MR扩散加权成像在乳腺良恶性病变鉴别诊断中的价值

目的 探讨MR扩散加权成像(diffusion weighted imaging,DWI)及表观扩散系数(apparent diffusion coeffi-cient,ADC)在乳腺良恶性病变鉴别诊断中的价值.资料与方法 43例经钼靶或彩超诊断为乳腺肿瘤的患者采用单次激发回波平面成像(echo planar imaging,EPI)技术行双侧乳腺DWI,扩散敏感系数(b值)分别为600、750、1000 s/mm2.同时选取10名知情的健康志愿者及4例患者对侧正常乳腺作为对照组.观察乳腺病变在DWI上的大小、形态及信号特征,测量24个正常乳腺、手术病理证实的24个恶性病灶、23个良性病灶分别在b=600、750、1000 s/mm2时的ADC值,比较良、恶性病变、正常腺体间ADC值差异及b=600、750、1000 s/mm2时ADC值差异.根据恶性组平均ADC值的95%可信区间的上限,计算3组不同b值下诊断乳腺癌的敏感性、特异性和准确性.结果 乳腺良、恶性病变、正常腺体间ADC值差异均有统计学意义(F=101.113,P<0.0001),恶性病变ADC值明显低于良性病变和正常腺体组织(P<0.0001),良性病变ADC值明显低于正常腺体组织(P<0.0001);3组b值间ADC值差异均有统计学意义(F=15.539,P<0.0001),b值越低,ADC值越大(P<0.05).b=600、750、1000 s/mm2时,根据恶性组平均ADC值的95%可信区间的上限诊断乳腺癌的敏感性分别为91.7%、70.8%和79.1%,特异性分别为89.4%、89.4%和93.6%,准确性分别为93.0%、69.0%和88.7%.结论 根据ADC值可以对乳腺良、恶性病变做出鉴别诊断,其敏感性、特异性和准确性较高,具有较高的临床应用价值.     

扩散加权成像中不同扩散敏感系数对乳腺病变的诊断价值

目的 研究扩散加权成像(DWI)中不同扩散敏感系数(b值)对乳腺病变的诊断价值及影响因素,并探讨其鉴别良、恶性乳腺肿瘤的最佳界值.资料与方法 对155例患者行不同b值的DWI检查,其中136例选取b值(0,500 s/mm2),122例选取b值为(0,1000 s/mm2).所有病例结果均经手术病理证实,将DWI表现与组织病理学进行对照.结果 两组b值中恶性病变的ADC值均明显低于良性病变,且乳腺良、恶性病变的表观扩散系数(ADC)值均随b值增大而降低.采用非参数法受试者操作特性曲线(ROC)统计学分析方法确定鉴别良、恶性病变的最佳界值,应用此界值对乳腺病变诊断的敏感性和特异性分别为83.3%和56.9%(b=500 s/mm2)、73.6%和80.0%(b=1000 s/mm2).结论 高b值DWI对乳腺病变诊断的特异性高于低b值DWI,是乳腺动态增强成像检查的一个有益的补充.     

乳腺良恶性病变的3.0T磁共振扩散加权成像鉴别诊断及b值优化

目的:探讨3.0T扩散加权成像(DWI)在乳腺良恶性病变鉴别诊断中的诊断价值并对b值使用进行优化。方法:34例患者共20个良性和16个恶性乳腺病灶纳入研究,同期20例正常乳腺受检者列为对照组。采用3.0T MR行乳腺DWI成像检查,b值分别取0,750 s/mm2,1000 s/mm2,1250 s/mm2。比较不同b值DWI图像质量,测量病灶的对比噪声比(CNR)以及表观扩散系数(ADC)值,以病理诊断为金标准,计算诊断乳腺癌的敏感度、特异度及准确性,绘制受试者工作特征曲线(ROC)并进行比较。结果:不同b值时DWI图像主观质量评分没有统计学差异(F=3.02,P=0.0516>0.05)。b=750 s/mm2时病灶的CNR明显优于b=1000s/mm2及1250s/mm2时(P值为0.004及0.000),而b=1000s/mm2与1250s/mm2之间没有统计学差异(P=0.800>0.05)。相同b值时,正常乳腺组织的平均ADC值>乳腺良性病变>乳腺恶性病变(P均=0.000)。以各b值恶性病变平均ADC值95%可信区间的上限作为界定乳腺癌ADC的阈值,则b=750 s/mm2、1000 s/mm2、1250s/mm2时,ADC阈值分别为1.33×10-3mm2/s、1.25×10-3mm2/s、1.16×10-3mm2/s。以上述阈值判断乳腺癌的敏感度、特异度及准确性分别为81.25%、87.5%、85.71%,81.25%、77.5%、78.57%及81.25%、82.5%、82.14%。三个b值的ROC曲线下面积无显著性差异(P=0.1925>0.05)。结论:乳腺的3.0T DWI中,以b=750s/mm2时病灶CNR最高,值得推荐应用。应用DWI鉴别乳腺良恶性病变时,需要结合ADC值判断。     

MR扩散加权成像鉴别乳腺良恶性病变的研究

目的　探讨磁共振扩散加权成像(diffusion weightedMRimaging, DW MRI)的表观扩散系数(apparentdiffusioncoefficient, ADC)在乳腺病变鉴别诊断中的价值。方法　DW- MRI采用单次激发平面回波成像(echo planarimaging, EPI)技术, 扩散敏感系数(b值)分别为0、500、1000s/mm2。计算26个正常乳腺、手术病理证实的24个恶性病灶、30个良性病灶分别在b=1000~0、1000~500、500~0s/mm2 时的ADC值,比较良恶性病变、正常腺体间ADC值差异的统计学意义及b=1000~0、1000~500、500~0s/mm2 间ADC值差异的统计学意义。结果　乳腺良、恶性病变、正常腺体间ADC值差异均有统计学意义(F= 565. 74,P<0 .01),恶性病变ADC值明显低于良性病变和正常腺体组织,良性病变ADC值明显低于正常腺体组织; 3组b值间ADC值差异均有统计学意义(F=21. 30,P<0 .01),b值越低,ADC值越大;把恶性肿瘤ADC值95%可信区间上界( 1. 01×10-3 )mm2 /s定为良恶性病变鉴别的界值,诊断敏感性为64 .0%,特异性为96 .7%。结论　根据ADC值可以对乳腺良恶性病变做出鉴别诊断,其特异性较高,但敏感性较低。     

1.5T DWI在肺内良、恶性病变鉴别诊断中最适b值的探讨

目的:探讨1.5TDWI对肺内良、恶性病变的鉴别诊断价值及b值的优化。方法:搜集40例经病理/临床证实的肺内良、恶性病变患者(恶性病变23例,良性病变17例)的影像及临床资料,40例均经MSCT检查发现肺部病变,并行常规T1WI、T2WI以及多b值DWI(b=0,300,600,1000s/mm2)检查,测量3组b值测得的ADC值,分析不同b值对图像质量、信噪比(SNR)、对比噪声比(CNR)的影响,根据受试者工作特征(ROC)曲线评价不同b值下ADC值鉴别肺部良、恶性病变的诊断效能;并比较同一b值下良、恶性病变ADC值的差异。结果:随着b值的增加,DWI图像信号逐渐增高,ADC、SNR及CNR值逐渐下降;b值为300和600s/mm2两组图像SNR值差异无统计学意义(P>0.05),b值为300与1000s/mm2以及600与1000s/mm2两组SNR值差异均具有统计学意义(P均<0.05);CNR值在两两组间的差异均具有统计学意义(P均<0.05)。b值为300、600和1000s/mm2时,ROC的曲线下面积(AUC)分别为0.78、0.83和0.81,且均具有诊断意义(AUC均>0.5),当b=600s/mm2时,诊断效能最高。在同一b值下,恶性病变图像信号高于良性病变,且ADC值低于良性病变(P均<0.05)。结论:1.5T DWI多b值胸部扫描有助于鉴别肺内良、恶性病变,当b=600s/mm2时,对肺良、恶性病变的鉴别诊断效能最高。     

MR扩散加权成像在乳腺良恶性病变诊断及鉴别诊断中的应用研究

目的 探讨磁共振扩散加权成像(DWI)及表观扩散系数(ADC)在乳腺良恶性病变鉴别诊断中的价值.方法 DWI采用自旋回波-回波平面成像(SE-EPI),扩散敏感系数(即b值)分别为500 s/mm2、1 000 s/mm2.测量正常乳腺组(80例)、经手术病理证实的良性(32个病灶)和恶性病变组(48个病灶)共75例ADC值,比较同b值下3组间ADC值差异的统计学意义及不同b值(b = 500 s/mm2、1 000 s/mm2)时各组内ADC值差异的统计学意义.以恶性组平均ADC值的95%可信区间的上限值作为良恶性病变的界值,与病理结果比较,计算b值为500 s/mm2、1 000 s/mm2时诊断的灵敏度、特异度、阳性预测值、阴性预测值、正确率、Youden指数、阳性似然比、阴性似然比.结果 乳腺良、恶性病变在DWI图上均呈高信号.乳腺良、恶性病变,正常腺体间ADC值差异均有统计学意义;2组b值间ADC值差异有统计学意义,并且b值越低,ADC值越大;根据恶性组平均ADC值的95%可信区间的上限值作为诊断乳腺癌的阈值,b值为500 s/mm2、1 000 s/mm2时诊断的各项诊断指标均较高.结论 DWI及ADC值可以作为乳腺良恶性病变诊断及鉴别诊断的重要依据,与MRI其他扫描序列结合可提高乳腺癌的早期诊断率.     

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。     

1.5TMR乳腺扩散加权成像b值的优化

目的 通过分析水模、正常乳腺腺体、乳腺良性及恶性病变的ADC值及图像信噪比(SNR)随b值的变化规律,探讨1.5 TMR乳腺DWI合理的b值取值范围.方法 对32例经病理证实的乳腺病变(恶性18例,良性14例)及对侧正常腺体进行乳腺MR检查,采用EPI-DWI序列;b值分别采用0、50、100、200、400、600、800、1000、1200、1400、1600、1800、2000、2200、2400、2600 s/mm2.测量不同b值下水模、正常乳腺腺体、乳腺良性及恶性病变的平均ADC值和图像SNR,采用Pearson相关分析法分析不同b值时的变化规律.结果 DWI的SNR均随b值的增加逐渐下降,二者呈负相关(r=-0.802,P＜0.01),乳腺良、恶性病变的ADC值均随着b值的增加而下降(r=-0.923和-0.855,P＜0.01);当b值取800～1000 s/mm2时,恶性病变与良性病变和正常腺体之间的ADC值差异最大(0.7×10-3mm2/s);当b值＞1400 s/mm2,差异逐渐减小.结论 取b值800～ 1000 s/mm2时,既能取得良好的图像质量,又能有效地鉴别乳腺良、恶性病变,是1.5 TMR乳腺DWI最合理的b值取值范围.     

MR扩散加权成像对乳腺良恶性疾病的应用研究

目的探讨MR扩散加权成像（DWI）的技术方法及表观扩散系数（ADC）值对乳腺良、恶性疾病的诊断及鉴别诊断价值。资料与方法经病理证实的乳腺病变50例,58个病灶,其中恶性32个,良性26个。检查使用Siemens1.5T磁共振仪、专用双穴乳腺表面线圈。所有病例采用单次激发自旋回波-回波平面成像（SE-EPI）序列行DWI,扩散敏感系数（b值）取0、400、600、800、1000s/mm^2。以恶性病变ADC值95%可信区间的上界作为诊断病变良、恶性的界值,所得结果与病理结果比较。结果DWI显示92.3%（24/26）的良性病变和96.9%（31/32）的恶性病变,敏感性为94.8%（55/58）。各b值良性组、恶性组和正常组之间的ADC值差异均有统计学意义（P〈0.05）。取b=1000s/mm^2,以恶性病变ADC值95%可信区间的上界1.4276×10^-3mm/s为界诊断良、恶性的敏感性为90.6%,特异性为84.6%,准确性为87.9%。结论（1）DWI对乳腺疾病的敏感性非常高。（2）ADC值是诊断和鉴别诊断乳腺良、恶性疾病的有价值的参数。（3）b=1000s/mm^2时对乳腺疾病的诊断最有价值。     

乳腺疾病的MRI扩散加权成像量化分析

目的 探讨MR扩散加权成像(DWI)对乳腺疾病的诊断价值.方法 58例共计 62个乳腺病灶(均经病理证实)及10例20个正常乳腺进行常规MR扫描及DWI检查.DWI采用单次激发平面回波(EPI)技术,b值为1000 s/mm2.以病理结果为金标准,动态增强减影图像为参照,比较正常乳腺组织、乳腺良性及恶性病变平均表观扩散系数(ADC)值的差异,分析平均ADC值与乳腺良恶性病变的相关性,同时评价DWI在预测乳腺恶性病变中的效能.结果 正常乳腺、良性病变、恶性病变的平均ADC值分别为(1.882±0.119)、(1.307±0.196)、(0.941±0.164)×10-3 mm2/s,差异有统计学意义(F=213.5, P<0.01).浸润性导管癌的平均ADC值低于导管原位癌(U=60.0,P<0.05),而乳腺腺病与纤维腺瘤的平均ADC值无显著差异(U=42.0,P=0.38).同时平均ADC值与乳腺良恶性病变呈负性相关(r=-0.715,P<0.01).利用平均ADC值对乳腺病变是否为乳腺癌进行诊断试验,ROC曲线下面积(Az)值为0.924,最佳临界点为1.065 × 10-3 mm2/s,此时诊断的敏感性为78.95%(30/38),特异性为87.50%(21/24),准确性为82.26%(51/62).结论 DWI量化分析ADC值有助于乳腺疾病的诊断及鉴别诊断.     

A monitoring,feedback, and triggering system for reproducible breath-hold MR imaging

A technique is described that provides improved reproducibility of breath-holding for MR image acquisition by monitoring the superior-inferior (S/I) position of the diaphragm. The method incorporates detection of the level of inspiration using an MR signal, rapid display to the patient of diaphragm position to enable breath-hold adjustment, and triggering of image data acquisition once appropriate position is attained. The response time of the system is short, approximately 10 ms. Studies in six volunteers using this method demonstrate a considerable decrease in the S/I range of diaphragm position over 10 consecutive periods of suspended respiration. The mean range is 1.3 mm with the system, while it is 8.3 mm without using it is expected that this method will be of assistance in many abdominal and cardiothoracic studies that use breath-hold techniques.     

DSA功能性参数的提取与利用

本文介绍了在临床实际中利用功能性参数，对冠状动脉ＤＳＡ心肌血流灌注成像、冠状动脉血流量测定、左心室功能测定、肺动脉高压程度的评价等项目研究结果。重点讨论了提取ＤＳＡ功能性参数的一般方法，认为功能性参数在现代影像诊断学中的作用是对疾病做出程度、定量、动态及功能诊断。     

Fast imaging of phosphocreatine in the normal human myocardium using a three-dimensional RARE pulse sequence at 4 Tesla

PURPOSE: To investigate the use of a three-dimensional rapid acquisition with relaxation enhancement (RARE) pulse sequence for direct acquisition of phosphocreatine (PCr) images of the human myocardium. MATERIALS AND METHODS: A short elliptical birdcage radiofrequency (RF) body coil was constructed to produce a uniform flip angle throughout the chest cavity. In vivo images using a spectrally-selective RARE sequence with a spatial resolution of 1.2 cm x 1.2 cm x 2.5 cm (4 cm(3)) were acquired in nine minutes and 40 seconds. RESULTS: Scans of phantoms demonstrated excellent spectral selectivity. The signal-to-noise ratio in the myocardium ranged from 12.6 in the anterior wall to 5.3 in the mid septum. CONCLUSION: This study demonstrates that PCr data can be acquired using a three-dimensional RARE sequence with greater spatial and temporal resolution than spectroscopic techniques.     

Simultaneous multislice (SMS) imaging techniques

Simultaneous multislice imaging (SMS) using parallel image reconstruction has rapidly advanced to become a major imaging technique. The primary benefit is an acceleration in data acquisition that is equal to the number of simultaneously excited slices. Unlike in‐plane parallel imaging this can have only a marginal intrinsic signal‐to‐noise ratio penalty, and the full acceleration is attainable at fixed echo time, as is required for many echo planar imaging applications. Furthermore, for some implementations SMS techniques can reduce radiofrequency (RF) power deposition. In this review the current state of the art of SMS imaging is presented. In the Introduction, a historical overview is given of the history of SMS excitation in MRI. The following section on RF pulses gives both the theoretical background and practical application. The section on encoding and reconstruction shows how the collapsed multislice images can be disentangled by means of the transmitter pulse phase, gradient pulses, and most importantly using multichannel receiver coils. The relationship between classic parallel imaging techniques and SMS reconstruction methods is explored. The subsequent section describes the practical implementation, including the acquisition of reference data, and slice cross‐talk. Published applications of SMS imaging are then reviewed, and the article concludes with an outlook and perspective of SMS imaging. Magn Reson Med 75:63–81, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.     

Current Status of Optical Imaging for Evaluating Lymph Nodes and Lymphatic System

Optical imaging techniques use visual and near infrared rays. Despite their considerably poor penetration depth, they are widely used due to their safe and intuitive properties and potential for intraoperative usage. Optical imaging techniques have been actively investigated for clinical imaging of lymph nodes and lymphatic system. This article summarizes a variety of optical tracers and techniques used for lymph node and lymphatic imaging, and reviews their clinical applications. Emerging new optical imaging techniques and their potential are also described.     

Echo-Time-Encoded Burst Imaging (EBI): A Novel Technique for Spectroscopic Imaging

A new technique for rapid spectroscopic imaging is presented. The proposed experiment enables a complete mapping of the two-dimensional reciprocal space k_x, k_o, and thus the acquisition of a 1D spectroscopic image in a single scan. The properties of the pulse sequence, based on the use of a burst of low flip angle pulses, are analyzed in the framework of linear response theory, and it is shown that chemical shift information may be introduced into the spatially encoded echoes. First experimental results are presented demonstrating that 32 x 32 proton spectroscopic images may be acquired within less than 1 min with a conventional imaging system.     

RARE spiral T2-weighted imaging

Spiral imaging has a number of advantages for fast imaging, including an efficient use of gradient hardware. However, inhomogeneity-induced blurring is proportional to the data acquisition duration. In this paper, we combine spiral data acquisition with a RARE echo train. This allows a long data acquisition interval per excitation, while limiting the effects of inhomogeneity. Long spiral k-space trajectories are partitioned into smaller, annular ring trajectories. Each of these annular rings is acquired during echoes of a RARE echo train. The RARE refocusing RF pulses periodically refocus off-resonant spins while building a long data acquisition. We describe both T₂-weighted single excitation and interleaved RARE spiral sequences. A typical sequence acquires a complete data set in three excitations (32 cm FOV, 192 × 192 matrix). At a TR = 2000 ms, we can average two acquisitions in an easy breath-hold interval. A multifrequency reconstruction algorithm minimizes the effects of any off-resonant spins. Though this algorithm needs a field map, we demonstrate how signal averaging can provide the necessary phase data while increasing SNR. The field map creation causes no scan time penalty and essentially no loss in SNR efficiency. Multiple slice, 14-s breath-hold scans acquired on a conventional gradient system demonstrate the performance.     

Molecular imaging programs in the United States: results of a national survey

RATIONALE AND OBJECTIVES: We sought to identify and describe the characteristics of molecular imaging (MI) programs in the United States and to determine the factors considered critical for their future. MATERIALS AND METHODS: In a cross-sectional study, a validated survey was sent to members of the Society of Chairmen in Academic Radiology Departments (SCARD) in the United States, and 26 variables were studied. RESULTS: The response rate was 40.3%; 67.9% of the departments surveyed have an MI program. The main focus of 47.4% of departments is oncology. The number of radiologists working for the department was the only variable found to be significantly positively correlated with (1) number of researchers in the MI program, (2) number of MI modalities available, (3) total number of grants, and (4) having ongoing MI clinical trials. These four variables plus the number of federal grants and the space used by MI programs were independent of the geographical region, hospital size (number of beds), and department size (number of radiological examinations per year). All the MI programs received grants during 2005. Only 16.1% have no alliances with industry. Among all the departments, 82% identified staff training and recruitment as the keys for success; 78.57% considered oncology the most important future application of MI and cancer management the hospital service most affected by MI. CONCLUSION: MI programs are starting to be more widespread throughout the United States, and the trend is for more academic radiology departments to become engaged in MI activities; their development is independent of department characteristics. Radiology departments strongly agreed about the key components for success of MI initiatives and the areas that will be most affected by MI applications.     

Partially parallel imaging with phase-sensitive data: Increased temporal resolution for magnetic resonance temperature imaging.

Magnetic resonance temperature imaging can be used to monitor the progress of thermal ablation therapies, increasing treatment efficacy and improving patient safety. High temporal resolution is important when therapies rapidly heat tissue, but many approaches to faster image acquisition compromise image resolution, slice coverage, or phase sensitivity. Partially parallel imaging techniques offer the potential for improved temporal resolution without forcing such concessions. Although these techniques perturb image phase, relative phase changes between dynamically acquired phase-sensitive images, such as those acquired for MR temperature imaging, can be reliably measured through partially parallel imaging techniques using reconstruction filters that remain constant across the series. Partially parallel and non-accelerated phase-difference-sensitive data can be obtained through arrays of surface coils using this method. Average phase differences measured through partially parallel and fully Fourier encoded images are virtually identical, while phase noise increases with g(sqrt)L as in standard partially parallel image acquisitions..