Analyzing 3-tesla magnetic resonance imaging units for implementation in radiosurgery
Analyzing 3-tesla magnetic resonance imaging units for implementation in radiosurgery
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DOI：
10.3171/jns.2005.102.s_supplement.0158
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发表时间：
2005-01-01
影响因子：
4.1
通讯作者：
Seifert, V
中科院分区：
文献类型：
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作者：
Mack, A;Wolff, R;Seifert, V
Object.伽玛刀手术中影响准确性的限制因素是图像质量。新一代磁共振（MR）成像单元的场强高达3特斯拉，保证了解剖分辨率和对比度的上级图像质量。然而，有化学位移或磁化率的影响，这是本文的主题的问题。分析了3特斯拉MR成像单元（Siemens Trio），并与1特斯拉单元（Siemens Magnetom Expert）和1.5特斯拉单元（Philips Gyroscan）进行了比较。通过使用带有嵌入式网格的圆柱体模，在两个方向（轴向/冠状）的横向切片内进行误差幅度评价。确定了立体定向框架内已知几何位置的平板体模中21个靶点的偏差。在头部模型中分析了化学位移和/或磁化率效应引起的失真。数据分析采用Inhouse软件，轴向平均偏差小于0.3min，冠状面平均偏差小于0.4mm。对于已知目标，最大偏差为1.16 mm。通过优化方案中的这些参数，可以将这些不准确性降低至小于1.1 mm。由于不均匀性，观察到数据集在z方向上的位移高达1.5圈，显示压缩了1.2 mm。与已建立的1特斯拉和1.5特斯拉装置相比，3特斯拉成像装置显示出上级解剖对比度和分辨率;然而，由于高场强，头部线圈内的场对不均匀性非常敏感，因此将小心处理3特斯拉成像数据。
Object. The limiting factor affecting accuracy during gamma knife surgery is image quality. The new generation of magnetic resonance (MR) imaging units with field strength up to 3 teslas promise superior image quality for anatomical resolution and contrast. There are, however, questions about chemical shifts or susceptibility effects, which are the subject of this paper.Methods. The 3-tesla MR imaging unit (Siemens Trio) was analyzed and compared with a 1-tesla unit (Siemens Magnetom Expert) and to a 1.5-tesla unit (Philips Gyroscan). Evaluation of the magnitude of error was performed within transverse slices in two orientations (axial/coronal) by using a cylindrical phantom with an embedded grid. Deviations were determined for 21 targets in a slab phantom with known geometrical positions within the stereotactic frame. Distortions caused by chemical shift and/or susceptibility effects were analyzed in a head phantom. Inhouse software was used for data analyses.The mean deviation was less than 0.3 min in axial and less than 0.4 mm in coronal orientations. For the known targets the maximum deviation was 1.16 mm. By optimizing these parameters in the protocol these inaccuracies could be reduced to less than 1.1 mm. Due to inhomogeneities a shift in the z direction of up to 1.5 turn was observed for a dataset, which was shown to be compressed by 1.2 mm.Conclusions. The 3-tesla imaging unit showed superior anatomical contrast and resolution in comparison with the established 1-tesla and 1.5-tesla units; however, due to the high field strength the field within the head coil is very sensitive to inhomogeneities and therefore 3-tesla imaging data will have be handled with care.