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Evaluation of the keyhole technique applied to the proton resonance frequency method for magnetic resonance temperature imaging
Author(s) -
Han YongHee,
Mun ChiWoong
Publication year - 2011
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.22708
Subject(s) - keyhole , magnetic resonance imaging , proton magnetic resonance , nuclear magnetic resonance , resonance (particle physics) , proton , materials science , physics , radiology , atomic physics , nuclear physics , medicine , welding , metallurgy
Purpose: To evaluate the temporal and spatial resolution of magnetic resonance (MR) temperature imaging when using the proton resonance frequency (PRF) method combined with the keyhole technique. Materials and Methods: Tissue‐mimicking phantom and swine muscle tissue were microwave‐heated by a coaxial slot antenna. For the sake of MR hardware safety, MR images were sequentially acquired after heating the subjects using a spoiled gradient (SPGR) pulse sequence. Reference raw ( k ‐space) data were collected before heating the subjects. Keyhole temperature images were reconstructed from full k ‐space data synthesized by combining the peripheral phase‐encoding part of the reference raw data and the center phase‐encoding keyhole part of the time sequential raw data. Each keyhole image was analyzed with thermal error, and the signal‐to‐noise ratio (SNR) was compared with the self‐reference (nonkeyhole) images according to the number of keyhole phase‐encoding (keyhole‐data size) portions. Results: In applied keyhole temperature images, smaller keyhole‐data sizes led to more temperature error increases, but the SNR did not decreased comparably. Additionally, keyhole images with a keyhole‐data size of <16 had significantly different temperatures compared with fully phase‐encoded self‐reference images ( P < 0.05). Conclusion: The keyhole technique combined with the PRF method improves temporal resolution and SNR in the measurement of the temperature in the deeper parts of body in real time. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.