Evaluation of Magnetic Resonance Safety of Veterinary Radiofrequency Identification Devices at 1 t

Abstract

Implants containing metallic components have the potential to become heated or move within the patient while in the magnetic resonance (MR) environment. Despite containing a ferromagnetic core and having been in use for over 20 years, no information is available on the safety of veterinary radiofrequency identification devices during MR examinations. These devices are the most commonly encountered metallic implants in dogs and cats undergoing MR imaging. Three commercial veterinary microchips were evaluated for safety in the MR environment at 1 T. Parameters tested were translational force, torque, heating, artifact production, and function. Translation and torque were larger than that expected from normal activity under normal gravity. No significant heating was observed. Signal void artifacts may affect diagnosis if they are too close to the area of clinical importance. Microchip function was unaffected by routine clinical MR imaging. Capsule formation around devices is a major factor in counteracting translation and torque. Our findings support that is acceptable for patients to undergo MR imaging with this 1 T system following an interval of 3 months postimplantation to allow capsule growth. Because of the complex interactions involved, these observations may not be translatable to MR scanners of different field strength and/or manufacturer. Further safety testing of these and other radiofrequency identification devices is therefore recommended at different field strengths and equipment specifications.

Interference Issuses of Radio Frequency Identification Devices in Magnetic Resonance Imaging Systems and Computed Tomography Scan

“…We found that the functionalities of card tags remain unchanged after exposure to MRI examination. Although functional alteration of active 2.4 GHz RFID tags was not reported under 1.5 T MRI scanners, we need such investigation for lower field systems because of the complexities involved in the design of MRI scanners [24]. We found severe artifacts in the captured MRI when the region of interest (ROI) was closer to the RFID tags.…”

“…To the best of the author's knowledge, only one study [21] has discussed the usage of active 2.4 GHz RFID tags (card tags) in an MRI environment of 1.5 T, and concluded that tested tags were safe with no change in their functionality and induced severe artifacts in captured MRI images if the area of imaging is closer to tags. Since these results cannot be generalized to other MRI scanners with different field strengths, because of the difference in the design of MRI scanners by various manufacturers and complexity involved in the EM field interactions [24]. Thus, we decided to conduct similar tests with low field 0.3 T MRI scan using more number of sequences and different types of tags.…”

Functionality of Veterinary Identification Microchips Following Low‐ (0.5 Tesla) and High‐field (3 Tesla) Magnetic Resonance Imaging

“…It can be assumed that scanners of field strength between these extremes should similarly not damage the information stored on the transponder. Results from recent studies, analyzing the function of different types of implanted microchips with 1.0 and 1.5 Tesla systems have also shown that all microchips can be read out correctly after the application of routine scan protocols , …”

“…There are several ways in which the MRI scanner and the microtransponder might interact: for example, the magnetic forces or the radio waves involved in each technology may interfere with one another. Deterioration of image quality due to susceptibility of artifacts, movement of microchips, and the heating of the transponder is documented . The technical components of the transponder could be damaged by heating.…”

“…Temperature increases as high as 25°C in a brain stimulation implant (1.5 Tesla), 48°C in intravascular guidewires (1.5 Tesla), 63°C in a cardiac‐pacing electrode (1.5 Tesla), and 64°C in an intracranial pressure transducer (3 Tesla) have been reported. Recent studies have looked for alteration in function of identification microchips in 1.0 (41 dogs; 53 dogs) and 1.5 Tesla MR scanners (three dogs) . The results showed that under the practical conditions of a routine MR study, the identification number allocated on the implanted microchips was displayed correctly.…”