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MR Image Reconstruction

Thomas Huber, Lukas Rotkopf, Benedikt Wiestler, Wolfgang G Kunz, Stefanie Bette, Jens Gempt, Christine Preibisch, Jens Ricke, Claus Zimmer, Jan S Kirschke, Wieland H Sommer, Kolja M Thierfelder
OBJECTIVES: Parameter maps based on wavelet-transform post-processing of dynamic perfusion data offer an innovative way of visualizing blood vessels in a fully automated, user-independent way. The aims of this study were (i) a proof of concept regarding wavelet-based analysis of dynamic susceptibility contrast (DSC) MRI data and (ii) to demonstrate advantages of wavelet-based measures compared to standard cerebral blood volume (CBV) maps in patients with the initial diagnosis of glioblastoma (GBM)...
December 14, 2018: European Radiology
Jiansen Li, Qiegen Liu, Jun Zhao
PURPOSE: A novel method, named Self-Prior Image guided MRI reconstruction with Dictionary LEarning (SPIDLE), is developed to improve the performance of MR imaging with high acceleration rates. "Self-prior" means that the prior image is obtained from the target image itself and any extra MRI scans are not needed. METHODS: The proposed method integrates self-prior image constraint with compressed sensing (CS) and dictionary learning technique. The self-prior image is a preliminary result reconstructed using the undersampled k-space measurements of the target image...
December 13, 2018: Medical Physics
José Richart, Vicente Carmona-Meseguer, Teresa García-Martínez, Antonio Herreros, Antonio Otal, Santiago Pellejero, Ana Tornero-López, José Pérez-Calatayud
Brachytherapy plays an essential role in the curative intent management of locally advanced cervical cancer. The introduction of the magnetic resonance (MR) as a preferred image modality and the development of new type of applicators with interstitial components have further improved its benefits. The aim of this work is to review the current status of one important aspect in the cervix cancer brachytherapy procedure, namely catheter reconstruction. MR compatible intracavitary and interstitial applicators are described...
November 2018: Reports of Practical Oncology and Radiotherapy
Marina Filipovic, Eric Barat, Thomas Dautremer, Claude Comtat, Simon Stute
In PET image reconstruction, it would be useful to obtain the entire posterior probability distribution of the image, because it allows for both estimating image intensity and assessing the uncertainty of the estimation, thus leading to more reliable interpretation. We propose a new entirely probabilistic model: the prior is a distribution over possible smooth regions (distance-driven Chinese restaurant process), and the posterior distribution is estimated using a Gibbs MCMC sampler. Data from other modalities (here one or several MR images) are introduced into the model as additional observed data, providing side information about likely smooth regions in the image...
December 10, 2018: IEEE Transactions on Medical Imaging
Mohammad Shahdloo, Efe Ilicak, Mohammad Tofighi, Emine U Saritas, A Enis Cetin, Tolga Cukur
The compressed sensing (CS) framework leverages the sparsity of MR images to reconstruct from undersampled acquisitions. CS reconstructions involve one or more regularization parameters that weigh sparsity in transform domains against fidelity to acquired data. While parameter selection is critical for reconstruction quality, the optimal parameters are subject and dataset specific. Thus, commonly practiced heuristic parameter selection generalizes poorly to independent datasets. Recent studies have proposed to tune parameters by estimating the risk of removing significant image coefficients...
December 7, 2018: IEEE Transactions on Medical Imaging
Karin Knešaurek, Abbas Tuli, Sara D Pasik, Sherif Heiba, Lale Kostakoglu
OBJECTIVE: The aim of our study was to compare yttrium -90 (90 Y) dosimetry obtained from pre-therapy 99m Tc-macroaggregated albumin (MAA) SPECT/CT versus post-therapy PET/MRI imaging among patients with primary or metastatic hepatic tumors. MATERIALS AND METHODS: Prior to 90 Y radioembolization (RE), 32 patients underwent a scan using MAA mimicking 90 Y distribution. After RE with 90 Y microspheres, the patients were imaged on a PET/MRI system. Reconstructed images were transferred to a common platform and used to calculate 90 Y dosimetry...
December 2018: European Journal of Radiology
Nian Wang, Gary Cofer, Robert J Anderson, Yi Qi, Chunlei Liu, G Allan Johnson
To evaluate the feasibility of compressed sensing (CS) for accelerating quantitative susceptibility mapping (QSM) acquisition in MR histology, control, demyelination, and remyelination mice were scanned using a modified 3D gradient echo pulse sequence (allowing undersampling the k-space in two phase dimensions) at 9.4 T. Fully sampled and compressed sensing data at various acceleration factors (4.0 ~ 16.0) were acquired with high spatial resolution of 22.5 μm3 isotropic. For prospective scans, the local phase was reconstructed slice-by-slice using a nonlinear reconstruction algorithm with phase cycling, and the QSM was calculated using the iLSQR method...
November 15, 2018: Physics in Medicine and Biology
Xiaofeng Yang, Tonghe Wang, Yang Lei, Kristin Higgins, Tian Liu, Hyunsuk Shim, Walter J Curran, Hui Mao, Jonathon A Nye
Deriving accurate attenuation maps for PET/MRI remains a challenging problem because MRI voxel intensities are not related to properties of photon attenuation and bone/air interfaces have similarly low signal. This work presents a learning-based method to derive patient-specific computed tomography (CT) maps from routine T1-weighted MRI in their native space for attenuation correction of brain PET. We developed a machine-learning-based method using a sequence of alternating random forests under the framework of an iterative refinement model...
December 4, 2018: Physics in Medicine and Biology
Xinwei Shi, Evan Levine, Hans Weber, Brian A Hargreaves
PURPOSE: To accelerate imaging near metallic implants with multi-spectral imaging (MSI) techniques by exploiting a signal model in the spectral dimension. METHODS: MSI techniques resolve metal-induced field perturbations by acquiring separate 3D spatial encodings at multiple excitation frequencies, which are referred to as spectral bins. The proposed model-based reconstruction exploits the correlation between spectral bins in image reconstruction by enforcing a signal model to describe the signal profile across bins...
December 4, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Yan Yang, Jian Sun, Huibin Li, Zongben Xu
Compressive sensing (CS) is an effective technique for reconstructing image from a small amount of sampled data. It has been widely applied in medical imaging, remote sensing, image compression, etc. In this paper, we propose two versions of a novel deep learning architecture, dubbed as ADMM-CSNet, by combining the traditional model-based CS method and data-driven deep learning method for image reconstruction from sparsely sampled measurements. We first consider a generalized CS model for image reconstruction with undetermined regularizations in undetermined transform domains, and then two efficient solvers using Alternating Direction Method of Multipliers (ADMM) algorithm for optimizing the model are proposed...
November 28, 2018: IEEE Transactions on Pattern Analysis and Machine Intelligence
Lei Xiang, Yong Chen, Weitang Chang, Yiqiang Zhan, Weili Lin, Qian Wang, Dinggang Shen
T1-weighted image (T1WI) and T2-weighted image (T2WI) are the two routinely acquired magnetic resonance (MR) modalities that can provide complementary information for clinical and research usages. However, the relatively long acquisition time makes the acquired image vulnerable to motion artifacts. To speed up the imaging process, various algorithms have been proposed to reconstruct high-quality images from under-sampled k-space data. However, most of the existing algorithms only rely on mono-modality acquisition for the image reconstruction...
November 29, 2018: IEEE Transactions on Bio-medical Engineering
Xiaomei Yang, Wen Xu, Ruisen Luo, Xiujuan Zheng, Kai Liu
In magnetic resonance (MR) imaging, for highly under-sampled k-space data, it is typically difficult to reconstruct images and preserve their original texture simultaneously. The high-degree total variation (HDTV) regularization handles staircase effects but still blurs textures. On the other hand, the non-local TV (NLTV) regularization can preserve textures, but will introduce additional artifacts for highly-noised images. In this paper, we propose a reconstruction model derived from HDTV and NLTV for robust MRI reconstruction...
November 27, 2018: Magnetic Resonance Imaging
Jisook Yi, Young Han Lee, Ho-Taek Song, Jin-Suck Suh
OBJECTIVES: To investigate the agreement between double-inversion recovery (DIR) with synthetic magnetic resonance imaging (MRI) and T1-weighted contrast-enhanced (CE)-MRI for the assessment of knee synovitis. METHODS: T1-weighted CE-MRI and synthetic MRI of 30 patients were compared. Synthetic DIR image reconstruction was performed with two inversion times (280-330 ms and 2800-2900 ms). Subjective image quality, visibility of synovium, detection of synovitis, and total synovitis score in the knee joint were evaluated on both MR images...
November 28, 2018: European Radiology
Sa Xiao, He Deng, Caohui Duan, Junshuai Xie, Haidong Li, Xianping Sun, Chaohui Ye, Xin Zhou
Hyperpolarized (HP) gas (e.g. 3He or 129Xe) dynamic MRI could visualize the lung ventilation process, which provides characteristics regarding lung physiology and pathophysiology. Compressed sensing (CS) is generally used to increase the temporal resolution of such dynamic MRI. Nevertheless, the acceleration factor of CS is constant, which results in difficulties in precisely observing and/or measuring dynamic ventilation process due to bifurcating network structure of the lung. Here, an adaptive strategy is proposed to highly undersample pulmonary HP dynamic k-space data, according to the characteristics of both lung structure and gas motion...
November 20, 2018: IEEE Transactions on Medical Imaging
Nikolai J Mickevicius, Xinfeng Chen, Zachary Boyd, Hannah J Lee, Geoffrey S Ibbott, Eric S Paulson
Intrafraction motion (i.e. motion occurring during a treatment session) can play a pivotal role in the success of abdominal and thoracic radiation therapy. Hybrid magnetic resonance-guided radiotherapy (MR-gRT) systems have the potential to control for intrafraction motion. Recently, we introduced an MRI sequence capable of acquiring real-time cine imaging in two orthogonal planes (SOPI). We extend SOPI here to permit dynamic updating of slice positions in one-plane while keeping the other plane position fixed...
November 26, 2018: Physics in Medicine and Biology
Jackie Ma, Maximilian März, Stephanie Funk, Jeanette Schulz-Menger, Gitta Kutyniok, Tobias Schaeffter, Christoph Kolbitsch
High-resolution three-dimensional (3D) cardiovascular magnetic resonance (CMR) is a valuable medical imaging technique, but its widespread application in clinical practice is hampered by long acquisition times. Here we present a novel compressed sensing (CS) reconstruction approach using shearlets as a sparsifying transform allowing for fast 3D CMR (3DShearCS) using 3D radial phase encoding (RPE). An iterative reweighting scheme was applied during image reconstruction to ensure fast convergence and high image quality...
November 22, 2018: Physics in Medicine and Biology
Kathryn M Kingsmore, Andrea Vaccari, Daniel Abler, Sophia X Cui, Frederick H Epstein, Russell C Rockne, Scott T Acton, Jennifer M Munson
Glioblastoma (GBM), a highly aggressive form of brain tumor, is a disease marked by extensive invasion into the surrounding brain. Interstitial fluid flow (IFF), or the movement of fluid within the spaces between cells, has been linked to increased invasion of GBM cells. Better characterization of IFF could elucidate underlying mechanisms driving this invasion in vivo . Here, we develop a technique to noninvasively measure interstitial flow velocities in the glioma microenvironment of mice using dynamic contrast-enhanced magnetic resonance imaging (MRI), a common clinical technique...
September 2018: APL bioengineering
Islem Rekik, Gang Li, Weili Lin, Dinggang Shen
In vivo brain connectomics have heavily relied on using functional and diffusion Magnetic Resonance Imaging (MRI) modalities to examine functional and structural relationships between pairs of anatomical regions in the brain. However, research work on brain morphological (i.e., shape-to-shape) connections, which can be derived from T1-w and T2-w MR images, in both typical and atypical development or ageing is very scarce. Furthermore, the brain cannot be only regarded as a static shape, since it is a dynamic complex system that changes at functional, structural and morphological levels...
April 2018: Proceedings of the IEEE International Symposium on Biomedical Imaging: from Nano to Macro
Gerhard S Drenthen, Walter H Backes, Albert P Aldenkamp, Giel J Op 't Veld, Jacobus F A Jansen
PURPOSE: In vivo myelin quantification can provide valuable noninvasive information on neuronal maturation and development, as well as insights into neurological disorders. Multiexponential analysis of multiecho T2 relaxation is a powerful and widely applied method for the quantification of the myelin water fraction (MWF). In recent literature, the MWF is most commonly estimated using a regularized nonnegative least squares algorithm. METHODS: The orthogonal matching pursuit algorithm is proposed as an alternative method for the estimation of the MWF...
November 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Philip M Robson, MariaGiovanna Trivieri, Nicolas A Karakatsanis, Maria Padilla, Ronan Abgral, Marc R Dweck, Jason C Kovacic, Zahi A Fayad
Cardiac positron emission tomography (PET) imaging suffers from image blurring due to the constant motion of the heart that can impact interpretation. Hybrid PET/magnetic resonance (MR) has the potential to use radiation-free MR imaging to correct for the effects of cardio-respiratory motion in the PET data, improving qualitative and quantitative PET imaging in the heart. The purpose of this study was (i) to implement a MR image-based motion-corrected PET/MR method and (ii) to perform a proof-of-concept study of quantitative myocardial PET data in patients...
November 14, 2018: Physics in Medicine and Biology
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