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Magnetic Resonance Imaging

Dimitri Martel, Benjamin Leporq, Mary Bruno, Ravinder Regatte, Stephen Honig, Gregory Chang
OBJECT: To quantify and compare subregional proximal femur bone marrow fat composition in premenopausal and postmenopausal women using chemical shift-encoded-MRI (CSE-MRI). MATERIALS AND METHODS: A multi gradient-echo sequence at 3 T was used to scan both hips of premenopausal (n = 9) and postmenopausal (n = 18) women. Subregional fat composition (saturation, poly-unsaturation, mono-unsaturation) was quantitatively assessed in the femoral head, femoral neck, Ward's triangle, greater trochanter, and proximal shaft in bone marrow adipose tissue and separately within red and yellow marrow adipose tissue...
July 10, 2018: Magnetic Resonance Imaging
Akihiko Kanki, Tsutomu Tamada, Toshinori Abe, Hiroyuki Ikenaga, Koji Yoshida, Katsuyoshi Ito
PURPOSE: To clarify the relationship between transient sever motion artifact in arterial phase (TSMA) and changes in peripheral capillary oxygen saturation (SpO2 ) and heart rate (HR) after contrast media administration during MRI or CT of the liver. METHODS: 87 patients undergoing 61 MRI examination with gadoxetic acid or 26 CT examination with iodinated contrast were included. Dynamic contrast-enhanced imaging (DCEI) was obtained at four vascular phase acquisitions...
July 9, 2018: Magnetic Resonance Imaging
Jeon-Hor Chen, Yang Zhang, Siwa Chan, Ruey-Feng Chang, Min-Ying Su
BACKGROUND AND PURPOSES: The aim of this study was to develop morphological analytic methods to analyze the tumor-fat interface and in different peritumoral shells away from the tumor, and to compare the results among three molecular subtypes of breast cancer. MATERIALS AND METHODS: A total of 102 women (mean age 48.5 y/o) with solitary well-defined breast cancers were analyzed, including 46 human epidermal growth factor receptor 2 (HER2) (+), 46 HER2(-) hormonal receptor (HR) (+), and 10 triple negative (TN) breast cancers...
June 30, 2018: Magnetic Resonance Imaging
Thomas Lindner, Olav Jansen, Michael Helle
Flow territory mapping using Arterial Spin Labeling (ASL) methods allows for deeper insights into the physiology of the brain. However, in most approaches assumptions of the labeling efficiency are used for calculation of brain perfusion which might result in inaccuracies. This becomes more important in super-selective ASL as the labeling focus could be positioned not exactly at the artery of interest. Therefore, measuring the labeling efficiency of the current scan seems important to obtain reliable results and to correct for potential errors...
June 29, 2018: Magnetic Resonance Imaging
Jesse I Hamilton, Yun Jiang, Dan Ma, Wei-Ching Lo, Vikas Gulani, Mark Griswold, Nicole Seiberlich
This study aims to improve the accuracy and consistency of T1 and T2 measurements using cardiac MR Fingerprinting (cMRF) by investigating and accounting for the effects of confounding factors including slice profile, inversion and T2 preparation pulse efficiency, and B1 + . The goal is to understand how measurements with different pulse sequences are affected by these factors. This can be used to determine which factors must be taken into account for accurate measurements, and which may be mitigated by the selection of an appropriate pulse sequence...
June 29, 2018: Magnetic Resonance Imaging
Paul Kinchesh, Stuart Gilchrist, John S Beech, Ana L Gomes, Veerle Kersemans, Robert G Newman, Borivoj Vojnovic, Philip D Allen, Michael Brady, Ruth J Muschel, Sean C Smart
PURPOSE: Cardiac and respiratory motion derived image artefacts are reduced when data are acquired with cardiac and respiratory synchronisation. Where steady state imaging techniques are required in small animals, synchronisation is most commonly performed using retrospective gating techniques but these invoke an inherent time penalty. This paper reports the development of prospective gating techniques for cardiac and respiratory motion desensitised MRI with significantly reduced minimum scan time compared to retrospective gating...
June 28, 2018: Magnetic Resonance Imaging
Matthias Malzacher, Mathias Davids, Lothar R Schad, Jorge Chacon-Caldera
Specific absorption rate (SAR) simulations are performed for most clinical and research transmit coil configurations. Such simulations allow the determination of limits in transmit power for patient safety. Different human models and coil configurations have been previously investigated using these simulations. However, only a few works have accounted for the effect of the receive (Rx) arrays in the SAR calculations and they have used very specialized setups or simplified detuning modeling of the Rx elements...
June 26, 2018: Magnetic Resonance Imaging
Abinand C Rejimon, Diana Y Lee, Christopher M Bergeron, You Zhuo, Wenshu Qian, Richard G Spencer, Mustapha Bouhrara
PURPOSE: To extend the null signal method (NSM) for B1 mapping to 3 T magnetic resonance imaging (MRI). BACKGROUND: The NSM operates in the steady state regime and exploits the linearity of the spoiled gradients recalled echo (SPGR) signal around the 180° flip angle (FA). Using linear regression, B1 maps are derived from three SPGR images acquired at different FAs with a short repetition time. While the conventional NSM allows accurate mapping of B1 for moderate B1 variation, we observed that this method fails for the larger B1 variations typical of high-field MRI...
June 26, 2018: Magnetic Resonance Imaging
Deepa Thapa, Panying Wang, Guangyao Wu, Xiangyu Wang, Qunqi Sun
OBJECTIVE: To evaluate the diagnostic potential based on histogram analysis of IVIM parameters between uterine cervical cancers (CC) - normal myometrium (Myo) versus CC - gluteus maximus muscle (GM) and to study the feasibility of histogram analysis of IVIM parameters to differentiate the early from locally advanced stage CCs. METHODS: 64 patients with pathologically confirmed CC were enrolled. Histogram indices mean, median, 25th, and ð 75th percentile of apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) value of entire tumor were statistically analyzed and compared between CC - GM versus CC - Myo, as well as between early and locally advanced stage CCs...
June 25, 2018: Magnetic Resonance Imaging
Daniel S Weller, Michael Salerno, Craig H Meyer
This paper describes an adaptive approach to regularizing model-based reconstructions in magnetic resonance imaging to account for local structure or image content. In conjunction with common models like wavelet and total variation sparsity, this content-aware regularization avoids oversmoothing or compromising image features while suppressing noise and incoherent aliasing from accelerated imaging. To evaluate this regularization approach, the experiments reconstruct images from single- and multi-channel, Cartesian and non-Cartesian, brain and cardiac data...
June 20, 2018: Magnetic Resonance Imaging
Nima Yaghoobi, Reza P R Hasanzadeh
De-noising is a crucial topic in Magnetic Resonance Imaging (MRI) which focuses on less loss of Magnetic Resonance (MR) image information and details preservation during the noise suppression. Nowadays multiple-coil MRI system is preferred to single one due to its acceleration in the imaging process. Due to the fact that the model of noise in single-coil and multiple-coil MRI systems are different, the de-noising methods that mostly are adapted to single-coil MRI systems, do not work appropriately with multiple-coil one...
June 20, 2018: Magnetic Resonance Imaging
Jesse Knight, Graham W Taylor, April Khademi
Many algorithms have been proposed for automated segmentation of white matter hyperintensities (WMH) in brain MRI. Yet, broad uptake of any particular algorithm has not been observed. In this work, we argue that this may be due to variable and suboptimal validation data and frameworks, precluding direct comparison of methods on heterogeneous data. As a solution, we present Leave-One-Source-Out Cross Validation (LOSO-CV), which leverages all available data for performance estimation, and show that this gives more realistic (lower) estimates of segmentation algorithm performance on data from different scanners...
June 19, 2018: Magnetic Resonance Imaging
Gregory Simchick, Amelia Yin, Hang Yin, Qun Zhao
PURPOSE: To explore, at a high field strength of 7T, the performance of various fat spectral models on the quantification of triglyceride composition and proton density fat fraction (PDFF) using chemical-shift encoded MRI (CSE-MRI). METHODS: MR data was acquired from CSE-MRI experiments for various fatty materials, including oil and butter samples and in vivo brown and white adipose mouse tissues. Triglyceride composition and PDFF were estimated using various a priori 6- or 9-peak fat spectral models...
June 18, 2018: Magnetic Resonance Imaging
K A Smitha, K M Arun, P G Rajesh, Suresh E Joel, Ramesh Venkatesan, Bejoy Thomas, Chandrasekharan Kesavadas
BACKGROUND AND OBJECTIVES: Ensuring patient comfort and compliance by emphasizing reduced time frame for image acquisition, without compromising image quality is the key aspect with functional MRI examination. Multiband resting state fMRI (MB-rsfMRI) is a fairly new technique that potentially shortens MR image acquisition time by providing increased number of time points. The study aims to compare signal characteristics as well as the functional connectivity using conventional resting-state fMRI (rsfMRI) with that of MB-rsfMRI technique...
June 18, 2018: Magnetic Resonance Imaging
Caroline Bund, François Lefebvre, Roland Schott, Marie-Pierre Chenard, Benoît Lhermitte, Hélène Cebula, Stéphane Kremer, François Proust, Izzie-Jacques Namer
PURPOSE: The aim of this study was to study the relationship between MRSI, before and after surgery, and patient survival. The accuracy of pre-operative MRSI in differentiating low- from high-grade oligodendrogliomas (ODGs) was also studied. METHODS: Two hundred patients with ODG were retrospectively included in this study between 2000 and 2016. All patients underwent MRSI before any treatment or biopsy and/or after surgery for an intra-axial brain tumour. The R software was used for statistical data analysis...
June 11, 2018: Magnetic Resonance Imaging
Hirohito Kan, Nobuyuki Arai, Masahiro Takizawa, Kazuyoshi Omori, Harumasa Kasai, Hiroshi Kunitomo, Yasujiro Hirose, Yuta Shibamoto
PURPOSE: We developed a non-regularized, variable kernel, sophisticated harmonic artifact reduction for phase data (NR-VSHARP) method to accurately estimate local tissue fields without regularization for quantitative susceptibility mapping (QSM). We then used a digital brain phantom to evaluate the accuracy of the NR-VSHARP method, and compared it with the VSHARP and iterative spherical mean value (iSMV) methods through in vivo human brain experiments. MATERIALS AND METHODS: Our proposed NR-VSHARP method, which uses variable spherical mean value (SMV) kernels, minimizes L2 norms only within the volume of interest to reduce phase errors and save cortical information without regularization...
June 11, 2018: Magnetic Resonance Imaging
F Ziayee, A Müller-Lutz, J Gross, M Quentin, T Ullrich, P Heusch, C Arsov, R Rabenalt, P Albers, G Antoch, H J Wittsack, L Schimmöller
PURPOSE: Reproducibility of quantitative perfusion analysis of DCE requires a standardized AIF acquisition. However, there are many different approaches for AIF assessment so that the absolute values of perfusion parameters may vary depending on the used method. This study analyzes the influence of the method of AIF determination on quantitative DCE-MRI. METHODS: In this retrospective, single-center, cohort study three different methods of AIF determination in 50 consecutive patients with multiparametric MRI of the prostate were conducted...
June 11, 2018: Magnetic Resonance Imaging
Anne Slawig, Tobias Wech, Valentin Ratz, Henning Neubauer, Thorsten Bley, Herbert Köstler
Our study proposes the use of a frequency-modulated acquisition which suppresses banding artefacts in combination with a phase-sensitive water-fat separation algorithm. The performance of the phase-sensitive separation for standard bSSFP, complex sum combination thereof, and frequency-modulated bSSFP were compared in in vivo measurements of the upper and lower legs at 1.5 and 3 T. It is shown, that the standard acquisition suffered from banding artefacts and major swaps between tissues. The dual-acquisition bSSFP could alleviate banding artefacts and only minor swaps occurred, but it comes at the expense of a doubled acquisition...
June 11, 2018: Magnetic Resonance Imaging
Wei Wang, Ning Cao
In order to accelerate magnetic resonance imaging (MRI) scanning, fast MRI technique based on compressed sensing (CS) was proposed. The shrinkage thresholding algorithm (STA) is an efficient method in related algorithms to decrease the incoherent artifacts produced by the undersampling in k-space directly. The traditional STA uses the fixed iteration step size during the reconstruction progress, and it is not conducive to accelerate the convergence speed. In order to improve global iteration efficiency, in this paper, step adaptive fast iterative shrinkage thresholding algorithm (SAFISTA) was proposed for MRI reconstruction based on STA...
June 7, 2018: Magnetic Resonance Imaging
Antonella Costa, Anna Ronchi, Paolo D Pigatto, Gianpaolo Guzzi
No abstract text is available yet for this article.
June 6, 2018: Magnetic Resonance Imaging
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