RF power deposition magnification in MRI of fractured passive metallic implants

Motivation: MRI of (biodegradable) passively conducting implants is challenged by potential elevation of RF power deposition (SAR) in the vicinity of an implant. Accidental implant fractures or fissures due to dynamic degradation of biodegradable implants alter the implants’ structure. This mechanical impact induces changes in the electromagnetic response of the system versus an intact implant. Goal(s): Recognizing this clinical and patient safety challenge, this work first examines the SAR magnification caused by implant fractureApproach: The efficacy of an optimized parallel excitation vectors deduced from a multi-objective genetic algorithm is demonstrated. Results: Reduction of SAR magnification in fractured implant using the optimized excitation vector. Impact: Amplification of RF power deposition in MRI of fractured metallic implants constitutes a patient safety hazard. This risk can be mitigated with parallel transmission using GA-driven excitation. This approach provides a viable clinical alternative for MRI monitoring of implantation sites.