###### Abstract
Regarding the impact of the imaging landmark on the risk of unintended implant heating, in [24], it was demonstrated that the induced electric fields inside the body shifted when the body positioning was changed, and, in [28], less absorbed RF energy was calculated at an external fixation device when it was moved out of the coil. Similarly, in [22], it was shown that imaging positions around the lower sternum and the abdomen of non-homogenous numerical models tend to have higher induced electric fields inside the body. Moreover, in previous works, RF heating during MRI was reduced, modifying the trajectories of Deep Brain Stimulation (DBS) leads inside homogenous phantoms [29; 30], and in [31] it was concluded that the surgical modification of epicardial lead trajectory can substantially reduce RF heating at 1.5 T. On the other hand, although for endocardial CIED implantation the leads are placed through the subclavian vein and the implantable pulse generator (IPG) is consistently placed in the subclavian pocket, resulting in limited variation in their trajectories, in [32], it was noticed that differences in RF heating existed between various implantation paths inside anthropomorphic homogenous phantoms. The majority of previous studies focused on the 1.5 T coil, although 3 T MRI scanners are becoming more common in clinical practice as they show improved diagnostic accuracy and shorter procedure times [33]. The significant increase in local SAR (Specific Absorption Rate) for a given imaging sequence, the shorter RF wavelengths and the different RF field distribution in coils with higher static field strengths add another layer of complexity in heating patterns [34]. However, in [35], it was concluded that coils at higher resonant frequency performing a conservative safety criterion, such as the global SAR, tend to generate lower local SAR around implanted leads. The relevant safety guidance is IEC 60601-33 [36], with the guidelines suggesting maximum levels of SAR that limit RF heating in patients during MRI; these guidelines are used in MRI systems [37] and by most implant manufacturers to assess the safety of their product. The commercial MRI systems provide an estimation of the SAR based on the RF waveforms and sequence parameters, coil factors and anatomical properties of the patient with high uncertainty on the reliably estimation of SAR. Therefore, different metrics have been considered, such as the \(\text{B}_{1}{}^{+}\text{RMS}\) value at the iso-center of the coil. In summary, while a series of prior works have focused on the contribution of imaging conditions to induced heating at the tip of an implant, these were primarily conducted using measurements and numerical methods on homogeneous phantoms, with implant placements that did not correspond to real clinical scenarios. Moreover, these studies did not concentrate on cardiac implants and did not cover all the possible conditions (resonant frequency, landmark and coil configuration). Consequently, the present study addresses the gaps in the previous research, and its main contributions can be outlined as follows:  
1. For the first time, a comparative estimation of the induced tangential electric field along CIED leads is performed on a large dataset corresponding to real clinical scenarios. Specifically, cardiac implant paths were designed within six human anatomical models considering ten different landmarks (imaging positions) within ten characteristic configurations of 1.5 T and 3 T birdcage coils, resulting in 1,843,200 different cases of incident electric fields. In order for the results to be reliable and qualified, human models and birdcage coils accepted by the FDA (Food and Drug Administration) as Medical Device Development Tools (MDDTs) were used. 2. For each birdcage, landmark and model, the induced electric field was scaled to a constant \(\text{B}_{1}{}^{+}\text{RMS}\) value at the iso-center or to the corresponding SAR limits of the Normal Operating Mode of the MRI [36], aiming to identify the worst-case scenario.