Assessment of metallic patient support devices and other items at 7-Tesla: Findings applied to 46 additional devices

Safety Considerations of 7-T MRI in Clinical Practice

“…7Unintended pressure changes, many lost function Thirty torsional magnetic microactuators (38) No functional impairment when tested using animal 7-T MRI Twelve dental retainer wires (17) .45° deflection angle in six of the 12 wires Maximum temperature increases within a transmit RF head coil over 15 minutes at 16 W/kg SAR: 1.6°C for 4.7-cm-long wire in simulations and 1.4°C for 5.5-cm-length wire in experiment Eighteen metallic items, including dental restorations and implants, abutments, and magnetic attachment keepers (39) . Nonstandardized testing showed motion but no significant heating of some implants in Petri dishes and water baths when using animal 7-T MRI Twenty-three intraocular lenses with variable dyes, metals, and shapes (43) , 1° deflection angles and ,0.25°C temperature increases measured within a 6-cm-diameter transmit RF surface coil over 1 minute at 5 W/ kg SAR Ocular proton therapy markers (44) ,1° deflection angles Two 32-electrode EEG caps (45,46) Maximum temperature increases measured within a custom transmit RF head coil over 6 minutes at 10 W/kg SAR: 6.6°C in EEG paste and 3.8°C in phantom Thirty-two-electrode EEG cap (47) , (12) No deflections observed for 13 items, results extrapolated to 33 similar items with lower magnetic susceptibility Thirty-four ballistic objects: 31 bullets and three shotgun pellets (51) No noticeable deflections in objects tested at 7 T Four metal-containing intrauterine devices (52) No device displacement or statistically significant temperature increases Implants, tattoos (53) Retrospective study of 230 subjects over 7.5 years revealed no reports of heating or forces…”

“…The zone restrictions and standardized screening described in the American College of Radiology guidance document (11) should be followed to avoid inadvertent admittance of ferromagnetic materials into the MRI scanner room. Potential projectile accidents can be avoided with use of 7-T MRI conditional patient support equipment (12) such as gurneys, wheelchairs, oxygen tanks, and intravenous poles, in addition to appropriate training, screening, assessment, and warnings.…”

Ophthalmic Magnetic Resonance Imaging: Where Are We (Heading To)?

“…These studies revealed that all ocular tantalum markers commercially available today with CE certification for PT can be considered safe for MR at field strengths of up to and including 7.0 T 15 . It was also concluded that all the tested intraocular lenses currently in clinical use are considered safe for MRI up to and including 7.0 T. 167 Meanwhile, a large body of literature exists on the MR safety of passive conductive implants at 7.0 T. [168][169][170][171][172][173][174][175][176]…”