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Reducing the echo time of magnetic resonance spectroscopy experiments is appealing because it increases the available signal and reduces J-evolution of coupled metabolites. In this manuscript a novel sequence, referred to as Ultrashort echo TimE, SPin ECho, full Intensity Acquired Localized (UTE-SPECIAL), is described which is able to achieve ultrashort echo times (4 ms) on a standard clinical 3 T MR system while recovering the entirety of the available magnetization. UTE-SPECIAL obtains full 3D spatial localization through a 2D adiabatic inversion pulse which is cycled "on" and "off" every other repetition, in combination with a slice-selective excitation pulse. In addition to an ultrashort echo time, UTE-SPECIAL has negligible chemical shift displacement artefact and, because it uses no slice-selective refocusing pulse, has no signal cancellation at the borders for J-coupled metabolites. Spectra with an ultrashort echo time of 4 ms are demonstrated in vivo at 3 T, as well as J-resolved spectra obtained in a phantom and a healthy volunteer.
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http://dx.doi.org/10.1016/j.jmr.2019.106670 | DOI Listing |
J Magn Reson Imaging
September 2025
Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Background: Carotid artery stenosis is a major cause of stroke. Non-contrast MR angiography (MRA) using time-spatial labeling inversion pulse (Time-SLIP) may offer potential advantages over 3D time-of-flight (TOF)-MRA for simultaneous visualization of carotid, vertebral, and subclavian arteries, but remains uninvestigated.
Purpose: To determine optimal black blood inversion time (TI) for visualizing the carotid and subclavian arteries using three-dimensional (3D) fast field echo (FFE) Time-SLIP MRA, and to compare its image quality with 3D TOF-MRA.
J Magn Reson Imaging
September 2025
Department of Radiology, University of California, San Diego, La Jolla, California, USA.
Chaos
September 2025
School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Although many real-world time series are complex, developing methods that can learn from their behavior effectively enough to enable reliable forecasting remains challenging. Recently, several machine-learning approaches have shown promise in addressing this problem. In particular, the echo state network (ESN) architecture, a type of recurrent neural network where neurons are randomly connected and only the read-out layer is trained, has been proposed as suitable for many-step-ahead forecasting tasks.
View Article and Find Full Text PDFNMR Biomed
October 2025
Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
Understanding gastric physiology in rodents is critical for advancing preclinical neurogastroenterology research. However, existing techniques are often invasive, terminal, or limited in resolution. This study aims to develop a non-invasive, standardized MRI protocol capable of capturing whole-stomach dynamics in anesthetized rats with high spatiotemporal resolution.
View Article and Find Full Text PDFMagn Reson Med
September 2025
National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA.
Purpose: To achieve spectrally resolved in vivo detection of glutamate, glutamine, and glutathione at 3 T.
Methods: Difference editing of N-acetylaspartate CH protons (NAA-CH) combined with a new echo-time (TE) optimization approach is introduced. Difference editing was used to detect NAA-CH independently of NAA-CH, thereby eliminating systematic errors arising from constrained fitting of the entire NAA molecule.