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Bold Cardiac MRI

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https://www.readbyqxmd.com/read/28708550/unsupervised-myocardial-segmentation-for-cardiac-bold
#1
Ilkay Oksuz, Anirban Mukhopadhyay, Rohan Dharmakumar, Sotirios A Tsaftaris
A fully automated 2D+time myocardial segmentation framework is proposed for Cardiac Magnetic Resonance (CMR) Blood-Oxygen-Level-Dependent (BOLD) datasets. Ischemia detection with CINE BOLD CMR relies on spatiotemporal patterns in myocardial intensity but these patterns also trouble supervised segmentation methods, the de-facto standard for myocardial segmentation in cine MRI. Segmentation errors severely undermine the accurate extraction of these patterns. In this paper we build a joint motion and appearance method that relies on dictionary learning to find a suitable subspace...
July 12, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28216453/quantification-of-myocardial-oxygenation-in-heart-failure-using-blood-oxygen-level-dependent-t2-magnetic-resonance-imaging-comparison-with-cardiopulmonary-exercise-test
#2
Michinobu Nagao, Yuzo Yamasaki, Satoshi Kawanami, Takeshi Kamitani, Koji Sagiyama, Taiki Higo, Tomomi Ide, Atsushi Takemura, Umiko Ishizaki, Kenji Fukushima, Yuji Watanabe, Hiroshi Honda
PURPOSE: Quantification of myocardial oxygenation (MO) in heart failure (HF) has been less than satisfactory. This has necessitated the use of invasive techniques to measure MO directly or to determine the oxygen demand during exercise using the cardiopulmonary exercise (CPX) test. We propose a new quantification method for MO using blood-oxygen-level-dependent (BOLD) myocardial T2* magnetic resonance imaging (M-T2* MRI), and investigate its correlation with CPX results. METHODS: Thirty patients with refractory HF who underwent cardiac MRI and CPX test for heart transplantation, and 24 healthy, age-matched volunteers as controls were enrolled...
June 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28152238/assessment-of-segmental-myocardial-blood-flow-and-myocardial-perfusion-reserve-by-adenosine-stress-myocardial-arterial-spin-labeling-perfusion-imaging
#3
Andrew J Yoon, Hung Phi Do, Steven Cen, Michael W Fong, Farhood Saremi, Mark L Barr, Krishna S Nayak
PURPOSE: To determine the feasibility of measuring increases in myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) on a per-segment basis using arterial spin labeled (ASL) magnetic resonance imaging (MRI) with adenosine vasodilator stress in normal human myocardium. MATERIALS AND METHODS: Myocardial ASL scans at rest and during adenosine infusion were incorporated into a routine 3T MR adenosine-induced vasodilator stress protocol and were performed in 10 healthy human volunteers...
February 2, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28074492/confirmation-of-resting-state-bold-fluctuations-in-the-human-brainstem-and-spinal-cord-after-identification-and-removal-of-physiological-noise
#4
Shreyas Harita, Patrick W Stroman
PURPOSE: Resting-state functional MRI (rs-fMRI) has been used to investigate networks within the cortex, but its use in the brainstem (BS) and spinal cord (SC) has been limited. This region presents challenges for fMRI, partly because of sources of physiological noise. This study aims to quantify noise contributions to rs-fMRI, and to obtain evidence of resting-state blood oxygenation level-dependent (BOLD) fluctuations. METHODS: Resting-state-fMRI data were obtained from the BS/SC in 16 participants, at 3 Tesla, with T2 -weighted single-shot fast spin-echo imaging...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27973353/impact-of-physiological-noise-correction-on-detecting-blood-oxygenation-level-dependent-contrast-in-the-breast
#5
Tess E Wallace, Roido Manavaki, Martin J Graves, Andrew J Patterson, Fiona J Gilbert
Physiological fluctuations are expected to be a dominant source of noise in blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) experiments to assess tumour oxygenation and angiogenesis. This work investigates the impact of various physiological noise regressors: retrospective image correction (RETROICOR), heart rate (HR) and respiratory volume per unit time (RVT), on signal variance and the detection of BOLD contrast in the breast in response to a modulated respiratory stimulus. BOLD MRI was performed at 3 T in ten volunteers at rest and during cycles of oxygen and carbogen gas breathing...
January 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27916663/monitoring-cardiac-and-respiratory-physiology-during-fmri
#6
Daniel Bulte, Karolina Wartolowska
This article will consider how physiological monitoring can be used both as an intrinsic part of an experiment, or for removing unwanted physiological signals from the FMRI time series. As functional MRI is used for a wide variety of applications beyond the identification of regions involved in a task, different sources of noise in the time series become important. The use of arterial spin labelling sequences, either in isolation or combined with BOLD imaging, means that temporal noise must be dealt with differently...
July 1, 2017: NeuroImage
https://www.readbyqxmd.com/read/27177763/quantitative-mapping-of-cerebrovascular-reactivity-using-resting-state-bold-fmri-validation-in-healthy-adults
#7
Ali M Golestani, Luxi L Wei, J Jean Chen
In conventional neuroimaging, cerebrovascular reactivity (CVR) is quantified primarily using the blood-oxygenation level-dependent (BOLD) functional MRI (fMRI) signal, specifically, as the BOLD response to intravascular carbon dioxide (CO2) modulations, in units of [%ΔBOLD/mmHg]. While this method has achieved wide appeal and clinical translation, the tolerability of CO2-related tasks amongst patients and the elderly remains a challenge in more routine and large-scale applications. In this work, we propose an improved method to quantify CVR by exploiting intrinsic fluctuations in CO2 and corresponding changes in the resting-state BOLD signal (rs-qCVR)...
September 2016: NeuroImage
https://www.readbyqxmd.com/read/26854203/comparison-of-peripheral-near-infrared-spectroscopy-low-frequency-oscillations-to-other-denoising-methods-in-resting-state-functional-mri-with-ultrahigh-temporal-resolution
#8
Lia M Hocke, Yunjie Tong, Kimberly P Lindsey, Blaise de B Frederick
PURPOSE: Functional MRI (fMRI) blood-oxygen level-dependent (BOLD) signals result not only from neuronal activation, but also from nonneuronal physiological processes. These changes, especially in the low-frequency domain (0.01-0.2 Hz), can significantly confound inferences about neuronal processes. It is crucial to effectively identify these nuisance low-frequency oscillations (LFOs). METHOD: A high temporal resolution (repetition time, ∼0.5 s) fMRI resting state study was conducted with simultaneous physiological measurements to compare LFOs measured directly by near-infrared spectroscopy (NIRS) in the periphery and three methods that model LFOs from the respiration or cardiac signal: 1) the respiration volume per time (RVT), 2) the respiratory variation (RVRRF), and 3) the cardiac variation method (HRCRF)...
December 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/26505301/carbon-wire-loop-based-artifact-correction-outperforms-post-processing-eeg-fmri-corrections-a-validation-of-a-real-time-simultaneous-eeg-fmri-correction-method
#9
Johan N van der Meer, André Pampel, Eus J W Van Someren, Jennifer R Ramautar, Ysbrand D van der Werf, German Gomez-Herrero, Jöran Lepsien, Lydia Hellrung, Hermann Hinrichs, Harald E Möller, Martin Walter
Simultaneous EEG-fMRI combines two powerful neuroimaging techniques, but the EEG signal suffers from severe artifacts in the MRI environment that are difficult to remove. These are the MR scanning artifact and the blood-pulsation artifact--strategies to remove them are a topic of ongoing research. Additionally large, unsystematic artifacts are produced across the full frequency spectrum by the magnet's helium pump (and ventilator) systems which are notoriously hard to remove. As a consequence, experimenters routinely deactivate the helium pump during simultaneous EEG-fMRI acquisitions which potentially risks damaging the MRI system and necessitates more frequent and expensive helium refills...
January 15, 2016: NeuroImage
https://www.readbyqxmd.com/read/26292338/dictionary-driven-ischemia-detection-from-cardiac-phase-resolved-myocardial-bold-mri-at-rest
#10
Marco Bevilacqua, Rohan Dharmakumar, Sotirios A Tsaftaris
Cardiac Phase-resolved Blood-Oxygen-Level Dependent (CP-BOLD) MRI provides a unique opportunity to image an ongoing ischemia at rest. However, it requires post-processing to evaluate the extent of ischemia. To address this, here we propose an unsupervised ischemia detection (UID) method which relies on the inherent spatio-temporal correlation between oxygenation and wall motion to formalize a joint learning and detection problem based on dictionary decomposition. Considering input data of a single subject, it treats ischemia as an anomaly and iteratively learns dictionaries to represent only normal observations (corresponding to myocardial territories remote to ischemia)...
January 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/26133583/exploitation-of-temporal-redundancy-in-compressed-sensing-reconstruction-of-fmri-studies-with-a-prior-based-algorithm-piccs
#11
C Chavarrías, J F P J Abascal, P Montesinos, M Desco
PURPOSE: Compressed sensing is a technique used to accelerate magnetic resonance imaging (MRI) acquisition without compromising image quality. While it has proven particularly useful in dynamic imaging procedures such as cardiac cine, very few authors have applied it to functional magnetic resonance imaging (fMRI). The purpose of the present study was to check whether the prior image constrained compressed sensing (PICCS) algorithm, which is based on an available prior image, can improve the statistical maps in fMRI better than other strategies that also exploit temporal redundancy...
July 2015: Medical Physics
https://www.readbyqxmd.com/read/25513556/structured-dictionaries-for-ischemia-estimation-in-cardiac-bold-mri-at-rest
#12
Cristian Rusu, Sotirios A Tsaftaris
Cardiac Phase-resolved Blood-Oxygen-Level-Dependent (CP-BOLD) MRI examines changes in myocardial oxygenation in response to ischemia without contrast and stress agents. Since signal intensity changes are subtle, quantitative approaches are necessary to examine variations in myocardial BOLD signals and identify ischemic myocardial territories. Here, using data from animal studies, we extract myocardial time series (BOLD signal as a function of cardiac phase) and explore such variations using a structured dictionary-learning framework, considering shift-invariant learning and spatial priors...
2014: Medical Image Computing and Computer-assisted Intervention: MICCAI ..
https://www.readbyqxmd.com/read/25485424/structured-dictionaries-for-ischemia-estimation-in-cardiac-bold-mri-at-rest
#13
Cristian Rusu, Sotirios A Tsaftaris
Cardiac Phase-resolved Blood-Oxygen-Level-Dependent (CP-BOLD) MRI examines changes in myocardial oxygenation in response to ischemia without contrast and stress agents. Since signal intensity changes are subtle, quantitative approaches are necessary to examine variations in myocardial BOLD signals and identify ischemic myocardial territories. Here, using data from animal studies, we extract myocardial time series (BOLD signal as a function of cardiac phase) and explore such variations using a structured dictionary-learning framework, considering shift-invariant learning and spatial priors...
2014: Medical Image Computing and Computer-assisted Intervention: MICCAI ..
https://www.readbyqxmd.com/read/24744722/studying-the-spatial-distribution-of-physiological-effects-on-bold-signals-using-ultrafast-fmri
#14
Yunjie Tong, Blaise Deb Frederick
The blood-oxygen-level dependent (BOLD) signal in functional MRI (fMRI) reflects both neuronal activations and global physiological fluctuations. These physiological fluctuations can be attributed to physiological low frequency oscillations (pLFOs), respiration, and cardiac pulsation. With typical TR values, i.e., 2 s or longer, the high frequency physiological signals (i.e., from respiration and cardiac pulsation) are aliased into the low frequency band, making it hard to study the individual effect of these physiological processes on BOLD...
2014: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/24691119/synthetic-generation-of-myocardial-blood-oxygen-level-dependent-mri-time-series-via-structural-sparse-decomposition-modeling
#15
Cristian Rusu, Rita Morisi, Davide Boschetto, Rohan Dharmakumar, Sotirios A Tsaftaris
This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for cardiac phase-resolved blood-oxygen-level-dependent (CP-BOLD) MRI. CP-BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns...
July 2014: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/24616025/robust-cardiac-bold-mri-using-an-fmri-like-approach-with-repeated-stress-paradigms
#16
Aurelien F Stalder, Michaela Schmidt, Andreas Greiser, Peter Speier, Jens Guehring, Matthias G Friedrich, Edgar Mueller
PURPOSE: Use repeated stress paradigms and an approach taken from neurological blood oxygen level dependent (BOLD) functional MRI (fMRI) to derive robust cardiac BOLD measurements. METHODS: Multiple-repetition, single-shot, electrocardiograph-triggered, T2-prepared BOLD balanced steady-state free precession was performed during repeated long breath-holds in 13 volunteers. Nonrigid motion correction was applied to the continuously acquired data and it was analyzed with a general linear model (GLM) taking into account the effects of the breath-hold duration, RR interval, motion, and baseline variations...
February 2015: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/24508639/obesity-metabolic-derangement-exacerbates-cardiomyocyte-loss-distal-to-moderate-coronary-artery-stenosis-in-pigs-without-affecting-global-cardiac-function
#17
Zi-Lun Li, Behzad Ebrahimi, Xin Zhang, Alfonso Eirin, John R Woollard, Hui Tang, Amir Lerman, Shen-Ming Wang, Lilach O Lerman
Obesity associated with metabolic derangements (ObM) worsens the prognosis of patients with coronary artery stenosis (CAS), but the underlying cardiac pathophysiologic mechanisms remain elusive. We tested the hypothesis that ObM exacerbates cardiomyocyte loss distal to moderate CAS. Obesity-prone pigs were randomized to four groups (n = 6 each): lean-sham, ObM-sham, lean-CAS, and ObM-CAS. Lean and ObM pigs were maintained on a 12-wk standard or atherogenic diet, respectively, and left circumflex CAS was then induced by placing local-irritant coils...
April 1, 2014: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/24272768/short-repetition-time-multiband-echo-planar-imaging-with-simultaneous-pulse-recording-allows-dynamic-imaging-of-the-cardiac-pulsation-signal
#18
Yunjie Tong, Lia M Hocke, Blaise deB Frederick
PURPOSE: Recently developed simultaneous multislice echo-planar imaging (EPI) sequences permit imaging of the whole brain at short repetition time (TR), allowing the cardiac fluctuations to be fully sampled in blood-oxygen-level dependent functional MRI (BOLD fMRI). A novel low computational analytical method was developed to dynamically map the passage of the pulsation signal through the brain and visualize the whole cerebral vasculature affected by the pulse signal. This algorithm is based on a simple combination of fast BOLD fMRI and the scanner's own built-in pulse oximeter...
November 2014: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/23831413/ferumoxytol-enhanced-resting-state-fmri-and-relative-cerebral-blood-volume-mapping-in-normal-human-brain
#19
Helen D'Arceuil, Alexandre Coimbra, Pamela Triano, Margaret Dougherty, Julie Mello, Michael Moseley, Gary Glover, Maarten Lansberg, Francis Blankenberg
The brain demonstrates spontaneous low-frequency (<0.1 Hz) cerebral blood flow (CBF) fluctuations, measurable by resting state functional MRI (rs-fMRI). Ultra small superparamagnetic iron oxide particles have been shown to enhance task-based fMRI signals (cerebral blood volume fMRI or CBV-fMRI), compared to the BOLD effect, by a factor of ≈2.5 at 3 T in primates and humans. We evaluated the use of ferumoxytol for steady state, resting state FMRI (CBV-rs-fMRI) and relative cerebral blood volume (rCBV) mapping, at 3T, in healthy volunteers...
December 2013: NeuroImage
https://www.readbyqxmd.com/read/23667641/non-invasive-magnetic-resonance-imaging-in-rats-for-prediction-of-the-fate-of-grafted-kidneys-from-cardiac-death-donors
#20
Jun-Ya Kaimori, Satomi Iwai, Masaki Hatanaka, Takumi Teratani, Yoshitsugu Obi, Hidetoshi Tsuda, Yoshitaka Isaka, Takashi Yokawa, Kagayaki Kuroda, Naotsugu Ichimaru, Masayoshi Okumi, Koji Yazawa, Hiromi Rakugi, Norio Nonomura, Shiro Takahara, Eiji Kobayashi
The main objective of this study was to assess cardiac death (CD) kidney grafts before transplantation to determine whether blood oxygen level-dependent (BOLD) and diffusion MRI techniques can predict damage to these grafts after transplantation. We assessed CD kidney tissue by BOLD and diffusion MRI. We also examined pathological and gene expression changes in CD kidney grafts before and after transplantation. Although there was significantly more red cell congestion (RCC) in the inner stripe of the outer medulla (IS) in both 1 h after cardiac death (CD1h) and CD2h kidneys destined for grafts before transplantation compared with CD0h (p<0...
2013: PloS One
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