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Magnetic Resonance Imaging

Miguel Silva Vieira, Markus Henningsson, Nathalie Dedieu, Vassilios S Vassiliou, Aaron Bell, Sujeev Mathur, Kuberan Pushparajah, Carlos Alberto Figueroa, Tarique Hussain, René Botnar, Gerald F Greil
BACKGROUND: CMRA in pediatrics remains challenging due to the smaller vessel size, high heart rates (HR), potential image degradation caused by limited patient cooperation and long acquisition times. High-relaxivity contrast agents have been shown to improve coronary imaging in adults, but limited data is available in children. We sought to investigate whether gadobenate dimeglumine (Gd-BOPTA) together with self-navigated inversion-prepared coronary magnetic resonance angiography (CMRA) sequence design improves coronary image quality in pediatric patients...
January 12, 2018: Magnetic Resonance Imaging
Guylaine Collewet, Saïd Moussaoui, Cécile Deligny, Tiphaine Lucas, Jérôme Idier
Multi-tissue partial volume estimation in MRI images is investigated with a viewpoint related to spectral unmixing as used in hyperspectral imaging. The main contribution of this paper is twofold. It firstly proposes a theoretical analysis of the statistical optimality conditions of the proportion estimation problem, which in the context of multi-contrast MRI data acquisition allows to appropriately set the imaging sequence parameters. Secondly, an efficient proportion quantification algorithm based on the minimisation of a penalised least-square criterion incorporating a regularity constraint on the spatial distribution of the proportions is proposed...
January 8, 2018: Magnetic Resonance Imaging
Bimin Chen, Yinghua Zhao, Xin Cheng, Yajun Ma, Eric Y Chang, Arthur Kavanaugh, Sirun Liu, Jiang Du
We present three-dimensional ultrashort echo time Cones (3D-UTE-Cones) imaging as well as quantification of T2* and magnetization transfer ratio (MTR) of Achilles tendon and its enthesis of healthy volunteers and patients with psoriatic arthritis (PsA) using a 3T scanner. Quantitative T2*, T2 and magnetization transfer ratio (MTR) measurements of Achilles tendon and its enthesis were performed on healthy volunteers (n=7) and PsA patients (n=9) with 3D-UTE-Cones and clinical sequences at 3T. T2* was measured via single-component fitting of UTE images from two interleaved dual echo 3D-UTE-Cones acquisitions...
January 5, 2018: Magnetic Resonance Imaging
Michael Hutchinson
No abstract text is available yet for this article.
January 4, 2018: Magnetic Resonance Imaging
Shivaprasad Ashok Chikop, Antharikshanagar Bellappa Sachin Anchan, Girish Koulagi, Arush Arun Honnedevasthana, Shaik Imam, Sairam Geethanath
The purpose of this study is to illustrate motion correction in Musculoskeletal (MSK) Magnetic Resonance Imaging (MRI) through utilization of information from an optical tracker to capture the extent and instant of motion. A Digital Single Lens Reflexive camera is employed as the optical tracker to capture the extent and instant of motion. A checkerboard is utilized as a marker that is placed on the coil. Shift of the checkerboard provides the extent of motion, which is captured by camera and is used for motion correction in (MSK)-MRI images...
January 4, 2018: Magnetic Resonance Imaging
Sirisha Tadimalla, Monique C Tourell, Robert Knott, Konstantin I Momot
Measurements of the orientational dispersion of collagen fibers in articular cartilage were made using diffusion tensor imaging (DTI) and small-angle X-ray scattering (SAXS) on matched bovine articular cartilage samples. Thirteen pairs of samples were excised from bovine knee joints; each pair was taken from neighboring locations in the same bone. One sample from each pair was used for DTI measurements and the other for SAXS measurements. Fractional anisotropy (FA) values were calculated from the DTI data both for the individual imaging voxels and for whole regions of interest (ROI)...
January 3, 2018: Magnetic Resonance Imaging
Tamar M van Veenendaal, Walter H Backes, Frank C G van Bussel, Richard A E Edden, Nicolaas A J Puts, Albert P Aldenkamp, Jacobus F A Jansen
PURPOSE: While PRESS is often employed to measure glutamate concentrations, MEGA-PRESS enables simultaneous Glx (glutamate and glutamine) and GABA measurements. This study aimed to compare validation, repeatability, and concordance of different approaches for glutamate quantification at 3T to aid future studies in their selection of the appropriate sequence and quantification method. MATERIALS AND METHODS: Nine phantoms with different glutamate and glutamine concentrations and five healthy participants were scanned twice to assess respectively the validation and repeatability of measurements with PRESS and MEGA-PRESS...
January 3, 2018: Magnetic Resonance Imaging
Jae Seok Bae, Roh-Eul Yoo, Seung Hong Choi, Seong Oh Park, Hak Chang, Minseok Suh, Gi Jeong Cheon
PURPOSE: To validate usefulness of magnetic resonance (MR) lymphangiography for evaluation of peripheral lymphedema in upper extremities by comparison with lymphoscintigraphy. MATERIALS AND METHODS: This prospective study had institutional review board approval and written informed consent was obtained from all patients. Initially, protocol of MR lymphangiography for upper extremity was established in seven healthy volunteers with 3.0T fat-saturated three-dimensional gradient-echo MR after gadobutrol injection...
January 3, 2018: Magnetic Resonance Imaging
Vaibhav Mohanty, Emilie T McKinnon, Joseph A Helpern, Jens H Jensen
PURPOSE: To compare estimates for the diffusional kurtosis in brain as obtained from a cumulant expansion (CE) of the diffusion MRI (dMRI) signal and from q-space (QS) imaging. THEORY AND METHODS: For the CE estimates of the kurtosis, the CE was truncated to quadratic order in the b-value and fit to the dMRI signal for b-values from 0 up to 2000s/mm2. For the QS estimates, b-values ranging from 0 up to 10,000s/mm2 were used to determine the diffusion displacement probability density function (dPDF) via Stejskal's formula...
January 3, 2018: Magnetic Resonance Imaging
Alexander Adair, Igor V Mastikhin, Benedict Newling
The pressure variations experienced by a liquid flowing through a pipe constriction can, in some cases, result in the formation of a bubble cloud (i.e., hydrodynamic cavitation). Due to the nature of the bubble cloud, it is ideally measured through the use of non-optical and non-invasive techniques; therefore, it is well-suited for study by magnetic resonance imaging. This paper demonstrates the use of Conical SPRITE (a 3D, centric-scan, pure phase-encoding pulse sequence) to acquire time-averaged void fraction and velocity information about hydrodynamic cavitation for water flowing through a pipe constriction...
January 2, 2018: Magnetic Resonance Imaging
Hyeong Cheol Moon, Soon-Tae You, Hyeon Man Baek, Young Jai Jeon, Chan-A Park, Jei Jun Cheong, Youn Joo Lee, Young Seok Park
7.0Tesla(T) high-resolution diffusion tensor imaging (DTI) can supply information on changing microstructures in cranial nerves. We investigated DTI parameters and the feasibility of DTI criteria for diagnosing trigeminal neuralgia (TN). In this study, 14 patients (28 hemispheres) of mean age 49.0years (range, 31-64) with TN underwent DTI using 7.0TMRI. We compared fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) of affected-side and unaffected-side trigeminal nerves using DTI...
January 2, 2018: Magnetic Resonance Imaging
Daniel V Olson, Volkan Arpinar, L Tugan Muftuler
PURPOSE: Diffusion kurtosis imaging (DKI) has gained popularity in recent years as an advanced diffusion-weighted MRI technique. This work aims to quantitatively compare the performance and accuracy of four DKI processing algorithms. For this purpose, a digital DKI brain phantom is developed. METHODS: Data from the Human Connectome Project database were used to generate a DKI digital phantom. In a Monte Carlo Rician noise simulation, four DKI processing algorithms were compared based on their mean square error, squared bias, and variance...
January 2, 2018: Magnetic Resonance Imaging
R Acquaviva, S Mangione, G Garbo
In order to reduce geometric distortion phenomena in MR images, every MRI system main magnet undergoes a shimming process. Since this process aims at optimizing magnetic field homogeneity within a so-called uniformity sphere, image quality outside this sphere is neglected. Since the fields vary smoothly in space, MR signal-to-noise ratio is still non-zero just outside the uniformity region, but correction of MR image distortion fails due to lack of magnetic field knowledge outside it. We propose a novel algorithm for measuring all the fields involved in the generation of images...
January 2, 2018: Magnetic Resonance Imaging
Christos G Xanthis, Sebastian Bidhult, Andreas Greiser, Kelvin Chow, Richard B Thompson, Håkan Arheden, Anthony H Aletras
Quantitative cardiovascular Magnetic Resonance Imaging techniques are gaining wide acceptance within the MR community due to their potential to diagnose non-localized disease, guide therapy and improve patient outcome. During the last decade, there has been an increasing interest for developing new techniques that allow for simultaneous quantification of both T1 and T2 maps of myocardium. Newer studies demonstrated that the incorporation of MRI simulations could yield similar results to conventional mapping techniques in the myocardium...
December 26, 2017: Magnetic Resonance Imaging
Paul Kokeny, Yu-Chung N Cheng, He Xie
Modeling MRI signal behaviors in the presence of discrete magnetic particles is important, as magnetic particles appear in nanoparticle labeled cells, contrast agents, and other biological forms of iron. Currently, many models that take into account the discrete particle nature in a system have been used to predict magnitude signal decays in the form of R2* or R2' from one single voxel. Little work has been done for predicting phase signals. In addition, most calculations of phase signals rely on the assumption that a system containing discrete particles behaves as a continuous medium...
December 26, 2017: Magnetic Resonance Imaging
Riccardo Lattanzi, Bei Zhang, Florian Knoll, Jakob Assländer, Martijn A Cloos
PURPOSE: Magnetic Resonance Fingerprinting reconstructions can become computationally intractable with multiple transmit channels, if the B1+ phases are included in the dictionary. We describe a general method that allows to omit the transmit phases. We show that this enables straightforward implementation of dictionary compression to further reduce the problem dimensionality. METHODS: We merged the raw data of each RF source into a single k-space dataset, extracted the transceiver phases from the corresponding reconstructed images and used them to unwind the phase in each time frame...
December 23, 2017: Magnetic Resonance Imaging
Yuanliang Xie, Hongfeng Zhang, Chaoling Jin, Xiang Wang, Xiaoqi Wang, Jingting Chen, Yikai Xu
To assess the value of T1ρ,T1ρ on hepatobiliary phase (HBP) and diffusion metrics in staging of Non-alcoholic fatty liver disease (NAFLD) activity scores, inflammation, fibrosis in NASH rabbits model. Non-alcoholic steatohepatitis (NASH) rabbits model was induced by feeding a varied duration of high-fat, high-cholesterol diet. T1ρ,T1ρ (HBP) 20min after administration of Gd-EOB-DTPA, and Intravoxel incoherent motion imaging (IVIM) diffusion-weighted imaging were performed on a 3.0T magnetic resonance (MR) imaging unit...
December 23, 2017: Magnetic Resonance Imaging
Soudabeh Kargar, Eric A Borisch, Adam T Froemming, Akira Kawashima, Lance A Mynderse, Eric G Stinson, Joshua D Trzasko, Stephen J Riederer
PURPOSE: To describe an efficient numerical optimization technique using non-linear least squares to estimate perfusion parameters for the Tofts and extended Tofts models from dynamic contrast enhanced (DCE) MRI data and apply the technique to prostate cancer. METHODS: Parameters were estimated by fitting the two Tofts-based perfusion models to the acquired data via non-linear least squares. We apply Variable Projection (VP) to convert the fitting problem from a multi-dimensional to a one-dimensional line search to improve computational efficiency and robustness...
December 23, 2017: Magnetic Resonance Imaging
Atefeh Kordzadeh, Nicola De Zanche
Placing dielectric pads adjacent to the imaging region is an effective method to increase the signal locally and also increase the radio frequency magnetic field homogeneity in magnetic resonance imaging. The use of local high permittivity pads is becoming more common, and this work focuses on the effect of larger dielectric pads on the transmit/receive performance of an array (e.g., coupling, efficiency and safety) having 8 channels, used to image a cylindrical phantom at 4.7T (200MHz). We investigate the effects of a dielectric liner surrounding the whole volume of interest both with and without an air gap...
December 23, 2017: Magnetic Resonance Imaging
Yunju Kim, Sung Hun Kim, Hye Won Lee, Byung Joo Song, Bong Joo Kang, Ahwon Lee, Yoonho Nam
PURPOSE: To determine the diagnostic performance of intravoxel incoherent motion (IVIM) diffusion-weighted (DW) magnetic resonance imaging (MRI) parameters in predicting response to neoadjuvant chemotherapy (NAC) in breast cancer patients. MATERIALS AND METHODS: Forty-six patients with stage II or III breast cancer underwent MRI including DW imaging with 10 b values before and after 2cycles of NAC. Apparent diffusion coefficient (ADC) and IVIM parameters (D, D*, and f) were obtained using histogram analysis derived from whole-tumor volumes...
December 23, 2017: Magnetic Resonance Imaging
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