A quadrature transmit/receive birdcage coil was optimized for squirrel monkey functional imaging at the high field of 9.4 T. The coil length was chosen to gain maximum coil efficiency/signal-to-noise ratio (SNR) and meanwhile provide enough homogenous RF field in the whole brain area. Based on the numerical simulation results, a 16-rung high-pass birdcage coil with the optimal length of 9 cm was constructed and evaluated on phantom and in vivo experiments. Compared to a general-purpose non-optimized coil, it exhibits approximately 25% in vivo SNR improvement. In addition to the volume coil, details about how to design and construct the associated animal preparation system were provided.
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http://dx.doi.org/10.1016/j.mri.2021.03.012 | DOI Listing |
Sensors (Basel)
December 2024
Department of Biomedical Engineering, Army Medical University, The Third Military Medical University, Chongqing 400038, China.
Magnetic induction phase shift is a promising technology for the detection of cerebral hemorrhage, owing to its nonradioactive, noninvasive, and real-time detection properties. To enhance the detection sensitivity and linearity, a zero-flow sensor was proposed. The uniform primary magnetic field and its counteraction were achieved.
View Article and Find Full Text PDFQuant Imaging Med Surg
December 2024
Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA.
Background: Low-field open magnetic resonance imaging (MRI) systems, typically operating at magnetic field strengths below 1 Tesla, has greatly expanded the accessibility of MRI technology to meet a wide range of patient needs. However, the inherent challenges of low-field MRI, such as limited signal-to-noise ratios and limited availability of dedicated radiofrequency (RF) coils, have prompted the need for innovative coil designs that can improve imaging quality and diagnostic capabilities. In this work, we introduce a multimodal axial array resonator and its implementation in a volume coil, or referred to as a coupled stack-up volume coil, to address these challenges in low-field open MRI.
View Article and Find Full Text PDFPLoS One
December 2024
Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON, Canada.
MRI of patients with Deep Brain Stimulation (DBS) implants is constrained due to radiofrequency (RF) heating of the implant lead. However, "RF-shimming" parallel transmission (PTX) has the potential to reduce DBS heating during MRI. As part of using PTX in such a "safe mode", maps of the RF transmission field (B1+) are typically acquired for calibration purposes, with each transmit coil excited individually.
View Article and Find Full Text PDFNMR Biomed
January 2025
Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
Fluorine-19 (F) MRI has become an established tool for in vivo cell tracking following ex vivo or in vivo labelling of various cell types with F perfluorocarbons (PFCs). Here, we developed and evaluated novel mouse-specific radiofrequency (RF) hardware for improved dual H anatomical imaging and deep tissue F MR detection of PFCs. Three linearly polarized birdcage RF coils were constructed-a dual-frequency H/F coil, and a pair of single-frequency H and F coils, designed to be used sequentially.
View Article and Find Full Text PDFMAGMA
November 2024
School of Biomedical Engineering and Imaging Science, King's College London, 3rd Floor Lambeth Wing, St Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, UK.
Objective: Tissue heating near the implanted deep brain stimulation (DBS) during magnetic resonance imaging (MRI) poses a significant safety constraint. This study aimed to evaluate the performance of parallel transmit (pTx) head transmit radiofrequency (RF) coils in DBS patients, with a focus on excitation fidelity under specific absorption rate (SAR) control for brain imaging at 3T MRI.
Materials And Methods: We employed electromagnetic simulations to assess different coil configurations, including multi-row pTx coils of 16-24 channels arranged in 1, 2, and 3 rows, and compared these to a circularly polarised and pTx birdcage coil using a realistic human model without and with DBS leads and electrodes.
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