Fabian J Kratzer1,2, Sebastian Flassbeck1,3,4, Sebastian Schmitter1,5, Tobias Wilferth6, Arthur W Magill1, Benjamin R Knowles1, Tanja Platt1, Peter Bachert1,2, Mark E Ladd1,2,7, Armin M Nagel1,6. 1. Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany. 2. Faculty of Physics and Astronomy, Ruprecht-Karls University Heidelberg, Heidelberg, Germany. 3. Center for Biomedical Imaging, Department of Radiology, New York University, New York, New York, USA. 4. Center for Advanced Imaging Innovation and Research, New York University, New York, New York, USA. 5. Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Berlin, Germany. 6. Institute of Radiology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), University Hospital Erlangen, Erlangen, Germany. 7. Faculty of Medicine, Ruprecht-Karls University Heidelberg, Heidelberg, Germany.
Abstract
PURPOSE: To develop a framework for 3D sodium (23 Na) MR fingerprinting (MRF), based on irreducible spherical tensor operators with tailored flip angle (FA) pattern and time-efficient data acquisition for simultaneous quantification of T1 , T 2 l ∗ , T 2 s ∗ , and T 2 ∗ in addition to ΔB0 . METHODS: 23 Na-MRF was implemented in a 3D sequence and irreducible spherical tensor operators were exploited in the simulations. Furthermore, the Cramér Rao lower bound was used to optimize the flip angle pattern. A combination of single and double echo readouts was implemented to increase the readout efficiency. A study was conducted to compare results in a multicompartment phantom acquired with MRF and reference methods. Finally, the relaxation times in the human brain were measured in four healthy volunteers. RESULTS: Phantom experiments revealed a mean difference of 1.0% between relaxation times acquired with MRF and results determined with the reference methods. Simultaneous quantification of the longitudinal and transverse relaxation times in the human brain was possible within 32 min using 3D 23 Na-MRF with a nominal resolution of (5 mm)3 . In vivo measurements in four volunteers yielded average relaxation times of: T1,brain = (35.0 ± 3.2) ms, T 2 l , brain ∗ = (29.3 ± 3.8) ms and T 2 s , brain ∗ = (5.5 ± 1.3) ms in brain tissue, whereas T1,CSF = (61.9 ± 2.8) ms and T 2 , CSF ∗ = (46.3 ± 4.5) ms was found in cerebrospinal fluid. CONCLUSION: The feasibility of in vivo 3D relaxometric sodium mapping within roughly ½ h is demonstrated using MRF in the human brain, moving sodium relaxometric mapping toward clinically relevant measurement times.
PURPOSE: To develop a framework for 3D sodium (23 Na) MR fingerprinting (MRF), based on irreducible spherical tensor operators with tailored flip angle (FA) pattern and time-efficient data acquisition for simultaneous quantification of T1 , T 2 l ∗ , T 2 s ∗ , and T 2 ∗ in addition to ΔB0 . METHODS: 23 Na-MRF was implemented in a 3D sequence and irreducible spherical tensor operators were exploited in the simulations. Furthermore, the Cramér Rao lower bound was used to optimize the flip angle pattern. A combination of single and double echo readouts was implemented to increase the readout efficiency. A study was conducted to compare results in a multicompartment phantom acquired with MRF and reference methods. Finally, the relaxation times in the human brain were measured in four healthy volunteers. RESULTS: Phantom experiments revealed a mean difference of 1.0% between relaxation times acquired with MRF and results determined with the reference methods. Simultaneous quantification of the longitudinal and transverse relaxation times in the human brain was possible within 32 min using 3D 23 Na-MRF with a nominal resolution of (5 mm)3 . In vivo measurements in four volunteers yielded average relaxation times of: T1,brain = (35.0 ± 3.2) ms, T 2 l , brain ∗ = (29.3 ± 3.8) ms and T 2 s , brain ∗ = (5.5 ± 1.3) ms in brain tissue, whereas T1,CSF = (61.9 ± 2.8) ms and T 2 , CSF ∗ = (46.3 ± 4.5) ms was found in cerebrospinal fluid. CONCLUSION: The feasibility of in vivo 3D relaxometric sodium mapping within roughly ½ h is demonstrated using MRF in the human brain, moving sodium relaxometric mapping toward clinically relevant measurement times.
Authors: Zidan Yu; Shota Hodono; Olga Dergachyova; Tom Hilbert; Bili Wang; Bei Zhang; Ryan Brown; Daniel K Sodickson; Guillaume Madelin; Martijn A Cloos Journal: Magn Reson Med Date: 2021-12-31 Impact factor: 4.668
Authors: Olgica Zaric; Hannes Beiglböck; Veronika Janacova; Pavol Szomolanyi; Peter Wolf; Michael Krebs; Siegfried Trattnig; Martin Krššák; Vladimir Juras Journal: BMC Musculoskelet Disord Date: 2022-10-20 Impact factor: 2.562
Authors: Benedikt Kamp; Miriam Frenken; Jan M Henke; Daniel B Abrar; Armin M Nagel; Lena V Gast; Georg Oeltzschner; Lena M Wilms; Sven Nebelung; Gerald Antoch; Hans-Jörg Wittsack; Anja Müller-Lutz Journal: Diagnostics (Basel) Date: 2021-12-08