Collins Christopher M, Smith Michael B
Center for NMR Research, Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
J Magn Reson Imaging. 2003 Sep;18(3):383-8. doi: 10.1002/jmri.10359.
To examine how fine a model resolution is necessary for calculation of specific energy absorption rate (SAR) for the human head in regions as small as 1 g.
Here we perform a simple study comparing the maximum SAR averaged over any 1 cm(3) and SAR averaged over the entire head for several models of the same human head within the same radiofrequency coil, but with spatial resolutions varying from 8-100 Yee cells per cm(3).
Over the range of model resolutions from 8-100 Yee cells per cm(3), there is only a 16% variation in maximum SAR in any 1 cm(3) of tissue in the head, and only a 7% variation in SAR averaged over the entire head.
While it is always desirable to perform SAR calculations with the greatest possible accuracy, in calculations of the maximum SAR levels in any 1 cm(3) of tissue, spatial resolutions greater than 5 mm may not yield notably different results than those with a spatial resolution of 5 mm.
研究对于计算人类头部小至1克区域的比吸收率（SAR）而言，模型分辨率需要多精细。
在此，我们进行一项简单研究，比较在同一射频线圈内，针对同一人类头部的几种模型，每立方厘米内任何1立方厘米体积上平均的最大SAR以及整个头部平均的SAR，但空间分辨率从每立方厘米8 - 100个Yee元胞不等。
在每立方厘米8 - 100个Yee元胞的模型分辨率范围内，头部任何1立方厘米组织中的最大SAR仅存在16%的变化，而整个头部平均的SAR仅存在7%的变化。
虽然始终希望以尽可能高的精度进行SAR计算，但在计算任何1立方厘米组织中的最大SAR水平时，大于5毫米的空间分辨率与5毫米空间分辨率相比，可能不会产生显著不同的结果。
