A5032462138- Advanced MRI Techniques and Applications
- Atomic and Subatomic Physics Research
- Advanced Neuroimaging Techniques and Applications
- Functional Brain Connectivity Studies
- Medical Imaging Techniques and Applications
- Advanced NMR Techniques and Applications
- NMR spectroscopy and applications
- Cardiac Imaging and Diagnostics
- MRI in cancer diagnosis
- Neural dynamics and brain function
- Cerebrospinal fluid and hydrocephalus
- Nuclear Physics and Applications
- Cerebrovascular and Carotid Artery Diseases
- Advanced X-ray and CT Imaging
- Traumatic Brain Injury and Neurovascular Disturbances
- Neurological disorders and treatments
- Medical Image Segmentation Techniques
- Magnetic Properties of Alloys
- Advanced X-ray Imaging Techniques
- Simulation Techniques and Applications
- Electron Spin Resonance Studies
- Photoreceptor and optogenetics research
- Superconducting Materials and Applications
- Engineering Applied Research
- Scheduling and Optimization Algorithms
University of California, Berkeley
2015-2025
Advanced MRI Technologies (United States)
2002-2025
Imaging Center
2015-2024
University of Minnesota
2014
University of California, San Francisco
1984-2011
Cranbrook Academy of Art
2005
Washington University in St. Louis
2001-2002
Mallinckrodt (United States)
1998-2002
Pennsylvania Hospital
2001
University of Pennsylvania
2001
Echo planar imaging (EPI) is an MRI technique of particular value to neuroscience, with its use for virtually all functional (fMRI) and diffusion fiber connections in the human brain. EPI generates a single 2D image fraction second; however, it requires 2-3 seconds acquire multi-slice whole brain coverage fMRI even longer imaging. Here we report on large reduction scan time at 3 7 Tesla, without significantly sacrificing spatial resolution, while gaining sensitivity. The multiplexed-EPI...
Present theory holds that pulsatile pressure of cerebrospinal fluid (CSF) is driven by the force expansion choroid plexus. Alternate theories postulating a possible movement brain involved in pumping CSF have not, to authors' knowledge, been substantiated heretofore. In this study, vivo, quantitative magnetic resonance (MR) imaging methods were developed show reproducible magnitudes and directions flow. Measurements obtained with new MR velocity technique at high resolution (0.4 mm/sec),...
Abstract To increase granularity in human neuroimaging science, we designed and built a next-generation 7 Tesla magnetic resonance imaging scanner to reach ultra-high resolution by implementing several advances hardware. improve spatial encoding the image signal-to-noise ratio, developed head-only asymmetric gradient coil (200 mT m −1 , 900 T s ) with an additional third layer of windings. We integrated 128-channel receiver system 64- 96-channel arrays boost signal cerebral cortex while...
Abstract A fast multi‐section MR imaging technique is described. Gradient‐ and spin‐echo (GRASE) utilizes the speed advantages of gradient refocusing while overcoming image artifacts arising from static field inhomogeneity chemical shift. Image contrast determined by T2 in Hahn spin echoes. novel k ‐space trajectory temporally modulates signals demodulates artifacts. © 1991 Academic Press, Inc.
Abstract Arterial spin labeling (ASL) can be used to measure perfusion without the use of contrast agents. Due small volume fraction blood vessels compared tissue in human brain (typ. 3–5%) ASL techniques have an intrinsically low signal‐to‐noise ratio (SNR). In this publication, evidence is presented that SNR improved by using arterial combination with single‐shot 3D readout techniques. Specifically, a 3D‐GRASE sequence presented, which yields 2.8‐fold increase 2D EPI at same nominal...
Conjugation can be used to synthesize half of the data acquired during a conventional two-dimensional Fourier transform imaging procedure, thus reducing time by nearly half. The images this process have same object contrast and spatial resolution as do, but with 40% reduction in signal-to-noise ratio (S/N). advantage magnetic resonance units which S/N levels are higher than needed permit single acquisition each projection.
Although cross-sectional magnetic resonance examination of the head and body is useful for screening large regions tissue, subsectional often need to be examined. Orthogonally directed, selectively irradiated planes with different flip angles produce a spatially limited signal region from which two- or three-dimensional volume images can reconstructed. Images fields-of-view acquired in reduced imaging time. We present general description this technique. These "inner volume" eliminate...
Recent work has established that cerebral blood flow is regulated at a spatial scale can be resolved by high field fMRI to show cortical columns in humans. While represent cluster of neurons with similar response properties (spanning from the pial surface white matter), important information regarding neuronal interactions and computational processes also contained within single column, distributed across six lamina. A basic understanding underlying circuitry or computations may revealed...
A novel technique of magnetic resonance (MR) imaging, which combines gradient-echo and spin-echo (GRASE) technique, accomplishes T2-weighted multisection imaging in drastically reduced time, currently 24 times faster than imaging. The GRASE maintains contrast mechanisms, high spatial resolution, image quality is compatible with clinical whole-body MR systems without modification gradient hardware. Image acquisition time 18 seconds for 11 body images (2,000/80 [repetition msec/echo msec]) 36...
Functional magnetic resonance imaging (fMRI) at high fields has made it possible to investigate the columnar organization of human brain in vivo with degrees accuracy and sensitivity. Until now, these results have been limited principles early visual cortex (V1). While middle temporal area (MT) first identified extra-striate shown exhibit a monkeys, evidence MT's response properties topographic layout humans remained elusive. Research using various approaches suggests similar as monkeys but...
Abstract Normal aging is associated with diminished brain perfusion measured as cerebral blood flow (CBF), but previously it difficult to accurately measure various aspects of hemodynamics including: bolus arrival times and delays through small arterioles, expressed arterial‐arteriole transit time. To study in greater detail, volumetric arterial spin labeling MRI variable postlabeling was used together a distributed, dual‐compartment tracer model. The main goal determine how CBF other vary...
Abstract Objective To assess the possible influence of third-order shim coils on behavior gradient field and in gradient–magnet interactions at 7 T above. Materials methods Gradient impulse response function measurements were performed 5 sites spanning strengths from to 11.7 T, all them sharing same exact whole-body coil design. Mechanical fixation boundary conditions altered several ways one site study impact mechanical coupling with magnet perturbations. Vibrations, power deposition He...
Abstract We applied diffusion‐sensitive echo planar (Instascan) imaging to study thermal changes caused by a Nd:YAG laser. Images of phantom materials and normal rabbit brain tissue in vivo , acquired 150 ms, every 2 s, clearly showed the dynamics temperature‐related signal intensity regions irradiated © 1991 Academic Press, Inc.
Encoding the precession phase angle of proton nuclei for Fourier analysis has produced accurate measurement fluid velocity vector components by MRI. A pair identical gradient pulses separated in time exactly 1/2 TE, are used to linearly encode flow without changing stationary nuclei. Two-dimensional transformation signals gave density images laminar angled tubes which were agreement with laws addition. These profile provide a quantitative method investigation dynamics and hemodynamics.
The development of neuroimaging methods to characterize flow-metabolism coupling is crucial for understanding mechanisms that subserve oxygen delivery. Functional magnetic resonance imaging (fMRI) using blood-oxygenation-level-dependent (BOLD) contrast reflects composite changes in cerebral blood volume (CBV), flow (CBF), and the metabolic rate consumption (CMRO 2 ). However, it difficult separate these parameters from BOLD signal, thereby hampering MR-based studies. Here, a novel,...
Functional magnetic resonance imaging (fMRI) allows studying human brain function non-invasively up to the spatial resolution of cortical columns and layers. Most fMRI acquisitions rely on blood oxygenation level dependent (BOLD) contrast employing T(*) 2 weighted 2D multi-slice echo-planar (EPI). At ultra-high field (i.e., 7 T above), it has been shown experimentally by simulation, that T2 yield a signal is spatially more specific site neuronal activity at cost functional sensitivity. This...
Field inhomogeneity related phase errors in multi-shot echo planar imaging (EPI) are directly visualized and analyzed the spatial frequency domain data or 'k-space'. The time shift (ETS) technique incrementally moves position of train improves error function by redistributing discontinuities away from center k-space.
Single shot 3D GRASE is less sensitive to field inhomogeneity and susceptibility effects than gradient echo based fast imaging sequences while preserving the acquisition speed. In this study, a continuous arterial spin labeling (CASL) pulse was added prior single readout quantitative perfusion measurements were carried out at 3 T, rest during functional activation. The sequence performance evaluated by comparison with CASL EPI readout. It shown that using can be performed safely on humans T...
Arterial spin labelling (ASL) has proved to be a promising magnetic resonance imaging (MRI) technique measure brain perfusion. In this study, volumetric three-dimensional (3D) gradient and echo (GRASE) ASL was used produce cerebral blood flow (CBF) arterial arrival time (AAT) maps during rest an infusion of remifentanil. Gradient perfusion-weighted images were collected at multiple inflow times (500 2,500 ms in increments 250 ms) accurately fit perfusion model. Fit estimates assessed using...
An improved arterial spin labeling (ASL) perfusion technique that combines pseudo-continuous and a T2*-insensitive sequence (GRASE) with background suppression was used to acquire maps in normal volunteers stroke patients. It is shown measurements obtained less than 1 min of scan time are reproducible, coefficient variation 7%. The generated from these data can be characterize the lesion.