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MR Image Reconstruction

Abolfazl Mehranian, Martin A Belzunce, Colm J McGinnity, Aurelien Bustin, Claudia Prieto, Alexander Hammers, Andrew J Reader
PURPOSE: To propose a framework for synergistic reconstruction of PET-MR and multi-contrast MR data to improve the image quality obtained from noisy PET data and from undersampled MR data. THEORY AND METHODS: Weighted quadratic priors were devised to preserve common boundaries between PET-MR images while reducing noise, PET Gibbs ringing, and MR undersampling artifacts. These priors are iteratively reweighted using normalized multi-modal Gaussian similarity kernels...
October 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Cheng-Chieh Cheng, Frank Preiswerk, W Scott Hoge, Tai-Hsin Kuo, Bruno Madore
PURPOSE: Quantitative parameter maps, as opposed to qualitative grayscale images, may represent the future of diagnostic MRI. A new quantitative MRI method is introduced here that requires a single 3D acquisition, allowing good spatial coverage to be achieved in relatively short scan times. METHODS: A multipathway multi-echo sequence was developed, and at least 3 pathways with 2 TEs were needed to generate T1 , T2 , T2 * , B1 + , and B0 maps. The method required the central k-space region to be sampled twice, with the same sequence but with 2 very different nominal flip angle settings...
October 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Camila Munoz, Radhouene Neji, Karl P Kunze, Stephan G Nekolla, Rene M Botnar, Claudia Prieto
PURPOSE: To develop a framework for efficient and simultaneous acquisition of motion-compensated whole-heart coronary MR angiography (CMRA) and left ventricular function by MR and myocardial integrity by PET on a 3T PET-MR system. METHODS: An acquisition scheme based on a dual-phase CMRA sequence acquired simultaneously with cardiac PET data has been developed. The framework is integrated with a motion-corrected image reconstruction approach, so that non-rigid respiratory and cardiac deformation fields estimated from MR images are used to correct both the CMRA (respiratory motion correction for each cardiac phase) and the PET data (respiratory and cardiac motion correction)...
October 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Abubakr Eldirdiri, Stefan Posse, Lars G Hanson, Rie B Hansen, Pernille Holst, Christina Schøier, Annemarie T Kristensen, Helle Hjorth Johannesen, Andreas Kjaer, Adam E Hansen, Jan Henrik Ardenkjaer-Larsen
Here, we developed a symmetric echo-planar spectroscopic imaging (EPSI) sequence for hyperpolarized 13 C imaging on a clinical hybrid positron emission tomography/magnetic resonance imaging system. The pulse sequence uses parallel reconstruction pipelines to separately reconstruct data from odd-and-even gradient echoes to reduce artifacts from gradient imbalances. The ramp-sampled data in the spatiotemporal frequency space are regridded to compensate for the chemical-shift displacements. Unaliasing of nonoverlapping peaks outside of the sampled spectral width was performed to double the effective spectral width...
September 2018: Tomography: a Journal for Imaging Research
Luisa Altabella, Sara Broggi, Paola Mangili, Gian Marco Conte, Valentina Pieri, Antonella Iadanza, Antonella Del Vecchio, Nicoletta Anzalone, Nadia di Muzio, Riccardo Calandrino, Andrea Falini, Antonella Castellano
INTRODUCTION: Fractionated radiotherapy in brain tumors is commonly associated with several detrimental effects, largely related to the higher radiosensitivity of the white matter (WM) with respect to gray matter. However, no dose constraints are applied to preserve WM structures at present. Magnetic Resonance (MR) Tractography is the only technique that allows to visualize in vivo the course of WM eloquent tracts in the brain. In this study, the feasibility of integrating MR Tractography in tomotherapy treatment planning has been investigated, with the aim to spare eloquent WM regions from the dose delivered during treatment...
October 9, 2018: Physica Medica: PM
Jorge Delgado, Jeffrey I Berman, Carolina Maya, Robert H Carson, Susan J Back, Kassa Darge
BACKGROUND: Ureteropelvic junction (UPJ) obstruction is a common cause of renal injury in children. Indications for surgery are still controversial. Currently, there is no threshold to differentiate patients with suspected UPJ obstruction requiring surgery from the ones that do not, or to predict renal outcome after surgery. Several studies have demonstrated that diffusion tensor imaging (DTI) results may correlate with microstructural changes in the kidneys. OBJECTIVE: To evaluate the feasibility of using DTI to identify UPJ obstruction kidneys...
October 8, 2018: Pediatric Radiology
James Bland, Martin A Belzunce, Sam Ellis, Colm J McGinnity, Alexander Hammers, Andrew J Reader
Positron emission tomography (PET) is a highly sensitive functional and molecular imaging modality which can measure picomolar concentrations of an injected radionuclide. However, the physical sensitivity of PET is limited, and reducing the injected dose leads to low count data and noisy reconstructed images. A highly effective way of reducing noise is to reparameterise the reconstruction in terms of MR-derived spatial basis functions. Spatial basis functions derived using the kernel method have demonstrated excellent noise reduction properties and maintain shared PET-MR detailed structures...
September 2018: IEEE Transactions on Radiation and Plasma Medical Sciences
Jihye Jang, Cory M Tschabrunn, Michael Barkagan, Elad Anter, Bjoern Menze, Reza Nezafat
Visualization of the complex 3D architecture of myocardial scar could improve guidance of radio-frequency ablation in the treatment of ventricular tachycardia (VT). In this study, we sought to develop a framework for 3D holographic visualization of myocardial scar, imaged using late gadolinium enhancement (LGE), on the augmented reality HoloLens. 3D holographic LGE model was built using the high-resolution 3D LGE image. Smooth endo/epicardial surface meshes were generated using Poisson surface reconstruction...
2018: PloS One
Bo Zhao, Justin P Haldar, Congyu Liao, Dan Ma, Yun Jiang, Mark A Griswold, Kawin Setsompop, Lawrence L Wald
Magnetic resonance (MR) fingerprinting is a new quantitative imaging paradigm, which simultaneously acquires multiple MR tissue parameter maps in a single experiment. In this paper, we present an estimation-theoretic framework to perform experiment design for MR fingerprinting. Specifically, we describe a discrete-time dynamic system to model spin dynamics, and derive an estimation-theoretic bound, i.e., the Cramér-Rao bound (CRB), to characterize the signal-to-noise ratio (SNR) efficiency of an MR fingerprinting experiment...
October 4, 2018: IEEE Transactions on Medical Imaging
Mark Bydder, Wafaa Zaaraoui, Ben Ridley, Manon Soubrier, Marie Bertinetti, Sylviane Confort-Gouny, Lothar Schad, Maxime Guye, Jean-Philippe Ranjeva
A novel magnetic resonance imaging (MRI) acquisition and reconstruction method for obtaining a series of dynamic sodium 23 Na-MRI acquisitions was designed to non-invasively assess the signal variations of brain sodium during a hand motor task in 14 healthy human volunteers on an ultra high field (7T) MR scanner. Regions undergoing activation and deactivation were identified with reference to conventional task-related BOLD functional MRI (fMRI). Activation observed in the left central regions, the supplementary motor areas and the left cerebellum induced an increase in the sodium signal observed at ultra short echo time and a decrease in the 23 Na signal observed at long echo time...
October 4, 2018: NeuroImage
Ziying Yin, Anthony J Romano, Armando Manduca, Richard L Ehman, John Huston
Brain magnetic resonance elastography (MRE) was developed on the basis of a desire to "palpate by imaging" and is becoming a powerful tool in the investigation of neurophysiological and neuropathological states. Measurements are acquired with a specialized MR phase-contrast pulse sequence that can detect tissue motion in response to an applied external or internal excitation. The tissue viscoelasticity is then reconstructed from the measured displacement. Quantitative characterization of brain viscoelastic behaviors provides us an insight into the brain structure and function by assessing the mechanical rigidity, viscosity, friction, and connectivity of brain tissues...
October 2018: Topics in Magnetic Resonance Imaging: TMRI
Ethan Zaccagnino, Craig Devincent, Nattinee Leelakanok, Andrew S Phelps, Matthew Zapala, Pauline Wong Worters, Jesse Courtier
INTRODUCTION: Elevated acoustic noise during Magnetic Resonance Imaging (MRI) has been associated with patient anxiety and altered cochlear function. Acoustic Reduction Technique (ART) T2 weighted (T2w) periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) has been studied in brain MR but not abdominopelvic imaging. The purpose of our study was to evaluate the image quality and acoustic noise level of ART T2w PROPELLER sequence in comparison with the conventional T2w PROPELLER sequence in pediatric abdomino-pelvic imaging...
September 26, 2018: Clinical Imaging
Limin Li, Alice M Wyrwicz
We report the design and implementation of a parallel two-dimensional fast Fourier transform (2D FFT) algorithm on a Field Programmable Gate Array (FPGA) for real-time MR image processing. Although a number of architectures of 2D FFT hardware processors have been reported, these generic processors or IP cores are not always effective for processing MRI data. The key feature of our design is that our processors are customized solely for real-time MRI applications. We demonstrate that by considering the unique features of real-time MRI data streams, we were able to develop and implement the 2D FFT processors that are resource-efficient and flexible enough to handle both regular and irregular data...
September 2018: Review of Scientific Instruments
Madison Kretzler, Jesse Hamilton, Mark Griswold, Nicole Seiberlich
Non-Cartesian trajectories are advantageous in the collection and reconstruction of dynamic MR images. Like many other fast imaging methods, the reconstruction technique k-t BLAST has been extended to non-Cartesian k-t BLAST through a Conjugate Gradient based approach. However, it is necessary to transform and grid the data to a Cartesian domain as part of the reconstruction, a process which can be time consuming and computationally intensive. In this manuscript, a new non-iterative reconstruction, a-f BLAST, is proposed to extend k-t BLAST to radial sampling...
September 27, 2018: IEEE Transactions on Medical Imaging
Cristina Falcinelli, Zhi Li, Wilfred W Lam, Greg J Stanisz, Anne M Agur, Cari M Whyne
Accurate characterization of the craniomaxillofacial (CMF) skeleton using finite element (FE) modeling requires representation of complex geometries, heterogeneous material distributions, and physiological loading. Musculature in CMF FE models are often modeled with simple link elements that do not account for fiber bundles (FBs) and their differential activation. Magnetic resonance (MR) diffusion-tensor imaging (DTI) enables reconstruction of the three-dimensional (3D) FB arrangement within a muscle. However, 3D quantitative validation of DTI-generated FBs is limited...
November 1, 2018: Journal of Biomechanical Engineering
Georg R Spinner, Johannes F M Schmidt, Constantin von Deuster, Christian Federau, Christian T Stoeck, Sebastian Kozerke
Intravoxel incoherent motion (IVIM) imaging of diffusion and perfusion parameters in the brain using parallel imaging suffers from local noise amplification. To address the issue, signal correlations in space and along the diffusion encoding dimension are exploited jointly using a constrained image reconstruction approach. IVIM imaging was performed on a clinical 3 T MR system with diffusion weighting along six gradient directions and 16 b-values encoded per direction across a range of 0-900 s/mm2 . Data were collected in 11 subjects, retrospectively undersampled in k-space with net factors ranging from 2 to 6 and reconstructed using CG-SENSE and the proposed k-b PCA approach...
September 28, 2018: NMR in Biomedicine
Evan McNabb, Raimond Wong, Michael D Noseworthy
Magnetic resonance imaging (MRI) has superior soft tissue contrast and lower interobserver variability compared to computed tomography and advances in equipment and pseudo-CT estimation have allowed for MR-only radiation therapy planning. Dedicated MR sequences have been used to localize paramagnetic structures with positive contrast, and most implanted seeds are gold fiducial markers (GFMs). We used a fast, dual-plane co-RASOR sequence to localize implanted GFMs with positive contrast in phantom and tissue to
 assess their resolution and registration accuracy of registration to CT...
September 27, 2018: Physics in Medicine and Biology
Brian J Lee, Ronald D Watkins, Keum Sil Lee, Chen-Ming Chang, Craig S Levin
PURPOSE: An "RF-penetrable" PET insert that allows the MR body coil to be used for RF transmission was developed to make it easier for an existing MR center to achieve simultaneous PET/MRI. This study focuses on experiments and analyses to study PET/RF coil configurations for simultaneous PET/MR studies. METHODS: To investigate the appropriate RF coil design, a transmit/receive (TX/RX) birdcage coil and an RX-only phased-array coil (TX from body coil), both fitting inside the PET ring were built and characterized...
September 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Naoko Mori, Keiko Tsuchiya, Deepa Sheth, Shunji Mugikura, Kei Takase, Ulrich Katscher, Hiroyuki Abe
OBJECTIVES: To evaluate the diagnostic utility of electric properties tomography (EPT) in differentiating benign from malignant breast lesions in comparison with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS: In this institutional review board-approved retrospective study, 116 consecutive patients with 141 breast lesions (50 benign and 91 malignant) underwent 3-T MRI, including 3D turbo-spin echo (TSE) sequence and standard DCE-MRI scans between January 2014 and January 2017...
September 25, 2018: European Radiology
Li Feng, Jean Delacoste, David Smith, Joseph Weissbrot, Eric Flagg, William H Moore, Francis Girvin, Roy Raad, Priya Bhattacharji, David Stoffel, Davide Piccini, Matthias Stuber, Daniel K Sodickson, Ricardo Otazo, Hersh Chandarana
BACKGROUND: Computed tomography (CT) and spirometry are the current standard methods for assessing lung anatomy and pulmonary ventilation, respectively. However, CT provides limited ventilation information and spirometry only provides global measures of lung ventilation. Thus, a method that can enable simultaneous examination of lung anatomy and ventilation is of clinical interest. PURPOSE: To develop and test a 4D respiratory-resolved sparse lung MRI (XD-UTE: eXtra-Dimensional Ultrashort TE imaging) approach for simultaneous evaluation of lung anatomy and pulmonary ventilation...
September 25, 2018: Journal of Magnetic Resonance Imaging: JMRI
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