A review of current evidence-based clinical applications for breast magnetic resonance imaging

Magnetic resonance imaging (MRI) is an important new tool for imaging of the breast. MRI has now been demonstrated to be the most sensitive imaging method for detecting breast carcinoma, allowing depiction of cancers that are occult on mammography, ultrasound, and clinical breast examination. This is tempered by imperfect specificity due to overlap in the features of benign and malignant lesions, and by higher examination cost and more limited availability compared to other breast imaging tests. This article describes the current evidence-based clinical indications for use of breast MRI. Specifically, MRI has been shown to be advantageous for cancer assessment for screening patients at high risk, evaluating patients with a new breast cancer diagnosis, monitoring patients undergoing neoadjuvant chemotherapy, and evaluating patients with metastatic axillary adenocarcinoma and unknown primary site. This tool has also been shown to be useful for the evaluation of silicone breast implant integrity. Employment of breast MRI as a problem solving technique for equivocal mammographic or clinical findings is controversial. For each of these clinical applications, the evidence regarding the diagnostic accuracy of breast MRI will be reviewed. An understanding of the current evidence will facilitate the most appropriate utilization of this important medical resource.     

Future directions in body magnetic resonance imaging

Technologic innovations in instrumentation and contrast agents naturally lead to new clinical and research applications in body MRI. Although long-range predictions of innovation are an uncertain process, short-term trends in development are more readily discernable. This review will provide examples of recent developments in magnetic resonance spectroscopic imaging, contrast agent development and molecular imaging, instrumentation, post-processing, and screening in an attempt to describe areas of active research.     

Evolving cardiovascular applications for magnetic resonance imaging

Improvements in magnetic resonance imaging (MRI) have increased its value in existing cardiovascular applications and opened the door to new uses. The image quality and spatial resolution of cardiovascular MRI is better than that of most other noninvasive imaging procedures. In addition, MRI can measure and map biochemical markers diminished by ischemic damage.     

Diffusion magnetic resonance imaging of the breast

Several studies have investigated the role of advanced magnetic resonance imaging (MRI) techniques, such as diffusion-weighted imaging (DWI), to improve the specificity of MRI for the evaluation of breast lesions. Potential roles for DWI and the apparent diffusion coefficient in characterizing breast tumors and distinguishing malignant from benign tissues have been reported. This article discusses the clinical applications of breast DWI, including literature results, technical issues and limitations, and the potential applications. The analysis of DWI at our institution is also discussed. The establishment of standard DWI protocols and diagnostic criteria is necessary to ensure accuracy and reproducibility at different centers.     

Noninvasive imaging and spectroscopy--broad applications of magnetic resonance.

The present utility of nuclear magnetic resonance (NMR) spectroscopy in chemical analysis and magnetic resonance imaging (MRI) in the clinical environment has made this technology commonplace in the chemical industry, clinical medicine, and academic research. The attributes of nuclear magnetism that make the technique especially powerful in biology are discussed. This paper reviews the uses of NMR and MRI, with an emphasis on spatially resolved applications. These applications include imaging, localized spectroscopy, flow sensing, and diffusion mapping from using magnetic-field gradients. The limits of spatially resolved NMR and imaging will be examined in terms of both scientific principles and engineering practice. Block diagrams of both imaging and spectroscopy apparatus are presented and technical requirements of the critical components are discussed. Developing trends in sensing probes, magnets, and applications are highlighted.     

Chest applications of magnetic resonance imaging in children

Mediastinal anatomy is well depicted by MRI. This article discusses the role of thoracic MRI in evaluating mediastinal, parenchymal, and pleural abnormalities in children. It is particularly useful in the evaluation of vascular anomalies and assessment of extension of neuroblastoma and can obviate other, more invasive, studies.     

Diffusion-weighted magnetic resonance imaging in the upper abdomen: technical issues and clinical applications

Recent technological achievements have enabled the transposition of diffusion-weighted imaging (DWI) with good diagnostic quality into other body regions, especially the abdomen and pelvis. Many emerging and established applications are now being evaluated on the upper abdomen, the liver being the most studied organ. This article discusses imaging strategies for DWI on the upper abdomen, describes the clinical protocol, and reviews the most common clinical applications of DWI on solid abdominal organs.     

Computed tomography versus magnetic resonance imaging and three-dimensional applications

An attempt has been made to simplify and to provide an understanding of some of the new modalities for evaluation of head and neck pathology. Both CT and MRI are complementary to each other: MRI being superior to CT in evaluating soft tissue, and CT being superior to MRI in assessing fine bony details and in identifying microcalcifications. MRI is the modality of choice for tumor evaluation because it has several advantages over CT in assessing the location, spread, and staging of the disease. HRCT scanning remains the procedure of choice in the evaluation of middle ear and base of the skull, and in the evaluation of benign sinonasal disease. CPA and IAC lesions are best evaluated by MRI. Three-dimensional surface reformations of axial CT scans enable the surgeon to plan the operative approach needed to reduce facial fractures and to repair cranial deformities.     

Technical challenges and clinical applications of magnetic resonance enteroclysis

With the advent of gradient systems the image quality of ultrafast pulse sequences, i.e., half Fourier acquisition single shot turbo spin echo (HASTE), true fast imaging with steady-state processing and fast low angle shot (FLASH), improved substantially and clinical applications including small bowel imaging became feasible. Within this context, magnetic resonance enteroclysis was developed as a comprehensive examination of the small bowel, providing luminal, transmural, and exoenteric diagnostic information of small bowel abnormalities. Clinical applications of magnetic resonance enteroclysis include diagnostic evaluation and follow-up of patients with inflammatory or neoplastic diseases and small bowel obstruction.     

磁共振氨基质子转移成像的临床应用

磁共振氨基质子转移(amide proton transfer,APT)成像是一种基于化学交换饱和转移技术且可反映生物组织中内源性游离蛋白和肽类含量以及氨基质子交换速率的无创性分子磁共振成像方法。APT加权图像是通过对Z谱中水频率两侧±3.5 ppm处的非对称性磁化转移率进行计算得到的。近年来,APT磁共振成像(magnetic resonance imaging,MRI)已被越来越多地应用于疾病诊断中。本文针对目前APT MRI在临床应用和科学研究方面的进展予以综述。     

Indirect magnetic resonance arthrography: applications in sports imaging

Indirect magnetic resonance (MR) arthrography is an imaging tool with several advantages over both direct MR arthrography and unenhanced musculoskeletal magnetic resonance imaging. It is based upon the idea that paramagnetic contrast agents injected intravenously into the plasma compartment ultimately will perfuse the articular space. Advantages of indirect MR arthrography include enhancement of both intra-articular and extra-articular pathology without the need for an invasive, fluoroscopically guided arthrogram, as well as high sensitivity for reinjury in postoperative patients. Some potential disadvantages of this technique are enhancement of normal vascular tissues and difficulty in making a diagnosis dependent upon joint space distension in the absence of an effusion. Important technical issues when performing indirect arthrography include choosing an appropriate delay between contrast injection and imaging, as well as the potential use of patient exercise to improve image quality. In sports medicine, indirect MR arthrography is most useful in and about small joints such as the wrist and ankle; in articulations with potential internal derangements, as well as bony or osteochondral injuries; and in injured joints that have been altered surgically.     

三阴乳腺癌磁共振成像研究

三阴性乳腺癌(TNBC)具有特殊的生物学和临床病理学特征。由于侵袭性强,缺乏有效的靶向治疗和内分泌治疗,预后差。目前磁共振成像是诊断乳腺癌最准确的影像学检查方法,可协助诊断和预后评估。三阴性乳腺癌典型MRI表现为单一病灶,呈肿块型,形态不规则,边缘光滑,在T2WI上病变中心呈高信号。进一步的工作是研究磁共振成像的临床应用,动态增强磁共振成像(DCE-MRI)、DWI、MR波谱(MRS)等。     

Abdominal magnetic resonance imaging at 3 T: oncological applications

The gain in signal-to-noise ratio at 3 T magnetic resonance (MR) imaging produces many benefits for abdominal imaging applications, including the capability to reduce acquisition times and/or improve spatial resolution for a variety of pulse sequences, the potential for broader application of parallel imaging techniques, and an increased sensitivity to gadolinium-based contrast media. These advances have the potential of improving the accuracy of MR imaging in the detection, staging, treatment planning, and follow-up of patients with abdominal tumors. At the same time, because certain high-field-strength-related drawbacks could not be compensated for, abdominal 3 T MR imaging should be clinically implemented with caution in some patients (eg, patients with massive ascites).     

乳腺纤维瘤病的X线、磁共振影像表现及特征

目的分析乳腺纤维瘤病(BF)的X线、磁共振(MR)影像表现及特征。方法回顾性分析经手术及病理检查证实且术前均行X线、MR检查的15例BF患者的资料,包括病灶部位、X线和MR形态特征及强化特点、血流动力学特征。分析BF的影像特征及误诊原因。结果 15例患者共17个病灶, 1例为双侧发病(双乳各1个病灶), 1例单乳2个病灶;中位年龄31岁; 9例病灶位于乳腺腺体内, 5例(共7个病灶)靠近胸壁, 1例病灶位于乳头-乳晕复合体。17个病灶的X线显示合并结构扭曲10例,边缘毛刺样改变8例,均未见钙化。15个病灶MR增强扫描表现为结节或肿块, 14个病灶边缘不规则, 8个病灶可见毛刺样强化, 5个病灶可见“筋膜尾征”。病灶在T1WI上呈等或稍低信号,在T2WI上呈高或混杂信号,弥散加权成像(DWI)上呈稍高或高信号,平均表观弥散系数(ADC)值均1.25×10~(-3) mm~2/s;增强后时间-信号强化曲线(TIC)为Ⅰ型(上升型)或Ⅱ型(平台型)。结论 BF发生在腺体内多呈肿块样,若累及浅、深层筋膜组织,则X线上多合并结构扭曲及毛刺样改变,易误诊为恶性病变。MR上多表现为不规则肿块,可见“筋膜尾征”, ADC值及动态增强TIC多提示良性病变,对明确诊断价值较大。     

Current concepts and advances in clinical parallel magnetic resonance imaging

Parallel imaging (PI) is one of the most promising recent advances in MRI technology and has, similar to the introduction of multidetector helical scanning in CT, revolutionized MR imaging. The speed of all conventional MRI methods has been limited by either gradient strength or their switching times. The basic idea in PI is to use some of the spatial information contained in the individual elements of a radiofrequency (RF) receiver coil array to increase imaging speed. These PI techniques are removing some of the previous limitations in speed of MRI scanners and set the basis for accelerated image formation. Initially, PI was motivated by the wish to accelerate image acquisition without reducing the spatial resolution of the image. However, depending on the application, it turned out that PI harbors several other advantages. Among those is the possibility for higher spatial resolution, shorter breath-holds or multiple averaging to diminish motion artifacts, reduced image blurring and geometric distortions, better temporal resolution, and means for navigator correction. This overview focuses on technical aspects, clinical applications, and ongoing research in different areas of the human body. The critical review demonstrates PI's great versatility as well as the current trends to use this unique technique in the majority of clinical scan protocols.