颅内动脉瘤流动伪影在不同MRI序列上的表现差异

目的 探讨颅内动脉瘤流动伪影在不同MRI序列上的表现.方法 对经DSA或手术证实同时合并有流动伪影的19例颅内动脉瘤的MRI资料进行回顾分析.使用GE Signa 1.0T超导型MRI扫描仪.全部患者均行脑SE序列T1WI和T2WI、GRE序列、FLAIR序列、对比增强T1WI及3D TOF MRA扫描.结果 颅内动脉瘤流动伪影在所有MRI序列图像上均表现为动脉瘤残腔水平的不规则条带状影,且均位于相位编码方向.19例颅内动脉瘤在FLAIR序列上均可显示流动伪影,GRE序列上显示18例,T2WI上显示17例,T1WI上显示9例.行Gd-DTPA增强的7例病人T1WI图像均显示相位编码方向上的流动伪影.GRE序列及FLAIR序列图像上的流动伪影强度大于SE序列;T2WI上的流动伪影强度大于T1WI;对比剂注入后T1WI增强图像上的流动伪影强度明显大于增强前图像.结论 不同MRI序列上颅内动脉瘤流动伪影的强度不同.     

肝脏容积加速采集序列增强扫描对颅内病变的应用价值

目的探讨肝脏容积加速采集(LAVA)序列增强扫描在颅内病变中的应用价值。方法分析40例颅内病变病人的头颅MRI增强检查影像,男19例,女21例,年龄12~80岁,平均(48.1±16.1)岁,均进行LAVA与快速反转恢复(FIR)T1WI序列两种增强扫描,测量两种序列获得影像的信噪比、对比噪声比、病变的面积,采用Wilcoxon符号秩检验进行比较。计算血管流动伪影出现率,观察病变的边界、信号,采用配对χ2检验进行比较。结果FIR T1WI与LAVA影像显示病变的边界、信号、面积差异无统计学意义(P0.05),两者的信噪比、对比噪声比及血管流动伪影出现率分别为74.75(59.29~103.17)和26.72(22.61~34.78)、41.67(28.21~65.92)和22.89(14.76~32.27)、90%和27.5%,差异均有统计学意义(均P0.001),扫描时间分别为195 s、87 s。LAVA序列检出6例肿瘤的供血动脉及引流静脉、3例静脉窦血栓、2例动脉瘤,FIR T1WI序列均未检出;7例转移瘤病人采用LAVA与FIR T1WI序列发现的病变数目分别为35个、30个。结论LAVA序列增强扫描可同时观察颅内病变和血管情况,与FIR T1WI对比扫描时间缩短,血管流动伪影出现率低,有较大的临床应用价值。     

MR螺旋桨技术消除颅脑各种伪影的临床应用价值

目的:比较MR螺旋桨技术T2WI序列与常规FSE T2WI序列减少运动伪影效果,评价其临床应用价值。材料和方法:随机对82例行头部常规检查者,同时行螺旋桨技术T2WI序列扫描。由2名高职MR室医师分别评价其血管搏动、眼球运动、脑脊液波动、头部运动伪影。结果:82例中,常规T2WI扫描产生血管搏动伪影56例计106条、眼球运动伪影59例(1例因金属伪影无意义)、脑脊液波动伪影29例32条;头运动伪影35例(5例因金属伪影影响观察)。螺旋桨技术T2WI扫描未产生血管搏动和眼球运动伪影、脑脊液搏动伪影4例、头运动伪影2例。结论:螺旋桨技术在消除常规头颅扫描中产生伪影有显著效果,对疾病的确诊具有临床意义,有较好的应用前景。     

3D-ASL在短暂性脑缺血发作中的诊断价值

目的 探讨MR三维动脉自旋标记(3 D-ASL)灌注成像在短暂性脑缺血发作(TIA)中的诊断价值.方法 对78例临床诊断为TIA的患者行MR常规扫描[(T1 WI、T2 WI、T2-FLAIR、扩散加权成像(DWI)]、磁共振血管成像(MRA)和3D-ASL扫描.根据扫描结果进行χ2检验并分析.结果 78例患者中,常规扫描显示信号异常0例(0%);MRA显示血管异常41例(52.6%);3 D-ASL显示灌注异常47例(60.2%);两者联合应用显示异常患者60例(76.9%),其中MRA阳性+ASL阳性29例;MRA阳性+ASL阴性12例;MRA阴性+ASL阳性19例;MRA阴性+ASL阴性18例.结论 3 D-ASL技术在TIA的诊断上优于MR常规序列,且方便易行,应该作为TIA诊断的常规扫描序列.3 D-ASL、MRA、DWI 3种检查方法各具优缺点,联合应用可以提高TIA的诊断准确率.     

颅内表皮样囊肿MRI诊断的序列选择及应用价值

目的探讨MR各种扫描序列对颅内表皮样囊肿的诊断价值。资料与方法49例经手术及病理证实的颅内表皮样囊肿,均行T1WI、T2WI、液体衰减反转恢复序列(FLAIR)、扩散加权成像(DWI)及增强扫描。9例T1WI呈高信号者加扫脂肪抑制像。结果49例肿瘤中不规则形36例,圆形或类椭圆形13例。在T2WI上,38例呈高信号,另11例为高信号中夹杂斑片状等信号;肿瘤在T1WI上信号多变,其中40例为低信号,余9例为高低混杂信号(6例)或高信号(3例),经脂肪抑制后,其中3例部分高信号衰减;FLAIR为中等及低混杂信号;所有患者DWI均为高信号;增强后34例无强化,15例边缘弧线形强化。结论颅内表皮样囊肿在MR各序列上均有特征性表现。DWI扫描有助于鉴别诊断。MRI多方位、多序列扫描的综合应用,能术前准确诊断,使选择最佳手术方式和入路成为可能。     

磁共振B-TFE序列在胆囊癌诊断中的价值

目的评价B-TFE序列在胆囊癌诊断中的价值。方法回顾性分析经手术证实的32例胆囊癌患者(其中胆囊壁增厚型6例,腔内型8例,肿块型18例)腹部MR B-TFE序列和上腹部MR常规T1WI、T2WI及MRCP扫描图像。结果所有病例的B-TFE序列图像无明显伪影,对胆囊及胆囊病变的显示率100%,诊断符合率96.88%。与上腹部常规T1WI、T2WI及MRCP比较具有统计学差异性。结论B-TFE序列在胆囊癌的诊断中具有重要价值。     

肝细胞特异性对比剂泰乐影与腹部屏气扫描技术的研究

目的:探讨肝细胞特异性对比剂泰乐影增强扫描时最优的T1WI序列及成像参数。方法:对13例病例20个病灶行MR SE T1WI序列、FFE T1WI in phase序列、FFE T1WI out phase序列扫描,测量各序列肝脏病变及正常肝实质的平均信号强度,计算并比较各序列信噪比(signal/noise, S/N)、对比噪声比(contrast/noise, C/N)及对比伪影比(con trast/artifact,C/A)。结果:out phase和in phase序列图像的呼吸运动伪影最小,20个病灶中仅有2个(10%)有呼吸运动伪影,而SE序列则有8例(90%)有呼吸运动伪影。out phase序列显示肝内门静脉及肝静脉优于SE序列,显示病变比SE序列清楚。结论:FFE T1WI out phase序列为肝细胞特异性对比剂泰乐影T1WI成像的最优序列,TR 25 ms、TE 6.9 ms、翻转角20°为其最优成像参数。     

颅内巨大动脉瘤的MR影像学分析

目的　分析颅内巨大动脉瘤的MR影像学表现。方法　搜集 40例经手术病理证实的颅内巨大动脉瘤。结果　颅内巨大动脉瘤的MR信号表现多样 ,主要与动脉瘤内是否出现血栓 ,血栓的大小和形成时间的长短 ,和动脉瘤引起的继发改变等因素有关。瘤腔信号 :绝大部分巨大动脉瘤表现出典型的流空现象或流动信号。瘤腔水平可见的血管流动伪影 ,注药后明显强化。血栓信号 :大部分动脉瘤中出现了血栓 ,血栓信号差异很大 ,多呈层状或涡状的混杂信号 ,增强扫描无强化。无血管流空伪影。DSA和MRA可显示动脉瘤瘤腔 ,不能显示动脉瘤内是否存在血栓或闭塞 ,低估动脉瘤的大小。绝大部分动脉瘤可在MRA中证实。结论　MR可清楚显示颅内巨大动脉瘤的全貌 ,包括瘤腔和血栓形成情况 ,是DSA检查的必要补充。     

颅内柔脑膜转移瘤：低场MRI FLAIR序列与T1WI增强扫描对比分析

目的:评估低场MR液体衰减反转恢复(FLAIR)序列诊断颅内柔脑膜转移瘤的价值.材料和方法:回顾性分析30例颅内柔脑膜转移瘤的FLAIR序列平扫与T1WI常规剂量增强扫描的表现.结果:T1WI增强扫描检出柔脑膜转移瘤128个,而FLAIR检出117个,T1WI增强扫描检出病灶较FLAIR序列敏感(P<0.05);T1WI增强扫描明确所有病灶边界,而FLAIR序列对所有病灶的边界显示不清.结论:对于颅内柔脑膜转移瘤的低场MR诊断,T1WI增强扫描优于FLAIR序列.     

脑动脉瘤的MRI、MRA诊断

目的：探讨常规MR／、MRA以及不同后处理方法对脑动脉瘤的显示能力及诊断价值。方法：应用磁共振T1、T2WI以及3D-TOF-MRA对44例患者进行检查，并使用最大信号强度投影(MIP)、表面遮盖成像(SSD)、多平面重建(MRR)、容积重建(VR)等方法进行后处理。结果：44例患者MR／均发现单发病灶，呈类圆形、梭形、不规则形、葫芦状等，边界清楚。病灶较特异的信号表现为，流空低信号、涡流信号(混杂信号)及部分病灶周围的血流伪影。MRA可清晰显示动脉瘤部位、形态、大小，选择适当后处理方法显示瘤体生长方向、瘤颈形态以及与载瘤血管的关系，为外科手术治疗提供依据。结论：MPI、MRA为无创性显示脑血管的有效方法，提高对脑动脉瘤常规MRI、MRA典型征象的认识，熟练掌握并灵活运用MRA后处理方法可以有效提高磁共振对脑动脉瘤的诊断率。     

颈动脉体瘤的MRI和MRA表现

目的 探讨颈动脉体瘤的ＭＲＩ及ＭＲＡ表现。材料与方法 １３例１５个颈动脉体瘤术前ＳＥＴ１ＷＩ检查,其中行２ＤＴＯＦ ＭＲＡ检查者１２个,ＳＥＴ１ＷＩ增强检查者１０个。结论 １５个颈动脉体瘤均位于颈动脉分叉水平,１３个骑跨于颈动脉分叉（８６．６６％）。Ｔ１ＷＩ表现为等或略高信号,Ｔ２ＷＩ表现为混合高信号。ＳＥＴ１Ｗ１３个肿块内可见流空信号（８６．６６％）,ＦＳＥ Ｔ２ＷＩ均可见流空信号（１００％）。     

颅内动脉瘤的MR诊断

目的:探讨MR对颅内动脉瘤的诊断价值,提高颅内动脉瘤MR及临床表现的认识。方法:回顾性分析8例颅内动脉瘤患者的MR及临床表现资料,男3例,女5例,年龄2.5～70岁,平均48.1岁,所有病例均经临床或DSA证实。突发头痛、呕吐4例,双眼视力障碍2例,间歇性头痛、头晕2例。所有患者均行MR平扫及增强扫描。结果:本组8例患者共发现动脉瘤8处,均为单发,位于鞍上池附近,圆形或类圆形,大小约0.7cm×0.5cm×0.6cm～2.2cm×2.4cm×2.5cm不等;信号混杂,T1WI以等、高信号为主,T2WI为低、等或高信号,7例可见附壁血栓;增强扫描病灶信号从内到外表现一定层次感:内部血流强化呈明显高信号,新月形附壁血栓强化不明显或轻度强化,最外层瘤壁成环形强化。结论:作为无创性影像学检查手段,MR对颅内动脉瘤具有重要诊断价值。     

MR evaluation ex vivo and in vivo of a covered stent-graft for abdominal aortic aneurysms: ferromagnetism, heating, artifacts, and velocity mapping

Magnetic resonance imaging (MRI) safety was evaluated at 1.5 T in a covered nickel titanium stent-graft (Vanguard) used for endovascular treatment of abdominal aortic aneurysms (AAAs). Imaging artifacts were assessed on MRI with contrast-enhanced (CE) three-dimensional (3D) MR angiography (MRA) and spiral computed tomography (CT) in 10 patients as well as ex vivo. Velocity mapping was performed in the suprarenal aorta and femoral arteries in 14 patients before and after stent-graft placement. For comparison it was also performed in six healthy volunteers. No ferromagnetism or heating was detected. Metal artifacts caused minimal image distortion on MRI/MRA. The artifacts disturbed image evaluation on CT at the graft bifurcation and graft limb junction. No significant differences in mean flow were found in patients before and after stent-graft placement. Our study indicates that MRI at 1.5 T may be performed safely in patients with the (Vanguard) stent-graft. MRI/MRA provides diagnostic image information. Velocity mapping is not included in our routine protocol.     

MR angiography at 3T versus digital subtraction angiography in the follow-up of intracranial aneurysms treated with detachable coils

BACKGROUND AND PURPOSE: Digital subtraction angiography (DSA) is used to follow-up intracranial aneurysms treated with detachable coils to identify recurrence and determine need for additional treatment. However, DSA is invasive and involves a small risk of neurologic complications. We assessed the feasibility and usefulness of 3D time-of-flight (TOF) MR angiography (MRA) performed at 3T compared with DSA for the follow-up of coil-treated intracranial aneurysms. METHODS: In a prospective study, 20 consecutive patients with 21 intracranial aneurysms treated with coils underwent DSA and nonenhanced and enhanced multiple overlapping thin-slab acquisition 3D TOF MRA at 3T on the same day at a mean follow-up of 6 months (range, 4-14 months) after coil placement. MRA images were evaluated for presence of artifacts, presence and size of aneurysm remnants and recurrences, patency of parent and branch vessels, and added value of contrast material enhancement. MRA and DSA findings were compared. RESULTS: Interobserver agreement of MRA was good, as was agreement between MRA and DSA. All three recurrences that needed additional treatment were detected with MRA. Minor disagreement occurred in four cases: three coil-treated aneurysms were scored on MRA images as having a small remnant, whereas on DSA images these aneurysms were occluded; the other aneurysm was scored on MRA images as having a small remnant, whereas on DSA images this was a small recurrence. Use of contrast material had no additional value. Coil-related MR imaging artifacts were minimal and did not interfere with evaluation of the occlusion status of the aneurysm. CONCLUSION: High-spatial-resolution 3D TOF MRA at 3T is feasible and useful in the follow-up of patients with intracranial aneurysms treated with coil placement.     

Diagnostic accuracy of 3D time-of-flight MR angiography compared with digital subtraction angiography for follow-up of coiled intracranial aneurysms: influence of aneurysm size

BACKGROUND AND PURPOSE: 3D time-of-flight MR angiography (3D TOF MRA) may be used as noninvasive alternative to digital subtraction angiography (DSA) for the follow-up of patients with intracranial aneurysms treated with Guglielmi detachable coils (GDCs). We aimed to determine the influence of aneurysm size and location on diagnostic accuracy of 3D TOF MRA for follow-up of intracranial aneurysms treated with GDCs. MATERIALS AND METHODS: Two hundred and one 3D TOF MRAs in 127 consecutive patients with 136 aneurysms were compared with DSA as standard of reference. Sensitivity and specificity of 3D TOF MRA for detection of residual or reperfusion of the aneurysms was calculated with regard to aneurysm size and location. RESULTS: Overall sensitivity and specificity of MRA was 88.5% and 92.9%, respectively. Sensitivity was lower for aneurysms 相似文献   

Intracranial aneurysm stenting: follow-up with MR angiography

Intracranial stenting is increasingly being used to treat intracranial aneurysms and stenoses. We wanted to assess the utility of magnetic resonance angiography (MRA) in the follow-up of patients treated with various types of intracranial stents and to assess the utility of performing gadolinium-enhanced MRA. A total of 19 patients having undergone intracranial stenting for aneurysms were imaged by MRI at 1.5T. A total of 20 stents were placed in 19 patients. In addition to conventional T2- and diffusion-weighted MRI, 3D time-of-flight MRA was performed before and after contrast administration. In the case of metallic INX stents (N = 7), there was a signal drop at the level of the vessel. which did not allow to evaluating the parent vessel, whereas this was visible in Nitinol stents (N = 8). Additionally a stent with a wire had a small artifact (N = 3). Contrast administration also improved vessel lumen visualization. In the case of Nitinol stents, MRA can be used to reliably demonstrate the vessel lumen after intracranial stenting. The use of postcontrast 3D time-of-flight imaging helps improve the intraluminal definition.     

三维主动脉增强磁共振造影技术（附32例报告）

目的：探讨三维增强磁共振血管造影（three dimensional contrast enhancement magnetic resonance angiography,3DCEMRA）技术及其临床应用价值。方法：32例动脉瘤病例中男性23例,女性9例。最大年龄为82岁,最小年龄为32岁,平均年龄64岁。所有病例均进行3DCEMRA检查。增强对比剂为钆-喷替酸萄甲胺（Gd-DTPA）。增强扫描前先行横断位FSE序列T1WI和/或T2WI。CEMRA扫描后行横断位FSET1WI。观察指标包括动脉瘤的起始位置、真假性、范围（长度和最宽直径）、有无血栓、动脉瘤周围结构有无异常等。结果：①动脉瘤的位置：32例动脉瘤中,8例为胸主动脉瘤,22例腹主动脉瘤,1例髂血管动脉瘤,1例肠系膜上动脉瘤;②动脉瘤的真假性：25例呈真性,7例呈假性;③动脉瘤的范围：长度范围为25～162mm,平均长度为80.4mm;宽度范围为32～101mm,平均宽度为54.8mm;④伴有血栓情况：12例动脉瘤内可见附壁血栓形成;⑤动脉瘤累及分支情况：1例累及右侧颈总动脉,7例压迫左肾动脉,9例向髂动脉延伸或累及;⑥动脉瘤周围情况：2例动脉瘤可见周围组织炎症表现。结论：3D CE MRA是一种对评价胸腹部大血管动脉瘤的有效微创伤技术。     

Cerebrovascular pathology. Comparison of magnetic resonance and magnetic resonance angiography]

After making the visualization of the intracranial circulation possible without contrast media, the radiologist is now evaluating the diagnostic role of the different techniques of MRA. Attempts are also being made to characterize the main patterns of intracranial vascular diseases. The authors examined, with 3D TOF MRA, 40 patients presenting with 50 vascular lesions on MRI scans. Twenty of 40 patients were also studied with angiography. Seventeen aneurysms were detected, together with 3 stenoses of the cerebral arteries, 13 arteriovenous malformations, 12 dolichobasilar arteries, 3 postoperative and 2 post-embolization controls. MRI was performed with a superconductive magnet (1.5 T), a dedicated coil and gradient-echo 3D TOF FT sequences. The refocused sequence for flux, FISP 3DFT, required the following parameters: TR = 0.04 s, TE = 10 ms, flip angle = 15 degrees, 256 x 256 matrix, 1 acquisition. The 64-80 mm volume along the axial plane was divided so that an actual 1-mm thickness was excited. In post-processing, the maximum-intensity projection was employed on the axial plane 0 degrees-90 degrees (15 degrees interval). In the various conditions, the results obtained with MRA were correlated and compared with MRI findings. MRA provided useful additional information in 27.4% of cases in the study of aneurysms, arteriovenous malformations, vascular occlusion and dolichobasilar arteries, as well as in the follow-up of these lesions. MRA is currently suggested in the evaluation of cerebral circulation and is considered a complementary technique to MRI. MRA is also to be used preliminary to angiography.     

脊髓血管母细胞瘤的MR影像研究

目的　分析脊髓血管母细胞瘤的MR影像表现。方法　经手术病理证实的脊髓血管母细胞瘤 29例,男 20例,女 9例,所有病例均行MR检查,回顾分析其MR影像表现。结果　12例单发(41. 4% ), 17例多发(58. 6% ),合并颅内血管母细胞瘤 7例。MR平扫时肿瘤表现为等T1 等T2 信号 36个,等和低混杂T1 信号、等和高混杂T2 信号 16个,长T1 长T2 信号 1个。小的肿瘤倾向于等T1 等T2 信号。增强扫描后肿瘤显著强化,边界清楚。17例患者中的 21个肿瘤在T2 加权像上可见血管流空信号。27例患者中的 40个肿瘤合并有较长的脊髓空洞或囊肿。结论　脊髓血管母细胞瘤常多发或合并颅内血管母细胞瘤,肿瘤结节边界清楚,强化显著以及肿瘤相关的血管流空信号对该肿瘤的诊断最有意义。     

获得性胸主动脉病变的MRI诊断

目的：评价ＭＲＩ对获得性胸主动脉病变的诊断价值。材料和方法：共３０例,２１例在ＧＥＶｅｃｔｒａ０．５Ｔ上行ＳＥ和ＣｉｎｅＭＲＩ检查,９例在ＧＥＳｉｇｎａ１．５Ｔ上行ＳＥ、ＣｉｎｅＭＲＩ、ＧａｔｅｄＴＯＦ和３Ｄ动态增强ＭＲＡ检查。成像采用横断面、主动脉长轴和左室长轴观,部分加扫矢状面和冠状面。结果：共发现升主动脉瘤１０例、主动脉夹层１０例、主动脉扩张９例和降主动脉溃疡１例。经对照表明ＣｉｎｅＭＲＩ对合并的瓣膜病变、夹层真假腔、血栓和瘤内异常血流方式的显示较ＳＥ为佳,而ＧａｔｅｄＴＯＦ和３Ｄ动态增强ＭＲＡ对整个胸主动脉形态及头臂血管的显示最佳。结论：多种ＭＲＩ技术综合运用诊断获得性胸主动脉病变可基本达到心血管造影效果。