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https://www.readbyqxmd.com/read/28328013/validation-of-surface-to-volume-ratio-measurements-derived-from-oscillating-gradient-spin-echo-on-a-clinical-scanner-using-anisotropic-fiber-phantoms
#1
Gregory Lemberskiy, Steven H Baete, Martijn A Cloos, Dmitry S Novikov, Els Fieremans
A diffusion measurement in the short-time surface-to-volume ratio (S/V) limit (Mitra et al., Phys Rev Lett. 1992;68:3555) can disentangle the free diffusion coefficient from geometric restrictions to diffusion. Biophysical parameters, such as the S/V of tissue membranes, can be used to estimate microscopic length scales non-invasively. However, due to gradient strength limitations on clinical MRI scanners, pulsed gradient spin echo (PGSE) measurements are impractical for probing the S/V limit. To achieve this limit on clinical systems, an oscillating gradient spin echo (OGSE) sequence was developed...
March 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28268369/optimal-experiment-design-for-magnetic-resonance-fingerprinting
#2
Bo Zhao, Justin P Haldar, Kawin Setsompop, Lawrence L Wald
Magnetic resonance (MR) fingerprinting is an emerging quantitative MR imaging technique that simultaneously acquires multiple tissue parameters in an efficient experiment. In this work, we present an estimation-theoretic framework to evaluate and design MR fingerprinting experiments. More specifically, we derive the Cramér-Rao bound (CRB), a lower bound on the covariance of any unbiased estimator, to characterize parameter estimation for MR fingerprinting. We then formulate an optimal experiment design problem based on the CRB to choose a set of acquisition parameters (e...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28261851/low-rank-alternating-direction-method-of-multipliers-reconstruction-for-mr-fingerprinting
#3
Jakob Assländer, Martijn A Cloos, Florian Knoll, Daniel K Sodickson, Jürgen Hennig, Riccardo Lattanzi
PURPOSE: The proposed reconstruction framework addresses the reconstruction accuracy, noise propagation and computation time for magnetic resonance fingerprinting. METHODS: Based on a singular value decomposition of the signal evolution, magnetic resonance fingerprinting is formulated as a low rank (LR) inverse problem in which one image is reconstructed for each singular value under consideration. This LR approximation of the signal evolution reduces the computational burden by reducing the number of Fourier transformations...
March 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28247879/rapid-and-specific-detection-of-cell-derived-microvesicles-using-a-magnetoresistive-biochip
#4
Solène Cherré, Elisabete Fernandes, José Germano, Tomás Dias, Susana Cardoso, Moisés S Piedade, Noemi Rozlosnik, Marta I Oliveira, Paulo P Freitas
Microvesicles (MVs) are a promising source of diagnostic biomarkers which have gained a wide interest in the biomedical and biosensing field. They can be interpreted as a "fingerprint" of various diseases. Nonetheless, MVs implementation into clinical settings has been hampered by the lack of technologies to accurately characterize, detect and quantify them. Here, we report the specific sensing and quantification of MVs from endothelial cells using a portable magnetoresistive (MR) biochip platform, in less than one hour and within physiologically relevant concentrations (1 × 10(8) MVs per ml)...
March 13, 2017: Analyst
https://www.readbyqxmd.com/read/28238942/algorithm-comparison-for-schedule-optimization-in-mr-fingerprinting
#5
Ouri Cohen, Matthew S Rosen
In MR Fingerprinting, the flip angles and repetition times are chosen according to a pseudorandom schedule. In previous work, we have shown that maximizing the discrimination between different tissue types by optimizing the acquisition schedule allows reductions in the number of measurements required. The ideal optimization algorithm for this application remains unknown, however. In this work we examine several different optimization algorithms to determine the one best suited for optimizing MR Fingerprinting acquisition schedules...
February 23, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28226533/optimal-experiment-design-for-magnetic-resonance-fingerprinting
#6
Bo Zhao, Justin P Haldar, Kawin Setsompop, Lawrence L Wald, Bo Zhao, Justin P Haldar, Kawin Setsompop, Lawrence L Wald, Bo Zhao, Lawrence L Wald, Justin P Haldar, Kawin Setsompop
Magnetic resonance (MR) fingerprinting is an emerging quantitative MR imaging technique that simultaneously acquires multiple tissue parameters in an efficient experiment. In this work, we present an estimation-theoretic framework to evaluate and design MR fingerprinting experiments. More specifically, we derive the Cramér-Rao bound (CRB), a lower bound on the covariance of any unbiased estimator, to characterize parameter estimation for MR fingerprinting. We then formulate an optimal experiment design problem based on the CRB to choose a set of acquisition parameters (e...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28187264/development-of-a-combined-mr-fingerprinting-and-diffusion-examination-for-prostate-cancer
#7
Alice C Yu, Chaitra Badve, Lee E Ponsky, Shivani Pahwa, Sara Dastmalchian, Matthew Rogers, Yun Jiang, Seunghee Margevicius, Mark Schluchter, William Tabayoyong, Robert Abouassaly, Debra McGivney, Mark A Griswold, Vikas Gulani
Purpose To develop and evaluate an examination consisting of magnetic resonance (MR) fingerprinting-based T1, T2, and standard apparent diffusion coefficient (ADC) mapping for multiparametric characterization of prostate disease. Materials and Methods This institutional review board-approved, HIPAA-compliant retrospective study of prospectively collected data included 140 patients suspected of having prostate cancer. T1 and T2 mapping was performed with fast imaging with steady-state precession-based MR fingerprinting with ADC mapping...
February 10, 2017: Radiology
https://www.readbyqxmd.com/read/28043909/magnetic-resonance-fingerprinting-based-on-realistic-vasculature-in-mice
#8
Philippe Pouliot, Louis Gagnon, Tina Lam, Pramod K Avti, Chris Bowen, Michèle Desjardins, Ashok K Kakkar, Eric Thorin, Sava Sakadzic, David A Boas, Frédéric Lesage
Magnetic resonance fingerprinting (MRF) was recently proposed as a novel strategy for MR data acquisition and analysis. A variant of MRF called vascular MRF (vMRF) followed, that extracted maps of three parameters of physiological importance: cerebral oxygen saturation (SatO2), mean vessel radius and cerebral blood volume (CBV). However, this estimation was based on idealized 2-dimensional simulations of vascular networks using random cylinders and the empirical Bloch equations convolved with a diffusion kernel...
December 31, 2016: NeuroImage
https://www.readbyqxmd.com/read/28034994/mr-fingerprinting-of-adult-brain-tumors-initial-experience
#9
C Badve, A Yu, S Dastmalchian, M Rogers, D Ma, Y Jiang, S Margevicius, S Pahwa, Z Lu, M Schluchter, J Sunshine, M Griswold, A Sloan, V Gulani
BACKGROUND AND PURPOSE: MR fingerprinting allows rapid simultaneous quantification of T1 and T2 relaxation times. This study assessed the utility of MR fingerprinting in differentiating common types of adult intra-axial brain tumors. MATERIALS AND METHODS: MR fingerprinting acquisition was performed in 31 patients with untreated intra-axial brain tumors: 17 glioblastomas, 6 World Health Organization grade II lower grade gliomas, and 8 metastases. T1, T2 of the solid tumor, immediate peritumoral white matter, and contralateral white matter were summarized within each ROI...
March 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28019022/use-of-pattern-recognition-for-unaliasing-simultaneously-acquired-slices-in-simultaneous-multislice-mr-fingerprinting
#10
Yun Jiang, Dan Ma, Himanshu Bhat, Huihui Ye, Stephen F Cauley, Lawrence L Wald, Kawin Setsompop, Mark A Griswold
PURPOSE: The purpose of this study is to accelerate an MR fingerprinting (MRF) acquisition by using a simultaneous multislice method. METHODS: A multiband radiofrequency (RF) pulse was designed to excite two slices with different flip angles and phases. The signals of two slices were driven to be as orthogonal as possible. The mixed and undersampled MRF signal was matched to two dictionaries to retrieve T1 and T2 maps of each slice. Quantitative results from the proposed method were validated with the gold-standard spin echo methods in a phantom...
December 26, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28019021/multiparametric-estimation-of-brain-hemodynamics-with-mr-fingerprinting-asl
#11
Pan Su, Deng Mao, Peiying Liu, Yang Li, Marco C Pinho, Babu G Welch, Hanzhang Lu
PURPOSE: Assessment of brain hemodynamics without exogenous contrast agents is of increasing importance in clinical applications. This study aims to develop an MR perfusion technique that can provide noncontrast and multiparametric estimation of hemodynamic markers. METHODS: We devised an arterial spin labeling (ASL) method based on the principle of MR fingerprinting (MRF), referred to as MRF-ASL. By taking advantage of the rich information contained in MRF sequence, up to seven hemodynamic parameters can be estimated concomitantly...
December 26, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28008911/geometrical-vortex-lattice-pinning-and-melting-in-ybacuo-submicron-bridges
#12
G P Papari, A Glatz, F Carillo, D Stornaiuolo, D Massarotti, V Rouco, L Longobardi, F Beltram, V M Vinokur, F Tafuri
Since the discovery of high-temperature superconductors (HTSs), most efforts of researchers have been focused on the fabrication of superconducting devices capable of immobilizing vortices, hence of operating at enhanced temperatures and magnetic fields. Recent findings that geometric restrictions may induce self-arresting hypervortices recovering the dissipation-free state at high fields and temperatures made superconducting strips a mainstream of superconductivity studies. Here we report on the geometrical melting of the vortex lattice in a wide YBCO submicron bridge preceded by magnetoresistance (MR) oscillations fingerprinting the underlying regular vortex structure...
December 23, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27937040/multiparametric-or-practical-quantitative-liver-mri-towards-millisecond-fat-fraction-kilopascal-and-function-era
#13
Emre Unal, Ilkay Sedakat Idilman, Muşturay Karçaaltıncaba
New advances in liver magnetic resonance imaging (MRI) may enable diagnosis of unseen pathologies by conventional techniques. Normal T1 (550-620 ms for 1.5 T and 700-850 ms for 3 T), T2, T2* (>20 ms), T1rho (40-50 ms) mapping, proton density fat fraction (PDFF) (≤5%) and stiffness (2-3kPa) values can enable differentiation of a normal liver from chronic liver and diffuse diseases. Gd-EOB-DTPA can enable assessment of liver function by using postcontrast hepatobiliary phase or T1 reduction rate (normally above 60%)...
February 2017: Expert Review of Gastroenterology & Hepatology
https://www.readbyqxmd.com/read/27883015/mr-vascular-fingerprinting-in-stroke-and-brain-tumors-models
#14
B Lemasson, N Pannetier, N Coquery, Ligia S B Boisserand, Nora Collomb, N Schuff, M Moseley, G Zaharchuk, E L Barbier, T Christen
In this study, we evaluated an MRI fingerprinting approach (MRvF) designed to provide high-resolution parametric maps of the microvascular architecture (i.e., blood volume fraction, vessel diameter) and function (blood oxygenation) simultaneously. The method was tested in rats (n = 115), divided in 3 models: brain tumors (9 L, C6, F98), permanent stroke, and a control group of healthy animals. We showed that fingerprinting can robustly distinguish between healthy and pathological brain tissues with different behaviors in tumor and stroke models...
November 24, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27851871/robust-sliding-window-reconstruction-for-accelerating-the-acquisition-of-mr-fingerprinting
#15
Xiaozhi Cao, Congyu Liao, Zhixing Wang, Ying Chen, Huihui Ye, Hongjian He, Jianhui Zhong
PURPOSE: To develop a method for accelerated and robust MR fingerprinting (MRF) with improved image reconstruction and parameter matching processes. THEORY AND METHODS: A sliding-window (SW) strategy was applied to MRF, in which signal and dictionary matching was conducted between fingerprints consisting of mixed-contrast image series reconstructed from consecutive data frames segmented by a sliding window, and a precalculated mixed-contrast dictionary. The effectiveness and performance of this new method, dubbed SW-MRF, was evaluated in both phantom and in vivo...
November 7, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27790751/repeatability-of-magnetic-resonance-fingerprinting-t1-and-t2-estimates-assessed-using-the-ismrm-nist-mri-system-phantom
#16
Yun Jiang, Dan Ma, Kathryn E Keenan, Karl F Stupic, Vikas Gulani, Mark A Griswold
PURPOSE: The purpose of this study was to evaluate accuracy and repeatability of T1 and T2 estimates of a MR fingerprinting (MRF) method using the ISMRM/NIST MRI system phantom. METHODS: The ISMRM/NIST MRI system phantom contains multiple compartments with standardized T1 , T2 , and proton density values. Conventional inversion-recovery spin echo and spin echo methods were used to characterize the T1 and T2 values in the phantom. The phantom was scanned using the MRF-FISP method over 34 consecutive days...
October 27, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27757570/mr-imaging-of-brain-pilocytic-astrocytoma-beyond-the-stereotype-of-benign-astrocytoma
#17
REVIEW
Simona Gaudino, Matia Martucci, Rosellina Russo, Emiliano Visconti, Emma Gangemi, Francesco D'Argento, Tommaso Verdolotti, Libero Lauriola, Cesare Colosimo
BACKGROUND: Pilocytic astrocytoma (PA) is the most common pediatric brain glioma and is considered the prototype of benign circumscribed astrocytoma. Despite its low malignancy, the CT and MRI features of brain PA may resemble those of much more aggressive brain tumors. Misdiagnosis of PA is particularly easy when it demonstrates MR morphological and non-morphological findings that are inconsistent with its non-aggressive nature and that overlap with the features of more aggressive brain tumors...
January 2017: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/27666486/agkihpin-a-novel-svtle-from-gloydius-halys-pallas-promotes-platelet-aggregation-in%C3%A2-vitro-and-inhibits-thrombus-formation-in%C3%A2-vivo-in-murine-models-of-thrombosis
#18
Huiqiong Xie, Miao Huang, Qiping Hu, Kejian Sun, Huayu Wu, Wei Shu, Xiaolong Li, Ling Fang
In previous work, a snake venom arginine esterase (SVAE), agkihpin from the venom of Gloydius halys Pallas, was isolated and its biochemical data including Mr, PI, amino acid components and sugar content was collected. Here, the agkihpin was cloned and further characterized and we found that agkihpin could promote ADP-induced platelets aggregation, hydrolyze fibrin, cleave Aα and Bβ chains of fibrinogen and reduce the thrombosis induced by thrombin. Moreover, agkihpin hydrolyzed TAME with optimum temperatures at 30 °C-45 °C, and the hydrolysis was inhibited by EDTA, PMSF, DTT and promoted by Ca(2+), Fe(3+), Mg(2+), Zn(2+)...
November 2016: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/27446810/in-vivo-magnetic-resonance-metabolic-and-morphofunctional-fingerprints-in-experimental-models-of-human-ovarian-cancer
#19
REVIEW
Rossella Canese, Delia Mezzanzanica, Marina Bagnoli, Stefano Indraccolo, Silvana Canevari, Franca Podo, Egidio Iorio
Epithelial ovarian cancer (EOC) is the gynecological malignancy with the highest death rate, characterized by frequent relapse and onset of drug resistance. Disease diagnosis and therapeutic follow-up could benefit from application of molecular imaging approaches, such as magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), able to monitor metabolic and functional alterations and investigate the underlying molecular mechanisms. Here, we overview the quantitative alterations that occur during either orthotopic or subcutaneous growth of preclinical EOC models...
2016: Frontiers in Oncology
https://www.readbyqxmd.com/read/27079826/pseudo-steady-state-free-precession-for-mr-fingerprinting
#20
Jakob Assländer, Steffen J Glaser, Jürgen Hennig
PURPOSE: This article discusses the signal behavior in the case the flip angle in steady-state free precession sequences is continuously varied as suggested for MR-fingerprinting sequences. Flip angle variations prevent the establishment of a steady state and introduce instabilities regarding to magnetic field inhomogeneities and intravoxel dephasing. We show how a pseudo steady state can be achieved, which restores the spin echo nature of steady-state free precession. METHODS: Based on geometrical considerations, relationships between the flip angle, repetition and echo time are derived that suffice to the establishment of a pseudo steady state...
April 15, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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