André Döring1,2, Victor Adalid1,2, Chris Boesch1, Roland Kreis1. 1. Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland. 2. Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
Abstract
PURPOSE: To combine the metabolite-cycling technique with diffusion-weighted 1 H-MR spectroscopy and to use the inherent water reference for compensation of motion-related signal loss for improved estimation of metabolite apparent diffusion coefficients (ADCs). METHODS: Diffusion-weighted spectra of water and metabolites were acquired simultaneously using metabolite-cycling at 3 T. The water information was used for signal correction of phase, frequency, and eddy currents, as well as for compensation of motion-induced signal loss. ADCs were estimated by 2D simultaneous fitting. The quality of ADC restoration was investigated in vitro. Subsequently, the new approach was applied in 13 subjects for enhanced metabolite ADC estimation in gray matter. RESULTS: Metabolite-cycled diffusion 1 H-MRS is suitable to measure metabolite and water ADCs simultaneously. The water reference facilitates signal amplitude restoration, compensating for motion-related artefacts. 2D fitting stabilizes the fitting procedure and allows the estimation of ADCs even for low signal-to-noise metabolites. Use of the motion-compensation scheme leads to estimation of smaller ADCs for virtually all metabolites (44% smaller ADC on average), to a reduction of fitting uncertainties for metabolite ADCs in individual subjects and reduced variance over the cohort (45% smaller SD on average). CONCLUSION: Using the simultaneously acquired water signal as internal reference allows not only for compensation of phase and frequency fluctuations but also for signal amplitude restoration, and thus improved metabolite ADC estimation. Combination with 2D simultaneous fitting promises access to the diffusion properties even for low signal-to-noise metabolites. The combination of both techniques increases the specificity and sensitivity of estimated metabolite ADC values in the cohort.
PURPOSE: To combine the metabolite-cycling technique with diffusion-weighted 1 H-MR spectroscopy and to use the inherent water reference for compensation of motion-related signal loss for improved estimation of metabolite apparent diffusion coefficients (ADCs). METHODS: Diffusion-weighted spectra of water and metabolites were acquired simultaneously using metabolite-cycling at 3 T. The water information was used for signal correction of phase, frequency, and eddy currents, as well as for compensation of motion-induced signal loss. ADCs were estimated by 2D simultaneous fitting. The quality of ADC restoration was investigated in vitro. Subsequently, the new approach was applied in 13 subjects for enhanced metabolite ADC estimation in gray matter. RESULTS: Metabolite-cycled diffusion 1 H-MRS is suitable to measure metabolite and water ADCs simultaneously. The water reference facilitates signal amplitude restoration, compensating for motion-related artefacts. 2D fitting stabilizes the fitting procedure and allows the estimation of ADCs even for low signal-to-noise metabolites. Use of the motion-compensation scheme leads to estimation of smaller ADCs for virtually all metabolites (44% smaller ADC on average), to a reduction of fitting uncertainties for metabolite ADCs in individual subjects and reduced variance over the cohort (45% smaller SD on average). CONCLUSION: Using the simultaneously acquired water signal as internal reference allows not only for compensation of phase and frequency fluctuations but also for signal amplitude restoration, and thus improved metabolite ADC estimation. Combination with 2D simultaneous fitting promises access to the diffusion properties even for low signal-to-noise metabolites. The combination of both techniques increases the specificity and sensitivity of estimated metabolite ADC values in the cohort.
Authors: Ivan Tkáč; Dinesh Deelchand; Wolfgang Dreher; Hoby Hetherington; Roland Kreis; Chathura Kumaragamage; Michal Považan; Daniel M Spielman; Bernhard Strasser; Robin A de Graaf Journal: NMR Biomed Date: 2020-12-16 Impact factor: 4.478
Authors: Martyna Dziadosz; Maike Hoefemann; André Döring; Malgorzata Marjańska; Edward John Auerbach; Roland Kreis Journal: Magn Reson Med Date: 2022-05-08 Impact factor: 3.737
Authors: Roland Kreis; Vincent Boer; In-Young Choi; Cristina Cudalbu; Robin A de Graaf; Charles Gasparovic; Arend Heerschap; Martin Krššák; Bernard Lanz; Andrew A Maudsley; Martin Meyerspeer; Jamie Near; Gülin Öz; Stefan Posse; Johannes Slotboom; Melissa Terpstra; Ivan Tkáč; Martin Wilson; Wolfgang Bogner Journal: NMR Biomed Date: 2020-08-17 Impact factor: 4.044