were compared using nonparametric tests. There was an inverse relationship between ADC and MTR in subacute/chronic infarct, infection, hamartoma, arachnoid cyst, and tumor relative to normal brain parenchyma. Both ADC and MTR were reduced in acute infarct. DWI and MTI had a complementary role in the differential diagnosis of acute infarct from infection with lower MTR, from hamartoma with higher ADC, and from low-grade gliomas and benign tumors that had higher ADCs and lower MTRs. ADCs increased and MTRs decreased with the duration of infarct and lower tumor grade.     

磁共振弥散加权成像在脑病变诊断中的应用价值

目的 评价磁共振弥散加权成像（DWI）在脑部病变诊断中的应用价值。材料与方法 对110例不同脑部病变（包括脑梗塞、脑出血、脑肿瘤、脑白质病变）的DWI图像以及同一病变在不同扫描序列之间进行比较分析。结果 DWI对急性、超急性脑梗塞高度敏感（达100％）,对急性出血性脑梗塞也很敏感,对脑肿瘤的敏感性（75％）低于T2／Flair(92％）,对脑白质病的敏感性低于T2／Flair,但可显示部分多发性化的活动病灶,对急性脑出血敏感性较差。结论 DWI能诊断常规MR序列不能显示的超急性期和急性期梗塞,对急性出血性脑梗塞的诊断也很有价值。能区别急性期和慢性期脑梗塞。还有助于脑肿瘤、脑白质病变的和鉴别诊断。     

介入治疗急性心肌梗死术中并发症的观察与护理

目的阐述临床护理工作在急性心肌梗死病人介入治疗中的重要性.方法22例急性心肌梗死病人在介入治疗术中发生的32例次并发症,诸如,低血压、心律失常、心绞痛,造影剂不良反应、以及速走神经反射等均在严密的临床观察与精心的护理下,得到应急处置.结果22例急性心肌梗死病人在介入治疗术中由于得到精心观察与护理,有效地控制了并发症的持续存在,手术成功率达100%.结论护理工作对于急性心肌梗死病人获得理想的介入治疗效果起着保证作用.     

Detection of acute cerebral infarction by dual echo subtraction technique in MR imaging

The purpose of this study was to develop an image enhancement technique to detect acute cerebral infarct regions in brain MR images. Transverse relaxation times for abnormal changes tend to be longer than those for normal tissues. In order to obtain MR images with two different echo times, we employed the fast spin echo sequence. We then employed the image subtraction technique using two T(2)-weighted images to enhance acute cerebral infarct regions. As a result, the areas of acute cerebral infarct regions were enhanced as regions of higher signal than normal regions of brain tissue. Further, high signal areas in dual echo subtraction images corresponded to cerebral infarct regions of high signal areas in diffusion weighted images (DWI). We found that the image subtraction technique is useful to enhance very subtle regions of acute cerebral infarction in MR images. Because we employ the difference between transverse relaxation times for normal and abnormal tissues, which does not depend on the strength of the magnetic field, the dual echo subtraction method can be used in many hospitals.     

无症状性脑梗塞的研究进展

无症状性脑梗塞是指临床症状轻微或一过性易被忽略,或只有神经系统症状体征,影像学上见到非责任病灶。危险因素与症状性脑梗塞一致。可能影响急性脑卒中的病程、临床表现和预后,是症状性脑梗塞的预兆,可能发展为假性球麻痹、多发梗塞性痴呆。所以对患高血压病或糖尿病的老年人,如发生眩晕、头痛、语言障碍等症状,虽未发现明显体征,也应及时作颅脑CT或MRI检查,以早发现、早治疗。其治疗方案除恢复期缺血性脑血管病的治疗方法外,主要是采用脑卒中二级或三级预防措施。另外,补充维生素B6、B12及叶酸可以降低高同型半胱氨酸血症性缺血性脑血管病的发生。以头痛为首发症状的无症状性脑梗塞脱水剂治疗无效反而加重,加用镁剂后效果明显。     

Final infarct size after acute stroke: prediction with flow heterogeneity

PURPOSE: To compare acute measurements of flow heterogeneity (FH) and mean transit time (MTT) with follow-up data to determine which method yields better predictive measures of final infarct volumes. MATERIALS AND METHODS: Twenty-three patients with symptoms of stroke underwent magnetic resonance (MR) imaging during the acute stage, and the tissue at risk was estimated from MTT maps and maps generated by means of detecting abnormal FH. Final infarct volumes were calculated from T2-weighted follow-up MR image measurement. The Wilcoxon signed rank test was performed to compare the two predictive maps (MTT and FH) with T2-weighted follow-up maps. RESULTS: Eleven (48%) patients experienced infarct growth. Both the MTT and the FH maps enabled prediction of 10 of these cases. There were five false-positive cases with MTT measurement but three with FH measurement. In terms of predicting final infarct volumes, the final infarct size on the MTT maps was overestimated by 75%. The final infarct size on the FH maps also was overestimated, but by only 15%. MTT map measurements were significantly different from follow-up MR image measurements (P =.005), but FH map measurements were not (P =.059). CONCLUSION: FH maps may enable more precise prediction of final infarct volume in stroke patients.     

Myocardial infarct size after reperfusion therapy: assessment with Gd-DTPA-enhanced MR imaging

In 21 patients with proved acute myocardial infarction, the size of the infarct was estimated with serial magnetic resonance (MR) imaging after intravenous injection of gadolinium diethylenetriaminepentaacetic acid (DTPA) (0.2 mmol per kilogram of body weight). Early reperfusion after thrombolytic therapy or percutaneous transluminal coronary angioplasty performed during the acute phase of infarction was documented with coronary angiography in nine patients (group 1). In 12 patients (group 2), no reperfusion was achieved (n = 5) or no thrombolytic therapy was given (n = 7). All group 2 patients were considered to have no reperfusion. Infarct sizes measured with MR imaging were significantly smaller in group 1 than in group 2 at 8 days +/- 4 after infarct onset (8% +/- 5% vs 15% +/- 4%, respectively; P less than .001). Serial MR images showed individual variations in infarct size, findings that may be clinically significant. Estimation of infarct size with Gd-DTPA-enhanced MR imaging is accurate in demonstrating the effect of successful reperfusion therapy on infarct size.     

Assessment of serum myoglobin as a marker for acute myocardial infarction.

The reliability of serum myoglobin as a marker for acute myocardial infarction was evaluated in 157 consecutive coronary-care admissions. Admission myoglobin was elevated in 47 of 52 patients with acute infarction. Excluding those patients who presented later than 24 hr after symptom onset, only one patient with acute infarct had a normal admission myoglobin. In 22 of 105 patients with no infarct, myoglobin was elevated in association with angina, congestive heart failure, arrhythmias, and renal insufficiency. The detection of acute infarction by serum myoglobin measurement equals that of serial serum creatine phosphokinase isoenzymes (CPK-MB) by electrophoresis, but an elevated myoglobin is not specific for what is now considered clinically significant myocardial infarction.     

Predicting final infarct size using acute and subacute multiparametric MRI measurements in patients with ischemic stroke

PURPOSE: To identify early MRI characteristics of ischemic stroke that predict final infarct size three months poststroke. MATERIALS AND METHODS: Multiparametric MRI (multispin echo T2-weighted [T2W] imaging, T1-weighted [T1W] imaging, and diffusion-weighted imaging [DWI]) was performed acutely (<24 hours), subacutely (three to five days), and at three months. MRI was processed using maps of apparent diffusion coefficient (ADC), T2, and a self-organizing data analysis (ISODATA) technique. Analyses began with testing for individual MRI parameter effects, followed by multivariable modeling with assessment of predictive ability (R(2)) on final infarct size. RESULTS: A total of 45 patients were studied, 15 of whom were treated with tissue plasminogen activator (tPA) before acute MRI. The acute DWI and DWI-ISODATA mismatch lesion size, and the interactions of ADC, T2, and T2W imaging lesion with tPA remained in the final multivariable model (R(2) = 70%). A large acute DWI lesion or DWI < ISODATA lesion independently predicted increase in the final infract size, with predictive ability 68%. Predictive ability increased (R(2) = 83%) when subacute MRI parameters were included along with acute DWI, DWI-ISODATA mismatch, and acute T2W image lesion size by tPA treatment interaction. Subacute DWI > acute DWI lesion size predicted an increased final infarct size (P < 0.01). CONCLUSION: Acute-phase DWI and DWI-ISODATA mismatch strongly predict the final infarct size. An acute-to-subacute DWI lesion size change further increases the predictive ability of the model.     

Combined SPECT and diffusion-weighted MRI as a predictor of infarct growth in acute ischemic stroke.

In acute ischemic stroke, the infarcted core is surrounded by a zone of tissue that has decreased perfusion. Some of this tissue may be salvaged by prompt, effective treatment. Diffusion-weighted MRI is sensitive in detecting the infarcted tissue, whereas SPECT also detects the hypoperfused tissue around the infarcted core. We studied the potential of combined diffusion-weighted MRI and SPECT to predict infarct growth and clinical outcome in patients not receiving thrombolytic treatment. METHODS: Sixteen patients with acute stroke were examined consecutively with diffusion-weighted MRI and 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPECT within 24 h of the onset of symptoms. Follow-up diffusion-weighted MRI was performed on the second day and after 1 wk. The volumes of infarcted and hypoperfused brain tissue were measured from diffusion-weighted MRI and SPECT, respectively. The volume difference between the hypoperfused and infarcted tissue on the first day was compared with the possible increase in infarct volume during the follow-up. Each patient's neurologic status was assessed with the National Institutes of Health Stroke Scale (NIHSS). RESULTS: The volume of infarcted tissue increased from 48 +/- 54 cm3 (mean +/- SD) on the first day to 88 +/- 93 cm3 on the second day (P = 0.001) and to 110 +/- 121 cm3 at 1 wk (P = 0.001). The volume of hypoperfused tissue on the first day was significantly greater than the infarct volume (102 +/- 135 cm3; P = 0.001). The volume difference between the hypoperfused and infarcted tissue on the first day correlated significantly with the infarct growth between the first day and 1 wk (r = 0.71; P < 0.01). Between the first day and 1 wk, the increase of the infarct volume correlated significantly with the change in the NIHSS (r = 0.54; P < 0.05). CONCLUSION: A large hypoperfusion zone around the infarct core in the acute phase of ischemic stroke predicts the infarct growth during the first week, and this correlates significantly with the change in the neurologic status of the patient. Combined diffusion-weighted MRI and SPECT performed within 24 h after the onset of symptoms can be useful in the evaluation of acute stroke to predict infarct growth.     

Does Preinterventional Flat-Panel Computer Tomography Pooled Blood Volume Mapping Predict Final Infarct Volume After Mechanical Thrombectomy in Acute Cerebral Artery Occlusion?

Purpose

Decreased cerebral blood volume is known to be a predictor for final infarct volume in acute cerebral artery occlusion. To evaluate the predictability of final infarct volume in patients with acute occlusion of the middle cerebral artery (MCA) or the distal internal carotid artery (ICA) and successful endovascular recanalization, pooled blood volume (PBV) was measured using flat-panel detector computed tomography (FPD CT).

Materials and Methods

Twenty patients with acute unilateral occlusion of the MCA or distal ACI without demarcated infarction, as proven by CT at admission, and successful Thrombolysis in cerebral infarction score (TICI 2b or 3) endovascular thrombectomy were included. Cerebral PBV maps were acquired from each patient immediately before endovascular thrombectomy. Twenty-four hours after recanalization, each patient underwent multislice CT to visualize final infarct volume. Extent of the areas of decreased PBV was compared with the final infarct volume proven by follow-up CT the next day.

Results

In 15 of 20 patients, areas of distinct PBV decrease corresponded to final infarct volume. In 5 patients, areas of decreased PBV overestimated final extension of ischemia probably due to inappropriate timing of data acquisition and misery perfusion.

Conclusion

PBV mapping using FPD CT is a promising tool to predict areas of irrecoverable brain parenchyma in acute thromboembolic stroke. Further validation is necessary before routine use for decision making for interventional thrombectomy.     

Measurement of myocardial infarct size at early and late time intervals using MR imaging: an experimental study in dogs

The current study assessed the capability of ECG-gated MR imaging to quantitate both the percentage of the left ventricle involved by acute myocardial infarction and the mass of acute myocardial infarction at 3 and 21 days after coronary occlusion in dogs. Infarct mass was measured from gated transverse MR images using computer-generated calculated-T2 images. T2 images provided accentuation of the boundary between infarcted and normal myocardium as well as objective, reproducible calculation of image voxels representing infarcted myocardium. Postmortem and in vivo MR infarct mass and percentage correlated closely at 3 days (r = .98, SEE = 0.73 g; r = .97, SEE = 1.2%), and 21 days (r = .94, SEE = 1.54 g; r = .95, SEE = 1.61%). Left ventricular mass, infarct mass, and percentage of infarct were measured on end-diastolic MR images. Infarct mass at 3 and 21 days was not significantly different, with a mean deviation of 0.63 g. There was close intra- and interobserver reproducibility (r = .99 and r = .90, respectively) for measurement of infarct mass. The quantitative technique employed for determining the mass of acute myocardial infarctions, based on the different T2 relaxation times of infarcted and normal myocardium, provides for objective analysis and reproducibility. With this technique, MR provides an accurate method for assessing the mass of acute infarcts and the percentage of the left ventricle involved by the infarct both early and late after coronary occlusion.     

Comparison of dobutamine echocardiography and 99mTc-sestamibi tomography for prediction of left ventricular ejection fraction outcome after acute myocardial infarction treated with successful primary coronary angioplasty.

For patients with acute myocardial infarction who undergo primary percutaneous transluminal coronary angioplasty (PTCA), it is important to promptly identify those in whom a significant delayed improvement of global left ventricular function is to be expected as a result of successful treatment. METHODS: In 51 patients with acute myocardial infarction who underwent primary PTCA with a good angiographic result, the late outcome of the left ventricular ejection fraction (LVEF) was established after a 6-mo follow-up. In the early phase after infarction (within approximately 1 wk of infarction), the contractile reserve of the infarct zone was evaluated using dobutamine echocardiography and compared with the assessment of infarct size, infarct severity, and mean tracer activity of the infarct zone obtained using resting 99mTc-sestamibi SPECT. Receiver-operating-curve (ROC) analysis was used to define the reliability of the various parameters for identifying the patients with a follow-up LVEF increase of > or = 5 LVEF units. RESULTS: Of the 48 patients without restenosis at follow-up, 34 showed significant LVEF improvement. The evaluation of the contractile reserve of the infarct zone achieved an ROC curve area of 0.75 +/- 0.07 with 74% sensitivity, 71% specificity, and 73% overall accuracy. Of the 99mTc-sestamibi SPECT parameters, the extent of the infarct had no diagnostic value according to ROC analysis. The mean activity of the infarct zone had an ROC curve area of 0.64 +/- 0.09 with 82% sensitivity, 50% specificity, and 73% overall accuracy. The infarct severity had an ROC area of 0.76 +/- 0.08 (not significant vs. mean activity and vs. contractile reserve) with 77% sensitivity, 71% specificity, and 75% overall accuracy. CONCLUSION: Evaluation of the contractile reserve of the infarct zone using dobutamine echocardiography and assessment of the tracer activity of the infarct zone or infarct severity using 99mTc-sestamibi SPECT in the early phase after infarction are able to identify the patients in whom successful primary PTCA will be followed by significant late LVEF improvement.     

高压氧对心肌梗死大鼠模型梗死面积及左室功能的影响

目的 探讨高压氧(HBO)治疗对急性心肌梗死(AMI)大鼠模型梗死面积及左室功能的影响.方法 50只健康雄性SD大白鼠,分为左冠状动脉未结扎组12只,另38只以手术方式结扎左冠状动脉,术后6 h 5只大鼠死亡,存活的33只再分为HBO对照组(n=16)和HBO组(n=17),HBO组心肌梗死后应用HBO治疗,7 d后测量心肌梗死面积、左心室收缩压和舒张压差(LVEDP)及左心室内压最大上升和下降速率(±dp/dtmax)的变化.结果 HBO组与HBO对照组相比,心肌梗死面积明显减小(P<0.05),左室功能明显好转(P<0.05).结论 及早应用HBO治疗可以明显减少AMI大鼠模型心肌坏死面积,并且可以改善左室的收缩及舒张功能.     

A characteristic feature of acute haematomas in the brain on echo-planar diffusion-weighted imaging

Diffusion-weighted MRI (DWI) is used in the diagnosis of acute ischaemic disease of the brain, but it is not clear whether or not it can be used to differentiate an acute haematoma from an infarct. Our purpose was to identify any characteristic feature of acute haematomas which can be recognised on DWI and to evaluate the usefulness of DWI in acute cerebral stroke. We examined nine patients with acute haemorrhage using CT and MRI including DWI. We measured the volume and apparent diffusion coefficient (ADC) of the haematomas. All showed heterogeneous signal on DWI, and the centre of the large (>20 ml) haematomas especially a mixed pattern with high and low signal. The characteristic feature of acute haematomas was a peripheral low-signal region, found in all subjects regardless of the size of the haematoma; acute infarcts did not show this. This low-signal rim on DWI may be useful for differentiating an acute haematoma from an infarct.     

急性颞顶叶局灶性脑梗死后胼胝体DTI变化的初步研究

目的探讨一侧颞顶叶急性脑梗死梗死灶面积与胼胝体不同区域各向异性之间可能存在的变化。资料与方法连续采集病灶位于一侧颞叶、顶叶或一侧颞叶、顶叶均有病灶的急性脑梗死患者资料66例,男38例,女28例。年龄40～85岁,其中40～49岁10例,50～59岁18例,60～69岁20例,70岁以上18例。病灶面积≤200mm2者44例,>200 mm2者22例(剔除)。选取同期连续采集获得的与病变组44例匹配的正常成人作为对照分析组。病变组及正常组均行正中矢状位25梯度方向扩散张量成像(DTI)扫描,在正中矢状位部分各向异性(FA)图上分别测量胼胝体膝部、体部前1/3处、体部中部、体部后1/3处及压部的FA值,测量值进行统计分析。结果在胼胝体体部前1/3处、体部中部及体部后1/3处的FA值均为正常组大于病变组,其中体部前1/3处及体部后1/3处正常组与病变组之间差异存在统计学意义(t=2.838,P<0.05;t=8.223,P<0.05)。病变组胼胝体膝部及压部FA值均大于正常组,两组之间差异均有统计学意义(t=-3.428,P<0.05;t=-2.392,P<0.05)。结论颞顶部发生面积≤200 mm2的急性梗死时...     

Quantitative evaluation of acute myocardial infarction by In-111 antimyosin Fab myocardial imaging]

For quantitative evaluation of acute myocardial infarction, In-111 antimyosin Fab myocardial imaging (InAM) was performed in 17 patients with myocardial infarction who underwent Tl-201 (TL) and Tc-99m pyrophosphate (PYP) myocardial imaging in acute phase. For calculating the infarct size, voxel counter method was used for analysis in PYP and InAM, and extent and severity score were used on bull's-eye polar map in TL. The most appropriate cut-off level ranged from 65 to 80% by the fundamental experiment using cardiac phantom. The cut-off level of 0.70 (InAM) and 0.65 (PYP) were used for clinical application of voxel counter analysis. The infarct size calculated by InAM and PYP was compared with wall motion abnormality index by echocardiography (WMAI), TL extent score, TL severity score, peak CK and sigma CK. Infarct size by InAM showed the following correlations with other indices. PYP: r = 0.26 (ns), TL extent score: r = 0.72 (p less than 0.01), TL severity score: r = 0.65 (p less than 0.05), WMAI: r = 0.69 (p less than 0.05). The infarct size by PYP did not show any correlations with these indices. Therefore, the infarct size by InAM showed better correlations with TL and WMAI than that of PYP. So InAM was considered superior to PYP for quantitative evaluation of acute myocardial infarction.