A strategy to reduce the sensitivity of inhomogeneous Magnetization Transfer (ihMT) imaging to radiofrequency transmit field variations at 3 T

Autor: Maxime Guye, Thomas Troalen, Gopal Varma, Jean-Philippe Ranjeva, Andreea Hertanu, David C. Alsop, Guillaume Duhamel, Lucas Soustelle, Olivier M. Girard, Samira Mchinda
Přispěvatelé: Centre de résonance magnétique biologique et médicale (CRMBM), Assistance Publique - Hôpitaux de Marseille (APHM)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Centre d'Exploration Métabolique par Résonance Magnétique [Marseille] (CEMEREM), Hôpital de la Timone [CHU - APHM] (TIMONE), Siemens Healthcare [France], Siemens AG [Munich], Beth Israel Deaconess Medical Center [Boston] (BIDMC), Harvard Medical School [Boston] (HMS), Aix Marseille Université (AMU)-Assistance Publique - Hôpitaux de Marseille (APHM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Exploration Métabolique par Résonance Magnétique [Hôpital de la Timone - APHM] (CEMEREM), Hôpital de la Timone [CHU - APHM] (TIMONE)-Centre de résonance magnétique biologique et médicale (CRMBM), Aix Marseille Université (AMU)-Assistance Publique - Hôpitaux de Marseille (APHM)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Assistance Publique - Hôpitaux de Marseille (APHM)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE18-0030,verISMO,IRM du transfert d'aimantation inhomogène : vers un nouveau biomarqueur in vivo spécifique et sensible de la myéline(2017)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Magnetic Resonance in Medicine
Magnetic Resonance in Medicine, Wiley, 2021, ⟨10.1002/mrm.29055⟩
Magnetic Resonance in Medicine, 2021, ⟨10.1002/mrm.29055⟩
ISSN: 0740-3194
1522-2594
Popis: International audience; PurposeTo minimize the sensitivity of inhomogeneous magnetization transfer gradient-echo (ihMT-GRE) imaging to radiofrequency (RF) transmit field (urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0003) inhomogeneities at 3 T.MethodsThe ihMT-GRE sequence was optimized by varying the concentration of the RF saturation energy over time, obtained by increasing the saturation pulse power while extending the sequence repetition time (TR). Different protocols were tested using numerical simulations and human in vivo experiments in the brain white matter (WM) of healthy subjects at 3 T. The sensitivity of the ihMT ratio (ihMTR) to urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0004 variations was investigated by comparing measurements obtained at nominal transmitter adjustments and following a 20% global urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0005 drop. The resulting relative variations (δihMTR) were evaluated voxelwise as a function of the local urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0006 distribution. The reproducibility of the protocol providing minimal urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0007 bias was assessed in a test-retest experiment.ResultsIn line with simulations, ihMT-GRE experiments conducted at high concentration of the RF energy over time demonstrated strong reduction of the urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0008 inhomogeneity effects in the human WM. Under the optimal conditions of 350-ms TR and 3-µT root mean square (RMS) saturation power, 73% of all WM voxels presented δihMTR below 10%. Reproducibility analysis yielded a close-to-zero systematic bias (ΔihMTR = −0.081%) and a high correlation (ρ² = 0.977) between test and retest experiments.ConclusionConcentrating RF saturation energy in ihMT-GRE sequences mitigates the sensitivity of the ihMTR to urn:x-wiley:07403194:media:mrm29055:mrm29055-math-0009 variations and allows for clinical-ready ihMT imaging at 3 T. This feature is of particular interest for high and ultra-high field applications.
Databáze: OpenAIRE
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