On the Validity of the AIMD Transfer Function Model Developed Over Different Implantation Trajectories

The transfer function (TF) method is crucial in assessing radio frequency induced heating in active implantable medical devices (AIMDs) during magnetic resonance imaging scans within the human body. Despite numerous implementations to develop TF models for AIMDs, a lingering question remains: TFs are typically developed in a straight pathway configuration, which may differ from TFs in the clinically relevant curved implantation pathways. This article explores the validity of TFs developed in a straight configuration for curved pathways. To address this, a robotic arm capable of three-dimensional measurements is introduced, facilitating the direct development of TFs along curved trajectories. Various curved pathways, including three clinically relevant trajectories, are selected for TF development. The results demonstrate the consistency of TFs obtained along curved and straight pathway configurations in all the cases. This indicates the applicability of TFs developed along a straight configuration for clinically relevant scenarios. Further insights into this trajectory-independent TF model are gained through numerical simulations. Additionally, the article discusses the conditions under which the straight TF remains valid for curved trajectories. For the commercially available AIMDs investigated in the article, the TFs remain consistent regardless of the trajectories, implying its invariance with respect to implantation trajectories.