MR imaging of the fetal brain at 1.5T and 3.0T field strengths: comparing specific absorption rate (SAR) and image quality

作者：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

来源：Journal of Perinatal Medicine, 2015, 43(2): 209-220.

DOI：10.1515/jpm-2014-0268

• 3.0T
• fetal imaging
• fetal MRI
• radio frequency energy
• signal to noise
• specific absorption rate

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.

• 出版日期2015-3