【摘要】 目的　探讨 0 .3T、1.5T场强下影响介入性磁共振穿刺针成像的因素。以便提供正确的穿刺方法及成像技术参数 ,确保介入性磁共振操作的安全性及准确性。方法　将MR相容性介入穿刺针置于琼脂模型内 ,在 0 .3T、1.5T场强下 ,采用自旋回波序列、快速自旋回波序列、梯度回波序列 ,将穿刺针平行、垂直于主磁场 ,频率编码方向平行或垂直于穿刺针的方向进行扫描 ,在工作站测量图像上穿刺针的宽度及针尖的位置 ,比较图像上和实际针尖位置的差异 ,并比较不同场强下影响穿刺针伪影的因素。结果　各序列中梯度回波序列产生的伪影较大 ,快速自旋回波序列产生的伪影较小 ,自选回波序列产生的伪影最小 ,但快速自旋回波序列与自旋回波序列产生的伪影无明显差异。快速自旋回波序列与自旋回波序列中 ,当频率编码轴垂直于穿刺针长轴时伪影较大 ;当穿刺针方向逐渐平行于主磁场方向时 ,伪影逐渐减小。所有图像上针尖位置与实际针尖位置的差异在 1cm内。结论　 1.5T场强下伪影宽度大于 0 .3T场强。在 0 .3T、1.5T场强下改变频率编码方向、脉冲序列、成像参数时 ,针尖位置的变化在 1cm内 ,穿刺针平行于主磁场方向时 ,在不同场强下明显降低伪影的宽度更多还原

【Abstract】 Objective To investigate the factors affecting the artifacts created on interventional needling MR images of 0.3 T and 1.5 T and to provide a framework for biopsy approach and imaging technique parameter ensuring the safety and accuracy of the MR-guided procedure.Methods Titanium alloy MR-compatible biopsy devices were immersed in the phantoms and placed into 0.3T and 1.5T MR systems for clinical imaging. Spin-echo, turbo spin-echo, and gradient-echo sequences were performed and images were obtained with the needle shafts of the biopsy devices placed parallel to, perpendicular to the static magnetic field of the scanner. All images were obtained with the frequency-encoding direction parallel to and perpendicular to the needle shaft. Needle width and tip position were measured from the workstation, and compared the demonstrated tip position with the actual one. The difference between these values was analyzed. Results Artifacts at both field strengths were most pronounced with gradient-echo sequence, less so with turbo spin-echo sequence, and least with spin-echo sequence. For spin-echo and turbo spin-echo sequences, when the frequency-encoding axis was perpendicular to the needle shaft, the needle width would be larger. Artifacts were much less apparent as the orientation of the needle shaft to more parallel with the direction of the magnetic field. Artifactual widening was much more apparent at 1.5T than at 0.3T. Needle tip localization within 1-mm was obtained at both 0.3T and 1.5T with the appropriate frequency-encoding direction, pulse sequence, and imaging parameters.Conclusion Oriention of the needle parallel to the magnetic field could significantly reduce the apparent width of the needle at both field strengths outcoming with more accuracy of the interventional needling MRI.更多还原