A5029802945- Advanced MRI Techniques and Applications
- Advanced NMR Techniques and Applications
- Medical Imaging Techniques and Applications
- MRI in cancer diagnosis
- Atomic and Subatomic Physics Research
- Energy Harvesting in Wireless Networks
- NMR spectroscopy and applications
- Advanced Neuroimaging Techniques and Applications
- Full-Duplex Wireless Communications
- Ultrasound and Hyperthermia Applications
- Optical Imaging and Spectroscopy Techniques
- Microwave Imaging and Scattering Analysis
- Ultrasound Imaging and Elastography
- Electromagnetic Compatibility and Measurements
- Advanced MIMO Systems Optimization
- Superconducting Materials and Applications
- Electric Motor Design and Analysis
- Radiomics and Machine Learning in Medical Imaging
- Functional Brain Connectivity Studies
- Wireless Body Area Networks
- Electron Spin Resonance Studies
- Medical Image Segmentation Techniques
- Cardiac Imaging and Diagnostics
- Particle accelerators and beam dynamics
- Wireless Power Transfer Systems
National Institute of Standards and Technology
2023-2025
Physical Measurement Laboratory
2023-2025
University of Colorado Boulder
2023-2024
Texas A&M University
2015-2020
King's College London
2020
Abstract Introduction Specific absorption rate (SAR) is crucial for monitoring radiofrequency power during MRI. Although local SAR distribution usually calculated through numerical simulations, they are impractical exams, limiting real‐time patient‐specific assessment. This study confirms the feasibility of deriving in vivo, subject‐specific, image‐based and 10‐g maps directly from MRI data. Methods Complex B 1 + were derived by combining a product (XFL) magnitude sequence with balanced...
To measure healthy brain [Formula: see text] and relaxation times at 0.064 T.[Formula: were measured in vivo for 10 volunteers using a T magnetic resonance imaging (MRI) system test samples on both the MRI separate nuclear (NMR) system. In values are reported white matter (WM), gray (GM), cerebrospinal fluid (CSF) automatic segmentation regions manual of interest (ROIs).[Formula: sample measurements within 10% NMR measurement 9 samples, one was 11%. Eight 25% measurement, two longest had...
Existing magnetic resonance imaging (MRI) reference objects, or phantoms, are typically constructed from simple liquid gel solutions in containers with specific geometric configurations to enable multi-year stability. However, there is a need for phantoms that better mimic the human anatomy without barriers between tissues. Barriers result regions MRI signal different tissue mimics, which an artificial image artifact. We created anatomically representative 3D structure of brain mimicked T1...
Purpose This work describes the construction and evaluation of a bilateral 32‐channel receive array for breast imaging at 7T. Methods The consisted 32 coils, placed on two 3D‐printed hemispherical formers. Each side 16 loops, each loop having corresponding detachable board with match/tune capacitors, active detuning circuitry, balun. Coil performance was evaluated homogeneous canola oil phantoms using Philips Achieva 7T system. Array coil compared forced current excitation volume in...
Most MRI scanners are equipped to receive signals from 1H array coils but few support multi-channel reception for other nuclei. Using arrays can provide significant SNR benefits, usually exploited enable accelerated imaging, the extension of these non-1H nuclei has received less attention because relative lack broadband receivers. Non-1H often have low sensitivity and stand benefit greatly increase in that provide. This paper presents a cost-effective approach adapting standard receivers use...
Considering the reported elevation of ω-6/ω-3 fatty acid ratios in breast neoplasms, one particularly important application 13C MRS could be more fully understanding lipidome's relationship to cancer incidence. However, low natural abundance and gyromagnetic ratio isotope lead detection sensitivity challenges. Previous studies have relied on use small surface coils with limited field-of-view shallow penetration depths achieve adequate signal-to-noise (SNR), receive array is still mostly...
Multi-channel receivers are commonplace in MRI, but very few of these capable operating over a broad enough bandwidth to accommodate nuclei other than <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> H. While this is fine for imaging, the recent surge interest vivo NMR has created need receive arrays improve often-poor sensitivity nuclei. However, development been slowed by scarcity multi-channel, multinuclear receivers. Frequency...
Motivation: The fractional T1 differences between healthy and abnormal tissue are significant larger in the ultra-low-field (ULF) regime (&lt;10 mT) compared to high field. Goal(s): Despite challenges of imaging at ULF (predominately low SNR spatial-temporal resolution), we demonstrate vivo mapping breast 6.5 mT 43 minutes. Approach: A variable flip angle (VFA) method with B1 correction was used. Results: CuSO4 solutions showed an average deviation &lt;7% reference measurements....
Motivation: Currently, we do not know how frequently quality assurance (QA) should be performed on an MRI scanner to detect changes that impact quantitative measurements. Goal(s): Our goal is determine the frequency of QA measurements needed during course a in vivo study have confidence Approach: Phantom were made immediately before or after over duration repeatability study. Results: All phantom had variation well below 10 % 99 day Impact: We now for using magnetic resonance fingerprinting...
Abstract Breast cancer screening is necessary to reduce mortality due undetected breast cancer. Current methods have limitations, and as a result many women forego regular screening. Magnetic resonance imaging (MRI) can overcome most of these but access conventional MRI not widely available for routine annual Here, we used an scanner operating at ultra-low field (ULF) image the left breasts 11 (mean age, 35 years ±13 years) in prone position. Three radiologists reviewed were able discern...
The assessment of brain morphology requires geometric accuracy, and the monitoring pathologies like dementia stability over time between systems. We aim to assess accuracy a head-only 64 mT system by imaging cylindrical phantom provided manufacturer, positioned with 3D-printed holder for stability, analyzing fidelity images produced variety product sequences. initial examines perimeter how it varies along S-I direction.
We present a full closed form solution focusing on S-parameters to achieve tuning and matching of the coils by extending circuit co-simulation (CCS) enabling introduction arbitrary networks into CCS without requiring RF simulation network. validate method against demonstrate its applicability evaluate full-field solutions for 5 different coil model using MARIE.
Tissue-mimicking reference phantoms are indispensable for the development and optimization of magnetic resonance (MR) measurement sequences. Phantoms have greatest utility when they mimic MR signals arising from tissue physiology; however, many properties underlying these signals, including relaxation characteristics, can vary as a function field strength. There has been renewed interest in imaging (MRI) at strengths less than 1 T, developed higher may not be physiologically relevant lower...
Motivation: To enable quantitative techniques at low-field, it is necessary to establish expected T1 and T2 values within the brain for healthy adults. Goal(s): measure compare of human 64mT. Approach: 20 volunteers were imaged The resulting images segmented using SynthSeg, average computed over gray matter, white cerebrospinal fluid regions. Results: Mean determined. Partial volume effects may limit accuracy image segmentation lead large variations in matter measurements. Impact: normative...
Abstract The proposed extension to the conventional circuit co-simulation (CCS) method reliably and efficiently introduces arbitrary matching networks into CCS routines is here dubbed as (MCCS). It further achieves coil tuning for resonance an optimum scattering parameters condition that resembles a fully matched coil. Combined with magnetic integral equations (MARIE), MCCS accurately produces full EM simulation of coils. We first validated MARIE routine use it model simple single-channel...
Quantitative MRI at 7T has advantages of enhanced resolution and uniform tissue contrast however protocol optimisation can be challenging as B1(+) field variability is increased. We maximized the precision T1 estimation for a dual flip angle SPGR acquisition using Cramer-Rao Lower Bound framework validated results Monte Carlo simulation both phantom in-vivo experiments. For TR 20ms, simulations suggested optimal angles 4&deg; 26&deg; similar to 28&deg;. By accounting other...
We present the first continuous 30-channel loop receive coil array combined with 10-channel dipole parallel-transmit for 7 Tesla body imaging. Array comprises a flexible anterior part 6 dipoles and 18 loops, 35cm longitudinal coverage along hard plastic posterior containing 4 12 loops. Special features were added to help patient comfort overcome cabling limitations. Simulations computational human model show adequate B 1 + in areas of interest such as prostate. Phantom images taken showing...
A typical parallel transmit system has an equal number of RF power amplifiers individually connected to coil elements. When performing B 1 + shimming, the maximum available is limited by single channel amplifier performance. networks which allow for be shared between channels have been proposed as a way overcome this limitation, but fixed only offer performance gains over ranges relative phases channels. Adding high-power phase shifter power-sharing network and element can combat this, even...
Simultaneously interrogation of multiple nuclei has been interest since the very earliest days MRI [1]-[3]. Our group and several others are revisiting this topic [4]-[6]. Very fast broadband electronics make it possible to digitize a wide spectrum, including nuclei, but places great demands on data throughput. Another issue is that there can be variance between RF preamplifier gain required for different nuclei. To overcome problem, desirable use undersampling, requires passband filtering...