Baudendistel K T, Heverhagen J T, Knopp M V
Department of Radiology, College of Medicine--The Ohio State University, Columbus, 43210, USA.
Radiologe. 2004 Jan;44(1):11-8. doi: 10.1007/s00117-003-0995-3.
Clinical MRI is mostly performed at field strengths up to 1.5 Tesla (T). Recently, approved clinical whole-body MR-systems with a field strength of 3 T became available. Its installation base is more rapidly growing than anticipated. While site requirements and operation of these systems do not differ substantially from systems with lower field strength, there are differences in practical applications. Imaging applications can use the gain in signal-to-noise for increased spatial resolution or gain in speed. This comes at a trade off in increased sensitivity to field inhomogeneities and changes in relaxation times, which lead to changes in image contrast. The benefit of high field for spectroscopy consists in increased signal-to-noise-ratio and improvement in frequency resolution. The increase in energy deposition necessitates the use of special strategies to reduce the specific absorption rate (SAR). This paper summarizes the current state of MR at 3 T.
临床磁共振成像(MRI)大多在高达1.5特斯拉(T)的场强下进行。最近,已批准的场强为3T的临床全身磁共振系统开始投入使用。其装机量的增长速度比预期更快。虽然这些系统的场地要求和操作与低场强系统没有实质性差异,但在实际应用中存在不同。成像应用可以利用信噪比的提高来增加空间分辨率或提高速度。这是以增加对场不均匀性和弛豫时间变化的敏感性为代价的,而这会导致图像对比度的变化。高场强对波谱学的好处在于提高了信噪比并改善了频率分辨率。能量沉积的增加需要采用特殊策略来降低比吸收率(SAR)。本文总结了3T磁共振成像的当前状况。