3.0T磁共振磁敏感成像在脑出血性病变中的应用探讨

目的 探讨3.0T磁共振磁敏感加权成像(susceptibility weighted imaging,SWI)在颅脑出血性病变中的应用价值.方法 对临床疑有颅脑出血的56例患者进行检查.其中男32例,女24例.受检者年龄14～72岁,平均45.9岁.设备:飞利浦Achieva3.0T X-series 磁共振扫描仪.全部采用常规T1WI、T2WI、FLAIR、DWI及SWI扫描,有8例患者追加MRA检查.对各扫描序列显示的异常信号,尤其是出血灶的显示及出血灶大小、多少及病灶分布进行分析.同时对脑静脉分支显示进行后处理,以提高脑静脉的显示质量.结果 56例患者脑静脉分支均显示清楚.SWI显示22例有出血灶(22/56),T1WI显示8例有出血灶(8/56),T2WI显示11例有出血灶(11/56),FLAIR显示10例有出血灶(10/56),DWI显示7例有出血灶(7/56).13例脑梗死患者,4例提示治疗后梗死区有低信号出血灶.3例脑血管瘤合并出血者,SWI显示出血灶明显大于和多于常规T1WI及T2WI序列显示.1例CT扫描阴性,SWI显示大脑前动脉畸形并少量蛛网膜下腔出血.结论 3.0T磁共振扫描仪磁敏感序列(SWI)对脑出血的敏感性明显高于其他常规序列,是一种显示少量脑出血及提高出血灶检出率的有效检查方法,值得在临床疑有脑出血性病变的患者检查中运用.     

磁敏感加权成像在出血性脑梗死诊断中的初步应用

目的探讨磁敏感加权成像（SWI）诊断出血性脑梗死的临床价值。方法20例亚急性期出血性脑梗死患者分别行常规MRI、扩散加权成像（DWI）和SWI检查,根据图像分析结果比较不同扫描序列所显示的梗死灶内出血灶数目及其阳性检出率;测量SWI序列出血最大层面出血灶面积和T2WI序列梗死灶最大层面的梗死灶面积,并行相关分析;观察SWI序列对梗死灶内静脉血管的显示程度,以及梗死灶以外区域微出血灶的诊断敏感性。结果20例患者SWI序列均显示梗死灶内出血,两名医师共诊断43个出血灶,其中SWI序列显示42个、T1WI序列25个、DWI序列15个、T2WI序列12个;SWI序列阳性检出率与T1WI、T2WI、DWI序列相比,差异具有统计学意义（X^2=51．516,P=0．000）。T2WI序列梗死灶最大层面的梗死灶面积为（18．08±12．47）cm^2,SWI为（5．02±6．27）cm^2,梗死灶面积与出血灶范围之间呈明显正相关（r=0．562,P=0．010）。其中,13例患者SWI序列检出梗死灶以外区域的微出血灶;12例显示梗死灶内小静脉血管分支减少和（或）变细,6例血管增多、增粗和（或）扭曲。结论SWI序列对出血性脑梗死病灶内出血的显示优于常规MRI和DWI序列,并能显示梗死灶内静脉血管的变化及梗死灶以外区域的微出血灶,可作为诊断出血性脑梗死的MRI常规扫描序列。     

磁敏感加权成像检查对自发性脑出血急性期的诊断价值

目的探讨磁敏感加权成像检查(SWI)对自发性脑出血急性期的诊断价值。方法142例自发性脑出血急性期患者,分析其临床资料,常规行头颅CT扫描。统计头颅CT的出血灶,MR各序列的出血灶显示率。结果近一半的自发性脑出血患者有高血压史,最常见的出血部位位于基底节及丘脑。SWI对出血灶的检出率100%,T1检出率16.32%,T2检出率18.40%,FLAIR检出率19.0%。统计发现SWI对自发性脑出血急性期出血灶显示最高,与T1WI、T2WI及FLAIR序列间差异有统计学意义(P0.05),而T1WI、T2WI及FLAIR序列间差异无统计学意义(P0.05)。结论 SWI对自发性脑出血急性期出血灶的显示明显高于其他序列,为脑出血早期出血灶的有效检查方法,对脑内出血有极高的诊断价值。     

3.0 T MR磁敏感加权成像对脑干微量出血的诊断价值

目的探讨磁敏感加权成像(SWI)对脑干微量出血的诊断价值。方法对50例脑干微量出血患者行头颅常规MRI(T_1WI、T_2WI)、弥散加权成像(DWI)序列、SWI序列扫描。结果 50例脑干微量出血患者中共计检测出116个出血灶。SWI序列清晰显示50例脑干微量出血患者的116个出血灶,以此为金标准。DWI序列(b值=1 000)共检出26例67个出血灶,患者检出的阳性率为52.00%,出血灶的检出率为57.76%。T_2WI序列共检出19例35个出血灶,患者检出的阳性率为38.00%,出血灶的检出率为30.17%。T_1WI序列共检出11例14个出血灶,患者检出的阳性率为22.00%,出血灶的检出率为12.07%SWI序列对脑干微量出血患者病灶检出数目显著高于DWI序列、T_2WI和T_1WI序列(均P0.05)。结论 SWI序列对脑干微量出血患者检出的阳性率和出血灶的检出率明显高于DWI序列、T_2WI和T_1WI序列,对脑干微量出血灶的诊断方面有明显的优势。     

DWI联合SWI在急性自发性微量脑出血的临床研究

目的探讨磁共振弥散加权成像(DWI)联合磁敏感加权成像(SWI)在急性自发性微量脑出血中的诊断价值及与急性脑梗死的区别。方法急性脑血管病患者57例,其中自发性微量脑出血25例(微出血组),脑梗死32例(脑梗死组)。所有患者行常规头颅MRI、SWI、DWI序列扫描,分析微出血组以及脑梗死组在各序列上的影像学特点,统计各序列对出血灶或梗死灶的检出率,比较2组间血肿中心的ADC值及PW值,进行统计分析。结果微出血组在SWI上血肿呈类圆形低信号或者类圆形低信号混杂点状高信号影,周围见高信号,与其他MRI序列相比,SWI序列对出血灶的检出率最高。脑梗死组在DWI表现为显著高信号,且边缘清晰,与其他序列比较,DWI序列对梗死灶的检出率最高。脑梗死组血肿中心的ADC值及PW值均明显高于微出血组(P0.05)。结论 SWI对急性自发性微量脑出血的诊断准确性最高,几乎无漏诊。DWI对脑梗死的诊断具有明显的特异性及准确性。DWI联合SWI能有效诊断急性微量脑出血,并能与梗死后的微量脑出血相鉴别,能合理指导临床治疗。     

磁敏感加权成像在出血性脑梗死诊断中的初步应用

目的 探讨磁敏感加权成像(SWI)诊断出血性脑梗死的临床价值.方法 20例亚急性期出血性脑梗死患者分别行常规MRI、扩散加权成像(DWI)和SWI检查,根据图像分析结果比较不同扫描序列所显示的梗死灶内出血灶数目及其阳性检出率;测量SWI序列出血最大层面出血灶面积和T2WI序列梗死灶最大层面的梗死灶面积,并行相关分析;观...     

磁敏感加权成像在脑微出血诊断中的应用价值

目的探讨磁敏感加权成像在脑微出血诊断中的应用价值。方法选取我院收治的120例疑似脑微出血患者为研究对象,对120例疑似脑微出血患者分别行MRI常规序列扫描以及SWI序列扫描,对检出CMBs阳性例数、脑微出血灶位置分布情况、脑微出血灶数量的显示情况进行比较。结果 90例患者通过SWI检测均显示出磁敏感效应,SWI主要表现为条状、点状以及类圆形等,检出率为100%;86例常规序列检出CMBs阳性,检出率为76.5%,二者具有显著性差异(P0.05)。90例患者中通过T1WI序列扫描表示病灶显示不明显,通过T2WI序列扫描共检出232个低信号灶。SWI序列共检出1 392个低信号灶。结论磁敏感加权成像技术具有高度的敏感性,在现阶段的临床应用中可检出脑微出血的最佳序列,从而更好的为临床治疗提供参考。     

SWI DWI序列在颈椎手术后并发急性脑梗死脑出血中的诊断价值

目的探讨磁共振磁敏感加权像(SWI)、弥散加权成像(DWI)在颈椎术后并发急性脑梗死、脑出血中的诊断价值。方法 2010-01—2015-12我院行颈椎手术、临床确诊术后并发急性脑梗死37例和急性脑出血14例,采用GE 1.5T磁共振,全部行常规横断位T1WI、T2WI、FLAIR、SWI(磁敏感加权成像)、DWI(磁共振扩散加权成像)扫描,所得影像学资料进行对比分析。结果 37例颈椎术后急性期脑梗死患者,常规MRI序列2例未检出;DWI序列全部检出,其信号表现为均匀的高信号影;SWI表现为等信号,出血继发性转化时,其信号成斑片样低信号影。14例颈椎术后急性脑出血期患者,常规序列、DWI序列1例未检出;SWI全部检出。DWI序列表现为血肿中心呈低信号影,周围环绕稍高信号的水肿区;SWI序列表现为血肿中心区均匀片样低信号,周围环绕高信号水肿区。结论 DWI、SWI较常规颅脑MRI序列可及早、准确的检出早期颈椎手术后并发的急性脑梗死、脑出血,并根据其影像表现不同,行快速诊断及鉴别,对患者的预后有重要意义。     

DWI序列及SWI序列在弥漫轴索损伤中的诊断价值

目的探讨DWI序列及SWI序列检查在DAI中的诊断价值。方法 36例DAI患者按颅脑CT是否发现脑实质内出血分为脑CT阳性组及阴性组。评价2组MRI平扫(T1WI、T2WI)及弥散加权成像(DWI)、磁敏感成像(SWI)影像学资料,观察不同检查方法对DAI的敏感性。结果 CT阳性组CT、T1WI、T2WI、FLAIR、DWI、SWI出血病灶检出率分别为16%、21.6%、38.9%、42.8%、62.1%、98.2%,CT阴性组分别为2.7%、14.4%、17.8%、21.9%、100%、23%,DWI序列在非出血性弥漫轴索损伤的检出率最高,与MRI常规平扫及CT相比有显著性差异(P0.05);而SWI序列在出血组检出率最高,与MRI常规平扫及CT相比有显著性差异(P0.05)。结论 DAI影像中DWI序列在非出血病灶及SWI序列在出血性病灶的检出率高于CT及MRI常规序列,应将DWI及SWI序列作为诊断DAI的常规检查。     

SWI 技术在脑血管疾病诊断中的应用

目的：探讨磁共振磁敏感加权成像技术在脑血管疾病诊断中的临床应用价值。方法回顾分析我院2012-09-2013-12收治的74例脑血管疾病患者的常规序列 T1WI、T2WI、DWI、FLAIR及SWI、增强 T1WI、MRA图像,评价SWI序列显示小出血灶、小静脉、海绵状血管瘤、脑内铁钙异常沉积等方面的优越性。结果 SWI可鉴别海绵状血管瘤出血与血管,发现更多的小出血灶,发现常规序列扫描不能发现的小静脉畸形并显示向大静脉的引流,显示脑外伤平扫时难以发现的更多小出血灶和脑梗死伴发的小出血灶。结论 SWI是显示脑部低流量血管畸形、小静脉的结构,多发小灶性出血以及铁钙沉积十分敏感的脉冲序列,作为M RI常规序列的重要补充,对脑血管疾病的诊断和鉴别诊断具有重要意义。     

磁敏感加权成像在轻型颅脑损伤患者中的诊断价值

目的探讨磁共振磁敏感加权成像(SWI)对轻型颅脑损伤(MTBI)患者的诊断价值。方法回顾分析32例MTBI患者(格拉斯哥昏迷量表评分13~15分)的临床资料。患者伤后1周内给予头部CT、MRI及SWI检查,结合CT及相位图排除气体、血管和颅底伪影后,SWI图上的低信号为脑内挫伤出血灶。分别记录MRI常规序列和SWI探查到的病灶数目、发生部位,并结合临床症状进行分析。结果 SWI对脑外伤微小挫伤出血灶检查阳性率明显高于CT及MRI普通序列扫描,特别是在伤后出现晕厥昏迷史或持续性出现临床症状的患者中更为明显。结论 SWI比常规CT及MRI对MTBI患者脑内微小挫伤及出血灶的检出有更高的准确性和客观的诊断价值,并对指导临床治疗及判断预后有重大意义。     

Hypointensity of draining veins on susceptibility-weighted magnetic resonance images might indicate normal venous flow and a lower risk of intracerebral hemorrhage in patients with intracranial arteriovenous shunt(s)

Patients with intracranial arteriovenous shunt(s) have a risk of intracerebral hemorrhage (ICH). We investigated the signal intensity of draining veins on susceptibility-weighted imaging (SWI) and the status of venous drainage shown by digital subtraction angiography (DSA). We then evaluated whether the signal intensity of draining veins on SWI is related to normal venous flow (NVF) and/or ICH. We analyzed SWI and DSA in 10 consecutive patients with intracranial arteriovenous shunt(s). Opacification of draining veins in the normal venous phase by DSA was judged as NVF. We evaluated the relationship between the intensity of draining veins on SWI and the presence of NVF before and after treatment. The relationship between the intensity of draining veins on SWI and the presence of ICH surrounding the draining veins was also evaluated. Of 10 patients with untreated arteriovenous shunt(s), two had arteriovenous malformation and eight had a dural arteriovenous fistula with cortical venous reflux. We analyzed 26 draining veins before treatment. In preoperative analysis, draining veins with hypointensity were significantly more likely to show NVF than were draining veins with isointensity or hyperintensity (45.5% vs. 0.0%, P = 0.007). While 69.2% of the areas surrounding draining veins with isointensity or hyperintensity showed ICH, no veins with hypointensity showed ICH (P = 0.011, odds ratio 0.036; 95% confidence interval 0.0017–0.80). In conclusion, draining veins with hypointensity on SWI may contain NVF, despite arteriovenous shunting. The areas surrounding these veins might have a lower risk of ICH because of less venous hypertension.     

Utility of magnetic resonance imaging in acute intracerebral hemorrhage.

The authors determine whether magnetic resonance imaging (MRI) during acute hospitalization for spontaneous intracerebral hemorrhage (ICH) provides new diagnostic information. ICD-9 codes were used to identify consecutive patients with spontaneous ICH at Hermann Hospital, Houston, Texas, between January 1995 and August, 1997. Two investigators employed rigorous criteria to determine whether the MRI findings led to a specific new diagnosis. Two hundred ninety-one patients met inclusion and exclusion criteria. Sixty-seven (23%) patients underwent brain MRI during the acute hospitalization. MRI provided a new diagnosis in 15 of these 67 patients (22%). Amyloid angiopathy and vascular malformation (four each) were the most frequently identified etiologies. The yield of MRI was low in basal ganglia and thalamic hemorrhage. Two of 23 (9%) patients with deep ICH and 13 of 44 (30%) patients with lobar and infratentorial hemorrhage had etiology determined by MRI. Timing of MRI did not affect yield.     

MRI features of intracerebral hemorrhage within 2 hours from symptom onset.

BACKGROUND AND PURPOSE: MRI has been increasingly used in the evaluation of acute stroke patients. However, MRI must be able to detect early hemorrhage to be the only imaging screen used before treatment such as thrombolysis. Susceptibility-weighted imaging, an echo-planar T2* sequence, can show intracerebral hemorrhage (ICH) in patients imaged between 2.5 and 5 hours from symptom onset. It is unknown whether MRI can detect ICH earlier than 2.5 hours. We describe 5 patients with ICH who had MRI between 23 and 120 minutes from symptom onset and propose diagnostic patterns of evolution of hyperacute ICH on MRI. METHODS: As part of our acute imaging protocol, all patients with acute stroke within 24 hours from symptom onset were imaged with a set of sequences that included susceptibility-weighted imaging, diffusion- and perfusion-weighted imaging, T1- and T2-weighted imaging, fluid-attenuated inversion recovery (FLAIR), and MR angiography using echo-planar techniques. Five patients with ICH had MRI between 23 and 120 minutes from the onset of symptoms. RESULTS: ICH was identified in all patients. Distinctive patterns of hyperacute ICH and absence of signs of ischemic stroke were the hallmark features of this diagnosis. The hyperacute hematoma appears to be composed of 3 distinct areas: (1) center: isointense to hyperintense heterogeneous signal on susceptibility-weighted and T2-weighted imaging; (2) periphery: hypointense (susceptibility effect) on susceptibility-weighted and T2-weighted imaging; and (3) rim: hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging, representing vasogenic edema encasing the hematoma. CONCLUSIONS: MRI is able to detect hyperacute ICH and show a pattern of evolution of the hematoma within 2 hours from the onset of symptoms.     

Susceptibility weighted magnetic resonance imaging of brain: A multifaceted powerful sequence that adds to understanding of acute stroke

Context:

To evaluate the additional information that susceptibility weighted sequences and datasets would provide in acute stroke.

Aims:

The aim of this study were to assess the value addition of susceptibility weighted magnetic resonance imaging (SWI) of brain in patients with acute arterial infarct.

Materials and Methods:

All patients referred for a complete brain magnetic resonance imaging (MRI) between March 2010 and March 2011 at our institution had SWI as part of routine MRI (T1, T2, and diffusion imaging). Retrospective study of 62 consecutive patients with acute arterial infarct was evaluated for the presence of macroscopic hemorrhage, petechial micro-bleeds, dark middle cerebral artery (MCA) sign and prominent vessels in the vicinity of infarct.

Results:

SWI was found to detect hemorrhage not seen on other routine MRI sequences in 22 patients. Out of 62 patients, 17 (10 petechial) had hemorrhage less than 50% and 5 patients had greater than 50% area of hemorrhage. A “dark artery sign” due to thrombus within the artery was seen in 8 out of 62 patients. Prominent cortical and intraparenchymal veins were seen in 14 out of 62 patients.

Conclusions:

SWI has been previously shown to be sensitive in detecting hemorrhage; however is not routinely used in stroke evaluation. Our study shows that SWI, by virtue of identifying unsuspected hemorrhage, central occluded vessel, and venous congestion is additive in value to the routine MR exam and should be part of a routine MR brain in patients suspected of having an acute infarct.     

无蛛网膜下腔出血的破裂脑动脉瘤

目的 总结无蛛网膜下腔出血(SAH)的破裂脑动脉瘤的诊治经验.方法 对15例在起病后2 d内首次CT或MRI上表现为脑内出血(ICH),和(或)脑室内出血(IVH)、硬脑膜下血肿(SDH)和壁间出血(IMH)而无SAH的破裂脑动脉瘤患者的临床表现、影像学检查结果 、治疗方法 和预后进行回顾性分析.结果 本组首次CT或MRI检查表现为ICH者3例、IVH合并ICH者6例、SDH者1例、IVH者1例、IMH者3例和等高混合密度者1例.其中动脉瘤位于大脑中动脉6例、前交通动脉4例、后交通动脉3例、大脑前动脉1例和小脑后下动脉1例.开颅手术夹闭动脉瘤13例,血管内栓塞2例.出院时GOS评分:恢复良好8例、中残3例、重残3例和植物生存1例.本组15例占同期破裂脑动脉瘤的3.8%.结论 破裂脑动脉瘤首次CT扫描可表现为单纯ICH,和(或)IVH、SDH、IMH而无SAH,与CT扫描时间、动脉瘤的部位和指向以及出血量有关.早期控制颅内高压、及时诊断和有效处理破裂动脉瘤,是改善预后的关键.     

Thrombolysis for ischemic stroke in patients with old microbleeds on pretreatment MRI

BACKGROUND: Old asymptomatic microbleeds (MBs) visualized on T2-weighted MRI are indicative of microangiopathy. They may be a marker of increased risk of intracerebral hemorrhage (ICH) following thrombolysis. However, data regarding this potential risk are limited. METHODS: A retrospective analysis of pretreatment T2-weighted MRI was performed in consecutive stroke patients who received intravenous tissue plasminogen activator (tPA). We aimed to assess the impact of MBs on the risk of cerebral bleeding. The frequency and location of MBs were assessed and compared with the location of ICH after thrombolysis. RESULTS: Forty-four patients were studied. MBs were present on pretreatment MRI in 8 cases (18.2%). At day 1, symptomatic ICH occurred in none of 8 patients with MBs versus 1 of 36 patients without (NS). At day 1, ICH occurred in 3 of 8 patients with MBs versus 10 of 36 patients without (NS). At day 7, symptomatic ICH occurred in 1 of 8 patients with MBs versus 2 of 36 patients without (NS). At day 7, ICH occurred in 5 of 8 patients with MBs versus 12 of 36 patients without (NS). No ICH occurred at the site of an MB. ICH occurred within the ischemic area in all patients who bled. CONCLUSIONS: Our study suggests that stroke patients with a small number of MBs on pretreatment MRI could be treated safely with thrombolysis. Larger prospective studies are needed to address the predictive value of detection of MBs with regard to the risk of tPA-induced ICH.