Klein Hans-Martin
MRI, Medical Center Siegerland Airport, Burbach, Germany.
Rofo. 2020 Jun;192(6):537-548. doi: 10.1055/a-1123-7944. Epub 2020 May 12.
For more than two decades, the focus of technological progress in MRI was restricted to systems with a field strength of 1.5 T and higher. Low- and mid-field MRI systems, which offer some specific advantages, are vanishing from the market. This article is intended to initiate a re-evaluation of the factor 'field strength' in MR imaging.
Literature review was carried out using MEDLINE database (via Pubmed) over a time span from 1980 to 2019 using free-text and Medical Subject headings (MeSH). Article selection was based on relevance and evidence.
Low-field MR systems are meanwhile rare in clinical imaging. MRI systems with a lower field strength provide a reduced signal-noise ratio (SNR) and spectral differentiation. However, these systems offer a variety of advantages: Shorter T1 relaxation, better T1 contrast, fewer metal artifacts, reduced susceptibility and chemical shift artifacts, fewer dielectric effects, better tissue penetration, less RF-power deposition, fewer 'missile effects', reduced effect on biomedical implants such as shunt valves, less energy and helium consumption. If we free ourselves from the constraints of high-field strength, we are able to offer multiple medical, economic and ecologic advantages to our patients. The development of high-quality low-field MRI is possible and necessary.
· Static magnetic field strength is only one of many parameters influencing image quality in MR imaging.. · Lower field strength results in a lower signal-to-noise ratio (SNR).. · Modern MR systems offer technical tools to improve signal strength and reduce noise. This makes it possible to provide a diagnostic SNR at a lower field strength.. · Low-field MR systems offer important advantages which have to be made available to our patients..
· Klein H-M. Low-Field Magnetic Resonance Imaging. Fortschr Röntgenstr 2020; 192: 537 - 548.
二十多年来，磁共振成像（MRI）技术进步的重点一直局限于场强为1.5T及更高的系统。具有一些特定优势的低场和中场MRI系统正在从市场上消失。本文旨在引发对MR成像中场强因素的重新评估。
使用MEDLINE数据库（通过PubMed），在1980年至2019年的时间跨度内，使用自由文本和医学主题词（MeSH）进行文献综述。文章选择基于相关性和证据。
低场MR系统目前在临床成像中很少见。场强较低的MRI系统提供的信噪比（SNR）和频谱分辨率较低。然而，这些系统具有多种优势：T1弛豫时间较短、T1对比度更好、金属伪影较少、敏感性和化学位移伪影减少、介电效应较少、组织穿透性更好、射频功率沉积较少、“导弹效应”较少、对生物医学植入物（如分流阀）的影响较小、能量和氦消耗较少。如果我们摆脱高场强的限制，就能为患者带来多种医学、经济和生态优势。高质量低场MRI的开发是可能且必要的。
·静磁场强度只是影响MR成像图像质量的众多参数之一。·较低的场强会导致较低的信噪比（SNR）。·现代MR系统提供了提高信号强度和降低噪声的技术工具。这使得在较低场强下提供诊断性SNR成为可能。·低场MR系统具有重要优势，必须让我们的患者能够享受到。
·Klein H-M. Low-Field Magnetic Resonance Imaging. Fortschr Röntgenstr 2020; 192: 537 - 548.
