École Polytechnique de Montréal Nanorobotics Laboratory, chemin de Polytechnique, Montréal, QC H3T 1J4, Canada.
Med Phys. 2011 Sep;38(9):4994-5002. doi: 10.1118/1.3622599.
The authors quantify the deflections of a catheter and a guidewire in MR setting with different designs of ferromagnetic tips and a system of high gradient coils which can generate gradients, and thus forces, 20 times larger than a conventional scanner.
Different designs of catheter tips are experimentally tested in an effort to maximize the deflections. One to two ferromagnetic spheres are attached at the distal tip of the catheter (or guidewire) with different spacing between the spheres. The effect of dipole-dipole interaction on the steering of the catheter is studied through experimentation and theoretical modeling. The effect of using many spheres on the artefact generated in fast imaging sequences is also investigated.
A catheter and a guidewire are successfully steered by applying magnetic gradients inside a magnetic resonance scanner. More ferromagnetic material allows for larger magnetic forces, however, the use of two ferromagnetic spheres introduces undesired dipole-dipole interactions. Two ferromagnetic spheres generate a single larger artefact as they are close together.
By varying the distance between the two ferromagnetic spheres, a balance can be struck between the need to minimize the size of the tip and the undesirable dipole-dipole interaction.
作者量化了导管和导丝在具有不同铁磁尖端设计和可产生梯度的高梯度线圈系统的磁共振环境中的偏转，该系统可以产生比传统扫描仪大 20 倍的力。
在实验中测试了不同设计的导管尖端，以最大程度地增加偏转。将一个或两个铁磁球附着在导管（或导丝）的远端尖端，球之间的间距不同。通过实验和理论建模研究了偶极子-偶极子相互作用对导管转向的影响。还研究了在快速成像序列中使用多个球体对产生的伪影的影响。
通过在磁共振扫描仪内施加磁场梯度，成功地控制了导管和导丝。更多的铁磁材料允许产生更大的磁力，但是使用两个铁磁球会引入不希望的偶极子-偶极子相互作用。两个铁磁球由于彼此靠近而产生单个较大的伪影。
通过改变两个铁磁球之间的距离，可以在最小化尖端尺寸的需求和不希望的偶极子-偶极子相互作用之间取得平衡。
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