扩散敏感因子800时乳腺良恶性病变ADC界值的确定

目的：确定扩散敏感因子为800s/mm^2时乳腺良恶性病变的ADC界值,评价MR扩散加权成像（DWI）对乳腺良恶性病变鉴别诊断的价值。方法：回顾性分析经手术病理证实的70例（78个病灶）乳腺病变的DWI图像,其中良性病变26例（31个病灶）,恶性病变44例（47个病灶）。测量DWI图像上显示的病变表观扩散系数（ADC）值。通过ROC曲线确定ADC值的诊断阈值,并以此值进行鉴别诊断,同时计算ROC曲线下面积。结果：良恶性病变的ADC值均符合正态性分布,良恶性病变的ADC平均值分别为（1.46±0.26）×10^-3mm^2/s和（1.02±0.19）×10^-3mm^2/s,恶性病变的ADC值明显低于良性病变（P〈0.05）。约登指数最大法确定的ADC诊断阈值为1.28×10^-3mm^2/s,以此值进行鉴别诊断时的敏感度、特异度和诊断符合率分别为93.6%,75.9%,86.8%;阳性似然比最大法确定的ADC诊断阈值为1.035×103mm^2/s,以此值进行鉴别诊断时的敏感度、特异度和诊断符合率分别为46.8%,96.6%,65.8%;ROC曲线下面积为0.905（95%可信区间为0.836-0.975）。结论：扩散敏感因子为800s/mm^2时乳腺良恶性病变的ADC界值确定为1.28×10^-3mm^2/s,DWI的ADC值测定有助于乳腺良恶性病变的鉴别诊断。     

DWI及ADC值在脊柱转移瘤诊断中的应用

目的 :探讨DWI及ADC值在脊柱转移瘤诊断中价值。方法 :收集我院临床确诊的脊柱转移瘤30例脊柱转移组,脊柱良性病变25例(良性病变组)。55例均行常规矢状位、横轴位及DWI扫描,b值取0、800 s/mm2,分别测量得2组病变ADC值。主观评价并比较2组的DWI病灶信号强度。采用ROC曲线,获得最佳DWI及ADC值界值,以及诊断敏感度、特异度,两者联合指标的敏感度、特异度。结果:椎体病变T1WI呈低信号或以低信号为主的混杂信号,T2WI脂肪抑制后为高信号、混杂高信号。良性病变组DWI以稍高信号为主(17/25),脊柱转移瘤组DWI以高信号为主(24/30),2组差异有统计学意义(Z=4.477,P0.001)。测得平均ADC值:脊柱转移瘤组为(0.843±0.189)×10-3mm2/s;良性病变组为(1.204±0.184)×10-3mm2/s,2组差异有统计学意义(t=7.131,P0.001)。当病变DWI为稍高信号,鉴别脊柱良恶性病变ROC曲线下面积为0.812,敏感度80%,特异度80%;2组ADC值鉴别脊柱良恶性病变ROC曲线下面积为0.920,最佳临界值为0.947×10-3mm2/s,敏感度76.67%,特异度96%。DWI病变信号为稍高及高信号,ADC值≤0.947 4×10-3mm2/s,满足其中之一诊断为恶性病变的诊断敏感度90%,特异度80%。结论:常规MRI结合DWI及ADC值对诊断脊柱转移瘤具有重要价值。     

扩散加权成像与传统磁共振成像联合诊断乳腺疾病

目的探讨扩散加权成像(DWI)与常规MRI征象联合诊断乳腺疾病的模式及诊断效能。资料与方法采用前瞻性研究,99例乳腺疾病患者共109个病变术前行3.0T乳腺MRI及DWI检查,经术后病理或长期随访确诊。乳腺良恶性病变的表观扩散系数(ADC)值进行同一观察者、不同观察者共3次测量,采用受试者操作特征曲线、串联并联诊断试验、机器学习探讨多参数联合对乳腺良恶性疾病的诊断效能。结果 ADC值的观察者内组内相关系数为0.950(95%CI 0.928~0.965);观察者间组内相关系数为0.937(95%CI 0.909~0.956);良性病变与恶性病变的ADC值分别为(1.447±0.377)×10-3 mm2/s、(1.054±0.255)×10-3 mm2/s,差异有统计学意义(P<0.05)。以ADC值1.125×10-3 mm2/s为阈值鉴别良恶性病变的敏感度和特异度分别为82.4%、74.1%,联合其他传统MRI征象可使敏感度、特异度高于单一ADC值诊断。结论 ADC值具有良好的可重复性和稳定性,ADC值与传统MRI征象联合应用可以更好地鉴别乳腺病灶的良恶性。     

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。     

磁共振扩散加权成像在甲状腺良恶性病变鉴别诊断中的价值

目的：探讨MR扩散加权成像在甲状腺良恶性病变鉴别诊断中的价值。方法：采用平面回波成像（EPI）技术。对50例甲状腺局灶性病变（良性组36例,恶性组14例）行DWI检查,分别测量b值取0、150、300和500s/mm2时良恶性病灶的信号强度和ADC值,并比较其差异。所有患者均经手术（49例）或活检（1例）病理证实。结果：良性与恶性病变的信号强度在b值为0、150、300和500s/mm2时差异均无统计学意义（P〉0.05）。b值为150、300和500s/mm2时良性组与恶性组之间ADC值的差异均有统计学意义（P〈0.01）。以恶性组ADC值95%可信区间上限作为诊断阈值,则b值为150、300和500s/mm2时,诊断阈值分别为1.992×10^-3、1.582×10-3和1.410×10-3mm2/s。应用ROC曲线分析不同b值时ADC阈值诊断恶性病变的作用,显示b值为150s/mm2时价值最大,其诊断敏感度、特异度、符合率、阳性和阴性预测值分别为78.57%、84.62%、82.50%、73.33%和88.00%。结论：甲状腺恶性病变的ADC值低于良性病变,b值取150s/mm2、阈值设为1.992×10-3mm2/s有助于良恶性病变的鉴别。     

The role of low b value diffusion-weighted MR imaging and the apparent diffusion coefficient values in diagnosis of breasttnmors

目的:探讨小b值扩散加权成像(DWI)在诊断乳腺癌中的价值.方法:采用Philips 1.5T磁共振扫描仪对48例乳腺疾病患者行常规SE序列扫描、单次激发自旋回波-回波平面成像(SE-EPI)序列DWI及动态增强扫描.48例患者共检出53个病灶,其中良性肿瘤29个,恶性肿瘤24个,均经手术及病理证实;选择健康志愿者20例作为对照组.分析病灶与正常腺体组织的DWI信号特点,定量比较分析病变组与对照组之间及良恶性组之间表现扩散系数(ADC)值的差异.结果:除2例原位癌及1例小纤维瘤未显示外,其他良恶性病变DWI均可显示.恶性组平均ADC值[(1.41±0.37)×10-3mm2/s]明显低于对照组[(2.01±0.36)×10-3mm2/s]和良性组[(1.98±0.42)×10-3mm2/s],差异均有统计学意义(P＜0.05).良性组ADC值与对照组比较,差异无统计学意义(P＞0.05).以ADC值作为诊断指标进行ROC分析,诊断阈值为1.542×10-3 mm2/s,诊断敏感度为86.4％,特异度为89.3％.结论:ADC值是鉴别乳腺癌有价值的参数,小b值扩散加权成像对于乳腺癌的鉴别诊断具有重要价值.     

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.     

MRI扩散加权成像对乳腺良恶性病变的诊断

目的:探讨磁共振扩散加权成像(DWI)对乳腺良恶性疾病的诊断价值。方法:回顾性分析40例经病理确诊的乳腺疾病,其中良性病变22个,恶性病变18个;均行DWI检查,测定病灶区表观扩散系数(ADC值),与正常组织进行比较,计算相对表观扩散系数(rADC值),应用SPSS 16.0软件比较其平均值,并以病理结果为金标准,作ROC曲线,求其最佳诊断阈值。结果:良性病变及恶性病变的ADC值分别为(1.55±0.35)×10-3和1.00±0.18)×10-3 mm2/s,其rADC值分别为(0.82±0.19)和(0.52±0.08)。良恶性病变组间均有统计学差异,以ADC值及rADC值为诊断标准作受试者工作特征曲线(ROC曲线),其中ADC值的曲线下面积(AUC)为(0.927±0.04),rADC值的AUC为(0.965±0.03),诊断阈值分别为1.17×10-3 mm2/s、0.66,相应敏感度及特异度分别为(90.9%、88.9%)和(95.5%、94.4%),rADC值的AUC、敏感度及特异度均高于ADC值。结论:DWI对乳腺良恶性病变的的诊断具有重要作用,其中rADC值有更好诊断效能。     

DWI联合CT对肺内良恶性病变的鉴别诊断价值

【摘要】目的：探讨DWI联合CT对肺内良、恶性病变的鉴别诊断价值。方法：搜集经病理或治疗后随诊证实的肺内病变共68例,其中恶性病变46例,良性病变22例,所有患者均在接受治疗及病理检查前行CT平扫+增强扫描及DWI检查,记录b值为800s/mm2时病变的平均表观扩散系数值（ADC值）,分析良、恶性病变的ADC值差异,计算ROC曲线下面积,判断ADC值的最佳阈值及鉴别诊断效能,对比分析单独使用CT与CT联合DWI的诊断效能。结果：肺内良性病变的平均ADC值为（1.712±0.293）×10-3mm2/s,恶性病变的平均ADC值为（1.219±0.138）×10-3mm2/s,良、恶性病变的平均ADC值差异有统计学意义（P＜0.05）。ADC值的最佳诊断阈值为1.522×10-3mm2/s时,ROC曲线的曲线下面积最大（0.942）,对肺内良、恶性病变鉴别诊断的敏感度为72.7%,特异度为100%,诊断符合率为91.2%;CT对肺内良恶性病变的诊断符合率为88.2%,CT与DWI联合的诊断符合率为95.6%。结论：DWI联合CT可提高对肺内良、恶性病变的鉴别诊断符合率。     

磁共振扩散加权成像对椎体良恶性骨折的鉴别诊断价值

目的探讨磁共振扩散加权成像(DWI)在椎体良恶性骨折中的鉴别诊断价值。方法31例共58个病变椎体均做了MRI常规扫描和扩散加权成像,良性组20例32个骨折椎体,恶性组8例18个椎体,结核组3例8个椎体,正常对照组31个椎体。b值为600s/mm2,分析病变椎体与正常椎体DWI信号特点,并测定ADC值,定量分析比较病变组与对照组之间,良、恶性组,恶性组与结核组之间ADC值有无统计学差异。结果良性组、恶性组、结核组以及对照组ADC值分别为(1.44±0.41)×10-3mm2/s、(0.94±0.17)×10-3mm2/s、(0.98±0.13)×10-3mm2/s、(0.42±0.16)×10-3mm2/s。病变组ADC值均显著高于对照组(P<0.001),良性组明显高于恶性组(P<0.01),恶性组与结核组无统计学差异(P>0.05)。以恶性组95%可信区间上界1.02×10-3mm2/s定为良恶性椎体骨折ADC值界值,诊断敏感性72.2%,特异性90.6%。结论DWI对脊椎良恶性骨折具有重要的鉴别诊断价值,可作为常规MRI检查的重要补充手段。     

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。     

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.     

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.     

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.     

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.     

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.     

Dynamic bioluminescence imaging for quantitative tumour burden assessment using IV or IP administration of <Emphasis Type="SmallCaps">d</Emphasis>-luciferin: effect on intensity,time kinetics and repeatability of photon emission

Introduction In vivo bioluminescence imaging (BLI) is a promising technique for non-invasive tumour imaging. d-luciferin can be administrated intraperitonealy or intravenously. This will influence its availability and, therefore, the bioluminescent signal. The aim of this study is to compare the repeatability of BLI measurement after IV versus IP administration of d-luciferin and assess the correlation between photon emission and histological cell count both in vitro and in vivo. Materials and methods Fluc-positive R1M cells were subcutaneously inoculated in nu/nu mice. Dynamic BLI was performed after IV or IP administration of d-luciferin. Maximal photon emission (PE_max) was calculated. For repeatability assessment, every acquisition was repeated after 4 h and analysed using Bland–Altman method. A second group of animals was serially imaged, alternating IV and IP administration up to 21 days. When mice were killed, PE_max after IV administration was correlated with histological cell number. Results The coefficients of repeatability were 80.2% (IV) versus 95.0% (IP). Time-to-peak is shorter, and its variance lower for IV (p < 0.0001). PE_max was 5.6 times higher for IV. A trend was observed towards lower photon emission per cell in larger tumours. Conclusion IV administration offers better repeatability and better sensitivity when compared to IP. In larger tumours, multiple factors may contribute to underestimation of tumour burden. It might, therefore, be beneficial to test novel therapeutics on small tumours to enable an accurate evaluation of tumour burden. Marleen Keyaerts is a Ph. D. fellow of the Research Foundation—Flanders (Belgium; FWO).     

Temporal resolution improvement in dynamic imaging

In some dynamic imaging applications, only a fraction, 1/n, of the field of view (FOV) may show considerable change during the motion cycle. A method is presented that improves the temporal resolution for a dynamic region by a factor, n, while maintaining spatial resolution at a cost of √n in signal-to-noise ratio (SNR). Temporal resolution is improved, or alternatively, total imaging time is reduced by reducing the number of phase encodes acquired for each temporal frame by 1/n. To eliminate aliasing, a representation of the signal from the static outer portion of the FOV is constructed using all the raw data. The k-space data derived from this representation is subtracted from the original data sets, and the differences correspond to the dynamic portion of the FOV. Improved resolution results are presented in phantom studies, and in vivo phase contrast quantitative flow imaging.