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Introduction: This computational study evaluates the accuracy of kinetic models and acquisition schemes in dynamic PET imaging using simulations of 18 F-fallypride PET in the human brain on the real-world data.
Methods: We employed a 2-tissue 4-k model to generate ideal tissue curves for three regions (putamen, thalamus, and temporal cortex) and a reference region (cerebellum), incorporating a simulated metabolite-corrected input function. Realistic measurements were simulated over a 240-min PET scan by defining acquisition protocols (frame timings and durations), modeling tracer decay, and adding noise. Distribution volume ratios (DVRs) were calculated using the Logan reference analysis and the simplified reference tissue model (SRTM), the relative error in DVR was also assessed across various acquisition protocols. Rate constants from the 2-tissue model were varied, and Bland-Altman analysis was quantified to determine bias relative to ground-truth DVR.
Results: Results indicate that, under low noise conditions, the Logan reference method performed optimally with a protocol involving a 60-min dynamic scan, a 60-min break, a 30-min scan, another 60-min break, and a final 30-min scan. In noisier conditions, the SRTM yielded the best results with a 150-min effective scan time incorporating three breaks.
Conclusion: These findings highlight the impact of noise and acquisition strategy on model performance, informing optimal PET imaging protocols.
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http://dx.doi.org/10.1097/MNM.0000000000001995 | DOI Listing |
Comput Biol Med
September 2025
Department of Electrical and Computer Engineering and the Institute of Biomedical Engineering, University of New Brunswick, Fredericton, E3B 5A3, NB, Canada.
Pattern recognition-based myoelectric control is traditionally trained with static or ramp contractions, but this fails to capture the dynamic nature of real-world movements. This study investigated the benefits of training classifiers with continuous dynamic data, encompassing transitions between various movement classes. We employed both conventional (LDA) and deep learning (LSTM) classifiers, comparing their performance when trained with ramp data, continuous dynamic data, and an LSTM pre-trained with a self-supervised learning technique (VICReg).
View Article and Find Full Text PDFMagn Reson Med
September 2025
Institute for Diagnostic and Interventional Radiology, School of Medicine and Health, TUM University Hospital, Technical University of Munich, Munich, Germany.
Purpose: To develop a method for abdominal simultaneous 3D water ( ) and ( ) mapping with isotropic resolution using a free-breathing Cartesian acquisition with spiral profile ordering (CASPR) at 3 T.
Methods: The proposed data acquisition combines a Look-Locker scheme with the modified BIR-4 adiabatic preparation pulse for simultaneous and mapping. CASPR is employed for efficient and flexible k-space sampling at isotropic resolution during free breathing.
Magn Reson Chem
September 2025
Servei de Ressonància Magnètica Nuclear, Facultat de Ciències i Biosciències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Catalonia, Spain.
Photo-chemically induced dynamic nuclear polarisation (photo-CIDNP) is a nuclear spin-selective magnetic resonance phenomenon that has traditionally been used to mechanistically study chemical reactions involving the (transient) formation of radical molecular species, extract EPR observables of short-lived radicals, probe biomolecular structure and interactions and, less importantly, increase the sensitivity of a nuclear magnetic resonance (NMR) measurement. Recently, the introduction of significant methodological advances as well as the advent of benchtop NMR spectroscopy has rekindled interest in this technique, which-serendipitously discovered more than half a century ago-has, as of late, matured into a powerful, highly sensitive and extremely versatile NMR hyperpolarisation method. In this tutorial, aimed primarily at the nonexpert user, we provide practical information on how to plan, set up and perform one-dimensional H and heteronuclear photo-CIDNP NMR experiments using a high-field NMR spectrometer and a continuous-wave (CW) illuminant.
View Article and Find Full Text PDFJ Cardiovasc Magn Reson
September 2025
Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), University of Leeds, Leeds, UK. Electronic address:
Background: Cardiac diffusion tensor imaging (cDTI) is sensitive to imaging parameters including the number of unique diffusion encoding directions (ND) and number of repetitions (NR; analogous to number of signal averages or NSA). However, there is no clear guidance for optimising these parameters in the clinical setting.
Methods: Spin echo cDTI data with 2 order motion compensated diffusion encoding gradients were acquired in ten healthy volunteers on a 3T MRI scanner with different diffusion encoding schemes in pseudo-randomised order.
Magn Reson Imaging
September 2025
Physikalisch-Technische Bundesanstalt (PTB), Berlin and Braunschweig, Germany.
Unlabelled: A novel steady-state CEST sequence design, based on the underlying physical model of longitudinal magnetization development during CEST saturation and data acquisition is presented and validated in-silico, in vitro and in vivo. This design ensures consistent data acquisition in the pure CEST steady-state, leading to high MTR scores and image quality, both in vitro and in vivo, when compared to contemporary sequential and steady-state CEST sequences.
Purpose: The aim of this study was to enhance CEST sequences by utilizing the pure CEST steady-state in order to deliver higher CEST effects and better sensitivity.