Diffusion-weighted magnetic resonance imaging in diagnosis of Creutzfeldt-Jakob disease

Background Creutzfeldt-Jakob disease （CJD）, a rare disease, is uncharacterized by computed tomography （CT） and magnetic resonance imaging （MRI）. This study was aimed to evaluate the diffusion-weighted MRI （DWI） manifestations of CJD and to discuss their diagnostic value. Methods The findings of T1-weighted MR/（T1WI）, T2-weighted MRI（T2WI）, DWI and post-contrast MRI in 5 patients （3 patients with biopsy-proven CJD and 2 patients with clinically-proven CJD） were retrospectively analyzed in this study. Results Four out of the 5 patients had cerebral atrophy of various degrees. One patient showed symmetric high signal intensity at the bilateral globus pallidus and the head of the caudate nucleus, with very high signal in the cerebral cortex on the DWI. This patient only had symmetric slightly high signal at the bilateral globus pallidus and putamen on T2WI. One patient had high signal intensity at the basal ganglia and cerebral cortex on DWI, but abnormal T2 signal intensity at the bilateral paraventricular white matter on MRI. Two patients presented with widely gyri-like high signal intensity at the cortex on DWI, but routine MRI showed bilateral paraventricular long T2 signal intensity in 1 patient and no abnormal findings in another. No abnormalities were shown by both routine MRIand DWI in the last patient. Conclusions DWI is more sensitive than its conventional counterpart in the depiction of CJD. DWI is more sensitive to detect cortical abnormal signal intensity in CJD not detected by T2WI.     

多序列磁共振在急性脑卒中诊断流程中的应用

目的 探讨急性脑卒中发生后最佳的影像诊断流程.方法 发病在1～72h的53例急性脑卒中患者在CT检查后行T1加权成像(T1WI)、T2加权成像(T2WI)、梯度回波T2*加权成像(GRE-T2*WI)、弥散加权成像(DWI)检查,缺血性卒中患者中15例行灌注加权成像(PWI)检查.结果 15例急性脑出血及1例瘤卒中患者的出血灶在GRE-T2*WI上全部清楚显影,3例TIA患者各项均正常.发病在6h内的18例脑梗死患者各项均呈等信号,其中7例患者行PWI检查:3例PWI≥DWI,4例PWI=DWI;发病大于6h的14例患者行GRE-T2*WI均为高信号,DWI均显示有与体征相对应的高信号病灶,其中8例行PWI检查,6例PWI=DWI,2例PWI正常,本组患者中有7例患者GRE-T2*WI呈现有1～18个直径为2～5mm的极低信号;另有1例头痛伴一侧肢体偏瘫的患者在CT上未见异常,T2*WI显示环池有低信号影后证实为蛛网膜下腔出血.结论 对急性脑卒中患者可直接通过MRI多序列检查流程在较短的时间内一站式地鉴别脑出血、脑梗死和TIA,明确微出血情况,确定缺血半暗带,指导溶栓治疗的选择.

Abstract：

Objective To study the best diagnostic imaging procedure after acute stroke.Methods 53 patients with acute stroke were recruited within 72 hours after symptom onset.CT was performed in all patients firstly, then T1 weighted-imaging( T1 WI), T2 weighted-imaging( T2WI ), gradient recalled echo T2 * weighted-imaging( GRE-T2 * WI) and diffusion-weighted imaging(DWI) were examined at 1.5T.Furthermore 15 patients with ischemic stroke received perfusion-weighted imaging(PWI) examination.Results 15 patients with acute cerebral hemorrhage and one patient of hemorrhagic brain tumor appeared clear on GRE-T2 * WI.3 patients with transient ischemic attack(TIA) were normal on T1WI ,T2WI ,GRE-T2* WI and DWI.18 cases with cerebral infarction appeared normal on GRE-T2 * WI within 6 hours after symptom onset, and 7 cases of them underwent PWI examination, the signal intensity of 3 cases were PWI ≥ DWI and of 4 cases were PWI = DWI.14 patients appeared hyperintense on GRE-T2 * WI within 6 ～72 hours after symptom onset.8 patients of them underwent PWI examination,the signal intensity of 6 cases were PWI≥DWI and of 2 cases were PWI = DWI.Of 14 patients,7 patients appeared as 1 ～ 18 dot or patchy hypointense whose diameter was about 2 ～ 5mm on GRE-T2 * WI.Another case of headache with hemiplegia and the side of the limb didnt show abnormalities on the CT, but showed a low signal in ambient cistern on T2 * WI and was proved to be subarachnoid hemorrhage.Conclusion After acute stroke,multi-sequence MRI enables the "one-stop shopping" imaging of cerebral hemorrhage,cerebral infarction and TIA in a shorter time,makes the state of micro-bleeding clear,determines ischemic penumbra,and even guides for thrombolytic treatment.     

NORMAL APPEARANCE OF LARGE FIELD DIFFUSION WEIGHTED IMAGING ON 3.0T MRI

Objective To evaluate the normal appearance of large field diffusion weighted imaging （DWI） on 3.0T magnetic resonance imaging （MRI）.
Methods Twenty healthy volunteers and thirty patients with benign prostate hyperplasia were included in this study. All patients were examined with large field DWI on 3.0T MRI. Normal tissue appearance was analyzed and apparent diffusion coefficient （ADC） of normal tissue with high signal intensity was measured. The ADC values of bilateral symmetrical tissue were also compared. The ADC values of intervertebral disks of healthy people younger than 50 years and exceeding 50 years were compared.
Results Salivary gland, spleen, kidney, gallbladder, bladder, prostate, seminal vesicle, testis, intervertebral disk, liquid in articular cavity and lymph node showed high signal intensity on large field DWI, while lung, liver and bone showed hypo-signal intensity. The mean ADC values of partial hyperintensity tissue were as followed： parotid gland （1.088 ± 0.114） ×10^-3 mm^2/s, submaxillary gland （1.309 ± 0.189） ×10^-3 mm^2/s, kidney （1.909 ± 0.143）×10^-3 mm^2/s, seminal vesicle （1.669 ± 0.168） ×10^-3 mm^2/s, testis （1.028 ± 0.075） ×10^-3 mm^2/s, spleen （0.963 ± 0.108） ×10^-3 mm^2/s, bladder （2.898 ± 0.267）×10^-3 mm^2/s, prostate （1.448 ± 0.132） ×10^-3 mm^2/s, intervertebral disks （1.360 ± 0.140） ×10^-3 mm^2/s. No statistical significance was found between the ADC values of bilateral symmetrical tissues. The difference of ADC values of intervertebral disks of healthy people younger than 50 years [（1.372 ± 0.142） ×10^-3 mm^2/s] and exceeding 50 years [（1.344 ± 0.134）×10^-3 mm^2/s] showed statistical significance （P = 0.040）.
Conclusion Understanding the high signal intensity of normal tissue on large field DWI may help to differentiate the normal tissues and abnormal ones.     

磁共振弥散加权成像在原位肝移植术后缺血性胆管病变的应用价值

目的 探讨弥散加权成像(DWI)及表观弥散系数(ADC)值在原位肝移植术后缺血性胆管病变中的应用价值.方法 以PTC或ERCP检查,病理或临床定期随访资料为标准,筛选出中山大学附属第三医院2005年4月至2009年3月46例肝移植术后患者,将其分为缺血性胆管病变组(TTBL组,29例)和无缺血性胆管病变组(C组,17例),测量移植肝实质的ADC值(b值=600 s/mm2),并对DWI序列上移植肝胆道系统信号和MRCP上胆管树进行观察.结果 ITBL组和C组的移植肝ADC值分别为(1.456±0.286)×10-3mm2/s和(1.716±0.391)×10-3mm2/s,ITBL组ADC值低于C组,两组间差异有统计学意义(P=0.015).DWI上ITBL组和C组胆管壁信号增高发生率分别为82.8%(24/29)和5.9%(1/17),ITBL组DWI上胆道壁信号增高主要发生在肝门部胆管及肝内小胆管(70.8%,17/24).ITBL组与C组之间差异有统计学意义(P＜0.001).ITBL组21例伴发胆泥,DWI上呈高、等、低信号,C组中胆管管腔内未见异常信号.结论 DWI上ITBL主要表现为肝门部及肝内小胆管管壁信号明显增高,移植肝ADC值下降,可在一定程度上反映其病理学改变,可能对ITBL的早期诊断是一种有效的、敏感的监测指标.DWI作为一种新颖、无创、简单、实用的方法在肝移植术后ITBL的诊断、鉴别诊断具有重要的临床意义.

Abstract：

Objective To discuss the application values of DWI (diffusion-weighted imaging) and ADC (apparent diffusion coefficient ) on ischemic-type biliary lesions (ITBL) after orthotopic liver transplantation. Methods According to whether there was ITBL after liver transplantation or not, 46 cases of liver transplantation were selected and divided into 2 groups on the basis of PTC (percutaneous transhepatic cholangiography ) or ERCP (endoscopic retrograde cholangiopancreatography ) examination,pathology or clinical follow-up data: ITBL group ( n = 29 ) and no ITBL group ( C group, n = 17). The ADC value was measured for right lobe of graft liver parenchyma ( b value =600 s/mm2 ). And the signal of biliary system of graft on DWI and biliary tract on MRCP were analyzed. Results ( 1 ) The ADC values of liver graft were ( 1. 456 ± 0. 286 ) × 10 -3 mm2/s and ( 1. 716 ± 0. 391 ) × 10 -3 mm2/s in ITBL and C groups respectively. The difference in ADC value was significant between two groups ( P = 0. 015 ); ( 2 ) the incidence of increased signal of bile duct on DWI was 82. 8% ( 24/29 ) and 5.9% ( 1/17 ) for ITBL and C groups respectively. The lesion was located in porta hepatis and intrahepatic small bile duct was seen in 17 of 24 patients (70. 8% ) in ITBL group. The difference was significant in signal of bile ducts between ITBL and C groups ( P ＜ 0. 001 ). Twenty-one cases with sludge on DWI in ITBL group had hyperintensity, isointensity or hypointensity. There was no abnormal signal in the lumen of bile duct in C group. Conclusion The major sign of ITBL is a hyperintensity of porta hepatis and small bile ducts on DWI. And the ADC value of graft liver parenchyma decreases. These reflect the pathological changes to an extent and may be an effective and sensitive monitoring tool of early ITBL. DWI is a novel, non-invasive, simple and practical method in the diagnosis and differential diagnosis of ITBL after liver transplantation.     

Influence of lesion ratio on diagnostic performance of in-phase/opposed-phase imaging and apparent diffusion coefficient for differentiating acute benign vertebral fractures and metastases

Background The usefulness of in-phase/opposed-phase imaging and diffusion weighted imaging （DWI） in differentiating benign and neoplastic vertebral fractures has been described. In this study, we aimed to evaluate the influence of the severity of vertebral damage on the diagnostic performance of these two technologies. Methods Totally 59 patients with 68 acute benign vertebral fractures and 43 patients with 79 vertebral metastases were included in this study. The MR protocol included DWls and sagittal in-phase/opposed-phase gradient recalled sequence. The severity of vertebral damage was expressed by lesion ratio （LR, the ratio of lesion area to vertebral area on the slices of largest abnormal signal area in the Tl-weighted sequence）. Quantitative （signal intensity ratio （SIR） defined as signal intensity （SI） on opposed-phase gradient recalled echo （GRE） images divided by SI on in-phase; apparent diffusion coefficient （ADC） value derived from DWl analysis was performed, the relationships between LR and the measurements of these two technologies were analyzed using linear regression. The covariate-specific receiver operating characteristic （ROC） curves were also fitted to evaluate the influence of LR on the diagnostic performance of ADC and SIR. Results The difference in both SIR and ADC for vertebral metastasis and acute benign vertebral fractures was significant （P 〈0.001）. A positive correlation between the LR and the SIR was found in benign fractures （P 〈0.05）. The severity of vertebral damage had a significant influence on the AUC （area under ROC curve） for SIR （P 〈0.05） but ADC （P 〉0.05）. More severe cases were associated with increased AUC for SIR. Conclusions LR is capable of affecting the diagnostic performances of chemical shift imaging. Thus, when applying these tests to make diagnoses on vertebral fractures, the severity of the vertebral damage should be taken into account. The covariate-specific ROC model is recommended because it substantially improves the ability to avoid bias when evaluating tests.     

Dysembryoplastic neuroepithelial tumors: magnetic resonance imaging and magnetic resonance spectroscopy evaluation

Background Dysembryoplastic neuroepithelial tumor （DNT） is a rare benign neoplasm of the central nervous system affecting young people. A correct preoperative diagnosis is helpful for planning surgical strategies and improving prognosis. The purpose of this study was to characterize DNTs using magnetic resonance imaging （MRI） and magnetic resonance spectroscopy （MRS） and to analyze the value of these two techniques in the diagnosis of DNTs. Methods MR images of 13 patients with DNTs were reviewed retrospectively; and five of the patients also underwent MRS. Tumors were confirmed by surgery. The distribution, extension and signal features of the lesions were assessed, and the MRS results were analyzed. Results All tumors were supratentorial. The cortex was the main area involved, with nine tumors located in the temporal lobe, three in the frontal lobe, and one on the boundary between the temporal and occipital lobes. All cases had decreased signal intensity on Tl-weighted MR images and increased signal intensity on T2-weighted images. On fluid attenuated inversion recovery weighted images, the hyperintense ＂ring sign＂ and internal septation of the lesion were seen in 9 cases. Eight tumors had well-demarcated borders. Peritumoral edema or mass effect was absent in all cases. A contrast enhancement examination was performed in 9 cases. Contrast enhancement was absent in five cases, and four cases showed significant enhancement. The MRS showed a low N-acetylaspartate peak and a lack of elevated choline-containing component （Cho） or Cho-Cr ratio （Cho/Cr） in five patients. Conclusions The MRI findings of DNTs were stereotypical. The combination of MRI and MRS techniques were helpful in making a correct presurgical diagnosis.     

An Early Continuous Experimental Study on Magnetic Resonance Diffusion-weighted Image of Focal Cerebral Ischemia and Reperfusion in Rats

Summary： The chronological and spatial rules of changes during focal cerebral ischemia and reperfusion in different brain regions with magnetic resonance diffusion-weighted imaging （DWI） in a model of occlusion of middle cerebral artery （MCAO） and the development of cytotoxic edema in acute phase were explored. Fifteen healthy S-D rats with MCA occluded by thread-emboli were randomly divided into three groups. 15 min after the operation, the serial imaging was scanned on DWI for the three groups. The relative mean signal intensity （RMSI） of the frontal lobe, parietal lobe, lateral cauda-putamen, medial cauda-putamen and the volume of regions of hyperintense signal on DWI were calculated. After the last DWI scanning, T2WI was performed for the three groups. After 15 rain ischemia, the rats was presented hyperintense signals on DWI. The regions of hyperintense signal were enlarged with prolonging ischemia time. The regions of hyperintense signal were back to normal after 60 min reperfusion with a small part remaining to show hyperintense signal. The RMSIs of parietal lobe and lateral cauda-putamen were higher than that of the frontal lobe and medial cauda-putamen both in ischemia phase and recanalization phase. The three groups were normal on T2WI imaging. DWI had good sensitivity to acute cerebral ischemia, which was used to study the chronological and spatial rules of development of early cell edema in ischemia regions.     

Magnetic resonance susceptibility weighted imaging in detecting intracranial calcification and hemorrhage

Background Computed tomography （CT） is better than routine magnetic resonance imaging （MRI） in detecting intracranial calcification. This study aimed to assess the value of MR susceptibility weighted imaging （SWI） in the detection and differentiation of intracranial calcification and hemorrhage.
Methods Enrolled in this study were 35 patients including 13 cases of calcification demonstrated by CT and 22 cases of intracerebral hemorrhage. MR sequences used in all the subjects included axial T1WI, T2WI and SWI. The phase shift （PS） of calcification and hemorrhage on SWI was calculated and their signal features on corrected phase images were compared. The sensitivity of T1WI, T2WI and SWI in detecting intracranial calcification and hemorrhage was analyzed statistically.
Results The detection rate of SWI for cranial calcification was 98.2%, significantly higher than that of T1WI and T2WI. It was not significantly different from that of CT （P 〉0.05）. There were 49 hemorrhagic lesions at different stages detected on SWI, 30 on T2WI and 18 on T1WI. The average PS of calcification and hemorrhage was ＋0.734±0.073 and -0.112±0.032 respectively （P 〈0.05）. The PS of calcification was positive and presented as a high signal or the mixed signal dominated by a high signal on the corrected phase images, whereas the PS of hemorrhage was negative and presented as a low signal or the mixed signal dominated by a low signal.
Conclusions SWI can accurately demonstrate intracranial calcification, not dependant on CT. Being more sensitive than routine MRI in detecting micro-hemorrhage, SWI may play an important role in differentiating cerebral diseases associated with calcification or hemorrhage.     

Bone tumor—— MRI diagnosis of neurilemmoma of the brachial plexus

Objective To investigate the value of magnetic resonance imaging （MRI） in the diagnosis of neurilemmoma of the brachial plexus. Methods Preoperative MRI images of 36 consecutive eases of neurliemmornas of the brachial plexus, proven surgically and pathologically, were reviewed. The MRI findings were analyzed for location, size, margin, signal intensity, contrast enhancement of the mass, and the extent of the lesions. Results The roots, trunks, and various divisions of the brachial plexus appeared as linear structures with low signal intensity on MR images obtained with all sequences. All patients had large schwannomas （mean size 〉 4.9 cm in diameter） presenting as masses along a braehial plexus nerve root as explored by MRI. 30 cases of the masses exhibited spindle or oblong shape with well-defined margins. 16 cases appeared as homogeneous hypo-or iso-intense to muscle in T1-wei- hgted images, hyper-intense in T2-weighted images, and moderate contrast enhancement after abministmtion of contrast media. 20 lesions were hypo-isointense to muscle on T1-weighted images and heterogeneous hyper-intense on T2-weighted images which may have central areas with low signal intensity, the so-called ＂target sign＂, and enhance intensely after administration of gadolinium-based contrast material. Conclusion The locations, morphologic features and MR signal characteristics are useful in making a proper preoperative diagnosis of neurilemmomas of the brachial plexus. 6 refs, 1 fig.     

EXPERIMENTAL STUDY OF INFLAMMATORY AND METASTATIC LYMPH NODES WITH DIFFUSION WEIGHTED IMAGING ON ANIMAL MODEL： COMPARISON WITH CONVENTIONAL METHODS

Objective To investigate the feasibility of magnetic resonance （MR） diffusion weighted imaging （DWI） in discriminating inflammatory from VX2 carcinoma metastatic lymph nodes in rabbit model.
Methods Twenty New Zealand white rabbits were randomly divided into 2 groups. Complete Freund＇s adjuvant was injected into the bilateral dorsal footpads to set up ipsilateral lymphadenitis model （n = 10）, and the other 10 rabbits received a subcutaneous implantation of VX2 tumor cell suspension （1.5×10^7 cells/mL） in both thighs to set up metastatic lymph node model. MR imaging scan covering the popliteal fossa and lilac fossa including short time inversion recovery echo-planar imaging DWI （STIR-EPI-DWI）, Tl-weighted imaging （T1WI） and T2-weighted imaging （T2WI） was performed 2 weeks after injection. T2WI signal intensity （SI）, DWI SI, long/short axial ratio （LSR） and apparent diffusion coefficient （ADC） values of the lymph nodes were evaluated in all cases. Right after MR imaging scan, popliteal and iliac fossa lymph nodes were collected for hematoxylin-eosin staining.
Results Totally 33 lymph nodes larger than 5 turn, including 22 inflammatory and 11 metastatic ones, were successfully isolated and taken into pathological analysis. LSR showed no significant difference between the inflammatory and malignant lymph nodes （P 〉 0.05）. Both benign and malignant lymph nodes appeared iso-intense on TlWI and hyperintense on both T2WI and DWI images with an even lower TlWI and higher T2WI SI core at the hilum. Both T2WI and DWI SI showed no significant difference between two pathological groups （P 〉 0.01） in popliteal fossa. The mean ADC value of inflammatory nodes [（1.199±0.281） ×10^-3 mm^2/s] was significantly higher than that of metastatic nodes [（0.858 ± 0.090） ×10^-3 mm^2/s, P 〈 0.01]. On ADC map, a high ADC value central area could be seen in most of the lymph nodes no matter benign or malignant. ADC value gave out the largest area under curve （AUCADC =     

弥散加权成像对急性期脑梗死的诊断价值

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 对临床上拟诊为急性脑梗死患者进行常规磁共振成像(MRI)扫描及DWI检查.回顾性分析60例在T2WI、T1WI、DWI、表现弥散系数(ADC)图上信号强度的变化.结果 发病3h内(6例)在T2WI上呈稍高信号2例,等信号4例,T1WI上均为等信号,DWI上均为高信号,ADC图上均为明显低信号;发病4～15 h(30例)在T2WI、DWI上均为稍高到高信号,在T1WI、ADC图上均为低信号;发病16～24 h(12例)T2WI 、DWI上均为高信号,在T1WI上11例为低信号,1例为等低信号,ADC图上,9例为低信号,3例为等低信号;发病24 h上(12例)在T2WI上均为稍高信号;DWI上10例为稍高信号,2例为等信号,T1WI上10例为稍低信号,2例为等低信号,ADC图上,5例为稍低信号,3例为等信号,4例为等低信号.结论 弥散加权成像能早期显示急性脑梗死的病灶,对急性脑梗死有非常重要的诊断价值.     

MRI对成人可逆性胼胝体压部病变综合征和脑梗死的鉴别诊断及预后评估

目的 探究成人可逆性胼胝体压部病变综合征(reversible spleniallesion syndrome,RESLES)与脑梗死的MRI表现特征差异,并分析MRI对疾病预后的评估价值.方法 选取21例RESLES患者和39例脑梗死患者作为研究对象,记录两组患者的MRI影像学中的病灶位置、形态和成像特点,分析两组患...     

不同b值弥散加权成像在前列腺癌诊断中的应用

目的：探讨不同b值弥散加权成像在前列腺癌诊断中的应用价值。方法收集我院2014年1月至2016年9月经病理确诊的前列腺癌患者40例进行研究,分别进行b值=300 s/mm2,800 s/mm2,1000 s/mm2 DWI扫描,测量不同b值条件下前列腺癌区信号强度(SI)及表观弥散系数(ADC),并对结果进行统计分析。结果40例前列腺癌患者在b=300 s/mm2时,25例患者DWI呈等低信号,7例稍高信号,8例高信号;b值=800 s/mm2时,11例呈稍高信号,29例高信号;b=1000 s/mm2时均呈高信号。随着b值增加,前列腺癌区信号强度及ADC值逐渐降低,不同b值条件下,信号强度及ADC值比较差异均有统计学意义(P<0.05)。结论随着b值增加,DWI对前列腺癌越敏感,信号对比越明显,但图像信噪比降低,在b值=1000 s/mm2时,有助于前列腺癌的诊断。     

DWI在超急性期脑梗死诊断中的应用

目的研究磁共振弥散加权成像(DWI)技术在超急性期脑梗死诊断中的应用价值。方法对发病6h内的临床疑似脑梗死病例128例,在CT排除急性脑出血后均进行常规MRI扫描及DWI扫描,对所得的结果进行总结分析。结果 128例超急性期脑梗死病人DWI全部显示为高信号,在表观弥散系数(ADC)图像上显示为低信号,检出率为100%;49例曾有脑梗死病史者MRI常规序列只发现陈旧性梗死灶,而DWI检查发现有新梗死灶;DWI的全方向比单方向对显示超急性期脑梗死的梗死灶更清楚。结论磁共振DWI是目前能够最早显示超急性脑梗死的方法。     

DWI上ADC在脑梗死缺血半暗带范围分析中的应用

[目的]应用磁共振弥散加权成像(DWI)上表观弥散系数(ADC)分析超急性、急性及亚急性期脑梗死的缺血半暗带范围.[方法]53例脑梗死患者中超急性期者为6例,急性期为18例,亚急性期为29例;给所有患者进行常规MRI,DWI检查,测量病灶平均ADC、相对表观弥散系数(rADC)及病灶旁3,5mm区ADC.[结果]53例脑梗死患者病灶平均rADC为55%～75%;超急性及急性期病灶旁3mm处平均rADC为78%～80%,亚急性期为100%;超急性、急性及亚急性期病灶旁5mm的平均rADC为100%～105%.[结论]脑梗死在超急性期及急性期存在缺血半暗带,其范围为病灶旁3mm区,亚急性期无缺血半暗带.     

磁共振扩散加权成像对不同时期脑梗死的诊断意义

目的 探讨磁共振扩散加权成像(diffusion weighted imaging,DWI)在不同时期脑梗死的信号变化特点.方法 搜集经临床确诊并经磁共振证实的脑梗死患者130例,均同时进行了磁共振平扫检查和DWI检查.根据发病到行磁共振检查的时间分为超急性期(<6 h)30例,急性期(6～72 h)40例,亚急性期(...     

DWI联合SWI诊断脑外伤后微病灶的临床价值

目的探讨弥散加权成像（DWI）联合磁敏感成像（SWI）诊断脑外伤后微病灶的价值。方法收集并分析经临床和影像证实的18例脑外伤后微病灶患者的MRI检查资料,所有患者均在常规扫描的基础上进行扩散加权及磁敏感成像检查。结果 18例患者中微梗死5例,脑挫裂伤的微出血17例（其中弥漫性轴索损伤5例）;微出血急性期病灶在DWI序列上呈高信号,在ADC图上呈低信号,随后DWI信号降低,ADC信号则相应由低信号转变为高信号,SWI系列上则一直为低信号;微脑梗死病灶在DWI序列上呈高信号,在ADC图上呈低信号,SWI呈稍高信号。结论脑外伤微病灶在DWI及SWI序列上有特征性表现,应作为脑外伤后患者的常规检查。     

磁共振弥散加权成像在脑梗死分期中的临床应用

目的：研究磁共振弥散加权成像（diffusion weighted imaging,DWI）和ADC图在脑梗死分期诊断中的临床应用价值。方法收集经临床及影像学证实的62例患者的DWI及ADC图资料,其中,超急性期12例,急性期38例,亚急性期12例。结果62例患者中,发生在脑干的2例超急性期腔隙性脑梗死3 h~4 h内未能明确诊断,约占3.2%,其余不同时期梗死病灶在DWI高信号,ADC图低信号,随时间延长,DWI信号逐渐降低,ADC信号升高,2周时接近等信号。结论 MRI检查是诊断缺血性脑梗死的有效方法,根据DWI和ADC图像信号特点,可以鉴别新、旧梗死并确定责任病灶,为临床治疗提供有力的证据。