arXiv subjects

Fuchang Jiang

Publications and source records attributed to Fuchang Jiang.

3 recordsLinked to original sources

arXiv2026

Body Habitus Dominates Solver Choice as a Source of Uncertainty in MRI Safety Assessment of Active Implantable Medical Devices

MRI is increasingly critical for patients with active implantable medical devices (AIMDs), yet access depends on safety labeling derived from computational heating predictions under ISO/TS 10974 Tier 3. Published assessments have relied predominantly on a single electromagnetic solver class and one or two standard-BMI reference anatomies, leaving the relative contributions of solver choice, tissue property uncertainty, and patient anatomy to predictive variability uncharacterized within a common workflow. We performed a cross-platform evaluation of finite-difference time-domain (FDTD, Sim4Life) and finite element method (FEM, ANSYS HFSS) implementations of the full Tier 3 workflow for a deep brain stimulation system at 1.5 T, extending the analysis across more than 250 clinically realistic trajectories spanning standard male and female references (Duke, HBM, Ella), an elderly male (Glenn), and elevated-BMI models of both sexes (Fats, Ella BMI 30). FDTD and FEM agreed closely in standard anatomies, with Maximum Allowable B1+ limits converging near 2.6-3.0 uT. The elderly male model produced a comparable limit to Duke, indicating BMI rather than age drives heating variability. Elevated BMI reduced safe B1+ by 19-31% in both sexes, while sex at matched BMI had no significant effect. Geometric morphing approximated the native obese limit, whereas dielectric property sweeps failed to reproduce elevated-BMI heating distributions. Body habitus is the dominant source of predictive uncertainty in Tier 3 assessment, exceeding solver choice, dielectric assumptions, and sex. Anatomical diversity, including elevated-BMI female phenotypes, should be treated as a primary variable.

physics.med-ph↗

arXiv2026

Weight-Guided Constraints for Body Model and Lead Selection in Pediatric CIED MRI Safety Simulations

Pediatric patients with cardiac implantable electronic devices (CIEDs) face limited MRI access due to RF-induced heating, and computational modeling is increasingly used to characterize this risk. The validity of these simulations, however, depends on pairing body models with clinically realistic lead configurations, guidance that is currently lacking. We retrospectively analyzed 302 CIED surgeries in 281 pediatric patients to derive weight-based constraints for simulation design. Weight alone discriminated epicardial from endocardial lead implantation with AUC = 0.90, and adding age and height yielded no improvement, supporting weight as a sufficient single-parameter selection metric. The probabilistic crossover between approaches occurred at 44 kg, substantially higher than the 10 to 15 kg threshold commonly cited in the literature, with a broad transition zone of 21 to 66 kg in which both lead types were routinely used. Lead length was likewise weight-constrained: only 25 cm leads were observed in patients below 6 kg, and leads of 45 cm or longer were uncommon below 50 kg. These findings yield a three-tier framework, with epicardial-only configurations below 21 kg, dual configurations within 21 to 66 kg, and weight-thresholded lead lengths throughout, enabling MRI safety simulations to focus on clinically realizable anatomy and device combinations.

physics.med-ph↗

arXiv2024

Comparative Study of RF Heating in Deep Brain Stimulation Devices During MRI at 1.5 T and 0.55 T: Challenging the Assumption of Safety at Low Field Strengths

Purpose: Low-field MRI has been assumed to be implant-friendly based on limited studies. However, RF-induced heating due to an implant is a complex resonance phenomenon, highly dependent on the implant's configurations and the applied RF frequencies. This study aims to evaluate the RF heating of DBS implants during MRI at low-field strengths compared to higher field 1.5 T MRI. Methods: A commercial deep brain stimulation (DBS) implant was used in full system as well as lead only configurations to evaluate and compare RF heating during MR imaging at 0.55 T and 1.5 T. The transfer function of the device at both configurations was measured and validated at each of the frequencies, which was then used for the in vivo prediction of RF heating for realistic DBS configurations at head, chest and abdomen imaging landmarks. Results: For the lead only case, the RF heating due to the DBS was substantially smaller during imaging at 0.55 T compared to that at 1.5 T. However, for the full DBS system (longer implant), the RF heating at 0.55 T was comparable to and for some cases even higher than that at 1.5 T, reaching a level that poses risk of tissue damage in patients. Conclusions: While RF heating generally tends to be lower at low-field MRI, the case with longer implanted leads demands extra caution, due to the higher possibility of matching resonant condition at low-field-strength frequencies. Thus, specific risk evaluation for each implant and configuration is required rather than assuming that lower field strength imaging is safer.

physics.med-ph↗