磁共振全身弥散成像的临床应用价值

从20世纪90年代以来,随着磁共振成像(MRI)技术的飞速进展,弥散加权成像(diffusion-weighted imaging,DWI)技术已广泛应用于扫描腹部、盆腔等颅外部位[1].高梯度场的应用、多通道线圈、平板回波成像(echo planar imaging,EPI)、并行采集(ASSET)等技术[2-3]拓展了DWI的应用范围,特别是并行采集技术缩短了TE时间、回波链长度及K-空间填充时间,从而使运动伪影大大减少,提高了弥散图像质量.     

磁共振全身弥散技术在恶性肿瘤筛查中的临床应用

目的评价磁共振全身弥散成像(WB-DWI)在恶性肿瘤筛查中的临床应用价值。方法回顾分析75例恶性肿瘤患者的WB-DWI与对照检查资料。对照检查包括常规MRI和/或CT检查,4例另行PET检查。通过按部位逐一与对照检查比较,评估WB-DWI对瘤灶检出的敏感性及特异性。结果 75例中,WB-DWI和/或对照检查显示瘤灶和可疑病灶的部位达174个。WB-DWI对瘤灶检出的整体敏感性及特异性分别为84.1%和96.7%;淋巴结、骨骼、肺和肝胆胰脾等恶性肿瘤常见转移部位的敏感性分别为93.2%、96.4%、78.6%和90.9%,特异性则分别为77.4%、83.0%、100%和98.1%。结论 WB-DWI对恶性肿瘤的检出具有较高准确性,通过技术改进以及与常规CT和MRI扫描的取长补短,有望在恶性肿瘤临床分期方面取代PET检查。     

全身磁共振扩散加权成像在肿瘤中的应用

磁共振成像具有良好的组织对比和空间分辨力,可以显示形态学的各种细微改变,因此其在肿瘤成像上有着很好的应用前景。以前MRI主要局限于某一器官或组织,随着快速成像序列的发展,如回波平面成像和并行采集技术的使用,磁共振扫描的应用范围越来越广泛。     

MR全身弥散加权成像在肝细胞癌M分期中的价值

目的探讨MR全身弥散加权成像(WB-DWI)在肝细胞肝癌(hepatic cell carcinoma,HCC)M分期中的价值。方法回顾性分析23例经临床、病理证实的HCC患者首次行WB-DWI检查的图像,统计肝外非淋巴结转移灶的分布及数目并进行对比分析。结果 WB-DWI未发现全身转移(M0)者11例,余12例均发现肝外转移灶(M1),主要为肺转移及骨转移。肺转移5例共14个病灶,WB-DWI发现12个,2个转移灶在WB-DWI上显示不清,结合胸部CT表现,肺部转移灶检出率较高(12/14,85.7%);骨转移8例共17个病灶,骨骼系统转移灶全部检出(17/17)。其余脏器脑部、脾、胰腺、肾上腺及泌尿生殖系统等均未见明显转移灶。全身非转移性病灶共计37处。结论 WB-DWI能够评估HCC患者全身情况,指导异常信号灶进行必要的相关检查,对于HCC患者M分期具有重要的价值。     

背景信号抑制磁共振弥散加权成像对急性胰腺炎的诊断价值

目的 探讨背景信号抑制磁共振弥散加权成像(diffusion weighted imaging with background signal suppression,DWIBS)检查对急性胰腺炎的诊断价值.方法 对81例急性胰腺炎患者及93例正常对照组进行常规MRI和DWIBS检查,测量DWIBS图像上胰腺及肝脏的信号强度,计算胰腺与肝脏的相对信号强度比(SIR).结果 DWIBS显示急性胰腺炎患者胰腺的信号强度明显高于肝脏(SIR=2.38),正常对照组的胰腺与肝脏信号相似(SIR=1.33),两者差异具有统计学意义(t=-17.889,P<0.01).SIR值的ROC曲线分析显示,DWIBS序列的曲线下面积0.983,当诊断界值SIR> 1.67时灵敏度为93.83%,特异度为91.4%,Youden指数0.85.预设的DWIBS专用窗位30,窗宽60有助于病变的显示.常规MRI检查的阳性率为88.9%,DWIBS检查的阳性率为97.5%(P<0.05).结论 DWIBS结合常规MRI检查可明显提高急性胰腺炎的检出率.     

磁共振全身弥散加权成像在体部肿瘤筛查中的应用

目的 评价磁共振全身弥散加权成像(WB-DWI)在体部肿瘤筛查中的应用价值.资料与方法 分析30例正常志愿者和54例(221处病灶)经手术病理证实的体部肿瘤的WB-DWI影像表现特征,均采用1.5T MR体部线圈进行扫描,观察正常志愿组的WB-DWI影像表现,利用三维最大密度投影(3DMIP)及黑白翻转技术重建出类PE...     

全身弥散加权成像对非小细胞肺癌诊断的价值

目的:探讨全身弥散加权成像(WB-DWI)对非小细胞肺癌的诊断价值。方法:对病理确诊的31例非小细胞肺癌的患者行全身弥散加权成像检查,将结果按病灶解剖部位不同分为4组,即肺内、纵膈内、远处淋巴结区、远处器官区,分别与病理及CT和(或)MRI的检查结果进行统计、分析。结果:与病理结果对照,四组不同解剖部位病灶检出率分别为90.3%、66.7%、81.8%、100%。与CT和(或)MRI结果对照,四组不同解剖病灶敏感性分别为65.12%,39.76%、98%、97.15%,特异性为100%、96.97%、63.04%、26.47%,差异有统计学意义(P(0.05)。结论:全身弥散加权成像对非小细胞肺癌远处淋巴结及器官转移的诊断优于CT和/或MRI,可以作为非小细胞肺癌诊断一种手段。     

磁共振弥散张量成像的基本原理和临床应用

磁共振弥散张量成像 (ＤｉｆｆｕｓｉｏｎＴｅｎｓｏｒＩｍａｇｉｎｇ ,ＤＴＩ)主要用来评价组织结构的完整性 ,是功能磁共振成像的一个重要组成部分。1　ＤＴＩ的基本原理1 1　磁共振弥散加权成像 (Ｄｉｆｆｕｓｉｏｎ ｗｅｉｇｈｔｅｄｉｍａｇｉｎｇ ,ＤＷＩ)　ＤＷＩ是一种测量自旋质子的微观随机位移运动的较新技术。目前在活体中主要是测量水分子的运动 ,其图像对比度主要关系于水分子的位移运动并非水的内容物 ,它通常是在标准ＭＲＩ序列上再加上对弥散敏感的梯度脉冲来获得。水分子的运动特性可以用弥散敏感梯度方向上的表观弥散系…     

不同年龄组健康小儿磁共振全身扩散加权成像的表现

目的：探讨不同年龄组健康小儿全身扩散加权成像（WB-DWI）表现,为此技术应用于临床疾病的诊断奠定基础。方法：70例健康体检儿,年龄1个月～15岁,按照年龄分成3组：1～12个月、1岁以上～5岁、5岁以上～15岁,在家长知情同意下接受WB-MRI检查,比较不同年龄组之间全身扩散加权图像上信号的差异,并进行相关性分析。结果：wBDwI上双肺、纵隔、肝脏、胰腺及周围软组织呈低信号,脑、脾、肾、睾丸及充盈的膀胱呈高信号,各脏器之间信号无明显差异。四肢长管状骨干骺端及骨干信号强度均随年龄增长而逐渐减低。1个月左右的小儿在WB-DwI上显示四肢骨结构模糊;在2～12个月组长管状骨干骺端表现为高信号者占66．7％,在12个月以上～5岁组占43．4％,5～15岁组为7．7％;长管状者骨干表现为高信号者在2～12个月组占28．6％,1岁以上～5岁组占17．3％,5岁以上～15岁组高信号基本消失。颈部、腋窝、颌下、髂血管周围淋巴结及中下腹、盆腔内部分肠管在WB-MRI上也显示为高信号。结论：WB-DWI技术作为一种无创性检查可在较短时间内完成小儿全身检查,图像能够满足临床诊断要求。正确认识小儿WB-DWI正常表现,为临床诊断疾病奠定基础。     

Low b-value diffusion-weighted imaging: emerging applications in the body

Thanks to recent advances in magnetic resonance imaging technology, it has become possible to perform intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) in any part of the body. Extracranial applications of DWI are currently under active investigation, especially for oncological imaging. However, the use of non-quantitative low b-value (10-100 s/mm(2)) DWI in the body is still a relatively unexplored field, and its potential is not fully recognized. Non-quantitative low b-value DWI may especially be useful for the evaluation of structures that have an inherently low signal at high b-value DWI, including (but not limited to) the liver, heart, and small bowel. This article will review and discuss the basic principles and potential applications of nonquantitative low b-value DWI in the body.     

Diffusion-weighted whole-body MR imaging with background body signal suppression: a feasibility study at 3.0 Tesla

The purpose was to provide a diffusion-weighted whole-body magnetic resonance (MR) imaging sequence with background body signal suppression (DWIBS) at 3.0 Tesla. A diffusion-weighted spin-echo echo-planar imaging sequence was combined with the following methods of fat suppression: short TI inversion recovery (STIR), spectral attenuated inversion recovery (SPAIR), and spectral presaturation by inversion recovery (SPIR). Optimized sequences were implemented on a 3.0- and a 1.5-Tesla system and evaluated in three healthy volunteers and six patients with various lesions in the neck, chest, and abdomen on the basis of reconstructed maximum intensity projection images. In one patient with metastases of malignant melanoma, DWIBS was compared with ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET). Good fat suppression for all regions and diagnostic image quality in all cases could be obtained at 3.0 Tesla with the STIR method. In comparison with 1.5 Tesla, DWIBS images at 3.0 Tesla were judged to provide a better lesion-to-bone tissue contrast. However, larger susceptibility-induced image distortions and signal intensity losses, stronger blurring artifacts, and more pronounced motion artifacts degraded the image quality at 3.0 Tesla. A good correlation was found between the metastases as depicted by DWIBS and those as visualized by FDG-PET. DWIBS is feasible at 3.0 Tesla with diagnostic image quality.     

脑白质纤维成像的基础研究和临床应用新进展

脑白质纤维成像是目前唯一能直观显示脑白质纤维束的非侵入性检查方法，基础是弥散加权威像，基本原理为脑白质水分子弥散的各向异性。应用最多的方法主要有线性延展法和椭球体表示法。在临床方面的应用主要集中在监测脑白质的发育、成熟及生理性老化；观察脑肿瘤与白质纤维束的关系；显示急性中风、炎症、脑外伤病变引起的脑白质改变；显示精神分裂症病入局部神经联合的中断。     

磁共振扩散加权成像在颅内表皮样囊肿中的诊断价值

目的：探讨磁共振扩散加权成像（DWI）在颅内表皮样囊肿中的诊断价值。方法：收集颅内表皮样囊肿病例16例，均行常规MRI和DWI检查，分析表皮样囊肿在T2WI、T1WI、增强扫描和DWI上的影像表现。结果：16例均呈长T2长T1信号，其中2例伴短T2间隔信号，增强扫描14例无强化，2例呈包膜和间隔强化。16例DWI上均呈明显高信号。结论：磁共振DWI在颅内表皮样囊肿中具有重要的诊断价值，可作为常规MRI的重要补充检查方法。     

磁共振扩散加权成像在乳腺良恶性病变中的诊断价值

目的探讨磁共振扩散加权成像在乳腺良恶性病变中的诊断价值。方法收集我院2010年2—8月经手术病理证实或穿刺活检证实的50例乳腺癌患者和50例乳腺良性病变患者。DWI扫描b值分别为400、600、8001、000 s/mm2,测量病灶区域的ADC值,并比较各组之间的差异。结果 b值分别为400、6008、001、000时乳腺癌及良性病变的ADC值,恶性组ADC值明显低于良性组(P<0.05)。四组不同b值的良恶性病变分别做ROC曲线,以b=1 000 s/mm2时,AUC最大,诊断价值最高,以ADC值为1.23×10-3mm2/s作为良恶性病变的诊断阈值,敏感性为90.0%,特异性为89.8%,准确性为89.9%。结论 DWI结合ADC值测量,对乳腺良恶性病变的鉴别诊断具有较高的临床应用价值。     

Whole body MR imaging in diabetes

Diabetes mellitus is a major cardiovascular risk factor and one of the major causes for morbidity and mortality worldwide. Diabetic complications have not only major impact on the quality of life of diabetic patients, but are also potentially life-threatening. Therefore prevention, diagnosis and therapy of these long-term complications are of high importance. However, diagnosis of the variety of complications from diabetes mellitus remains a diagnostic challenge and usually several diagnostic steps are necessary to diagnose or exclude these complications.In the last years whole body magnetic resonance imaging (WB-MRI) including whole body magnetic resonance angiography (WB-MRA) has been introduced for cardiovascular imaging and is now increasingly applied in clinical routine for the workup of patients with cardiovascular disease and for cardiovascular screening. The article summarizes rationales for WB-MRI in diabetes mellitus, technical concepts of disease specific cardiovascular WB-MRI in diabetes mellitus and discusses potential clinical consequences.     

全身扩散加权成像在恶性淋巴瘤诊断中的价值

目的：评价全身磁共振扩散加权成像（WB-DWI）在恶性淋巴瘤诊断及疗效评价中的作用。方法：回顾性分析47例经病理证实的恶性淋巴瘤患者WB-DWI表现;另选10例健康志愿者进行比较。8例霍奇金淋巴瘤（HD）患者,其中5例治疗前、后均行WB-DWI检查,3例为治疗后患者;39例非霍奇金淋巴瘤（NHL）患者,治疗前行WB-DWI检查19例,治疗前、后均行WB-DWI检查11例,仅治疗后检查9例。在ADC图上分别测量恶性淋巴瘤患者和健康志愿者淋巴结的ADC值,16例复查患者在初次检查相一致部位再次测量淋巴结的ADC值,并进行前后比较,同时与健康志愿者进行比较。结果：全身MR-DWI对淋巴瘤的显示较敏感,MR-DWI共检出大于1cm淋巴结372处。35例治疗前恶性淋巴瘤患者平均ADC值为（0.86±0.21）×10^-3mm^2/s,28例治疗后复查患者平均ADC值为（1.22±0.31）×10^-3mm^2/s,治疗前、后平均ADC值的差异具有统计学意义（P〈0.05）;10例健康志愿者颈部淋巴结平均ADC值为（1.29±0.12）×10^-3mm^2/s,与30例治疗前淋巴瘤患者ADC值比较,差异具有统计学意义,与28例治疗后患者ADC值比较,差异无统计学意义（P〉0.05）。结论：WB-DWI和ADC值的测量在恶性淋巴瘤的临床诊断、分期及疗效监测的评价方面是一种快速和行之有效的技术,具有一定的临床价值。     

磁共振扩散加权成像对于颅内表皮样囊肿的诊断价值

目的:探讨磁共振扩散加权成像(DWI)对于颅内表皮样囊肿的诊断价值。方法:回顾性分析11例经手术病理证实的颅内表皮样囊肿术前常规MRI和DWI的信号特征。结果:11例均为单发;7例表现为囊状均匀性长T1长T2信号,4例病灶信号不均匀,以长T1长T2信号为主,其内混杂少许等T1等T2信号;5例行增强扫描均未见异常强化;所有病灶在DWI上均表现为明显高信号,边界清楚,ADC图表现为中等信号。结论:DWI对于颅内表皮样囊肿的诊断及鉴别诊断具有重要价值,应作为首选检查与常规扫描同时应用。     

Whole-body diffusion-weighted magnetic resonance imaging

Diffusion-weighted magnetic resonance imaging (DWI) provides information on the diffusivity of water molecules in the human body. Technological advances and the development of the concept of diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) have opened the path for routine clinical whole-body DWI. Whole-body DWI allows detection and characterization of both oncological and non-oncological lesions throughout the entire body. This article reviews the basic principles of DWI and the development of whole-body DWI, illustrates its potential clinical applications, and discusses its limitations and challenges.