Premium
Imaging temperature changes in an interventional 0.5 T magnet: In‐vitro results
Author(s) -
Steiner Paul,
Schoenenberger Andreas W.,
Erhart Peter,
Penner Erik,
von Schulthess Gustav K.,
Debatin Jörg F.
Publication year - 1997
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/(sici)1096-9101(1997)21:5<464::aid-lsm8>3.0.co;2-o
Subject(s) - gradient echo , magnetic resonance imaging , laser , nuclear medicine , lesion , nuclear magnetic resonance , materials science , medicine , echo time , radiology , biomedical engineering , pathology , optics , physics
Abstract Background and Objective To evaluate the ability of monitoring laser induced temperature changes in an open, interventional 0.5T magnet, adopting fast T1‐weighted sequences. Materials and Methods A fast gradient echo‐ (FGRE) and a fast spoiled gradient echo‐sequence (FSPGR), both enabling an image update every 2.5 s, were investigated for their ability to visualize laser tissue effects at 5 Watt. Laser induced temperature was fluorooptically measured and correlated with signal intensity (SI) changes depicted by magnetic resonance imaging (MRI). MRI‐lesions were compared with macroscopic findings. Results SI changes on FGRE images appeared as early as 15s following the onset of laser application and were significantly more pronounced than those seen on FSPGR images ( p < .0001). A correlation of r = 0.94 (FGRE) and r = 0.92 (FSPGR) between temperature and SI loss was established. Owing to a steeper slope, the FGRE sequence was considered more sensitive to temperature changes. The areas of macroscopic tissue change correlated with those of SI loss, but lesion size was generally underestimated by MRI. Conclusion Laser monitoring is possible with rapid image updates in a midfield (0.5T) interventional MRI environment using fast gradient echo sequence designs. Lasers Surg. Med. 21:464–473, 1997. © 1997 Wiley‐Liss, Inc.