体素内不相干运动DWI对肝脏良恶性病变的诊断价值

目的：探讨体素内不相干运动（IVIM）扩散加权成像对肝脏良恶性病变的诊断价值。方法：搜集2014年12月－2015年7月临床怀疑为肝脏肿瘤、且经手术病理、穿刺活检、临床或随访明确诊断的92例患者（共93个病灶）的病例资料,其中恶性组69例、良性组23例（24个病灶）。所有患者均行常规 MRI平扫、多期动态增强扫描及IVIM（b＝0、20、50、100、200、400、600、800和1200s／mm2）。将ROI 放置于肿瘤最大实性区域,采用单指数及双指数模型获得以下参数值：表观扩散系数（ADC）、慢速表观扩散系数（D）、快速表观扩散系数（D*）及快速扩散成分所占比例（f）。采用独立样本t检验比较良恶性组间各参数的差异,并采用受试者工作特征曲线（ROC ）计算各参数的诊断效能。结果：良性病变的ADC、D、D*和f值分别为（1．67±0．59）×10－3、（1．23±0．34）×10－3、（36．13±17．84）×10－3mm2／s 和（29．96％±15．67％）,恶性组者分别为（1．20±0．36）×10－3、（0．88±0．21）×10－3、（34．84±19．75）×10－3mm2／s 和（21．77％±10．07％）。除D*值外,ADC值、D值及f值在两组间的差异有统计学意义（P值分别为0．001、0．000及0．023）,相应ROC下面积分别为0．764、0．804及0．665。以D值＜1．13×10－3mm2／s为阈值,诊断肝脏恶性肿瘤的敏感度及特异度分别为85．5％和62．5％。结论：体素内不相干运动扩散加权成像有助于肝脏良恶性病变的鉴别,其中使用双指数模型计算的慢速表观扩散系数值诊断效能最高。     

磁共振弥散加权成像在乙型肝炎肝纤维化程度评估中的价值

目的：探讨磁共振弥散加权成像（DWI）在乙型肝炎肝纤维化程度评估中的价值。方法62例乙型肝炎肝纤维化患者根据肝脏穿刺及组织病理学检查分为S1期（n=15例）、S2期（n=16例）、S3期（n=16例）、S4期（n=15例）,同期选择23例未发生肝纤维化的乙肝患者作为对照组,选择24例门诊健康体检者作为正常组。所有研究对象均接受磁共振平扫及DWI检查,比较各组不同b值时ADC值,分析ADC值与乙型肝炎肝纤维化分期的相关性。结果 b值为100s/mm2、200s/mm2、400s/mm2时各组ADC值比较无显著性差异（P>0.05）,b值为600s/mm2、800s/mm2时,肝纤维化组S3及S4期ADC值明显低于S0、S1及S2期（P<0.05）;b值为100s/mm2、200s/mm2、400s/mm2时,不同分期ADC值间比较无显著性差异（P>0.05）,b值为600s/mm2、800s/mm2时,ADC值与肝纤维化分期有负相关性（P<0.05）,b值为800s/mm2时,相关性最明显。结论 DWI在乙型肝炎肝纤维化程度评估中具有较高的临床价值,尤其当b值为800s/mm2时,各肝纤维化分期的ADC值存在较大的差异性,值得临床推广应用。     

体素内不相干运动扩散加权成像在良性脑膜瘤中的初步研究

目的 探讨多b值体素内不相干运动扩散加权磁共振成像（introvoxel incoherent motion MR imaging,IVIM MRI）的单、双指数模型在良性脑膜瘤中的应用价值.方法 纳入22例手术病理证实为良性脑膜瘤并术前行常规MR序列及IVIM序列扫描的患者.多b值IVIM序列包括14个b值（0～1 000s/mm2）,所得IVIM序列原始数据经单、双指数模型处理,得到单、双指数模型衰减曲线,并生成对应参数图,测量肿瘤实质区及正常脑白质的单指数模型的扩散系数ADC值和双指数模型的扩散系数D值、灌注分数f值、灌注系数D＊值,采用配对样本t检验进行统计学分析.结果 单、双指数模型衰减曲线显示肿瘤实质区信号强度随b值的增大而衰减.肿瘤实质区ADC值、D值、D＊值、f值分别为（0.87±0.13）μm2/ms、（0.79±0.10）μm2/ms、（58.68±27.52）μm2/ms、（7.68±3.59）％;正常脑白质的ADC值、D值、D＊值、f值分别为（0.74±0.06）μm2/ms、（0.69±0.04）μm2/ms、（93.43±31.64）μm2/ms、（4.48±2.39）％.单指数模型中肿瘤实质区ADC值较正常脑白质ADC值两者比较差异有统计学意义（t=5.793,P＜0.05）;双指数模型中,肿瘤实质与正常脑白质D、f、D＊值分别进行比较,肿瘤实质的D、f值均较正常脑白质增高（t=4.384,P＜0.05和t=3.349,P＜0.05）;而肿瘤实质D＊值较正常脑白质D＊值减低（t=-3.559,P＜0.05）.肿瘤实质区单指数模型ADC值与双指数模型D值两者差异有统计学意义,且单指数ADC值显著较双指数模型D高（t=6.492,P＜0.05）.结论 基于棠规DWI序列的多b值IVIM双指数模型可以更准确地描述良性脑膜瘤的扩散信息,同时非侵入性地获得肿瘤灌注信息.     

磁共振成像T1值、T2值和ADC值与肝脏纤维化模型病理评分分级纤维化分期诊断结果相关性研究

目的：探讨磁共振成像T1值、T2值、ADC值对肝脏纤维化病理评分分级纤维化分期诊断的价值和意义。方法：将大白兔分为正常对照组（4只）和肝脏纤维化模型组（13只）,分别对其进行常规MR扫描,测量肝脏组织T1值和T2值;磁共振弥散加权成像扫描（MR-DWI）,测量肝脏组织表观扩散系数（ADC值）。取肝脏组织标本做常规HE染色和网状纤维染色（Gomoris法）,以病理组织学评分分级和纤维化分期诊断结果为标准,研究分析T1值、T2值和ADC值在肝脏纤维化不同评分分级和纤维化分期间的变化情况;采用统计学相关分析法研究T1值、T2值和ADC值在与病理积分、评分分级和纤维化分期诊断结果之问的相关性。统计学分析采用SPSS13．0,单相分析法,P〈0．05为差异有统计学意义。结果：磁共振成像T1值、T2值、ADC值测量结果在对照组和不同评分分级和纤维化分期间的差异性具有显著的统计学意义（P〈0．05）;在肝脏纤维化模型组中T1值和T2值明显高于对照组,且随着评分分级和纤维化分期的增加而逐渐增加;肝脏纤维化模型组中ADC值明显低于对照组,随着评分分级和纤维化分期的增加降低越显著。相关分析结果表明T2值与病理积分、评分分级和纤维化分期诊断结果之间呈显著正相关性（P〈0．01）;ADC值与病理积分、评分分级和纤维化分期诊断结果之间表现显著负相关性（P〈0．01）。结论：在肝脏发生纤维化时,定量检测磁共振成像中的T1值、T2值和ADC值,能够评估肝脏纤维化病理评分分级和纤维化分期,作为非损伤性检查方法的磁共振成像可以用于临床肝脏纤维化定量诊断。     

肝硬化：体素不相干运动的MR成像——初步研究

目的 回顾性评价并行采集呼吸门控扩散加权MR成像序列允许计算的基于纯分子（D）和灌注相关（D＊,f）的扩散参数,在体素不相干运动（IVIM）理论基础上,判断这些参数在肝硬化病人及无肝纤维化病人间是否不同。材料与方法 本回顾性研究经机构审查委员会同意并免除知情同意。IVIM扩散加权成像经三烷模型测试,     

体素内不相干运动扩散加权成像对前列腺癌的诊断价值

目的：探讨多b值扩散加权成像（DWI）序列在前列腺癌诊断中的应用价值。方法：经超声引导下行前列腺穿刺活检病理证实为前列腺癌的7例患者及非前列腺癌的4例患者纳入本组研究,所有患者均行多b值DwI序列（b值分别为0、188、375、563和750s／mm2）扫描。应用双指数模型（体素不相干运动模型）进行分析,计算并比较分析前列腺癌区和非癌区的相对纯扩散值D和灌注分数f的差异。结果：癌区的D值和f值分别为（0．77±0．20）×10^-3mm^2／s和（8．66±3．07）％,非癌区的D值和f值分别为（1．53±0．48）×10^-3mm2／s和（2．27±1．16）％。癌区的D值低于非癌区,差异有统计学意义（P〈O．01）;癌区的f值高于非癌区,但差异无统计学意义（P〉0．05）。结论：多b值DWI序列可获取前列腺组织真实水分子扩散运动及微灌注相关信息,可为前列腺癌的诊断提供重要信息。     

治疗前IVIM-DWI预测肝癌介入治疗疗效的价值

【摘要】目的：探讨体素内不相干运动扩散加权成像(IVIM-DWI)预测肝癌介入治疗疗效的价值。方法：搜集在治疗前及经导管肝动脉化疗栓塞（TACE）治疗后4~6周内分别行IVIM-DWI检查的90例肝癌患者。IVIM序列设置12个b值(b=0、10、20、50、100、150、200、400、600、800、1000和1200s/mm2)。分析IVIM双指数模型D*值、D值、f值,与单指数模型ADC值进行比较,并进行疗效评价。根据mRECIST标准,将患者分为治疗稳定组和进展组。通过独立样本t检验、单因素方差分析、多因素Logistic回归和受试者特征曲线(ROC),分析和确定有预测价值的IVIM参数及阈值。结果：90例患者中稳定组48例,进展组42例。介入治疗后,IVIM参数中ADC值、D值均升高,D*值、f值降低。治疗前稳定组ADC值、D值略高于进展组,稳定组D*值、f值略低于进展组,其中仅治疗前ADC值在两组间差异有统计学意义（P=0.039）。治疗后稳定组ADC值、D值、f值均高于进展组,稳定组D*值略低于进展组,其中治疗后ADC值、D值在两组间差异有统计学意义（P疗后ADC=0.015;P疗后D=0.048）。治疗前D*值、治疗前f值、治疗后D*值及治疗前D值4个指标在TACE短期疗效预测时为独立影响因素,其曲线下面积（AUC）依次降低,分别为0.694、0.502、0.499、0.398;其P值依次为0.002、0.968、0.987、0.097。其中以治疗前D*值预测疗效最佳,当D*值>12.319×10-3mm2/s时预测为疗效差,其敏感度和特异度分别为76.2%和64.6%,准确度为70%。结论：IVIM-DWI有助于预测肝癌介入治疗疗效,尤以治疗前D*值预测效果最佳。     

双源CT 灌注成像联合血清学指标对肝纤维化诊断的价值探讨

目的：探讨双源CT灌注成像联合血清学指标对兔肝纤维化进行早期诊断的价值。方法采用四氯化碳法建立肝纤维化模型,共对46只肝纤维化成模兔及10只对照兔行灌注成像,取得不同肝纤维化级别肝灌注参数,包括：肝动脉灌注量（ALP）、门脉灌注量（PVP）、肝动脉灌注指数（HPI）、血流量（BF）、血容量（BV）。检测肝纤维化兔血清透明质酸（H A ）、Ⅲ型前胶原（PCⅢ）、IV型胶原（IV‐C ）和层黏连蛋白（L N ）值,随后行病检分期分组,分析组间灌注参数值,同时分析灌注参数及血清学指标与肝纤维化程度的相关性。结果随着肝纤维化分期增加,PV P值呈下降趋势（ P ＜0．05）;S0、S1期分别与S2、S3、S4期具有统计学差异（ P ＜0．05）;PVP、HPI与肝纤维化分期存在一定相关性（ r ＝‐0．84,P ＜0．05;r ＝0．62,P ＜0．05）。血清学指标随着肝纤维化程度加重而逐渐升高,其中,HA、IV‐C与肝纤维化分期关系较为密切（ P＜0．05）。结论双源CT灌注成像与血清学检查在判断肝纤维化程度各有优缺点,联合应用二者有助于临床对肝纤维化进行合理评价。     

鼻咽癌磁共振灌注定量参数及ADC值与T分期的关系

目的：探讨鼻咽癌（NPC）磁共振灌注成像（PWI）定量参数及扩散加权成像（DWI）参数ADC 值与T 分期之间的相关性。方法：对94例NPC初治患者行PWI、DWI和T分期,分析PWI参数及ADC值与T分期之间的相关性,比较高低T分期NPC之间各 MR参数值的差异。结果：T 分期分别与 Ktrans （r＝0．226,P＝0．029）和 Ve （r＝0．553,P＝0．000）呈正相关,与Kep呈负相关（r＝－0．350,P＝0．001）。未发现T 分期与 fPV（r＝－0．122,P＝0．240）及 ADC 值（r＝－0．056,P＝0．592）之间存在线性相关。Ktrans、Kep和 Ve 值在 Thigh组（T3和 T4期 NPC）分别为（0．386±0．171）、（1．333±0．436）min－1和（0．302±0．107）,在 Tlow组（T1和 T2期 NPC）分别为（0．313±0．115）min－1、（1．552±0．472）min－1和0．219±0．102,两组间的差异有统计学意义。fPV和ADC值在Thigh组分别为（0．017±0．021）和（0．935±0．144）×10－3 s／mm2,在Tlow组分别为（0．019±0．018）和（0．950±0．196）×10－3 s／mm2,两组间的差异无统计学意义。与Ktrans和Kep值相比,Ve 值在判别Thigh组和Tlow组上诊断效能最大,其敏感性为91．8％、特异性为63．2％。结论：PWI定量参数可以反映不同T分期NPC在内部微循环灌注上的差异,而ADC值难以区分不同T分期NPC之间在水分子扩散方面的差别。     

磁共振体素内不相干性运动在肌骨系统肿瘤定性诊断中的作用

目的：评价磁共振体素内不相干性运动（IVIM）参数在肌骨系统肿瘤定性诊断中的价值。方法：本研究中的38例肌骨系统肿瘤的患者,均采用1．5T MR 扫描仪进行检查,在常规扫描后进行 IVIM 扫描。IVIM 使用的9个 b 值分别为0,20,40,60,80,100,250,500和750 s／mm2。分别测量病变区和作为对照组的正常肌肉组织 IVIM 参数 ADC、ADCslow 、ADCfast 及 PF 值。根据病理结果,将病变分为良性（12例）、交界性（14例）及恶性肿瘤（12例）,并对三组肿瘤之间以及肿瘤与对照组之间 ADC、ADCslow 、ADCfast 及 PF 值的差异进行统计学分析。结果：交界性肿瘤的 ADC 及 ADCslow 值分别为（1．02±0．15）×10－3 mm2／s 和（1．02±0．16）×10－3 mm2／s,明显低于对照组（1．38±0．20）×10－3 mm2／s 和（1．38±0．17）×10－3 mm2／s,差异具有统计学意义（P ＝0．001）。恶性肿瘤的 ADC 及 ADCslow 值分别为（0．90±0．13）×10－3 mm2／s和（0．88±0．14）×10－3 mm2／s,明显低于对照组（1．48±0．12）×10－3 mm2／s 和（1．48±0．09）×10－3 mm2／s,差异具有统计学意义（P ＜0．001）。而良性肿瘤的 ADC 及 ADCslow 与对照组之间差异无统计学意义（P ＝0．564,0．480）。ADCfast 以及 PF 值在肿瘤与对照组之间无统计学差异。交界性、恶性肿瘤的 ADC 和 ADCslow 值明显低于良性肿瘤,差异具有统计学意义（P 值均＜0．001）,但交界性肿瘤与恶性肿瘤之间的 ADC 和 ADCslow 值差异无统计学意义。良性、交界性和恶性肿瘤之间的 ADCfast 和 PF 值的差异没有统计学意义。结论：IVIM 参数 ADC 和 ADCslow 有助于区分良性肿瘤与交界性、恶性肿瘤,提高肌骨系统肿瘤的诊断准确性。     

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.