Search results for: Karin Shmueli

Items from 1 to 20 out of 23 results

article

Brain volume in Tanzanian children with sickle cell anaemia: A neuroimaging study

Mboka Jacob, Jamie M. Kawadler, Russell Murdoch, Magda Ahmed, more

British Journal of Haematology > 201 > 1 > 114 - 124

Brain injury is a common complication of sickle cell anaemia (SCA). White matter (WM) and cortical and subcortical grey matter (GM), structures may have reduced volume in patients with SCA. This study focuses on whether silent cerebral infarction (SCI), vasculopathy or anaemia affects WM and regional GM volumes in children living in Africa. Children with SCA (n = 144; aged 5–20 years; 74 male) and...

article

Investigating the effect of oblique image acquisition on the accuracy of QSM and a robust tilt correction method

Oliver C. Kiersnowski, Anita Karsa, Stephen J. Wastling, John S. Thornton, more

Magnetic Resonance in Medicine > 89 > 5 > 1791 - 1808

Purpose Quantitative susceptibility mapping (QSM) is used increasingly for clinical research where oblique image acquisition is commonplace, but its effects on QSM accuracy are not well understood. Theory and Methods The QSM processing pipeline involves defining the unit magnetic dipole kernel, which requires knowledge of the direction of the main magnetic field

{\hat{B}}_{0}

...

article

Multi‐echo quantitative susceptibility mapping: how to combine echoes for accuracy and precision at 3 Tesla

Emma Biondetti, Anita Karsa, Francesco Grussu, Marco Battiston, more

Magnetic Resonance in Medicine > 88 > 5 > 2101 - 2116

Purpose To compare different multi‐echo combination methods for MRI QSM. Given the current lack of consensus, we aimed to elucidate how to optimally combine multi‐echo gradient‐recalled echo signal phase information, either before or after applying Laplacian‐base methods (LBMs) for phase unwrapping or background field removal. Methods Multi‐echo gradient‐recalled echo data were simulated in a numerical...

article

Quantitative susceptibility mapping of carotid arterial tissue ex vivo: Assessing sensitivity to vessel microstructural composition

Alan J. Stone, Brooke Tornifoglio, Robert D. Johnston, Karin Shmueli, more

Magnetic Resonance in Medicine > 86 > 5 > 2512 - 2527

Purpose To characterize microstructural contributions to the magnetic susceptibility of carotid arteries. Method Arterial vessels were scanned using high‐resolution quantitative susceptibility mapping (QSM) at 7 Tesla. Models of vessel degradation were generated using ex vivo porcine carotid arteries that were subjected to several different enzymatic digestion treatments that selectively removed...

article

Quantitative susceptibility mapping of the rat brain after traumatic brain injury

Karthik Chary, Mikko J. Nissi, Olli Nykänen, Eppu Manninen, more

NMR in Biomedicine > 34 > 2 > n/a - n/a

The primary lesion arising from the initial insult after traumatic brain injury (TBI) triggers a cascade of secondary tissue damage, which may also progress to connected brain areas in the chronic phase. The aim of this study was, therefore, to investigate variations in the susceptibility distribution related to these secondary tissue changes in a rat model after severe lateral fluid percussion injury...

article

Phase unwrapping with a rapid opensource minimum spanning tree algorithm (ROMEO)

Barbara Dymerska, Korbinian Eckstein, Beata Bachrata, Bernard Siow, more

Magnetic Resonance in Medicine > 85 > 4 > 2294 - 2308

Purpose To develop a rapid and accurate MRI phase‐unwrapping technique for challenging phase topographies encountered at high magnetic fields, around metal implants, or postoperative cavities, which is sufficiently fast to be applied to large‐group studies including Quantitative Susceptibility Mapping and functional MRI (with phase‐based distortion correction). Methods The proposed path‐following...

article

An optimized and highly repeatable MRI acquisition and processing pipeline for quantitative susceptibility mapping in the head‐and‐neck region

Anita Karsa, Shonit Punwani, Karin Shmueli

Magnetic Resonance in Medicine > 84 > 6 > 3206 - 3222

Purpose Quantitative Susceptibility Mapping (QSM) is an emerging technique sensitive to disease‐related changes including oxygenation. It is extensively used in brain studies and has increasing clinical applications outside the brain. Here we present the first MRI acquisition protocol and QSM pipeline optimized for the head‐and‐neck region together with a repeatability analysis performed in healthy...

article

Investigating the accuracy and precision of TE‐dependent versus multi‐echo QSM using Laplacian‐based methods at 3 T

Emma Biondetti, Anita Karsa, David L. Thomas, Karin Shmueli

Magnetic Resonance in Medicine > 84 > 6 > 3040 - 3053

Purpose Multi‐echo gradient‐recalled echo acquisitions for QSM enable optimizing the SNR for several tissue types through multi‐echo (TE) combination or investigating temporal variations in the susceptibility (potentially reflecting tissue microstructure) by calculating one QSM image at each TE (TE‐dependent QSM). In contrast with multi‐echo QSM, applying Laplacian‐based methods (LBMs) for phase...

article

Investigating the oxygenation of brain arteriovenous malformations using quantitative susceptibility mapping

Emma Biondetti, Alvaro Rojas-Villabona, Magdalena Sokolska, Francesca B. Pizzini, more

NeuroImage > 2019 > 199 > C > 440-453

Brain arteriovenous malformations (AVMs) are congenital vascular anomalies characterized by arteriovenous shunting through a network of coiled and tortuous vessels. Because of this anatomy, the venous drainage of an AVM is hypothesized to contain more oxygenated, arterialized blood than healthy veins. By exploiting the paramagnetic properties of deoxygenated hemoglobin in venous blood using magnetic...

article

Association of bone mineral density and fat fraction with magnetic susceptibility in inflamed trabecular bone

Timothy J.P. Bray, Anita Karsa, Alan Bainbridge, Naomi Sakai, more

Magnetic Resonance in Medicine > 81 > 5 > 3094 - 3107

Purpose To evaluate the relationship between bone mineral density (BMD) and magnetic susceptibility, and between proton density fat fraction and susceptibility, in inflamed trabecular bone. Methods Two different phantoms modeling the fat fraction (FF) and BMD values of healthy bone marrow and disease states were scanned using a multiecho gradient echo acquisition at 3T. After correction for fat‐water...

article

Noninvasive quantification of oxygen saturation in the portal and hepatic veins in healthy mice and those with colorectal liver metastases using QSM MRI

Eoin Finnerty, Rajiv Ramasawmy, James O’Callaghan, John J. Connell, more

Magnetic Resonance in Medicine > 81 > 4 > 2666 - 2675

Purpose This preclinical study investigated the use of QSM MRI to noninvasively measure venous oxygen saturation (SvO2) in the hepatic and portal veins. Methods QSM data were acquired from a cohort of healthy mice (n = 10) on a 9.4 Tesla MRI scanner under normoxic and hyperoxic conditions. Susceptibility was measured in the portal and hepatic veins and used to calculate SvO2 in each vessel under...

article

The effect of low resolution and coverage on the accuracy of susceptibility mapping

Anita Karsa, Shonit Punwani, Karin Shmueli

Magnetic Resonance in Medicine > 81 > 3 > 1833 - 1848

Purpose Quantitative susceptibility mapping (QSM) has found increasing clinical applications. However, to reduce scan time, clinical acquisitions often use reduced resolution and coverage, particularly in the through‐slice dimension. The effect of these factors on QSM has begun to be assessed using only balloon phantoms and downsampled brain images. Here, we investigate the effects (and their sources)...

article

Quantitative susceptibility mapping of articular cartilage: Ex vivo findings at multiple orientations and following different degradation treatments

Olli Nykänen, Lassi Rieppo, Juha Töyräs, Ville Kolehmainen, more

Magnetic Resonance in Medicine > 80 > 6 > 2702 - 2716

Purpose We investigated the feasibility of quantitative susceptibility mapping (QSM) for assessing degradation of articular cartilage by measuring ex vivo bovine cartilage samples subjected to different degradative treatments. Specimens were scanned at several orientations to study if degradation affects the susceptibility anisotropy. T2*‐mapping, histological stainings, and polarized light microscopy...

article

PRO‐QUEST: a rapid assessment method based on progressive saturation for quantifying exchange rates using saturation times in CEST

Eleni Demetriou, Mohamed Tachrount, Moritz Zaiss, Karin Shmueli, more

Magnetic Resonance in Medicine > 80 > 4 > 1638 - 1654

Purpose To develop a new MRI technique to rapidly measure exchange rates in CEST MRI. Methods A novel pulse sequence for measuring chemical exchange rates through a progressive saturation recovery process, called PRO‐QUEST (progressive saturation for quantifying exchange rates using saturation times), has been developed. Using this method, the water magnetization is sampled under non‐steady‐state...

article

Quantitative susceptibility mapping: Report from the 2016 reconstruction challenge

Christian Langkammer, Ferdinand Schweser, Karin Shmueli, Christian Kames, more

Magnetic Resonance in Medicine > 79 > 3 > 1661 - 1673

Purpose The aim of the 2016 quantitative susceptibility mapping (QSM) reconstruction challenge was to test the ability of various QSM algorithms to recover the underlying susceptibility from phase data faithfully. Methods Gradient‐echo images of a healthy volunteer acquired at 3T in a single orientation with 1.06 mm isotropic resolution. A reference susceptibility map was provided, which was computed...

article

Corrigendum to “Susceptibility contrast in high field MRI of human brain as a function of tissue iron content” [NeuroImage 44/4 (2009) 1259–1266]

Bing Yao, Tie-Qiang Li, Peter van Gelderen, Karin Shmueli, more

NeuroImage > 2012 > 62 > 3 > 2173

article

The contribution of myelin to magnetic susceptibility-weighted contrasts in high-field MRI of the brain

Jongho Lee, Karin Shmueli, Byeong-Teck Kang, Bing Yao, more

NeuroImage > 2012 > 59 > 4 > 3967-3975

T ₂ *-weighted gradient-echo MRI images at high field (≥7T) have shown rich image contrast within and between brain regions. The source for these contrast variations has been primarily attributed to tissue magnetic susceptibility differences. In this study, the contribution of myelin to both T ₂ * and frequency contrasts is investigated using a mouse model of demyelination based on...

article

Optimal MRI methods for direct stereotactic targeting of the subthalamic nucleus and globus pallidus

Ruth L. O’Gorman, Karin Shmueli, Keyoumars Ashkan, Michael Samuel, more

European Radiology > 2011 > 21 > 1 > 130-136

Objective Reliable identification of the subthalamic nucleus (STN) and globus pallidus interna (GPi) is critical for deep brain stimulation (DBS) of these structures. The purpose of this study was to compare the visibility of the STN and GPi with various MRI techniques and to assess the suitability of each technique for direct stereotactic targeting. Methods MR images were acquired from nine volunteers...

article

The contribution of chemical exchange to MRI frequency shifts in brain tissue

Karin Shmueli, Stephen J. Dodd, Tie‐Qiang Li, Jeff H. Duyn

Magnetic Resonance in Medicine > 65 > 1 > 35 - 43

Recent high‐field MRI studies based on resonance frequency contrast have revealed brain structure with unprecedented detail. Although subtle magnetic susceptibility variations caused by iron and myelin seem to be important to this contrast, recent research on protein solutions suggests that chemical exchange between water and macromolecular protons may contribute substantially to the observed gray‐white...

article

Sources of functional magnetic resonance imaging signal fluctuations in the human brain at rest: a 7 T study

Marta Bianciardi, Masaki Fukunaga, Peter van Gelderen, Silvina G. Horovitz, more

Magnetic Resonance Imaging > 2009 > 27 > 8 > 1019-1029

Signal fluctuations in functional magnetic resonance imaging (fMRI) can result from a number of sources that may have a neuronal, physiologic or instrumental origin. To determine the relative contribution of these sources, we recorded physiological (respiration and cardiac) signals simultaneously with fMRI in human volunteers at rest with their eyes closed. State-of-the-art technology was used including...

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Keywords

QUANTITATIVE SUSCEPTIBILITY MAPPING (7)
QSM (5)
MRI (4)
MAGNETIC RESONANCE IMAGING (3)
IRON (2)
MAGNETIC SUSCEPTIBILITY (2)
MULTI‐ECHO QSM (2)
QSM ACCURACY (2)
7-T BOLD FMRI (1)
ANIMAL MODELS (1)
ARTERIAL MICROSTRUCTURE (1)
ARTERIOVENOUS MALFORMATION (1)
ASSESSMENT (1)
ATHEROSCLEROSIS (1)
BONE MARROW (1)
BONE MINERAL DENSITY (1)
BRAIN (1)
BRAIN VOLUME (1)
CANCER (1)
CAROTID ARTERY (1)
CARTILAGE (1)
CEST (1)
CHALLENGE (1)
COLLAGEN MATRIX (1)
CUPRIZONE (1)
DECREASED CONTRAST (1)
DEEP BRAIN STIMULATION (1)
DEMYELINATION (1)
DIPOLE INVERSION (1)
DIRECT STEREOTACTIC TARGETING (1)
DISTORTION CORRECTION (1)
ELECTROMAGNETIC TISSUE PROPERTIES (1)
EXCHANGE RATE (1)
EXCHANGE‐INDUCED FREQUENCY SHIFT (1)
FERRITIN (1)
FMRI (1)
FORMALIN FIXATION (1)
GLOBUS PALLIDUS (1)
HEAD AND NECK (1)
HEPATIC VENOUS OXYGEN SATURATION (1)
INFLAMMATION (1)
LIVER (1)
LOW RESOLUTION (1)
LYMPH NODE (1)
MAGNETIC SUSCEPTIBILITY MAPPING (1)
MICROBLEEDS (1)
MRI PHASE (1)
MRI PHASE CONTRAST (1)
MULTI‐ECHO (1)
MYELIN (1)
NONTHERMAL NOISE (1)
OBLIQUE ACQUISITION (1)
OSTEOARTHRITIS (1)
PAROTID GLAND (1)
PHASE (1)
PHASE IMAGE (1)
PHASE UNWRAPPING (1)
PHYSIOLOGICAL NOISE (1)
PLAQUE (1)
PROTON CHEMICAL EXCHANGE (1)
PROTON DENSITY FAT FRACTION (1)
PRO‐QUEST (1)
QUANTITATIVE SUSCEPTIBILITY MAPPING (QSM) (1)
R2* RELAXATION (1)
RECONSTRUCTION ALGORITHMS (1)
REDUCED FIELD‐OF‐VIEW (1)
RELAXATION (1)
REPEATABILITY (1)
RESONANCE FREQUENCY IMAGE (1)
RESONANCE FREQUENCY SHIFT (1)
RESTING STATE (1)
SICKLE CELL ANAEMIA (1)
SILENT CEREBRAL INFARCTION (1)
SINGLE‐ECHO QSM (1)
SPONDYLOARTHRITIS (1)
SPONTANEOUS ACTIVITY (1)
SUBMANDIBULAR GLAND (1)
SUBTHALAMIC NUCLEUS (1)
SUSCEPTIBILITY (1)
SUSCEPTIBILITY MAPPING (1)
T2* DECAY (1)
TE‐DEPENDENT QSM (1)
TILTED SLICES (1)
TRAUMATIC BRAIN INJURY (1)
VASCULOPATHY (1)
VENOUS DENSITY (1)
VENOUS OXYGEN SATURATION (1)
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Wiley (15)
Elsevier (7)
Springer (1)

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Search results for: Karin Shmueli

Brain volume in Tanzanian children with sickle cell anaemia: A neuroimaging study

Investigating the effect of oblique image acquisition on the accuracy of QSM and a robust tilt correction method

Multi‐echo quantitative susceptibility mapping: how to combine echoes for accuracy and precision at 3 Tesla

Quantitative susceptibility mapping of carotid arterial tissue ex vivo: Assessing sensitivity to vessel microstructural composition

Quantitative susceptibility mapping of the rat brain after traumatic brain injury

Phase unwrapping with a rapid opensource minimum spanning tree algorithm (ROMEO)

An optimized and highly repeatable MRI acquisition and processing pipeline for quantitative susceptibility mapping in the head‐and‐neck region

Investigating the accuracy and precision of TE‐dependent versus multi‐echo QSM using Laplacian‐based methods at 3 T

Investigating the oxygenation of brain arteriovenous malformations using quantitative susceptibility mapping

Association of bone mineral density and fat fraction with magnetic susceptibility in inflamed trabecular bone

Noninvasive quantification of oxygen saturation in the portal and hepatic veins in healthy mice and those with colorectal liver metastases using QSM MRI

The effect of low resolution and coverage on the accuracy of susceptibility mapping

Quantitative susceptibility mapping of articular cartilage: Ex vivo findings at multiple orientations and following different degradation treatments

PRO‐QUEST: a rapid assessment method based on progressive saturation for quantifying exchange rates using saturation times in CEST

Quantitative susceptibility mapping: Report from the 2016 reconstruction challenge

Corrigendum to “Susceptibility contrast in high field MRI of human brain as a function of tissue iron content” [NeuroImage 44/4 (2009) 1259–1266]

The contribution of myelin to magnetic susceptibility-weighted contrasts in high-field MRI of the brain

Optimal MRI methods for direct stereotactic targeting of the subthalamic nucleus and globus pallidus

The contribution of chemical exchange to MRI frequency shifts in brain tissue

Sources of functional magnetic resonance imaging signal fluctuations in the human brain at rest: a 7 T study

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