Background: T and T* mapping are crucial components of quantitative magnetic resonance imaging, offering valuable insights into tissue characteristics and pathology. Single-shot methods can achieve ultrafast T or T* mapping by acquiring multiple readout echo trains. However, the extended echo trains pose challenges, such as compromised image quality and diminished quantification accuracy.
Purpose: In this study, we develop a single-shot method for ultrafast T and T* mapping with reduced echo train length.
Methods: The proposed method is based on ultrafast single-shot spatiotemporally encoded (SPEN) MRI combined with reduced field of view (FOV) and spiral out-in-out-in (OIOI) trajectory. Specifically, a biaxial SPEN excitation scheme was employed to excite the spin signal into the spatiotemporal encoding domain. The OIOI trajectory with high acquisition efficiency was employed to acquire signals within targeted reduced FOV. Through non-Cartesian super-resolved (SR) reconstruction, 12 aliasing-free images with different echo times were obtained within 150 ms. These images were subsequently fitted to generate T or T* mapping simultaneously using a derived model.
Results: Accurate and co-registered T and T* maps were generated, closely resembling the reference maps. Numerical simulations demonstrated substantial consistency (R > 0.99) with the ground truth values. A mean difference of 0.6% and 1.7% was observed in T and T*, respectively, in in vivo rat brain experiments compared to the reference. Moreover, the proposed method successfully obtained T and T* mappings of rat kidney in free-breathing mode, demonstrating its superiority over multishot methods lacking respiratory navigation.
Conclusions: The results suggest that the proposed method can achieve ultrafast and accurate T and T* mapping, potentially facilitating the application of T and T* mapping in scenarios requiring high temporal resolution.
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http://dx.doi.org/10.1002/mp.17268 | DOI Listing |
Bioengineering (Basel)
December 2024
Center of Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY 10016, USA.
Non-linear least squares (NLS) methods are commonly used for quantitative magnetic resonance imaging (MRI), especially for multi-exponential T1ρ mapping, which provides precise parameter estimation for different relaxation models in tissues, such as mono-exponential (ME), bi-exponential (BE), and stretched-exponential (SE) models. However, NLS may suffer from problems like sensitivity to initial guesses, slow convergence speed, and high computational cost. While deep learning (DL)-based T1ρ fitting methods offer faster alternatives, they often face challenges such as noise sensitivity and reliance on NLS-generated reference data for training.
View Article and Find Full Text PDFStruct Dyn
January 2025
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
Sub-ångström spatial resolution of electron density coupled with sub-femtosecond to few-femtosecond temporal resolution is required to directly observe the dynamics of the electronic structure of a molecule after photoinitiation or some other ultrafast perturbation, such as by soft X-rays. Meeting this challenge, pushing the field of quantum crystallography to attosecond timescales, would bring insights into how the electronic and nuclear degrees of freedom couple, enable the study of quantum coherences involved in molecular dynamics, and ultimately enable these dynamics to be controlled. Here, we propose to reach this realm by employing convergent-beam x-ray crystallography with high-power attosecond pulses from a hard-x-ray free-electron laser.
View Article and Find Full Text PDFMicrobiome
January 2025
Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark.
Background: Saliva is a protein-rich body fluid for noninvasive discovery of biomolecules, containing both human and microbial components, associated with various chronic diseases. Type-2 diabetes (T2D) imposes a significant health and socio-economic burden. Prior research on T2D salivary microbiome utilized methods such as metagenomics, metatranscriptomics, 16S rRNA sequencing, and low-throughput proteomics.
View Article and Find Full Text PDFPhys Med Biol
January 2025
The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of life Science and Technology, Xi'an Jiaotong University, Xi'an, People's Republic of China.
Estimating the high-resolution (HR) blood flow velocity and pressure fields for the diagnosis and treatment of vascular diseases remains challenging.. In this study, a physics-informed neural network (PINN) with a refined mapping capability was combined with ultrafast ultrasound image velocimetry (u-UIV) to predict HR hemodynamic parameters.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Catalysis & Fine Chemicals, CSIR- Indian Institute of Chemical Technology, Uppal Road, Hyderabad, Telangana State 500007, India.
Photoassisted CO reduction employing a metal-free system is both challenging and fascinating. In our study, we present a structural engineering strategy to tune the potential energy barrier, which, in turn, affects the photoreduction ability. A series of porphyrin-based porous organic polymers () were hydrothermally synthesized and the influence of keto-enol tautomerization on the CO photoreduction potential has been rigorously investigated.
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