Gradient heating of bulk metallic implants can be a safety concern in MRI

Peripheral nerve stimulation limits of a high amplitude and slew rate magnetic field gradient coil for neuroimaging

“…It would be of interest to combine these together with a moiety of human body models and nerve aging models to better predict PNS across a diverse population. Furthermore, the availability of higher gradient performance in vivo raises further MRI safety‐related questions about its impact on gradient‐induced heating in implants, presence of implants on PNS, and risks of cardiac stimulation; these questions motivate the need for more research into accurate and sophisticated E‐field and stimulation modeling.…”

Retrospective analysis of RF heating measurements of passive medical implants

“…Most of the implanted medical devices are passive implants with length less than 15 cm (e.g., stents and valves). The inherent risks of scanning patients with passive implants arises from mechanical forces caused by static magnetic field, RF‐induced heating, gradient field–induced heating, and image artifacts in the region of interest . Because of the medical need for MRI of patients with implants and inherent risks, the U.S. Food and Drug Administration (FDA) requires appropriate labeling for implanted devices in the MR environment.…”

Heating of hip joint implants in MRI: The combined effect of RF and switched‐gradient fields

“…Arduino et al 29 adopted a more complex approach, enabling the study of realistic clinical sequences. The computational procedure, validated by comparison with the experiments published in Brühl et al, 28 led to a maximum temperature elevation exceeding 3 K computed using an EPI sequence. The effects of body position, frequency‐encoding direction, and thermoregulation were also investigated.…”

“…Switched gradient-field heating has been investigated to a lesser extent. [22][23][24][25][26][27][28][29][30] Graf et al 22 evaluated the heating of metallic objects, including a titanium hip prosthesis and an aluminum replica, during a 3D true fast imaging sequence with steady precession (TrueFISP) and concluded that, under specific conditions (eg, high duty cycle, long measuring time, metallic components with low resistance), gradient-induced heating of conducting specimens could be expected. These general conclusions were in line with the results of experiments involving metallic components.…”

“…Brühl et al 28 investigated gradient‐switching heating involving the acetabular cup of a hip implant placed inside a gel phantom within a 3T scanner. The cup was placed orthogonally to the z‐axis in an off‐center position and exposed to an EPI sequence with continuous and trapezoidal z‐gradients.…”