TY - JOUR T1 - The Effects of MRI on RF-Based Contactless Smart Cards JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 3009 LP - 3009 VL - 62 IS - supplement 1 AU - Andrew Bulla AU - Sarah Frye AU - Ross Frye Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/62/supplement_1/3009.abstract N2 - 3009Objectives: Multiple MRI employees reported faulty radiofrequency-based contactless smart cards after leaving Zone 4 in the MRI department. This experiment was conducted to test if MRI-generated radiofrequency (RF) and/or the strong magnetic gradient was the cause of the microchip failures inside the contactless smart cards. RF-based contactless smart cards are typically constructed with a metallic chip and a loop of conductive metal wire serving as an antenna inside a plastic frame. A card reader near such a smart card will detect the card and transmit an RF pulse. This pulse induces a current in the wire that powers the smart card chip, which can then communicate with the card reader. Most common contactless smart cards operate at a frequency of either 125kHz or 13.56MHz. MRI scanners transmit much higher frequencies, with 1.5T scanners operating at approximately 63.87 MHz and 3T scanners at approximately 127.74 MHz. The RF signals generated by MRI are also much stronger than those generated by card readers. Additionally, current can be induced in metallic objects when exposed to a changing magnetic field, as described by Faraday’s law of induction. Due to the strong spatial gradient at the mouth of the MRI bore, current could potentially be induced in the card electronics by rapidly moving the cards in and out of these areas. Finally, the time-varying magnetic gradient rapidly changes during an MRI sequence, which could also potentially induce current in a conductive material. It was hypothesized that the electronics in a smart card would be overloaded when exposed to an MRI RF field and subsequently fail to function properly. Methods: MRI departments often use RF-based contactless smart cards to grant physical access into Zones 3 and 4. After multiple cards were reported to have failed, this study was conducted. The researchers obtained two decommissioned cards that were given access to a local smart card reader. Once it was verified that they were operational, the experiment was conducted. A total of four tests were conducted on both a 1.5 Tesla Siemens Aera MRI scanner and a 3.0 Tesla Siemens Skyra MRI scanner. The cards were tested for functionality after each test. Test 1: Cards were placed at isocenter inside the bore of a magnet and set a timer for thirty minutes, and subsequently removed the cards. This test served as a control to verify that the static magnetic field would not cause failure of the cards. Test 2: The cards were rapidly moved at the bore edge where the spatial magnetic gradient is highest to determine whether exposure to a rapidly varying gradient would induce a card failure. Test 3: The cards were placed on top of a quality control (QC) phantom and placed inside a neurovascular transmit/receive coil. The card was moved to isocenter and scanned using an axial T1-weighted turbo spin echo sequence. High levels of RF are transmitted into scanned areas during this type of sequence. Test 4: The cards were again placed on top of QC phantom and placed inside a neurovascular transmit/receive coil. The card was moved to isocenter and scanned using an axial diffusion-weighted echo planar imaging sequence. This sequence type heavily utilizes the time-varying magnetic gradient, and rapidly changes the magnetic field. Results: We were unable to induce failure on the cards using any of the described methods. Both experimental cards functioned properly when placed in proximity with a smart card reader after testing. Conclusions: After multiple tests, we were not able to overload either of the experimental RF smart cards. The magnetic field and the operational frequency of the MRI scanners did not negatively impact the operation of the proximity cards in our tests. Further testing would be needed to definitively determine if MRI has any negative effects on RF proximity cards. ER -