title: Safety and reliability of Radio Frequency Identification Devices in Magnetic Resonance Imaging and Computed Tomography.
abstract: BACKGROUND
  Radio Frequency Identification (RFID) devices are becoming more and more essential for patient safety in hospitals. The purpose of this study was to determine patient safety, data reliability and signal loss wearing on skin RFID devices during magnetic resonance imaging (MRI) and computed tomography (CT) scanning.
  
  
  METHODS
  Sixty RFID tags of the type I-Code SLI, 13.56 MHz, ISO 18000-3.1 were tested: Thirty type 1, an RFID tag with a 76 x 45 mm aluminum-etched antenna and 30 type 2, a tag with a 31 x 14 mm copper-etched antenna. The signal loss, material movement and heat tests were performed in a 1.5 T and a 3 T MR system. For data integrity, the tags were tested additionally during CT scanning. Standardized function tests were performed with all transponders before and after all imaging studies.
  
  
  RESULTS
  There was no memory loss or data alteration in the RFID tags after MRI and CT scanning. Concerning heating (a maximum of 3.6 degrees C) and device movement (below 1 N/kg) no relevant influence was found. Concerning signal loss (artifacts 2 - 4 mm), interpretability of MR images was impaired when superficial structures such as skin, subcutaneous tissues or tendons were assessed.
  
  
  CONCLUSIONS
  Patients wearing RFID wristbands are safe in 1.5 T and 3 T MR scanners using normal operation mode for RF-field. The findings are specific to the RFID tags that underwent testing.
authors.affiliation: Department of Surgery, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Steffen
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, CH-8091 Zurich, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Luechinger
authors.affiliation: Department of Radiology, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Wildermuth
authors.affiliation: InfoMedis AG, CH-6055 Alpnach, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Kern
authors.affiliation: Department of Radiology, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Fretz
authors.affiliation: Department of Surgery, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
authors.forename: Jochen
authors.initials: J
authors.lastname: Lange
authors.affiliation: Department of Surgery, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
authors.forename: Franc H
authors.initials: FH
authors.lastname: Hetzer