A5101743739- Advanced MRI Techniques and Applications
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- Quantum, superfluid, helium dynamics
- NMR spectroscopy and applications
- Elasticity and Material Modeling
- Functional Brain Connectivity Studies
- Non-Invasive Vital Sign Monitoring
- Ultrasound Imaging and Elastography
- Genetic and rare skin diseases.
- Medical Image Segmentation Techniques
- Automotive and Human Injury Biomechanics
- Lanthanide and Transition Metal Complexes
- Abdominal Surgery and Complications
- Hair Growth and Disorders
- Ocular Surface and Contact Lens
- Lung Cancer Research Studies
- ECG Monitoring and Analysis
- MRI in cancer diagnosis
- Neurosurgical Procedures and Complications
- Vascular Malformations Diagnosis and Treatment
- Phonocardiography and Auscultation Techniques
- Abdominal vascular conditions and treatments
- Inhalation and Respiratory Drug Delivery
Siemens (United States)
2021-2024
Kuo General Hospital
2019
University of Pennsylvania
2016-2017
Mallinckrodt (United States)
2011-2014
Washington University in St. Louis
2005-2013
National Science and Technology Council
2013
University of Cape Town
2013
National Taiwan University
2013
Chang Gung Memorial Hospital
2013
Institute of Biomedical Sciences, Academia Sinica
2013
Abstract We present a model of gas exchange for hyperpolarized 129 Xe in the lung, which we refer to as Model Xenon Exchange. The consists two expressions and characterizes uptake dissolved xenon lung at different resonance frequencies. are governed by following five critical pulmonary parameters that characterize both function structure: surface‐area‐to‐volume ratio, barrier‐to‐septum ratio (ratio between air–blood barrier thickness septal thickness), hematocrit, gas‐exchange time constant,...
<b><i>Background:</i></b> Neurosurgeons regularly plan their surgery using magnetic resonance imaging (MRI) images, which may show a clear distinction between the area to be resected and surrounding healthy brain tissue depending on nature of pathology. However, this is often unclear with naked eye during surgical intervention, it difficult infer depth an accurate volumetric interpretation from series MRI image slices. <b><i>Objectives:</i></b>...
The HEALthy Brain and Child Development (HBCD) Study, a multi-site prospective longitudinal cohort study, will examine human brain, cognitive, behavioral, social, emotional development beginning prenatally planned through early childhood. acquisition of multimodal magnetic resonance-based brain data is central to the study's core protocol. However, application Magnetic Resonance Imaging (MRI) methods in this population complicated by technical challenges difficulties imaging life. Overcoming...
Abstract Purpose A 128‐channel receive‐only array for brain imaging at 7 T was simulated, designed, constructed, and tested within a high‐performance head gradient designed high‐resolution functional imaging. Methods The coil used tight‐fitting helmet geometry populated with 128 loop elements preamplifiers to fit into 39 cm diameter space inside built‐in gradient. signal‐to‐noise ratio (SNR) parallel performance (1/ g ) were measured in vivo simulated using electromagnetic modeling....
Purpose To present in vivo, human validation of a previously proposed method to measure key pulmonary parameters related lung microstructure and physiology. Some parameters, such as blood–air barrier thickness, cannot be measured readily by any other noninvasive modality. Methods Healthy volunteers (n = 12) were studied 1.5T 3T whole body scanners using hyperpolarized xenon. Xenon uptake parenchyma blood was chemical shift saturation recovery sequence. Both dissolved‐xenon peaks at 197 ppm...
To evaluate the efficacy of using forward second harmonic generation (SHG) and 2-dimensional fast Fourier-transform (2D-FFT) analysis for label-free characterization quantification morphologic changes in corneal stroma after collagen crosslinking (CXL).Department Physics, National Taiwan University, Taipei, Taiwan.Experimental study.En face SHG imaging 2D-FFT were performed on ex vivo porcine corneas at depths 100, 200, 400, 800 μm. Morphologic stromal fiber control, ultraviolet-A (UVA),...
Arterial Spin Labeled (ASL) perfusion MRI enables non-invasive, quantitative measurements of tissue perfusion, and has a broad range applications including brain functional imaging. However, ASL suffers from low signal-to-noise ratio (SNR), limiting image resolution. Acquisitions using 3D readouts are optimal for background-suppression static signals, but can be SAR intensive typically suffer through-plane blurring. In this study, we investigated the use accelerated to obtain whole-brain,...
Purpose To extend the coverage of brain coil arrays to neck and cervical–spine region enable combined head imaging at 7 Tesla (T) ultra‐high field MRI. Methods The array structures a 64‐channel receive 16‐channel transmit were merged into one anatomically shaped close‐fitting housing. Transmit characteristics evaluated in B 1 + ‐field mapping study an electromagnetic model. Receive SNR encoding capability for accelerated compared with commercially available T coil. performance head–neck was...
Spatial and temporal variations in cortical growth were studied the neonatal ferret to illuminate mechanisms of folding cerebral cortex. Cortical surface representations created from magnetic resonance images acquired between postnatal day 4 35. Global measures shape (e.g., area, normalized curvature, sulcal depth) calculated. In 2 ferrets, relative was calculated surfaces vivo at P14, P21, P28. The isocortical area transitions a slower (12.7 mm(2)/day per hemisphere) higher rate (36.7...
We present a time efficient method to estimate gradient delay using single oscillating waveform. Single waveform-based estimation algorithm (SODA) was proposed. It estimated delays by measuring the relative shifts of echoes acquired at consecutive points. An acceleration achieved three spin-echo sequence acquiring measurements for all channels within excitation. Simulations and phantom experiments were carried out compare SODA with reference method. In addition, we monitored change over an...
Purpose The goal of this study was to develop a 3D acceleration and reconstruction method improve image quality resolution background‐suppressed arterial spin‐labeled perfusion MRI. Methods Accelerated acquisition implemented in all three k‐space dimensions stack‐of‐spirals readout using variable density spirals partition undersampling. A single self‐consistent parallel imaging (SPIRiT) kernel calibrated iteratively applied reconstruct each volume. Whole‐brain (including cerebellum) obtained...
Abstract Perfluorinated gases, particularly C 2 F 6 , are potentially suitable alternatives to hyperpolarized noble gases for pulmonary airspace spin density and diffusion MRI. This work focuses mainly on 19 imaging of gas in healthy emphysematous explanted lungs, avoiding regulatory issues human vivo measurements. Three‐dimensional gradient echo images lungs can be made 10 s with adequate signal‐to‐noise, demonstrating the feasibility breathing dynamics captured during a succession short...
Abstract Purpose To characterize the effect of diffusion time on short‐range hyperpolarized 3 He magnetic resonance imaging (MRI) measurements across a wide range emphysema severity. Materials and Methods MRI was performed 19 lungs or lobes resected from 18 subjects with varying degrees using three times (1.6 msec, 5 10 msec) at constant b value. Emphysema severity quantified as mean apparent coefficient (ADC) percentage pixels ADC higher than multiple thresholds 0.30–0.55 cm 2 /sec (ADC...
The long-range apparent diffusion coefficient (LRADC) of (3)He gas in lungs, measured over times several seconds and distances 1-3 cm, probes the connections between airways. Previous work has shown LRADC to be small health substantially elevated emphysema, reflecting tissue destruction, which is known create collateral pathways. To better understand what controls LRADC, we report computer simulations measurements healthy lungs. lung generated with a random algorithm using well-defined...
Purpose Parallel imaging can be used to reduce time and increase the spatial coverage in hyperpolarized gas magnetic resonance of lung. In this proof‐of‐concept study, we investigate effects parallel on morphometric measurement lung microstructure using diffusion with 3 He. Methods Fully sampled under‐sampled multi‐ b data were acquired from human subjects an 8‐channel He receive coil. A reconstruction technique (generalized autocalibrating partially acquisitions [GRAPPA]) was reconstruct...
Purpose Lung morphometry with hyperpolarized gas diffusion MRI is a highly sensitive technique for the noninvasive measurement of acinar microstructural parameters traditionally only accessible by histology. The goal this work to establish reproducibility these measurements in healthy volunteers and their dependence on direction applied diffusion-sensitizing gradient. Methods Hyperpolarized helium-3 (3He) lung was performed total five subjects. Two subjects received duplicate imaging same...
Folding of the cerebral cortex is a critical phase brain development in higher mammals but biomechanics folding remain incompletely understood. During folding, growth cortical surface heterogeneous and anisotropic. We developed applied new technique to measure spatial directional variations from longitudinal magnetic resonance imaging (MRI) studies single animal or human subject. MRI provides high resolution 3D image volumes at different stages development. Surface representations are...
Abstract We present a new phase‐based method for mapping the amplitude of radio‐frequency field ( B 1 ) transmitter coil in three‐dimension. This exploits noncommutation relation between rotations about orthogonal axes. Our implementation this principle current work results simple phase final magnetization and flip angle (FA). In study, we focus on FAs less than 90°. is rapid easy to implement compared with existing schemes. The sequence can be simply obtained by adding regular...
Purpose To determine whole‐brain cerebral metabolic rate of oxygen (CMRO 2 ), an improved imaging approach, based on radial encoding, termed OxFlow (rOxFlow), was developed to simultaneously quantify draining vein venous saturation (SvO ) and total blood flow (tCBF). Methods evaluate the efficiency precision rOxFlow sequence, 10 subjects were studied during a paradigm repeated breath‐holds with both Cartesian (cOxFlow) sequences. CMRO calculated at baseline from OxFlow‐measured data assuming...
To evaluate the use of inflation-fixed lung tissue for emphysema quantification with computed tomography (CT) and He magnetic resonance (MR) diffusion imaging.Fourteen subjects representing a range chronic obstructive pulmonary disease severity who underwent complete or lobar resection were studied. Computed tomographic measurements attenuation MR hyperpolarized 3He apparent coefficient (ADC) in resected specimens fixed inflation heated formalin vapor compared obtained before fixation.The...