高b值扩散加权成像在胶质瘤中的研究进展

胶质瘤是成人原发性颅内肿瘤中最常见的一种恶性肿瘤,不同级别的胶质瘤采用的治疗方法不同.因此,术前准确地判断肿瘤的级别对指导肿瘤治疗及判断预后有着重要的临床意义.常规影像学方法,利用扩散加权成像(DWI)对胶质瘤进行定性、定量分析是近年来的研究热点,就高b值DWI在胶质瘤术前分级、预测放化疗后治疗效果以及肿瘤术后复发与放射性脑损伤的鉴别作一综述.     

卵巢性索间质肿瘤的CT与MRI诊断

卵巢性索间质肿瘤是一组较少见的卵巢肿瘤,影像学上常与原发上皮性肿瘤和转移瘤相混淆.本文复习了卵巢性索间质肿瘤的CT与MRI表现,旨在提高影像诊断水平. 卵巢性索间质肿瘤(sex cord-stromal tumor)是一组有性激素分泌功能的卵巢肿瘤,约占卵巢肿瘤的8%.性索间质肿瘤来源于原始性腺中的性索及间质组织.原始性索包括卵巢的颗粒细胞、睾丸的支持细胞即Sertoli细胞,间质细胞包括成纤维细胞、卵泡膜细胞和睾丸间质细胞即Leyding细胞.卵巢性索间质肿瘤可由上述细胞单独形成或不同细胞以不同的组合形成[1].     

超声造影引导经皮穿刺活检在肿瘤诊断中的应用

尽管二维超声引导经皮穿刺活检在肿瘤诊断中具有很大优势,但是由于受到肿瘤形态、大小及内部结构等限制,可导致穿刺失败或者假阴性率增加.超声造影作为一种新的诊断技术,能够引导对肿瘤病灶的穿刺活检,提高诊断准确率.对超声造影引导经皮穿刺活检技术及其在不同部位肿瘤(肝脏肿瘤、肺部肿瘤及前列腺癌等)诊断中的应用价值予以综述.     

肿瘤干细胞在肿瘤放射治疗学中的研究进展

肿瘤细胞的放射敏感性是决定放射治疗能否成功的重要因素之一.研究表明,临床上肿瘤的放射敏感性主要取决于肿瘤的组织来源、分化程度、遗传背景、大体类型以及患者的一般状况,如是否存在严重贫血和糖尿病等.而放射生物学研究提示肿瘤细胞的内在敏感性、细胞周期、增殖情况以及肿瘤细胞所处的微环境,如乏氧等是影响肿瘤放射敏感性的重要因素.随着肿瘤基础研究的深入,现在认为恶性肿瘤是一种干细胞疾病,即肿瘤来源于肿瘤干细胞(cancer stemcell,CSC)[1].近年来,先后在脑胶质瘤、乳腺癌、肺癌、黑色素瘤和前列腺癌等多种实体瘤中克隆到了肿瘤干细胞.这类细胞虽然仅占整个肿瘤细胞的一小部分,但是它们具有自我更新能力和多向分化潜能,可能是形成不同分化程度肿瘤和肿瘤不断生长的根源,是肿瘤发生、扩散和复发等过程中的"起始细胞",也可能是肿瘤治疗失败的根源所在[1-2].肿瘤干细胞概念的提出,给传统肿瘤放射治疗学带来了新进展,也带来了新的挑战.为此,本文拟对肿瘤干细胞在肿瘤放射治疗中的研究进展作一综述.     

放疗在胸腺肿瘤治疗中的应用与研究进展

胸腺肿瘤是一种罕见的纵隔肿瘤,放疗是治疗胸腺肿瘤的重要手段之一,目前放疗在不同分期胸腺瘤之中的具体应用仍有诸多争议。本文综述术后/根治性放疗在不同分期胸腺肿瘤治疗中的应用、病理分型与预后的关系以及目前免疫治疗在胸腺肿瘤中的研究进展,旨在为临床诊疗和后续研究提供参考。     

乳腺常见病变的X线和MRI诊断及其病理基础

乳腺癌是女性肿瘤中发病率最高的一种,我国每年有4万人死于乳腺癌,发病率与5年前相比上升了3倍多.乳腺肿瘤包括良恶性一系列病变,其病理类型、生物学行为各异、治疗方式不同,当然其影像表现也依据不同的病理类型、甚至同一种病理类型但由于不同的亚型而表现多种多样.     

口腔癌放射治疗的优化研究

口腔癌是一种常见的黏膜上皮性肿瘤,发病率约占全身恶性肿瘤的3.5%.口腔癌中,鳞状细胞癌占90%以上,2005年WHO在头颈肿瘤病理学和遗传学分类中将口腔鳞状细胞癌定义为"一种具有不同程度分化的侵袭性肿瘤,倾向于早期、广泛的淋巴结转移,主要发生于40～70岁的烟酒嗜好者"[1].     

经腹彩色多普勒显像诊断卵巢恶性肿瘤的价值

目的 :探讨经腹彩色多普勒超声观察卵巢肿瘤血管定位和血流频谱形态对诊断卵巢恶性肿瘤的价值。方法 :使用彩色多普勒超声检查 2 8例卵巢恶性肿瘤和 4 1例良性肿瘤 ,测定肿瘤的血管定位 ,舒张期切迹 ,搏动指数 (PI)和阻力指数 (RI) ,将PI和RI与术后病理组织学结果对照 ,以此预测卵巢恶性肿瘤的灵敏性、特异性。结果 :卵巢恶性肿瘤PI为0 .5 4± 0 .15 ,良性为 1.4 8± 0 .6 5 ;恶性肿瘤RI为 0 .4 0± 0 .0 94 ,良性为 0 .85± 0 .0 0 9(P <0 .0 0 1)。卵巢恶性肿瘤 10 0 %可见血管 ,并定位于肿瘤中心 (96 .4 % ) ,92 .9%无舒张期切迹 ;良性肿瘤 4 6 .3%可见血管 ,并定位于肿瘤周边 (94 .7% ) ,89.5 %可见舒张期切迹。以 0 .76为PI界值 ,其预测卵巢恶性肿瘤的敏感性、特异性及阳性和阴性预测率分别为 92 .9%、94 .8%96 .3%和 90 .0 % ;以 0 .5 6为RI界值 ,其敏感性、特异性及阳性和阴性预测率分别为 89.3%、94 .7%、96 .2 %和 85 .7%。结论 :经腹彩色多普勒超声观察卵巢肿瘤血管定位 ,搏动指数、阻力指数和有无舒张期切迹是鉴别卵巢良恶性肿瘤有效参考价值的方法之一。     

胰腺导管内乳头状黏液性肿瘤的影像学进展

胰腺导管内乳头状黏液性肿瘤(IPMNs)是胰腺最常见的囊性肿瘤[1].1982年由Ohhashi首次报道,定义为一种胰腺产生黏液的肿瘤[2].以后陆续有文献对该肿瘤进行不同的命名,如:产黏液癌、高分泌黏液癌、导管内乳头状肿瘤等.     

磁敏感加权成像在脑外疾病的应用现状

磁敏感加权成像(susceptibility weighted imaging,SWI)是一种新兴的MRI技术,目前主要应用于脑部病变,在脑血管病、脑外伤、退行性疾病及肿瘤性病变的诊断中显示出重要价值[1-4].近年来,SWI的应用领域逐步向脑外拓展并显示出极大的应用潜力.笔者就SWI在脑外疾病中的应用现状作一综述,现报道如下.     

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.     

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.     

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.     

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).     

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.