CT perfusion parameter values in regions of diffusion abnormalities

BACKGROUND AND PURPOSE: Dynamic CT perfusion imaging is a rapid and widely available method for assessing cerebral hemodynamics in the setting of ischemia. Nevertheless, little is known about perfusion parameters within regions of diffusion abnormality. Since MR diffusion-weighted (DW) imaging is widely considered the most sensitive and specific technique to examine the ischemic core, new knowledge about CT perfusion findings in areas of abnormal diffusion would likely provide valuable information. The purpose of our study was to measure the CT-derived perfusion values within acute ischemic lesions characterized by 1) increased signal intensity on DW images and 2) decreased apparent diffusion coefficient (ADC) and compare these values with those measured in contralateral, normal brain tissue. METHODS: Analysis was performed in 10 patients with acute middle cerebral artery territory stroke of symptom onset less than 8 hours before imaging who had undergone both CT perfusion and DW imaging within 2 hours. After registration of CT perfusion and DW images, measurements were made on a pixel-by-pixel basis in regions of abnormal hyperintensity on DW images and in areas of decreased ADC. RESULTS: Significant decreases in cerebral blood flow and cerebral blood volume with elevated mean transit times were observed in regions of infarct as defined by increased signal intensity on DW images and decreased ADC. Comparison of perfusion parameters in regions of core infarct differed significantly from those measured in contralateral normal brain. CONCLUSION: CT perfusion findings of decreased cerebral blood flow, mean transit time, and cerebrovascular volume correlate with areas of abnormal hyperintensity on DW images and regions of decreased ADC. These findings provide important information about perfusion changes in acute ischemia in areas of diffusion abnormality.     

脑脂肪栓塞的CT和MRI诊断(附3例分析)

目的 :分析脑脂肪栓塞 (CFE)的CT和MRI表现 ,以提高对此病的早期诊断。方法 :对 3例CFE患者的临床及CT和MRI资料进行分析。结果 :3例CFE患者CT检查均为阴性 ,MRI示双侧额叶皮层下脑白质区、基底节、放射冠、半卵圆中心区多发散在点状异常信号影 ,1例T1WI表现为低信号 ,2例未见异常 ,3例T2 WI均表现为点状较高信号 ,DWI上 3例均有点状高信号。结论 :有近期骨折病史者 ,一旦出现神经系统症状 ,要想到CFE的可能 ,应早期行颅脑MRI检查 ,常规选择T1WI、T2 WI和DWI多种序列成像技术进行检查。     

磁共振弥散加权成像对急性皮层下脑梗塞的评价

目的 研究磁共振弥散加权成像（DWI）诊断急性皮层下脑梗塞的准确性以及对急性与非急性皮层下脑梗塞的鉴别诊断。材料与方法 对32例临床诊断为急性皮层下脑梗塞的患者和20例对照者在不同时间内进行常规MRI检查和弥散加权MRI检查,并用盲法进行对照观察。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 DWI诊断急性皮层下脑梗塞的敏感性、特异性及准确性分别为97％、95％和96％。32例中有3例常规MRI检查未发现急性梗塞性。另20例常规MRI检查均显示为多发梗塞,而DWI只显示单个急性病灶,且患者的症状、体征与DWI上显示的病灶相符。结论 DWI对诊断急性皮层下脑梗塞有很高的准确性,能发现常规T2WI不能发现的早期脑梗塞,并能鉴别急性与非急性梗塞。     

Transparent color-coded three-dimensional diffusion-weighted magnetic resonance imaging for the numerical analysis of reversible and irreversible hyperacute ischemic stroke—case report

Although diffusion-weighted (DW) magnetic resonance (MR) imaging can detect hyperacute ischemic parenchyma with high sensitivity, the ability of DW images to reveal subtle change in abnormal diffusion may be limited by the conventional visual evaluation. To overcome the limitation, we have developed a method of transparent color-coded three-dimensional (3D) DW MR imaging for the computer-aided numerical analysis of hyperacute ischemic stroke. The 3D images were reconstructed from volume data of source DW images by using a parallel volume-rendering algorithm with transluminal imaging technique. By selecting a threshold range from a signal intensity opacity chart of volume-rendering data set, several high signal intensity areas were depicted and assigned to different colors, transparently through contours of the brain. This imaging was applied in a case of a recanalized middle cerebral artery (M2) occlusion with partially reversible ischemic parenchyma accompanied by partial recovery from ischemic neurological deficit. Complex and dynamic change in hyperacute ischemic parenchyma, with regression of subtle high signal intensity areas and progression of ischemic parenchyma, was depicted three-dimensionally. Transparent color-coded 3D DW MR imaging may provide computer-aided numerical analysis of hyperacute ischemic stroke appearing as a high signal intensity area on the source DW images.     

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     

脑脱髓鞘性假瘤的磁共振成像表现

目的探讨脑脱髓鞘性假瘤的磁共振成像表现,提高对该病的磁共振(MR)诊断水平。方法回顾性分析2例均行常规MRI检查、氢质子磁共振波谱成像(1H-MRS)及脑灌注成像,并与病理结果对照,总结脱髓鞘性假瘤的MRI特点。结果 2例患者均为青年男性,急性起病入院,MRI表现为T1WI高低混杂信号,T2WI高信号,1H-MRS为NAA峰降低,胆碱(Cho)峰升高,并出现乳酸(Lac)和胶质(Lip)峰,MR灌注成像(PWI)示脑血流量、脑血容量降低,平均通过时间及峰值时间延长。结论脑脱髓鞘性假瘤常规MRI表现具有一定特征性,联合功能成像有助于作出正确诊断。     

低场磁共振弥散加权成像诊断急性脑梗死的可行性

目的探讨低场磁共振弥散加权成像（DWI）在急性期脑梗死诊断中的可行性。方法对临床疑诊或确诊为脑梗死的116例患者包括11例超急性期（发病后6h内），35例急性期（发病后6-24h）及70例亚急性期（发病后2～7d）进行DWI和常规MRI检查，对超急性、急性、亚急性期的MRI表现进行分析，总结病变演变规律。结果DWI较常规MRI序列显示梗死灶更有明显优势，对超急性期脑梗死灶的敏感度为100％。急性期脑梗死灶在DWI序列上为异常高信号，且信号强度随b值升高而增强，各期脑梗死灶在DWI中异常信号强度由低逐渐增高。弥散全方向比单方向DWI成像显示病变效果好。结论低场磁共振弥散加权成像技术，通过精心调整扫描技术参数，对急性期脑梗死能作出诊断，尤其对超急性期脑梗死的诊断及治疗可提供可靠依据。     

3T磁共振头部扩散加权像中3种不同b值对比研究

目的:探讨3T磁共振扩散加权成像(DWI)参数中适用于急性脑梗塞诊断的扩散敏感系数(b值)。方法:对20例发病时间在3天以内,临床高度怀疑为急性脑梗塞患者进行常规MRI和3种扩散敏感系数(b值)的DWI成像,测量图像信噪比(SNR)、对比噪声比(CNR)以及病变区与健侧对称区信号强度比并进行统计比较。结果:与b值为1000s/mm2相比,b值为2000s/mm2和3000s/mm2时SNR分别下降15.66%和28.30%,CNR下降9.57%和11.08%,差别不具统计学意义(P>0.05)。3种b值DWI中病变区与健侧对称区信号强度比值分别为1.76,2.24和2.61,差别有统计学意义(P<0.05),3种b值ADC图像中病变区与健侧对称区信号强度比值分别为0.63,0.60和0.63,差别不具统计学意义(P>0.05)。结论:3T磁共振用于脑梗塞检查的扩散加权序列成像参数中,b值设置为2000s/mm2时,可增强病变显示能力,并且用病变区与健侧对称区ADC比值判断病变性质能沿用已有标准。     

MRI and SPECT findings in amyotrophic lateral sclerosis

Summary MRI was performed in 21 patients and single photon emission computed tomography (SPECT) withN-isopropyl-p-¹²³I iodoamphetamine in 16 patients, to visualize upper motor neurone lesions in amyotrophic lateral sclerosis. T2-weighted MRI revealed high signal along the course of the pyramidal tract in the internal capsule and cerebral peduncle in 4 of 21 patients. SPECT images were normal in 4 patients, but uptake was reduced in the cerebral cortex that includes the motor area in 11.     

Audit of a policy of magnetic resonance imaging with diffusion-weighted imaging as first-line neuroimaging for in-patients with clinically suspected acute stroke

AIM: To audit the feasibility and use of diffusion-weighted (DW) magnetic resonance imaging (MRI) as initial neuroimaging for in-patients with clinically suspected acute stroke. MATERIALS AND METHODS: In April 2000, MRI with DW and T2-weighted sequence was locally instituted as initial neuroimaging for patients with clinically suspected acute stroke. This retrospective study reviewed imaging performed for in-patients with suspected acute stroke over a 9-month period. Data were collected on image type, result and need for repeat imaging. RESULTS: During the study period, 124 patients had neuroimaging for suspected cerebrovascular accident, and 119 were MRI safe. Eighty-eight (73.9%) patients underwent DW MRI as first-line investigation. Five patients were not MRI safe and 31 had computed tomography (CT) as first-line imaging due to lack of available MRI capacity. Repeat neuroimaging was performed in 16 (12.9%) patients. Study times were comparable for both types of neuroimaging: a mean of 13 min for MRI and 11 min for CT. CONCLUSION: The audit standard was achieved in 88 (73.9%) patients. The use of DW MRI as a first-line investigation for patients with a clinical diagnosis of acute stroke is achievable in a district general hospital setting.     

SPECT脑血流灌注显像在老年人脑梗塞中的应用

目的：评价ＳＰＥＣＴ脑血流灌注显像在老年病中的临床应用价值。材料和方法：４６例脑梗塞患者行９９ｍＴｃ－ＥＣＤ脑血流灌注显像，并与ＣＴ、ＭＲＩ、对照。其中４例行Ｄｉａｍｏｘ脑血流负荷检查。结果：４６例脑梗塞患者４５例脑血流灌注异常，占９７．８％．３３例同时做过ＣＴ，其灵敏度９６．７％．２５例做过ＭＲＩ，灵敏度９６％。ＳＰＥＣＴ脑血流显像灵敏度与ＣＴ及与ＭＲＩ间无显著性差异（Ｐ＞０．０５）。７例ＳＰＥＣＴ图像上出现＂交叉性小脑神经失联络征＂。４例行Ｄｉａｍｏｘ脑血流负荷检查，１例原梗塞灶血流明显改善；两例显示病灶范围更广泛；另１例除小脑血流分布改善外．余处未见明显改变。４例中３例有＂交叉性小脑神经失联络征＂，使用Ｄｉａｍｏｘ后小脑血流改善。结论：本组病例ＳＰＥＣＴ灵敏度与ＣＴ及ＭＲＩ无显著差异；ＳＰＥＣＴ脑血流灌注显像可探测梗塞后存活的脑组织，为临床治疗提供客观依据；结合Ｄｉａｍｏｘ脑血流负荷检查有望进一步提高诊断的阳性率     

Cerebral perfusion changes in traumatic diffuse brain injury; IMP SPECT studies

Diffuse brain injury (DBI) is characterized by axonal degeneration and neuronal damage which cause diffuse brain atrophy. We have investigated the time course of abnormalities in cerebral perfusion distribution in cases of DBI by using Iodine-123-IMP SPECT, and the relationship to the appearance of diffuse brain atrophy. SPECT scans were performed on eight patients with diffuse brain injury due to closed cranial trauma in acute and chronic stages. All patients showed abnormalities in cerebral perfusion with decreases in perfusion, even in non-depicted regions on MRI, and the affected areas varied throughout the period of observation. Diffuse brain atrophy appeared in all patients. In some patients, diffuse brain atrophy was observed at or just after the time when the maximum number of lesions on SPECT were seen. The abnormalities in cerebral perfusion in cases of DBI might therefore be related to axonal degeneration and neuronal damage which causes diffuse brain atrophy.     

急性期脑内血肿3.0T MR扩散加权成像表现

目的:探讨3.0T MR设备中平面回波扩散加权成像(EPI-DWI)和表观扩散系数(ADC)图对急性脑内血肿的诊断价值及与脑梗死的鉴别诊断能力。方法:对18例急性期脑内血肿患者行EPI-DWI检查,获得ADC图并与CT及常规MRI进行对比。同期选择发病时间、病变体积相近的急性脑梗死患者18例,比较急性期脑内血肿与脑梗死的MRI表现。结果:所有急性期脑内血肿在EPI-DWI及ADC图上均为混杂信号,尤其是较大血肿;不同大小血肿周边均可见低信号环。所有急性脑梗死病变均未见周边环状低信号。结论:血肿周边低信号环为急性期脑内血肿的特异性DWI表现,可资与急性脑梗死相鉴别。     

脑胶质瘤病的MRI及MRS研究

目的 :回顾性分析大脑胶质瘤病磁共振成像 (MRI)及磁共振波谱 (MRS)特点 ,以探讨两者对本病诊断的临床价值。方法 :综合 7例患者的临床表现、影像学特点及病理诊断 ,均符合大脑胶质瘤病诊断标准。常规行SE序列平扫及增强。其中 3例行MRS研究 ,二维多体素、点分辨法 (PRESS)、TE 14 4ms。结果 :所有病例均侵犯 2个脑叶或以上。病变区呈长T2 、稍长T1异常信号 ,受累区脑组织肿胀 ,占位效应轻。 3例增强扫描见小结节或片状强化 ,4例无明显强化。 3例MRS表现均有不同程度NAA降低 ,Cho上升 ,Cho/Cr和Cho/NAA的比值上升。结论 :MRI是目前诊断大脑胶质瘤病的首选影像学方法 ,MRS对于鉴别诊断有较大价值。     

Pattern of cortical changes in sporadic Creutzfeldt-Jakob disease

BACKGROUND AND PURPOSE: High cortical signal intensity on diffusion-weighted (DW) or fluid-attenuated inversion recovery (FLAIR) images is increasingly described in sporadic Creutzfeldt-Jakob disease (sCJD). The aim of this study was to assess the extent and location of high cortical signal intensity, to investigate whether DW or FLAIR is superior in showing changes in cortical signal intensity, and to find out whether the distribution of the signal intensity changes is random or follows a common pattern. MATERIALS AND METHODS: We analyzed FLAIR and DW MR imaging scans of 39 patients with sCJD for hyperintense cortical signal intensity. We compared the sensitivity of the DW and FLAIR scans. We correlated the extent and location of the cortical signal intensity changes with concomitant changes in deep gray matter and the genotype of codon 129 of the prion protein gene. RESULTS: There was high signal intensity in the insula, the cingulate gyrus, and the superior frontal gyrus in 95%. The cortical areas near the midline also frequently showed the abnormal signal intensity (precuneus 87%, paracentral lobe 77%). The precentral and postcentral gyri were affected less frequently (41% and 28%, respectively). The DW MR imaging showed the cortical changes more effectively than FLAIR. There was no correlation between the distribution of changes and additional signal alterations in deep gray matter or the genotype of codon 129. CONCLUSION: The distribution of cortical signal intensity abnormalities in patients with sCJD follows a common pattern, affecting mainly the cortical areas near the midline, the insula, cingulum, and the superior frontal cortex. DW imaging is superior to FLAIR in the detection of cortical high signal intensity.     

Magnetic resonance imaging of musculoaponeurotic fibromatosis

Musculoaponeurotic fibromatosis can be mistaken for soft-tissue sarcoma both clinically and on X-ray computed tomography. Magnetic resonance imaging (MRI) in three patients with this condition enabled the correct diagnosis to be made prospectively in two. The appearance on MRI of a heterogeneous mass with well-defined, predominantly peripheral areas of very low signal intensity due to dense fibrous tissue and areas of medium to high signal intensity corresponding to a more cellular stroma should raise the the suspicion of musculoaponeurotic fibromatosis. Cellular areas within the tumour showed moderate enhancement after gadolinium diethylene triamine pentaacetic acid administration.     

Video/EEG,SPECT和MRI对部分性癫痫定位诊断作用及临床意义探讨

目的：探讨录像脑电图检测（Ｖｉｄｅｏ／ＥＥＣ）,ＳＰＥＣＴ和ＭＲＩ３种方法对部分性癫痫的无创性定位和病因诊断的作用及临床意义。材料与方法：对５２例部分性癫痫患者分别进行Ｖｉｄｅｏ／ＥＥＧ,＾９９ｍＴｃ－ＨＭＰＡＯ－ＳＰＥＣＴ脑血流显像,＾１２３Ｉ－Ｉｏｍａｚｅｎｉｌ ＳＰＥＣＴ脑受体显像和全脑ＭＲＩ检查。根据Ｖｉｄｅｏ／ＥＥＧ记录的癫痫发作类型,ＳＰＥＣＴ显示的ｒＣＢＦ和ＢＺＤ的分布以及ＭＲＩ显示     

Perirolandic hypoperfusion on single-photon emission computed tomography in term infants with perinatal asphyxia: comparison with MRI and clinical findings

We describe the findings on single-photon emission computed tomography (SPECT) in patients with perinatal asphyxia at term, with perirolandic cortico-subcortical changes on MRI, and to correlate them with clinical features. SPECT of 7 patients was obtained after injection of 185–370 MBq of Tc-99m-ECD (ethyl cysteinate dimer). The patients had spastic quadriplegia (7/7) with perinatal asphyxia (6/7) at term (7/7). The results were correlated with the MRI findings. Hypoperfusion of the perirolandic cortex was clearly seen on SPECT in all patients, even in two with subtle changes on MRI. SPECT demonstrated a more extensive area of involvement than MRI, notably in the cerebellum (in 4), the thalamus (in 7) and basal ganglia (in 5), where MRI failed to show any abnormalities. Received: 5 October 1999/Accepted: 11 November 1999     

MRI of intramedullary cavernous haemangiomas

We reviewed 11 cases of intramedullary cavernous haemangiomas (IMCH) studied by MRI, to assess its diagnostic value in these lesions. Follow-up MRI was obtained in five patients 7 days-2 years following the initial study. In one case a postoperative examination was obtained. The diagnosis was pathologically proven in ten cases, and supported in the last by a family and personal history of cavernous haemangiomas. A reticulate appearance with areas of mixed signal intensity in both T1-and T2-weighted images was the most common finding. Homogeneous high, low or intermediate signal intensity was each found in one case, Two small lesions gave low signal. A rim of low signal was less common than in cerebral cavernous haemangiomas. In one case, the brain showed more than 20 lesions with the MRI appearances of cavernous haemangiomas. In two of five patients, serial preoperative MRI showed progressive disappearance of high-signal areas on both T1-and T2-weighted images. To find a haemorrhagic intramedullary lesion on MRI is not rare. Although the appearances are not pathognomonic, an IMCH can be suggested. We suggest that the following characteristics may help: (1) a personal and/or family history of cavernous haemangiomas; (2) typical MRI appearances of mixed acute, subacute and chronic haemorrhage; (3) a tendency for signal intensity to decrease on follow-up; (4) normal spinal angiography; and (5) associated brain lesions.     

High signal in cerebrospinal fluid mimicking subarachnoid haemorrhage on FLAIR following acute stroke and intravenous contrast medium

We describe five cases of high signal in the cerebrospinal fluid (CSF) on fast-FLAIR images 24–48 h after onset of stroke. All the patients had undergone perfusion-weighted MRI within 6 h of the onset of the symptoms. The CSF was far brighter than the cortical gyri. The high signal was diffusely around both cerebral hemispheres in two cases and around one hemisphere in two others; it was focal, around the acute ischaemic lesion, in one. CT was normal in all cases. The CSF high signal was transient, decreasing in extent and intensity with time and resolving completely within 3–6 days. It was not associated with worsening of the clinical state or poor outcome. Our explanation of this phenomena is hypothetical: we speculate that it could be due to disruption of the blood-brain barrier resulting in leakage of protein, gadolinium chelates, or both in to the subarachnoid space. It should not be confused with subarachnoid haemorrhage. Received: 23 July 1999 Accepted: 24 September 1999