1.5T和3.0T场强下胎儿脑部的磁共振成像：比较比吸收率（SAR）和图像质量
MR imaging of the fetal brain at 1.5T and 3.0T field strengths: comparing specific absorption rate (SAR) and image quality.
作者信息
Krishnamurthy Uday, Neelavalli Jaladhar, Mody Swati, Yeo Lami, Jella Pavan K, Saleem Sheena, Korzeniewski Steven J, Cabrera Maria D, Ehterami Shadi, Bahado-Singh Ray O, Katkuri Yashwanth, Haacke Ewart M, Hernandez-Andrade Edgar, Hassan Sonia S, Romero Roberto
出版信息
J Perinat Med. 2015 Mar;43(2):209-20. doi: 10.1515/jpm-2014-0268.
OBJECTIVES
Our two objectives were to evaluate the feasibility of fetal brain magnetic resonance imaging (MRI) using a fast spin echo sequence at 3.0T field strength with low radio frequency (rf) energy deposition (as measured by specific absorption rate: SAR) and to compare image quality, tissue contrast and conspicuity between 1.5T and 3.0T MRI.
METHODS
T2 weighted images of the fetal brain at 1.5T were compared to similar data obtained in the same fetus using a modified sequence at 3.0T. Quantitative whole-body SAR and normalized image signal to noise ratio (SNR), a nominal scoring scheme based evaluation of diagnostic image quality, and tissue contrast and conspicuity for specific anatomical structures in the brain were compared between 1.5T and 3.0T.
RESULTS
Twelve pregnant women underwent both 1.5T and 3.0T MRI examinations. The image SNR was significantly higher (P=0.03) and whole-body SAR was significantly lower (P<0.0001) for images obtained at 3.0T compared to 1.5T. All cases at both field strengths were scored as having diagnostic image quality. Images from 3.0T MRI (compared to 1.5T) were equal (57%; 21/37) or superior (35%; 13/37) for tissue contrast and equal (61%; 20/33) or superior (33%, 11/33) for conspicuity.
CONCLUSIONS
It is possible to obtain fetal brain images with higher resolution and better SNR at 3.0T with simultaneous reduction in SAR compared to 1.5T. Images of the fetal brain obtained at 3.0T demonstrated superior tissue contrast and conspicuity compared to 1.5T.
目的
我们的两个目标是评估在3.0T场强下使用快速自旋回波序列并具有低射频（rf）能量沉积（通过比吸收率：SAR测量）进行胎儿脑磁共振成像（MRI）的可行性，以及比较1.5T和3.0T MRI之间的图像质量、组织对比度和清晰度。
方法
将1.5T时胎儿脑的T2加权图像与同一胎儿使用3.0T改良序列获得的类似数据进行比较。比较1.5T和3.0T之间的定量全身SAR、归一化图像信噪比（SNR）、基于名义评分方案的诊断图像质量评估以及脑内特定解剖结构的组织对比度和清晰度。
结果
12名孕妇接受了1.5T和3.0T MRI检查。与1.5T相比，3.0T获得的图像的图像SNR显著更高（P = 0.03），全身SAR显著更低（P < 0.0001）。两个场强下的所有病例均被评为具有诊断图像质量。3.0T MRI的图像（与1.5T相比）在组织对比度方面相同（57%；21/37）或更优（35%；13/37），在清晰度方面相同（61%；20/33）或更优（33%，11/33）。
结论
与1.5T相比，在3.0T时可以获得具有更高分辨率和更好SNR的胎儿脑图像，同时降低SAR。与1.5T相比，3.0T获得的胎儿脑图像显示出更优的组织对比度和清晰度。
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