摘要:

Fast spin-echo (FSE) imaging is a recently modified rapid-acquisition relaxation-enhanced technique that affords rapid magnetic resonance (MR) imaging while retaining true spin-echo (SE) contrast features. By manipulating factors such as echo train length, echo spacing, and order of phase encoding, dual-echo brain images currently may be obtained many times faster than with conventional SE techniques. The time advantage of FSE may be used simply to obtain images much more rapidly or to acquire images of much higher contrast or spatial resolution compared with conventional SE images in a comparable period of time. Lesion appearance and conspicuity are usually quite similar to those on conventional SE images, with the important exception of some hemorrhagic blood products, which may appear less conspicuous on FSE images because of reduced magnetic susceptibility effects. Another important difference is the bright appearance of fat on all routine FSE sequences (T1-weighted, proton-density, and T2-weighted), although this may be eliminated easily by using routine fat-suppression techniques. Recent applications of FSE include three-dimensional multislab imaging and high-resolution imaging with large-matrix, small-field of view, thin-slice, and multiple-excitation imaging parameters. FSE techniques appear quite promising for rapid MR imaging of the brain, and they have largely replaced conventional SE technique at some institutions.

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Ultrafast magnetic resonance (MR) imaging allows the acquisition of anatomic images of the brain in a fraction of a second. Recently developed imaging techniques have the potential to increase the specificity of information provided by MR imaging, MR imaging techniques that are based on ultrafast scanning have enabled the collection of functional as well as anatomic information concerning tumor microvasculature. These techniques promise to increase knowledge of the tissue characteristics of human brain tumors, their progress, and their responses to therapy.

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

The article reviews recent progress made in the field of diffusion and perfusion magnetic resonance (MR) imaging and presents possible applications in brain tumors. Diffusion, a new parameter, provides useful data to assess tissue structure and function. Perfusion MR imaging gives results that are somewhat similar to those obtained with classic non-MR imaging methods, but it offers several potential advantages.

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

In vivo nuclear magnetic resonance (NMR) spectroscopy is a rapidly developing, noninvasive analytical technique that allows sequential studies of brain tumor metabolism. It can be implemented on most conventional high-field magnetic resonance imaging scanners. In animal tumor models. NMR spectroscopy has been used extensively to characterize the metabolic changes associated with tumor growth and response to therapy. Preliminary data in humans indicate the feasibility of recording phosphorus and proton spectra from focal lesions within the brain. It is hoped that the technique will provide useful prognostic information in terms of tumor growth behavior and prediction and detection of response to therapy. However, the technique suffers from relatively coarse spatial resolution, and the methodology is still under development. More studies with larger patient groups are required before the clinical utility of the technique can be fully evaluated.

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

This article reviews the magnetic resonance imaging technique employed in children. It discusses preparing children for the examination, sedation techniques, imaging sequences, and the use of contrast media.

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Magnetic resonance angiography (MRA) is a novel technique that uses gradient echo pulse sequences and computer postprocessing technology to create vascular-flow images. The technique is easy to apply, noninvasive, and frequently yields information not available by other noninvasive means. The utility and benefits of MRA are amply documented by clinical studies in the neuroimaging literature. This article reviews the techniques of MRA and the current literature in the application of MRA in pediatric imaging. Illustrative cases demonstrating the use of MRA in pediatric neuroradiology are presented. The utilization of MRA in congenital lesions such as aberrant internal carotid artery and arteriovenous malformation and in differing causes of ischemic disease is highlighted. There is an ever-expanding number of applications of MRA in pediatric neuroimaging. Despite the lack of standardized protocols, with a thorough knowledge of the basic principles, MRA can be successfully applied in many imaging situations. The ease of use and noninvasive nature of MRA make it an ideal tool in the evaluation of the pediatric neurovasculature.

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID

ISSN:0899-3459    

出版商:OVID    

年代:1993

数据来源: OVID