A5052174845- Advanced MRI Techniques and Applications
- Advanced NMR Techniques and Applications
- Atomic and Subatomic Physics Research
- Advanced Neuroimaging Techniques and Applications
- Electron Spin Resonance Studies
- Liver Disease Diagnosis and Treatment
- Cardiovascular Function and Risk Factors
- Ultrasound Imaging and Elastography
- Diet, Metabolism, and Disease
- NMR spectroscopy and applications
- Neonatal and fetal brain pathology
- Neurological disorders and treatments
- Fetal and Pediatric Neurological Disorders
- Neurological diseases and metabolism
- Non-Destructive Testing Techniques
- Neuroscience and Neural Engineering
- Face Recognition and Perception
- Cardiac Imaging and Diagnostics
- MRI in cancer diagnosis
- Cerebrovascular and Carotid Artery Diseases
- Cardiovascular Health and Disease Prevention
- Dialysis and Renal Disease Management
- Genetics and Neurodevelopmental Disorders
- Spectroscopy Techniques in Biomedical and Chemical Research
- Magnetic confinement fusion research
Western University
2012-2024
Robarts Clinical Trials
2008-2021
McMaster University
2018
University of British Columbia
2007
A new noninvasive, nonradioactive approach for glucose imaging using spin hyperpolarization technology and stable isotope labeling is presented. analog labeled with 13 C at all six positions increased the overall hyperpolarized signal; deuteration seven directly bonded proton prolonged spin–lattice relaxation time. High‐bandwidth overcame large carbon chemical shift dispersion. Hyperpolarized images in live rat showed time‐dependent organ distribution patterns. At 8 s after start of bolus...
The STRAT-PARK initiative aims to provide a platform for stratifying Parkinson's disease (PD) into biological subtypes, using bottom-up, multidisciplinary biomarker-based and data-driven approach. PD is heterogeneous entity, exhibiting high interindividual clinicopathological variability. This diversity suggests that may encompass multiple distinct entities, each driven by different molecular mechanisms. Molecular stratification identification of subtypes therefore key priority understanding...
Purpose To accurately analyze vibroacoustics in MR head gradient coils. Theory and Methods A detailed theoretical model for coil vibroacoustics, including the first description modeling of Lorentz damping, is introduced implemented a multiphysics software package. Numerical finite‐element method simulations were used to establish highly accurate vibroacoustic coils detail, newly damping effect. Vibroacoustic coupling was examined through an additional modal analysis. Thorough experimental...
To implement and optimize a single-shot spiral encoding strategy for rapid 2D IDEAL projection imaging of hyperpolarized (Hp) (129) Xe in the gas phase, pulmonary tissue (PT) red blood cells (RBCs) compartments rat lung, respectively.A theoretical experimental point spread function analysis was used to k-space read-out time phantom. Hp images from five healthy rats were to: (i) flip angles by Bloch equation using measured kinetics exchange (ii) investigate feasibility approach characterize...
Carotid atherosclerosis measurements for eight subjects at baseline and 14 ± 2 days later were examined using 1.5 T 3.0 magnetic resonance imaging (MRI). A single observer blinded to field strength, subject timepoint manually segmented carotid artery wall lumen boundaries in randomized images five measurement trials. Mean increases the signal-to-noise ratios (SNR) T1-weighted acquired compared 90% (scan) 80% (rescan). Despite significantly improved SNR contrast-to-noise (CNR) T, vessel...
Purpose To develop a new method of reducing T 1 bias in proton density fat fraction (PDFF) measured with iterative decomposition water and echo asymmetry least‐squares estimation (IDEAL). Materials Methods PDFF maps reconstructed from high flip angle IDEAL measurements were simulated acquired phantoms volunteer L4 vertebrae. was corrected using priori values for fat, both without correction. Signal‐to‐noise ratio (SNR) used to measure precision the maps. small angles then compared sets large...
Purpose To test the feasibility of hyperpolarized [1‐ 13 C]pyruvate magnetic resonance imaging (MRI) for noninvasive examination guinea pig fetoplacental metabolism and nutrient transport. Materials Methods Seven pregnant pigs with a total 30 placentae fetuses were anesthetized scanned at 3T. T 1 ‐weighted H images obtained from maternal abdomen. An 80 mM solution (hereafter referred to as pyruvate) was injected into vein in foot. Time‐resolved 3D C acquired starting 10 seconds after...
Purpose To examine the feasibility of using MRI to identify differences in liver size and fat deposition fetal guinea pigs exposed an utero environment influenced by maternal consumption a Western diet. Materials methods Female fed either energy-dense Diet (WD), comprised increased saturated fats simple sugars, or Control (CD) from weaning through pregnancy, underwent MR scanning near term (~ 60 days; ~ 69 days). Maternal weights were collected at mating scanning. T1-weighted, T2-weighted,...
To demonstrate a reconstruction technique for separating signal from different hyperpolarized carbon-13 metabolites.A method is described chemical shift encoded separation of the pyruvate and its downstream metabolites. This uses consistency data with model rather than an additional free-induction decay (FID) acquisition to estimate B0 offset. Compressed sensing was also integrated into allowing metabolite images undersampled datasets. The performance assessed using thermal phantoms, digital...
Purpose To assess the feasibility of choline MRI using a new molecular probe for dynamic nuclear polarization (DNP) hyperpolarized MRI. Materials and Methods Male Sprague‐Dawley rats with an average weight 400 ± 20 g (n = 5), were anesthetized injection tubing was placed in tail vein. [1,1,2,2‐D 4 , 1‐ 13 C]choline chloride (CMP1) by DNP injected into at doses ranging from 12.6 to 50.0 mg/kg. Coronal projection C imaging performed on 3 Tesla clinical scanner (bore size 60 cm) variable flip...
Vessel size imaging was used to assess changes in the average vessel of Shionogi tumors throughout tumor growth cycle. Changes R2 and R2* relaxivities caused by injection a superparamagnetic contrast agent (ferumoxtran-10) were measured using 2.35-T animal magnetic resonance system, index (VSI) calculated for each stage progression: growth, regression, relapse. Statistical analysis Spearman rank correlation test showed no dependence between volume at any Paired Student's t statistical...
To demonstrate a new multigradient echo bipolar acquisition sequence for fat quantification.A multiecho is used such that the even echoes have opposite polarity to odd echoes. In addition, readout gradients alternate their polarities every other phase-encode line. Each echo, therefore, consists of lines with both positive and negative polarities. Phase-encodes acquired same are grouped together, parallel imaging reconstruction obtain two full k-space maps at all By complex averaging,...
Abstract We report a novel radiofrequency (RF) transmit‐only/receive‐only (TO/RO) coil configuration providing excellent transmit B 1+ field uniformity as well high sensitivity for hyperpolarized 129 Xe MR lung imaging of rats at 3T (35.34 MHz). The TO/RO consisted two separate components: (i) high‐pass birdcage which produces homogeneous magnetic field, (ii) saddle‐shaped single‐turn receive‐only surface that couples closely to the rat lung. On transmit, is decoupled from using detuning...
A new approach to mapping the flip angle quickly and efficiently in 3D based on Look-Locker technique is presented.We modified accelerated T1 measurement allow rapid of angle. By removing inversion pulses interleaving two radio frequency with different amplitude, it possible fit directly for true using a reduced number parameters. This technique, non-inverted Double Angle Look-Locker, allows quick efficient 3D.non-inverted validated vitro against actual imaging range angles values. Flip maps...
Purpose To improve the SNR of hyperpolarized carbon‐13 MRI [1‐ 13 C]pyruvate using a multispectral variable flip angle (msVFA) scheme in which spectral profile and vary dynamically with time. Methods Each image acquisition time‐resolved imaging experiment used unique spectrally varying RF pulse shape for msVFA. Therefore, every was optimized pyruvate each its metabolites to yield highest across acquisition. Multispectral VFA compared constant flip‐angle excitation model through simulations...
The hepatic circulation is involved in adaptive systemic responses to circulatory stress. However, it vulnerable both chronic hypervolemia and cardiac dysfunction. influence of hemodialysis (HD) ultrafiltration (UF) upon liver water content has been understudied. We conducted a detailed pilot study characterize the effects HD stiffness, referenced peripheral fluid mobilization total body water. studied 14 established patients without disease. Magnetic resonance imaging (MRI) together with...
Background Alterations in glycolysis are central to the increasing incidence of non‐alcoholic fatty liver disease (NAFLD), highlighting a need for vivo, non‐invasive technologies understand development hepatic metabolic aberrations. Purpose To use hyperpolarized magnetic resonance spectroscopy (MRS) and proton density fat fraction (PDFF) imaging (MRI) techniques investigate effects chronic, life‐long exposure Western diet (WD) an animal model resulting NAFLD; hypothesis that WD will result...
A direct determination of<italic>K</italic><sub>m</sub>, a fundamental measure of enzyme–substrate affinity, is now possible without sample manipulation by real-time hyperpolarized<sup>13</sup>C-MRS.
Purpose: To demonstrate and validate E-field calculation PNS prediction methods that are accurate, computationally efficient could be used to inform regulatory standards. Methods: We describe a simplified method for calculating the spatial distribution of induced over volume body model given gradient coil vector potential field. The is easily programmed without finite element or difference software, allowing straightforward computationally-efficient evaluation. Using these calculations range...
Background Fetal myelination assessment is important for understanding neurodevelopment and neurodegeneration. Myelin water imaging (MWI) quantifies myelin fraction (MWF), a validated marker content, has been used to assess brain in children neonates . Purpose To demonstrate that MWI can quantify MWF fetal guinea pigs (GPs). Study Type Animal model. Model Nine pregnant, Dunkin‐Hartley GPs with 31 fetuses (mean ± standard deviation = 60 1.5 days gestation). Field Strength/Sequence 3D spoiled...
Motivation: Two interactions between gradient coils and their environment severely limit imaging performance: stimulation of peripheral nerves in human subjects deposition heat energy into the superconducting main magnet leading to helium loss or quench. This heating increases significantly for higher B0 switching frequencies. Goal(s): To address above limitations by recasting design problem a unique way simultaneously minimize both these interactions. Approach: Using new methods, we...
Motivation: Increased gradient performance can address several of technical and physics challenges UHF MRI. Goal(s): To develop a head coil (known as LH7) for insertion into the body 10.5T MRI system. Approach: Design innovations include: symmetric folded geometry with variable end-flange angle optimized shoulder geometry; double Z-primary layer. Results: With 650A, 2000V drivers, hardware limits LH7 are Gmax 117mT/m Smax 900T/m/s. Thermal results demonstrate cooling capacity &gt;45kW....