Felix V. Guettler, Presenter: Nothing to Disclose

Andreas Heinrich, Abstract Co-Author: Nothing to Disclose

Peter Krauß, Abstract Co-Author: Nothing to Disclose

Jonathan Guntermann, Abstract Co-Author: Nothing to Disclose

Maximilian De Bucourt MD, Abstract Co-Author: Nothing to Disclose

Ulf Karl Martin Teichgraeber MD, Abstract Co-Author: Nothing to Disclose

A real-time MR-imaging is feasible with an RFID system. The lost of the SNR on MR-images can be reduced with a shielding through an external radiofrequency source.

An RFID system allows the automatic identification and tracking of objects. The use of an RFID system in MRI was no longer pursued because of the interferences in MR-imaging. Only the MR-compatibility of the RFID transponder (tag) could be proved in several studies. The goal was the installation of an RFID system in MRI with a low influence on MR-imaging.

Compared to the SNR measurement without RFID system, a maximum SNR of 74/80/93 % (HASTE), respectively 45/65/84 % (TrueFISP) could be measured for the voxel size and a value of 39/44/53 % (HASTE); respectively, 26/40/37 % (TrueFISP) could be measured for the shielded and non-shielded cable. The highest SNR was identified in a distance of 230 cm between the reader and the isocentre of the MRI. At that distance, the tag in the isocentre could be read with a signal strength between 12 and 18 % .

For this experiment, a medical UHF reader PoE (amedo smart tracking solutions, Bochum, Germany) was installed in the magnet room of a MAGNETOM Sonata scanner (Siemens, Erlangen, Germany). A patch cable was connected to the reader with a computer in the anteroom. This cable was shielded with braided copper and was connected with the faradayc cage of the MRI room.The influence of the RFID readers, with a shielded and a non-shielded cable, on MR-imaging was analyzed for a phantom of 1000g H2O (dist.) with 1.25g NISO4x6H2O+5gNACL. For this, the signal-to-noise ratio (SNR) was defined with a HASTE (TR/TE 3000/60-63ms, NSA 1, ETL 256, FOV 260x260mm) and a TrueFISP (TR/TE 12.9/2.15 ms, NSA 1, flip angle 70°, FOV 250x250mm) sequence. The reader was 90 to 250 cm away from the isocentre of the MRI (increment 10 cm). A voxel size of (A) 1x1x3, (B) 2x2x4 und (C) 2x2x10 mm was used. During the examination, the reader sent continuously radio frequency radiation between 865.7 and 867.5 MHz. Furthermore, the signal strength in the isocentre between a RFID tag ALN-9640 Squiggle Inlay (Alien Technology, Butterfield, USA) and a RFID reader was determined.

Guettler, F, Heinrich, A, Krauß, P, Guntermann, J, De Bucourt, M, Teichgraeber, U, Shielding of an RFID (Radio-Frequency Identification) System for MRI Application.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12038272.html