A5040863782- Advanced MRI Techniques and Applications
- Medical Imaging Techniques and Applications
- MRI in cancer diagnosis
- Advanced Neuroimaging Techniques and Applications
- Cardiac Imaging and Diagnostics
- Atomic and Subatomic Physics Research
- Osteoarthritis Treatment and Mechanisms
- Ultrasound Imaging and Elastography
- Photoacoustic and Ultrasonic Imaging
- Muscle activation and electromyography studies
- Advanced X-ray Imaging Techniques
- Advanced NMR Techniques and Applications
- Knee injuries and reconstruction techniques
- NMR spectroscopy and applications
- Advanced Radiotherapy Techniques
- Prostate Cancer Diagnosis and Treatment
- Functional Brain Connectivity Studies
- Lower Extremity Biomechanics and Pathologies
- Ultrasound and Hyperthermia Applications
- Hepatocellular Carcinoma Treatment and Prognosis
- Cerebrovascular and Carotid Artery Diseases
- Veterinary Orthopedics and Neurology
- Orthopedic Surgery and Rehabilitation
- Neuroinflammation and Neurodegeneration Mechanisms
- Neurological disorders and treatments
University of Wisconsin Health
2024
University of Wisconsin–Madison
2014-2023
University Hospital Bonn
2010-2021
Loyola University New Orleans
2021
Wisconsin Institutes for Discovery
2015
National Institute on Aging
2015
National Institutes of Health
2015
Pontificia Universidad Católica de Chile
2013
UW Health University Hospital
2009
Konkuk University Medical Center
2008
Undersampled projection reconstruction (PR) is investigated as an alternative method for MRA (MR angiography). In conventional 3D Fourier transform (FT) MRA, resolution in the phase-encoding direction proportional to acquisition time. Since PR all directions determined by readout resolution, independent of number projections (Np), high can be generated rapidly. However, artifacts increase reduced Np. X-ray CT, undersampling from bright objects like bone dominate other tissue. where bright,...
Abstract Time‐resolved contrast‐enhanced 3D MR angiography (MRA) methods have gained in popularity but are still limited by the tradeoff between spatial and temporal resolution. A method is presented that greatly reduces this employing undersampled projection reconstruction trajectories. The variable density k ‐space sampling intrinsic to sequence combined with interpolation provide time frames as short 4 s. This resolution need for exact contrast timing while also providing dynamic...
Abstract Recent work in k‐t BLAST and undersampled projection angiography has emphasized the value of using training data sets obtained during acquisition a series images. These techniques have used iterative algorithms guided by set information to reconstruct time frames sampled at well below Nyquist limit. We present here simple non‐iterative unfiltered backprojection algorithm that incorporates idea composite image consisting portions or all acquired constrain process. This significantly...
Abstract Phase contrast (PC) magnetic resonance imaging with a three‐dimensional, radially undersampled acquisition allows for the of high resolution angiograms and velocimetry in dramatically reduced scan times. However, such an is sensitive to blurring artifacts from off‐resonance trajectory errors. A dual‐echo proposed novel calibration prescan data coupled multi‐frequency reconstruction correct these Comparisons phantom vivo results volunteer, patients arteriovenous malformations are...
We present MRiLab, a new comprehensive simulator for large-scale realistic MRI simulations on regular PC equipped with modern graphical processing unit (GPU). MRiLab combines tissue modeling numerical virtualization of an system and scanning experiment to enable assessment broad range approaches including advanced quantitative methods inferring microstructure sub-voxel level. A flexible representation is achieved in by employing the generalized model multiple exchanging water macromolecular...
To compare a vastly undersampled isotropic projection steady-state free precession (VIPR-SSFP) sequence and routine magnetic resonance (MR) imaging for evaluating the cartilage, ligaments, menisci, osseous structures of knee in symptomatic patients.All subjects signed written informed consent prior to participation this prospective, HIPAA-compliant, institutional review board-approved study. VIPR-SSFP was added 1.5-T MR performed on 95 patients (52 men, 43 women; average age, 41.6 years) who...
In time-resolved contrast-enhanced 3D MR angiography, spatial resolution is traded for high temporal resolution. A hybrid method presented that attempts to reduce this tradeoff in two of the dimensions. It combines an undersampled projection acquisition dimensions with variable rate k-space sampling third. Spatial plane determined by readout and limited primarily signal-to-noise ratio. Oversampling center combined interpolation provides time frames minimal venous contamination. Results...
Pseudocontinuous arterial spin labeling (PCASL) can be used to generate noncontrast magnetic resonance angiograms of the cerebrovascular structures. Previously described PCASL-based angiography techniques were limited two-dimensional projection images or relatively low-resolution three-dimensional (3D) imaging due long acquisition time. This work proposes a new 3D method that uses an accelerated radial technique (VIPR, spoiled gradient echo) as readout. Benefiting from sparsity provided by...
PURPOSE: To evaluate interactive magnetic resonance (MR) imaging-guided preoperative needle localization and hookwire placement in the noncompressed breast patients prone position. MATERIALS AND METHODS: Nineteen MR lesion procedures were performed 17 aged 38-70 years (mean age, 48 years) by using an open-platform coil either a 1.5-T, closed-bore imager (n = 14) or 0.5-T, open-bore 5). Rapid imaging (fast spin-echo, water-selective fast water-specific three-point Dixon gradient-echo) was...
Abstract Non‐Cartesian and rapid imaging sequences are more sensitive to scanner imperfections such as gradient delays eddy currents. These vary between scanners over time can be a significant impediment successful implementation eventual adoption of non‐Cartesian techniques by manufacturers. Differences the k ‐space trajectory desired actually acquired lead misregistration reduction in image quality. While early calibration methods required considerable scan time, recent work quickly making...
Purpose To develop a novel dynamic 3D noncontrast magnetic resonance angiography (MRA) technique that combines pseudo-continuous arterial spin labeling (dynamic PCASL), accelerated radial sampling (VIPR), and time-of-arrival (TOA) mapping to provide quantitative assessment of flow. Materials Methods Digital simulations were performed investigate the effects acquisition scheme sequence parameters on image quality TOA fidelity. Five patients with vascular malformations (arteriovenous...
Abstract Imaging of the blood vessels below knee using contrast‐enhanced (CE) MRI is challenging due to need coordinate image acquisition and arrival contrast in targeted vessels. Time‐resolved acquisitions have been successful consistently capturing images arterial phase bolus agent distal extremities. Although time‐resolved exams are robust this respect, higher spatial resolution for depiction tight stenoses small lower leg desirable. A modification a high‐spatial‐resolution T 1 ‐weighted...
Previously, the magnetic resonance (MR) imaging appearance of frozen tissues created during cryosurgery has been described as a signal void. In this work, very short echo times (1.2 msec) allowed MR signals from to be measured at temperatures down -35 degrees C. Ex vivo bovine liver, muscle, adipose tissue, and water were imaged steady-state -78 +6 Signal intensity, T2*, T1 using gradient-echo imaging. intensity T2* decrease monotonically with temperature. future, these parameters may useful...
Time-resolved contrast-enhanced magnetic resonance (MR) angiography (CE-MRA) has gained in popularity relative to X-ray Digital Subtraction Angiography because it provides three-dimensional (3-D) spatial resolution and is less invasive.We have previously presented methods that improve temporal CE-MRA while providing high by employing an undersampled 3-D projection (3D PR) trajectory.The increased coverage isotropic of the 3D PR acquisition simplify visualization vasculature from any...
Abstract This study describes a new approach to reconstruct data that has been corrupted by unfavorable magnetization evolution. In this framework, images are reconstructed in weighted least squares fashion using all available and measure of consistency determined from the itself. The reconstruction scheme optimally balances uncertainties noise error with those inconsistency, is compatible methods model signal corruption, may be advantageous for more accurate precise many squares‐based image...
Despite reduction in imaging times through improved hardware and rapid acquisition schemes, motion artifacts can compromise image quality magnetic resonance imaging, especially three‐dimensional with its prolonged scan durations. Direct extension of most state‐of‐the‐art two‐dimensional rigid body compensation techniques to the case is often challenging or impractical due a significant increase sampling requirements. This article introduces novel correction technique that capable restoring...
Purpose To determine the feasibility of using multicomponent-driven equilibrium single-shot observation T1 and T2 (mcDESPOT) for evaluating human knee joint at 3.0T to investigate depth-dependent regional-dependent variations in multicomponent parameters within articular cartilage. Materials Methods mcDESPOT was performed on 10 asymptomatic volunteers 3.0T. Single-component relaxation time (T2single), water tightly bound proteoglycan (T2PG) bulk loosely macromolecular matrix (T2BW), fraction...
Abstract Non‐Cartesian imaging sequences and navigational methods can be more sensitive to scanner imperfections that have little impact on conventional clinical sequences, an issue which has repeatedly complicated the commercialization of these techniques by frustrating transitions multicenter evaluations. One such imperfection is phase errors caused resonant frequency shifts from eddy currents induced in cryostat time‐varying gradients, a phenomenon known as B 0 currents. These substantial...
To compare multicomponent T2 parameters of the articular cartilage knee joint measured by using driven equilibrium single-shot observation T1 and (mcDESPOT) in asymptomatic volunteers patients with osteoarthritis.This prospective study was performed institutional review board approval written informed consent from all subjects. The mcDESPOT sequence 13 14 osteoarthritis knee. Single-component (T2(Single)), fast-relaxing water component (T2F) slow-relaxing (T2S), fraction (F(F)) were...
Abstract Reliable fat suppression is especially important with fast imaging techniques such as echo‐planar (EPI), spiral, and spin‐echo (FSE) T 2 ‐weighted imaging. Spectral‐spatial excitation has a number of advantages over spectrally selective presaturation techniques, including better resilience to B 0 1 , inhomogeneity. In this paper, FSE sequence using spectral‐spatial pulse for superior presented. Previous problems maintaining the CPMG condition are solved simple methods accurately...