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Active microcoil tracking in the lungs using a semisolid rubber as signal source
Author(s) -
Alt Stefan,
Homagk AnnKathrin,
Umathum Reiner,
Semmler Wolfhard,
Bock Michael
Publication year - 2010
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22424
Subject(s) - microcoil , signal (programming language) , tracking (education) , computer science , biomedical engineering , medicine , electromagnetic coil , engineering , electrical engineering , psychology , programming language , pedagogy
A new method to localize and track medical devices in air‐filled body cavities is proposed that uses active microcoils with a semisolid filling. In air spaces, e.g., the lung, microcoils require an independent signal source, which should be made of a biocompatible, solid and sterilizable material with a long shelf time. In a measurement of the T 1 and T * 2 and the relative spin density of several semisolid materials, latex was identified as a suitable material from which a prototype catheter was constructed with a microcoil at its tip. In a dual‐echo tracking pulse sequence, the very short T * 2 of the rubber material allowed suppressing the background signal from surrounding tissue with a subtraction technique and additional dephasing gradients. With a roadmapping reconstruction, the microcoil's trajectory could be visualized on a previously acquired reference image set with a tracking rate of up to 60 Hz at a spatial resolution of better than 2mm. In a real‐time tracking implementation, an image update rate of 4 Hz was achieved by combining the tracking with a fast real‐time imaging sequence. Both methods were successfully applied in vivo to track the catheter in the lung of a pig. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.