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A dual flip angle 3D bSSFP magnetization transfer‐like method to differentiate between recent and old myocardial infarction
Author(s) -
Germain Philippe,
Ghannudi Soraya,
Labani Aissam,
Jeung Mi Y.,
Gangi Afshin,
Ohlmann Patrick,
Roy Catherine
Publication year - 2018
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.25821
Subject(s) - flip angle , medicine , myocardial infarction , steady state free precession imaging , magnetic resonance imaging , population , receiver operating characteristic , infarction , magnetization transfer , nuclear medicine , cardiology , nuclear magnetic resonance , radiology , physics , environmental health
Background Magnetic resonance imaging (MRI) tissue signal is modulated by magnetization transfer (MT) phenomena, intrinsically induced by balanced steady‐state free precession (bSSFP) imaging. Purpose To investigate the possible value of such a MT‐like bSSFP approach in two clinical settings involving focal myocardial lesions highligthed by late gadolinium enhancement (LGE+): edema induced by recent myocardial infarction (MI) and fibrotic scar related to chronic infarction. Materials and Methods Population: 48 LGE + patients were studied: 26 with recent MI, 22 with chronic MI. 20 LGE‐normal subjects were considered the control group. Field strength/sequence: Navigator‐based short axis 3D‐bSSFP sequences with 20° and 90° excitation flip angles were acquired (1.5T). Assessment: Pixel‐wise normalized MT Ratio (nMTR) parametric images were calculated according to: nMTR = 100*(S 20 ‐S 90 *k)/S 20 , with S 20 and S 90 signal intensity in 20° and 90° flip angle images and k = Blood 20 /Blood 90 as a normalization ratio. Statistical tests: analysis of variance (ANOVA), receiver operating characteristic (ROC) analysis. Results Overall normal myocardial nMTR was 50.2 ± 3.6%. In recent MI, nMTR values were significantly reduced in LGE + regions (–22.3 ± 9.9%, P < 0.0001). In cases of chronic infarct, nMTR was significantly increased in LGE + regions (14.2 ± 11.4%, P < 0.0001). Comparison between observed results and theoretical values obtained with the Freeman‐Hill formula showed that most variations observed in MI are related to MT effects instead of relaxation effects. Conclusion In contrast to LGE imaging, which may show a similar hyperenhancement in recent and old infarctions, nMTR imaging demonstrates an opposite pattern: decreased values for recent infarction and increased values for old infarction, thus allowing to discriminate between these two clinical conditions without gadolinium injection. Level of Evidence : 3 Technical Efficacy : Stage 1 J. Magn. Reson. Imaging 2018;47:798–808.