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Liliana E Ma, Michael Markl, Kelvin Chow, Hyungkyu Huh, Christoph Forman, Alireza Vali, Andreas Greiser, James Carr, Susanne Schnell, Alex J Barker, Ning Jin
PURPOSE: To evaluate the accuracy and feasibility of a free-breathing 4D flow technique using compressed sensing (CS), where 4D flow imaging of the thoracic aorta is performed in 2 min with inline image reconstruction on the MRI scanner in less than 5 min. METHODS: The 10 in vitro 4D flow MRI scans were performed with different acceleration rates on a pulsatile flow phantom (9 CS acceleration factors [R = 5.4-14.1], 1 generalized autocalibrating partially parallel acquisition [GRAPPA] R = 2)...
February 25, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Daniel Polak, Stephen Cauley, Susie Y Huang, Maria Gabriela Longo, John Conklin, Berkin Bilgic, Ned Ohringer, Esther Raithel, Peter Bachert, Lawrence L Wald, Kawin Setsompop
BACKGROUND: Rapid volumetric imaging protocols could better utilize limited scanner resources. PURPOSE: To develop and validate an optimized 6-minute high-resolution volumetric brain MRI examination using Wave-CAIPI encoding. STUDY TYPE: Prospective. POPULATION/SUBJECTS: Ten healthy subjects and 20 patients with a variety of intracranial pathologies. FIELD STRENGTH/SEQUENCE: At 3 T, MPRAGE, T2 -weighted SPACE, SPACE FLAIR, and SWI were acquired at 9-fold acceleration using Wave-CAIPI and for comparison at 2-4-fold acceleration using conventional GRAPPA...
February 8, 2019: Journal of Magnetic Resonance Imaging: JMRI
Yilong Liu, Mengye Lyu, Markus Barth, Zheyuan Yi, Alex T L Leong, Fei Chen, Yanqiu Feng, Ed X Wu
PURPOSE: To provide simultaneous multislice (SMS) EPI reconstruction with k-space implementation and robust Nyquist ghost correction. METHODS: 2D phase error correction SENSE (PEC-SENSE) was recently developed for Nyquist ghost correction in SMS EPI reconstruction for which virtual coil simultaneous autocalibration and k-space estimation (VC-SAKE) was used to remove slice-dependent Nyquist ghosts and intershot 2D phase variations in multi-shot EPI reference scan...
October 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Hyungseok Jang, Xing Lu, Michael Carl, Adam C Searleman, Saeed Jerban, Yajun Ma, Annette von Drygalski, Eric Y Chang, Jiang Du
PURPOSE: In this study, we explore the feasibility of a new imaging scheme for quantitative susceptibility mapping (QSM): continuous single-point imaging (CSPI), which uses a pure phase encoding strategy to achieve true phase imaging and improve QSM accuracy. METHODS: The proposed CSPI is a modification of conventional SPI to allow acquisition of multiple echoes in a single scan. Immediately following a phase encoding gradient, the free induction decay is continuously sampled with extremely high temporal resolution to obtain k-space data at a fixed spatial frequency (i...
October 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Giulio Ferrazzi, Jean Pierre Bassenge, Clarissa Wink, Alexander Ruh, Michael Markl, Steen Moeller, Gregory J Metzger, Bernd Ittermann, Sebastian Schmitter
PURPOSE: In conventional multiband (MB) CAIPIRINHA, additional reference scans are acquired to allow the separation of the excited slices. In this study, an acquisition-reconstruction technique that makes use of the MB data to calculate these reference data is presented. The method was integrated into a 2D time-resolved phase-contrast MR sequence used to assess velocities of the myocardium. METHODS: The RF phases of the MB pulse are cycled through time so that consecutive cardiac phases can be grouped to form reference scans at a lower temporal resolution...
September 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Mehmet Akçakaya, Steen Moeller, Sebastian Weingärtner, Kâmil Uğurbil
PURPOSE: To develop an improved k-space reconstruction method using scan-specific deep learning that is trained on autocalibration signal (ACS) data. THEORY: Robust artificial-neural-networks for k-space interpolation (RAKI) reconstruction trains convolutional neural networks on ACS data. This enables nonlinear estimation of missing k-space lines from acquired k-space data with improved noise resilience, as opposed to conventional linear k-space interpolation-based methods, such as GRAPPA, which are based on linear convolutional kernels...
January 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Mohamed Ahmed Hamed, Abeer Shaban Goda, Reham Mohmmed Salah Eldein
Background: It is a challenge for anesthesiologists to balance between administering intravenous fluid, vasoactive agents, and inotropic drugs to maintain appropriate cardiac output. Aim: The aim of this study was to evaluate the effect of treatment algorithm guided either by pulmonary artery catheter (PAC) or by the fourth generation FloTrac/Vigileo system combined with monitoring of oxygen transport on hemodynamic management and outcome after coronary artery bypass graft surgery (CABG)...
April 2018: Anesthesia, Essays and Researches
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...
October 2018: Magnetic Resonance Imaging
Lixia Ni, Zhenxing Li, Haifeng Li, Xu Liu
This paper proposes a 360-deg large-scale multiprojection light-field 3D display system, which can reconstruct the light field of models in real space. The reconstructed contents can be observed by multiple viewers from different angles and positions simultaneously. In this system, 360 projectors project images onto a cylindrical light-field diffusion screen whose height is 1.8 m and diameter is 3 m. When moving around the system, viewers can see 3D scenes with smooth-motion parallax, and the frame rate can reach 30 fps and above...
March 10, 2018: Applied Optics
Mengye Lyu, Markus Barth, Victor B Xie, Yilong Liu, Xin Ma, Yanqiu Feng, Ed X Wu
PURPOSE: To improve simultaneous multislice (SMS) EPI by robust Nyquist ghost correction in both coil sensitivity calibration and SMS reconstruction. METHODS: To derive coil sensitivity and slice-dependent phase difference map between positive- and negative-echo images, single-band EPI reference data are fully sampled with EPI parameters matched to SMS acquisition. First, the reference data are organized into positive- and negative-echo virtual channels where missing data are estimated using low-rank-based simultaneous autocalibrating and k-space estimation (SAKE) at small matrix size...
October 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Uten Yarach, Yi-Hang Tung, Kawin Setsompop, Myung-Ho In, Itthi Chatnuntawech, Renat Yakupov, Frank Godenschweger, Oliver Speck
PURPOSE: To develop a reconstruction pipeline that intrinsically accounts for both simultaneous multislice echo planar imaging (SMS-EPI) reconstruction and dynamic slice-specific Nyquist ghosting correction in time-series data. METHODS: After 1D slice-group average phase correction, the separate polarity (i.e., even and odd echoes) SMS-EPI data were unaliased by slice GeneRalized Autocalibrating Partial Parallel Acquisition. Both the slice-unaliased even and odd echoes were jointly reconstructed using a model-based framework, extended for SMS-EPI reconstruction that estimates a 2D self-phase map, corrects dynamic slice-specific phase errors, and combines data from all coils and echoes to obtain the final images...
October 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Angus Z Lau, Justin Y C Lau, Albert P Chen, Charles H Cunningham
PURPOSE: To investigate the feasibility of performing large FOV hyperpolarized 13 C metabolic imaging using simultaneous multislice excitation. METHODS: A spectral-spatial multislice excitation pulse was constructed by cosine modulation and incorporated into a 13 C spiral imaging sequence. Phantom and in vivo pig experiments were performed to test the feasibility of simultaneous multislice data acquisition and image reconstruction. In vivo cardiac-gated images of hyperpolarized pyruvate, bicarbonate, and lactate were obtained at 1 × 1 × 1 cm3 resolution over a 48 × 48 × 24 cm3 FOV with 2-fold acceleration in the slice direction...
October 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Christopher Ebersole, Rizwan Ahmad, Adam V Rich, Lee C Potter, Huiming Dong, Arunark Kolipaka
PURPOSE: Magnetic resonance elastography is a noninvasive tool for quantifying soft tissue stiffness. Magnetic resonance elastography has been adopted as a clinical method for staging liver fibrosis. However, the application of liver magnetic resonance elastography requires multiple lengthy breath-holds. We propose a new data acquisition and processing method to reduce magnetic resonance elastography scan time. METHODS: A Bayesian image reconstruction method that uses transform sparsity and magnitude consistency across different phase offsets to recover images from highly undersampled data is proposed...
September 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Berkin Bilgic, Tae Hyung Kim, Congyu Liao, Mary Kate Manhard, Lawrence L Wald, Justin P Haldar, Kawin Setsompop
PURPOSE: To develop parallel imaging techniques that simultaneously exploit coil sensitivity encoding, image phase prior information, similarities across multiple images, and complementary k-space sampling for highly accelerated data acquisition. METHODS: We introduce joint virtual coil (JVC)-generalized autocalibrating partially parallel acquisitions (GRAPPA) to jointly reconstruct data acquired with different contrast preparations, and show its application in 2D, 3D, and simultaneous multi-slice (SMS) acquisitions...
August 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Yoshinori Tsuji, Satoshi Saitoh, Junji Takahashi, Chisato Abe, Tatsuya Hayashi, Masahiro Kobayashi
The controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique can decrease scan time. The purpose of this study was to determine whether an arterial phase scan can be performed in 5 s using the CAIPIRINHA short-scan and a reference scanning technique. The generalized autocalibrating partially parallel acquisition (GRAPPA), the CAIPIRINHA routine (CAIPI-routine), and the CAIPIRINHA short-scanning (CAIPI-short) methods were compared. The scan time for each method was preset to 20 s, 15 s, and 10 s, respectively...
March 2018: Radiological Physics and Technology
Gonzalo Vegas-Sánchez-Ferrero, Maria J Ledesma-Carbayo, George R Washko, Raúl San José Estépar
Computed tomography (CT) is a widely used imaging modality for screening and diagnosis. However, the deleterious effects of radiation exposure inherent in CT imaging require the development of image reconstruction methods which can reduce exposure levels. The development of iterative reconstruction techniques is now enabling the acquisition of low-dose CT images whose quality is comparable to that of CT images acquired with much higher radiation dosages. However, the characterization and calibration of the CT signal due to changes in dosage and reconstruction approaches is crucial to provide clinically relevant data...
February 2018: Medical Image Analysis
Shawn Chancy Countryman, Saulo Leonardo Sousa Melo, Manuella Dias Furtado Belem, Francisco Haiter-Neto, Marcos A Vargas, Veeratrishul Allareddy
OBJECTIVES: The aim of this study was to assess whether auto-calibrating medical-grade monitors perform better than off-the-shelf monitors and tablet computers in detecting artificial incipient and recurrent caries-like lesions. STUDY DESIGN: Sixty extracted teeth (30 premolars and 30 molars) were selected. All molars received class II amalgam and composite restorations. A 7-mm2 area on the crowns of half of the teeth was demineralized. Phantoms consisting of 4 teeth were created...
February 2018: Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Alexandra Cristobal-Huerta, Dirk H J Poot, Mika W Vogel, Gabriel P Krestin, Juan A Hernandez-Tamames
PURPOSE: To propose and evaluate new k-space trajectories for 3D-GRASE to improve scan time over 3D-FSE/TSE for high resolution structural imaging. METHODS: Five different Cartesian k-space trajectories were developed and evaluated. They combine ideas of existing k-space trajectories for 3D-GRASE and 3D-FSE/TSE. T2 and T2* are linearly or radially modulated in k-space to achieve the desired contrast while including the autocalibration region needed for the parallel imaging reconstruction technique...
May 2018: Magnetic Resonance Imaging
Antonio Calvo-López, Mar Puyol, Joan Manel Casalta, Julián Alonso-Chamarro
The construction and evaluation of a Cyclic Olefin Copolymer (COC)-based continuous flow potentiometric microanalyzer to simultaneously monitor potassium, chloride and nitrate ions in samples from an on-board water recycling process expected to be installed in future manned space missions is presented. The main goals accomplished in this work address the specific required characteristics for a miniaturized on-line monitoring system to control water quality in such missions. To begin with, the integration of three ion-selective electrodes (ISEs) and a reference electrode in a compact microfluidic platform that incorporates a simple automatic autocalibration process allows obtaining information about the concentration of the three ions with optimal analytical response characteristics, but moreover with low reagents consumption and therefore with few waste generation, which is critical for this specific application...
December 1, 2017: Analytica Chimica Acta
Omair Inam, Mahmood Qureshi, Shahzad A Malik, Hammad Omer
GRAPPA (Generalized Autocalibrating Partially Parallel Acquisition) is a widely used parallel MRI reconstruction technique. The processing of data from multichannel receiver coils may increase the storage and computational requirements of GRAPPA reconstruction. Random projection on GRAPPA (RP-GRAPPA) uses random projection (RP) method to overcome the computational overheads of solving large linear equations in the calibration phase of GRAPPA, saving reconstruction time. However, RP-GRAPPA compromises the reconstruction accuracy in case of large reductions in the dimensions of calibration equations...
2017: BioMed Research International
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