Safety and reliability of Radio Frequency Identification Devices in Magnetic Resonance Imaging and Computed Tomography.
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.
Steffen
Thomas
T
Department of Surgery, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
Luechinger
Roger
R
Institute for Biomedical Engineering, University and ETH Zurich, CH-8091 Zurich, Switzerland.
Wildermuth
Simon
S
Department of Radiology, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
Kern
Christian
C
InfoMedis AG, CH-6055 Alpnach, Switzerland.
Fretz
Christian
C
Department of Radiology, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
Lange
Jochen
J
Department of Surgery, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.
Hetzer
Franc H
FH
Department of Surgery, Hospital of the Canton of St Gallen (KSSG), CH-9007 St Gallen, Switzerland.