A5019642579- Advanced MRI Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- MRI in cancer diagnosis
- Atomic and Subatomic Physics Research
- NMR spectroscopy and applications
- Intracerebral and Subarachnoid Hemorrhage Research
- Dementia and Cognitive Impairment Research
- Neonatal and fetal brain pathology
- Functional Brain Connectivity Studies
- Fetal and Pediatric Neurological Disorders
- Optical Imaging and Spectroscopy Techniques
- Image Processing Techniques and Applications
- Autopsy Techniques and Outcomes
- Medical Image Segmentation Techniques
- Traumatic Brain Injury Research
- Non-Invasive Vital Sign Monitoring
- Geophysical Methods and Applications
- Cardiac Imaging and Diagnostics
- Acute Ischemic Stroke Management
- Traumatic Brain Injury and Neurovascular Disturbances
- Multiple Sclerosis Research Studies
- Advanced Computing and Algorithms
- Cell Image Analysis Techniques
- Photoacoustic and Ultrasonic Imaging
- Ultrasound and Hyperthermia Applications
University of British Columbia
2016-2024
University of British Columbia Hospital
2017-2023
Deleted Institution
2023
National Institute of Neurological Disorders and Stroke
2023
Astronomy and Space
2021
Purpose The aim of the 2016 quantitative susceptibility mapping (QSM) reconstruction challenge was to test ability various QSM algorithms recover underlying from phase data faithfully. Methods Gradient‐echo images a healthy volunteer acquired at 3T in single orientation with 1.06 mm isotropic resolution. A reference map provided, which computed using tensor imaging algorithm on 12 head orientations. Susceptibility maps calculated were compared against map. Deviations quantified following...
Susceptibility-sensitive magnetic resonance imaging (MRI) has gained importance in multiple sclerosis (MS) research because of its versatility, high resolution and excellent sensitivity to changes tissue structure composition. In particular, mapping the frequency MR signal quantitative susceptibility (QSM) have been explored for description MS lesions. Many current studies utilizing these techniques attribute increases or QSM elevated iron content, addition myelin loss. However, this common...
A variety of Magnetic Resonance Imaging (MRI) techniques are known to be sensitive brain iron content. In principle, MRI based on local magnetic field variations caused by particles in tissue. The purpose this study was investigate the sensitivity MR relaxation and magnetization transfer parameters changes oxidation state compared concentration. Therefore, quantitative including R1, R2, R2∗, susceptibility maps (QSM) ratio (MTR) post mortem human tissue were acquired prior after chemical...
Abstract R 2 * relaxation provides a semiquantitative method of detecting myelin, iron and white matter fibre orientation angles. Compared with standard histogram‐based analyses, angle‐resolved analysis has previously been shown to substantially improve the detection subtle differences in brain between healthy siblings subjects multiple sclerosis unrelated controls. Neonates, who are born very little myelin iron, an underdeveloped connectome, provide researchers opportunity investigate...
Myelin sensitive MRI techniques, such as diffusion tensor imaging and myelin water imaging, have previously been used to reveal changes in after sports-related concussions. What is not clear from these studies, however, how affected: whether it becomes degraded possibly removed, or the sheath loosens "decompacted". Previously, our team revealed specific ice hockey players 2 weeks post-concussion using imaging. In that study, 45 subjects underwent a pre-season baseline scan, 11 of which...
Purpose To develop a deep neural network to recover filtered phase from clinical MR images enable the computation of QSMs. Methods Eighteen learning networks were trained combinations 13 SWI phase‐filtering pipelines. SWI‐filtered data computed offline five multiorientation, multiecho MRI scans yielding 132 3D volumes (118/7/7 training/validation/testing). Two experiments conducted show efficacy networks. First, using QSM processing, local fields raw and subsequently SWI‐filtering The then...
It is difficult to distinguish punctate white matter lesions from focal hemorrhagic in neonates on conventional MR imaging because both kinds of show increased signal intensity T1-weighted images and, frequently, decreased T2-weighted images. Our aim was and using quantitative measures.In the current study, we acquired multiecho gradient recalled-echo data 24 with hypoxic-ischemic encephalopathy postprocessed them as R2* relaxation maps susceptibility maps. Seven subjects who were found have...
Purpose Reconstructing tissue magnetic susceptibility (QSM) from MRI phase data involves solving multiple consecutive ill‐posed inverse problems such as unwrapping, background field removal, and field‐to‐source inversion. Multi‐echo acquisitions present an additional challenge, the magnetization is typically computed prior to reconstructing map. Processing introduces errors during estimation, violating assumptions of subsequent problems, manifesting streaking artifacts in To address this we...
ABSTRACT: Background: A large proportion of Alzheimer’s disease (AD) patients have coexisting subcortical vascular dementia (SVaD), a condition referred to as mixed (MixD). Brain imaging features MixD presumably include those cerebrovascular and AD pathology, but are difficult characterize due their heterogeneity. Objective: To perform an exploratory analysis conventional non-conventional structural magnetic resonance (MRI) abnormalities in compare them observed SVaD. Methods: We conducted...
Abstract Functional Magnetic Resonance Imaging (fMRI) is typically acquired using gradient-echo sequences with a long echo time at high temporal resolution. Gradient-echo inherently encode information about the magnetic field in often discarded image phase. We demonstrate method for processing phase of reconstructed fMRI data to isolate fluctuations harmonic fields associated respiration by solving blind source separation problem. The fMRI-derived are shown be strong agreement breathing belt...
Quantitative susceptibility mapping is a possible modality with which to measure and identify diseases involving small vasculature in the brain. However, multi-echo gradient echo images that are requirement for high quality quantitative map reconstruction require long scan durations, limiting clinical utility. This duration can be reduced use of parallel imaging strategies, non-linear total generalized variation regularization an increasingly popular strategy undersampled reconstruction. We...
Functional Magnetic Resonance Imaging (fMRI) is routinely acquired using gradient-echo sequences with long echo times and short repetition time. Such encode information about the magnetic field in often discarded image phase. We demonstrate a method for processing phase of reconstructed fMRI data to isolate temporal fluctuations harmonic fields associated respiration by solving blind source separation problem. Computed respiratory from fMRI-derived was shown be strong agreement breathing...
$$$T_2$$$ distributions are typically computed using point estimates such as nonnegative least-squares (NNLS). This characterizes the most likely $$$T_2$$$-distribution arising from data, but disregards other plausible solutions - of which there many, due to ill-posed nature inverse problem. Here, we instead propose use Bayesian posterior sampling methods. To guide difficult high-dimensional problem, a data-driven domain transformation is learned alongside deep generative prior. The...
Abstract We investigated the effects of brain tissue orientation, diffusion, and perivascular spaces on dynamic susceptibility contrast MRI. A 3D numerical model a white matter voxel was created that consists an isotropic capillary bed anisotropic vessels run in parallel with tracts are surrounded by spaces. The signal within simulated solving Bloch-Torrey equation. Experimental perfusion data were acquired gradient echo scan. White fibre orientation mapped diffusion tensor imaging. Our...
Cerebral venous oxygen saturation can be used as an indirect measure of brain health, yet it often requires either invasive procedure or a noninvasive technique with poor sensitivity. We aimed to test whether cerebral could measured using quantitative susceptibility mapping, MR imaging technique, in 3 distinct groups: healthy term neonates, injured and preterm neonates. acquired multiecho gradient-echo data 16 neonates perinatal asphyxia moderate severe hypoxic-ischemic encephalopathy (8...
Objective: To evaluate the incidence, regional localization, volume, and change in volume of cerebral microbleeds (CMBs) over a three year period marginalized urban population. Background: Living environment is associated with exposure to large number variables, including physical violence, infection substance abuse, which can harm brain. Additionally, many people living this experience early life trauma have severe mental illness. CMBs are small, chronic brain hemorrhages that may represent...
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We propose a two-pass multi-echo nonlinear dipole inversion method. In the first pass an initial susceptibility map is obtained. The then further processed by deconvolving residual of forward computed phase and input to recover remnant low frequency sources. proposed method attains NRMSE 18.8 on QSM Reconstruction Challenge 2.0 calcification dataset (Sim2Snr1), decisively outperforming best scoring submissions challenge (NRMSE 26.3, 28.3, 28.5).
We performed quantitative susceptibility mapping (QSM) of the posterior limb internal capsule (PLIC) in human neonates. As PLIC is one earliest structures to myelinate, it clearly visible as a hypointense structure on QSM. This work investigates potential marker for brain health There were no significant differences magnetic between healthy controls, injured preterm, and term
Given the increased use of facemasks in everyday life, impacts these masks on cerebral blood flow (CBF) and oxygenation needs to be investigated. This study used pseudo-continuous arterial spin labeling (pCASL) quantitative susceptibility mapping (QSM) determine changes grey matter CBF respectively. was done by comparing facemask no scans for both 3-ply KN95 masks. The average percent change between oxygenation/susceptibility were insignificant mask types, only showed a statistically...
The coexistence of Alzheimer's disease (AD) and vascular dementia (VaD) is the most common type mixed (MD). More than half all clinically diagnosed AD cases show multiple pathologies at autopsy, but these are challenging to diagnose premortem. Hallmark features MD known include white-matter (WMD) deep grey matter (dGM) microbleeds, in-vivo imaging markers identify characterize needed. Quantitative susceptibility mapping (QSM), a magnetic resonance (MRI) measure that maps tissue properties...