扩散加权成像在乳腺肿瘤中的应用

扩散加权成像是指在分子水平研究组织中自由水质子随意运动的功能性磁共振技术,是一种评价正常及病理组织功能性改变的无创性方法.其在乳腺中的应用为乳腺肿瘤的检出及良恶性的鉴别开拓了新的前景.就扩散加权成像的技术原理、在乳腺肿瘤中的临床应用及与其他影像学检查手段比较等方面进行介绍.     

扩散加权成像在乳腺肿瘤中的应用

扩散加权成像是指在分子水平研究组织中自由水质子随意运动的功能性磁共振技术,是一种评价正常及病理组织功能性改变的无创性方法。其在乳腺中的应用为乳腺肿瘤的检出及良恶性的鉴别开拓了新的前景。就扩散加权成像的技术原理、在乳腺肿瘤中的临床应用及与其他影像学检查手段比较等方面进行介绍。     

脊髓扩散加权成像临床应用现状

脊髓扩散加权成像由于受到脊髓形态细小、脑脊液搏动的生理干扰等影响,长期被限制在实验研究范畴.随着相关技术的进步,脊髓扩散加权成像开始逐步应用于临床.主要介绍脊髓扩散加权成像的临床扫描技术、成像特点及在部分疾病中的初步应用价值.     

前列腺癌的扩散成像研究新进展

近年来扩散成像已不再局限于神经、乳腺等组织的研究,前列腺癌(PCa)扩散成像的研究愈趋广泛,包括扩散加权成像(DWI)及扩散张量成像(DTI),其能够从分子水平对PCa无创性成像,为诊断提供了极大的帮助。就PCa扩散成像技术、临床诊疗、联合其他功能磁共振成像等方面的最新进展进行综述。     

基于不同数学模型的扩散加权成像在乳腺肿瘤中的应用

MR扩散加权成像(DWI)是一种通过提取生物体组织内水分子扩散运动方向、扩散受限及位移偏离高斯分布程度等特征,并将其特征信息进行数字化、量化处理的成像技术。不同类型、不同分级的乳腺肿瘤,其组织间水分子的扩散方式和扩散程度存在差异,DWI能较好地反映乳腺不同肿瘤间的水分子扩散运动特征的差异,从而对不同肿瘤的鉴别诊断、肿瘤治疗后疗效评估等提供依据。就DWI的成像基础与原理及其在乳腺肿瘤的应用现状和局限性予以综述。     

脊髓扩散加权成像临床应用现状

脊髓扩散加权成像由于受到脊髓形态细小、脑脊液搏动的生理干扰等影响，长期被限制在实验研究范畴。随着相关技术的进步，脊髓扩散加权成像开始逐步应用于临床。主要介绍脊髓扩散加权成像的临床扫描技术、成像特点及在部分疾病中的初步应用价值。     

MR扩散加权成像在体部的应用

MR扩散加权成像在体部的应用逐渐增多,介绍体部多种组织器官的扩散加权成像技术、表现及其应用价值,并分析体部扩散加权成像存在的问题及原因.     

乳腺疾病的MRI研究进展

MRI具有极佳的软组织分辨率,近年来,该技术越来越广泛的应用于乳腺疾病的诊断.乳腺动态增强成像和灌注加权成像可从不同角度反映乳腺组织及病灶的血供灌注情况,弥散加权成像和磁共振波谱分析则从分子水平提供乳腺病变组织信息,磁共振乳腺导管成像为导管内病变提供了新的影像诊断方法.随着MRI技术的成熟、软硬件的迅速发展,MRI在乳腺疾病的检出和诊断方面显示出其独到的优势.     

MR扩散加权成像在体部的应用

MR扩散加权成像在体部的应用逐渐增多，介绍体部多种组织器官的扩散加权成像技术、表现及其应用价值，并分析体部扩散加权成像存在的问题及原因。     

心血管扩散加权成像:技术及临床应用进展

磁共振扩散加权成像无需使用外源性对比剂,可以通过探测水分子的扩散特征获取生物组织的物理特征和微观结构.在心血管领域,扩散加权成像相关研究已不断开展,克服技术上的局限性,在急性心肌损伤、心肌梗死和肥厚型心肌病等心血管疾病中体现应用价值,对早期诊断、风险评估和预后分析具有指导意义.本文对心肌扩散加权成像的基本原理、技术方面...     

Molecular imaging techniques in body imaging

Molecular imaging of the body involves new techniques to image cellular biochemical processes, which results in studies with high sensitivity, specificity, and signal-to-background. The most prevalently used molecular imaging technique in body imaging is currently fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). FDG PET has become the method of choice for the staging and restaging of many of the most common cancers, including lymphoma, lung cancer, breast cancer, and colorectal cancer. FDG PET has also become extremely valuable in monitoring the response to therapeutic drugs in many cancers. New PET agents, such as fluorothymidine and acetate, have also shown promise in the evaluation of response to therapy and in the staging of prostate cancer. Magnetic resonance (MR) spectroscopy has shown promise in the evaluation of prostate cancer. Breast cancer evaluation benefits from advances in spectroscopic imaging and contrast-enhanced kinetic evaluation of vascular permeability, which is altered in neoplastic processes because of release of angiogenic factors. Superparamagnetic iron oxide (SPIO) particles represent the first of an expanding line of MR contrast agents that target specific cellular processes. SPIO particles have also been used in the evaluation of the cirrhotic liver and at MR lymphangiography.     

Molecular imaging: integration of molecular imaging into the musculoskeletal imaging practice

Chronic musculoskeletal diseases such as arthritis, malignancy, and chronic injury and/or inflammation, all of which may produce chronic musculoskeletal pain, often pose challenges for current clinical imaging methods. The ability to distinguish an acute flare from chronic changes in rheumatoid arthritis, to survey early articular cartilage breakdown, to distinguish sarcomatous recurrence from posttherapeutic inflammation, and to directly identify generators of chronic pain are a few examples of current diagnostic limitations. There is hope that a growing field known as molecular imaging will provide solutions to these diagnostic puzzles. These techniques aim to depict, noninvasively, specific abnormal cellular, molecular, and physiologic events associated with these and other diseases. For example, the presence and mobilization of specific cell populations can be monitored with molecular imaging. Cellular metabolism, stress, and apoptosis can also be followed. Furthermore, disease-specific molecules can be targeted, and particular gene-related events can be assayed in living subjects. Relatively recent molecular and cellular imaging protocols confirm important advances in imaging technology, engineering, chemistry, molecular biology, and genetics that have coalesced into a multidisciplinary and multimodality effort. Molecular probes are currently being developed not only for radionuclide-based techniques but also for magnetic resonance (MR) imaging, MR spectroscopy, ultrasonography, and the emerging field of optical imaging. Furthermore, molecular imaging is facilitating the development of molecular therapies and gene therapy, because molecular imaging makes it possible to noninvasively track and monitor targeted molecular therapies. Implementation of molecular imaging procedures will be essential to a clinical imaging practice. With this in mind, the goal of the following discussion is to promote a better understanding of how such procedures may help address specific musculoskeletal issues, both now and in the years ahead.     

Molecular imaging will replace myocardial perfusion imaging

Conclusion   “The order is rapidly fadin’. And the first one now will later be last ...” In 2008 myocardial perfusion imaging is the main-stay of nuclear cardiology. However, the lyrics of Dylan from the 1960s are applicable today, as we are in rapidly changing times in medicine. We are seeing a paradigm shift in disease detection and treatment from a focus on cardiovascular morphology, function, and pathophysiology to genetic and molecular events. Cardiovascular molecular imaging will be the vanguard of noninvasive imaging in this era. Nuclear cardiology is uniquely positioned to play a central role in both the clinical and research applications of cardiovascular molecular imaging. The question should not be whether myocardial perfusion imaging will remain the dominant clinical application but how does nuclear cardiology transition to embrace and foster cardiovascular molecular imaging. If we do not do this, there are several other imaging specialties that will be more than willing to fill this void.     

用于肿瘤显像的三种显像剂

肿瘤阳性显像具有较高的敏感性和特异性,易于对肿瘤的原发、复发以及转移做出定性、定位诊断。201Tl、99mTc-甲氧基异丁基异腈已经用于鉴别诊断良恶性病灶、寻找转移灶、评价治疗效果和判断预后,99mTc-氮-二(N-乙基-N-乙氧基二硫代氨基甲酸盐)在肿瘤中的应用则尚在探讨中。     

Optimizing joint imaging: MR imaging techniques

For optimizing MR of the joints, a sophisticated knowledge of MR system hard-and software condition, and coil technologies, sequence and contrast preparation techniques, and the use of paramagnetic contrast agents is necessary. This review article discusses the basic principles of the appropriate use of surfacecoilsas well as the different conventional and fast imagingsequences, including three-dimensional (3D)MR imaging. In addition, the applications of contrast agents as well as the most important contrast prepaation techniques are reviewed.     

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented.     

Comparison of contrast-enhanced fundamental imaging, second-harmonic imaging, and pulse-inversion harmonic imaging

RATIONALE AND OBJECTIVES: To investigate the feasibility of recent contrast-specific ultrasound techniques in depicting vascular flow and the effects of changing the output power of the transducer and insonation mode on contrast enhancement, the authors performed an experimental study with a flow phantom. METHODS: While changing the mechanical index and the sound insonation mode (continuous and intermittent), images were obtained with three contrast-enhanced ultrasound techniques: fundamental, second-harmonic, and pulse-inversion harmonic imaging (PIHI) after a bolus injection of microbubble contrast agent. The images were compared on a time-intensity curve. RESULTS: In assessing fixed flow (10 cm/s), PIHI showed the best depiction of flow signal. In intermittent scanning, increases in the mechanical index caused stronger flow signals and longer enhancement duration in all techniques. However, continuous scanning revealed poor depiction of flow signal regardless of the technique or changes in the mechanical index because of significant bubble destruction. CONCLUSIONS: Microbubble-enhanced PIHI with intermittent scanning at a high mechanical index can depict vascular flow highly effectively without shortening the duration of enhancement.     

Undersampled projection-reconstruction imaging for time-resolved contrast-enhanced imaging.

In time-resolved contrast-enhanced 3D MR angiography, spatial resolution is traded for high temporal resolution. A hybrid method is presented that attempts to reduce this tradeoff in two of the spatial dimensions. It combines an undersampled projection acquisition in two dimensions with variable rate k-space sampling in the third. Spatial resolution in the projection plane is determined by readout resolution and is limited primarily by signal-to-noise ratio. Oversampling the center of k-space combined with temporal k-space interpolation provides time frames with minimal venous contamination. Results demonstrating improved resolution in phantoms and volunteers are presented using angular undersampling factors up to eight with acceptable projection reconstruction artifacts.