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MR Image Reconstruction

Tianbin Song, Bixiao Cui, Hongwei Yang, Jie Ma, Dongmei Shuai, Zhongwei Chen, Zhigang Liang, Yun Zhou, Jie Lu
OBJECTIVES: To investigate the value of diffusion-weighted imaging (DWI) in detection of small lesions (≤ 10 mm) in patients with primary abdominal and pelvic cancer in hybrid PET/MR with or without time-of-flight (TOF) technique. MATERIALS AND METHODS: Twenty patients (11 females and 9 males, mean age 67.23 ± 12.90 years) with histologically confirmed primary abdominal and pelvic cancer underwent hybrid PET/MR examination. A total of 64 small lesions were included in this study, which were divided into two groups (≤ 10 mm and 10-30 mm)...
March 12, 2019: Abdominal Radiology
Fang Liu, Li Feng, Richard Kijowski
PURPOSE: To develop and evaluate a novel deep learning-based image reconstruction approach called MANTIS (Model-Augmented Neural neTwork with Incoherent k-space Sampling) for efficient MR parameter mapping. METHODS: MANTIS combines end-to-end convolutional neural network (CNN) mapping, incoherent k-space undersampling, and a physical model as a synergistic framework. The CNN mapping directly converts a series of undersampled images straight into MR parameter maps using supervised training...
March 12, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Daeun Kim, Jessica L Wisnowski, Christopher T Nguyen, Justin P Haldar
Quantitative MR relaxometry can provide unique subvoxel information about the microscopic tissue compartments that are present in a large imaging voxel. However, unambiguously distinguishing between these tissue compartments continues to be challenging with conventional methods due to the illposedness of the inverse problem. This paper describes a new imaging approach, which we call T 1 Relaxation- T 2 Relaxation Correlation Spectroscopic Imaging (RR-CSI), that uses two-dimensional relaxation encoding combined with spatially-constrained reconstruction to help overcome illposedness...
April 2018: Proceedings of the IEEE International Symposium on Biomedical Imaging: from Nano to Macro
Alejandro Santos-Díaz, Michael D Noseworthy
Phosphorus MR spectroscopy and spectroscopic imaging (31 P-MRS/MRSI) provide information about energy metabolism, membrane degradation and pH in vivo. In spite of their proven utility, 31 P-MRS/MRSI are not often used primarily because of the challenges imposed by the low sensitivity and low concentration of metabolites leading to low signal to noise ratio (SNR), coarse spatial resolution and prolonged acquisition time. More recently there has been considerable interest in compressed sensing as an acceleration method for MR signal acquisition...
March 7, 2019: Magnetic Resonance Imaging
Cihan Göksu, Klaus Scheffler, Hartwig R Siebner, Axel Thielscher, Lars G Hanson
PURPOSE: MR Current Density Imaging (MRCDI) involves weak current-injection into the head. The resulting magnetic field changes are measured by MRI. Stray fields pose major challenges since these can dominate the fields caused by tissue currents. We analyze the sources and influences of stray fields. METHODS: First, we supply validation data for a recently introduced MRCDI method with an unprecedented noise floor of ∼0.1 nT in vivo. Second, we assess the accuracy limit of the method and our corresponding cable current correction in phantoms ensuring high signal-to-noise ratio (SNR)...
March 7, 2019: Physica Medica: PM
Arjuna Somanathan, Ankit Tandon, Lim Wei Yang
The anterior cruciate ligament (ACL) is an important stabiliser of the knee and is commonly torn in sports injuries. Common indications for imaging after ACL reconstruction include persistent symptoms, limitation of motion and re-injury. Important postoperative complications include graft failure, impingement, arthrofibrosis and graft degeneration. This article aimed to familiarise the radiologist with magnetic resonance (MR) imaging appearances of properly positioned intact ACL grafts and to provide a comprehensive review of MR imaging features of complications following ACL reconstruction...
February 2019: Singapore Medical Journal
Ute Lina Fahlenkamp, Günther Engel, Lisa Christine Adams, Sarah Maria Böker, Minh Huynh Anh, Moritz Wagner, Bernd Hamm, Marcus Richard Makowski
BACKGROUND: Detection of metastases can have a significant impact on therapy. Nevertheless, even in gadoxetate disodium-enhanced MR scans, very small hepatic metastases may be difficult to see. PURPOSE: To investigate the potential of a contrast-optimised (phase-sensitive) inversion recovery MR sequence in gadoxetate disodium-enhanced scans for detection of hepatic metastases. MATERIALS AND METHODS: With institutional review board approval and after written informed consent, 40 patients (18 male, 22 female) with suspected or known hepatic metastases were examined on a 1...
2019: PloS One
Neerav Karani, Lin Zhang, Christine Tanner, Ender Konukoglu
Navigated 2D multi-slice dynamic Magnetic Resonance (MR) imaging enables high contrast 4D MR imaging during free breathing and provides in-vivo observations for treatment planning and guidance. Navigator slices are vital for retrospective stacking of 2D data slices in this method. However, they also prolong the acquisition sessions. Temporal interpolation of navigator slices can be used to reduce the number of navigator acquisitions without degrading specificity in stacking. In this work, we propose a convolutional neural network (CNN) based method for temporal interpolation, with motion field prediction as an intermediate step...
February 13, 2019: Medical Image Analysis
Robert Frost, Paul Wighton, F Işık Karahanoğlu, Richard L Robertson, P Ellen Grant, Bruce Fischl, M Dylan Tisdall, André van der Kouwe
PURPOSE: To integrate markerless head motion tracking with prospectively corrected neuroanatomical MRI sequences and to investigate high-frequency motion correction during imaging echo trains. METHODS: A commercial 3D surface tracking system, which estimates head motion by registering point cloud reconstructions of the face, was used to adapt the imaging FOV based on head movement during MPRAGE and T2 SPACE (3D variable flip-angle turbo spin-echo) sequences. The FOV position and orientation were updated every 6 lines of k-space (< 50 ms) to enable "within-echo-train" prospective motion correction (PMC)...
February 28, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Guilhem J Collier, Paul J C Hughes, Felix C Horn, Ho-Fung Chan, Bilal Tahir, Graham Norquay, Neil J Stewart, Jim M Wild
PURPOSE: To develop and assess a method for acquiring coregistered proton anatomical and hyperpolarized 129 Xe ventilation MR images of the lungs with compressed sensing (CS) in a single breath hold. METHODS: Retrospective CS simulations were performed on fully sampled ventilation images acquired from one healthy smoker to optimize reconstruction parameters. Prospective same-breath anatomical and ventilation images were also acquired in five ex-smokers with an acceleration factor of 3 for hyperpolarized 129 Xe images, and were compared to fully sampled images acquired during the same session...
February 28, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Daniel Deidda, Nicolas A Karakatsanis, Philip M Robson, Claudia Calcagno, Max L Senders, Willem J M Mulder, Zahi A Fayad, Robert G Aykroyd, Charalampos Tsoumpas
Positron emission tomography (PET) provides simple noninvasive imaging biomarkers for multiple human diseases which can be used to produce quantitative information from single static images or to monitor dynamic processes. Such kinetic studies often require the tracer input function (IF) to be measured but, in contrast to direct blood sampling, the image-derived input function (IDIF) provides a noninvasive alternative technique to estimate the IF. Accurate estimation can, in general, be challenging due to the partial volume effect (PVE), which is particularly important in preclinical work on small animals...
2019: Contrast Media & Molecular Imaging
Christine S Kim, Umesh Patel, Gaetano Pastena, Mamie Higgins, Maria Peris-Celda, Tyler J Kenning, Carlos D Pinheiro-Neto
OBJECTIVE: At our institution, skull base reconstruction using a free mucosal graft from the nasal cavity floor has been the standardized technique after pituitary adenoma resection via transsellar approach. This study describes the expected appearance of the reconstruction on postoperative MRI scans and assesses its integrity and impact on the sinonasal cavity. METHODS: Fifty patients were selected, and their EMR were reviewed for postoperative course, SNOT-22 scores, and nasal endoscopy reports...
February 19, 2019: World Neurosurgery
Kimberly L Chan, Georg Oeltzschner, Muhammad G Saleh, Richard A E Edden, Peter B Barker
PURPOSE: To evaluate the feasibility of simultaneous MR spectroscopic imaging (MRSI) of gamma-aminobutyric acid (GABA) and glutathione (GSH) in the human brain using Hadamard Encoding and Reconstruction of MEGA-Edited Spectroscopy (HERMES). METHODS: Point RESolved Spectroscopy (PRESS)-localized MRSI was performed in GABA and GSH phantoms and in the human brain (n = 3) using HERMES editing and compared to conventional MEGA editing of each metabolite. Multiplet patterns, signal intensities, and metabolite crosstalk were compared between methods...
February 22, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Venkata Veerendranadh Chebrolu, Peter D Kollasch, Vibhas Deshpande, John Grinstead, Benjamin M Howe, Matthew A Frick, Andrew J Fagan, Thomas Benner, Robin M Heidemann, Joel P Felmlee, Kimberly K Amrami
BACKGROUND: MR image intensity nonuniformity is often observed at 7T. Reference scans from the body coil used for uniformity correction at lower field strengths are typically not available at 7T. PURPOSE: To evaluate the efficacy of a novel algorithm, Uniform Combined Reconstruction (UNICORN), to correct receive coil-induced nonuniformity in musculoskeletal 7T MRI without the use of a reference scan. STUDY TYPE: Retrospective image analysis study...
February 19, 2019: Journal of Magnetic Resonance Imaging: JMRI
Jisook Yi, Young Han Lee, Seok Hahn, Salman S Albakheet, Ho-Taek Song, Jin-Suck Suh
OBJECTIVES: To investigate the feasibility of three-dimensional fast spin echo (3D-FSE) imaging with compressed sensing (CS) and parallel imaging (PI) compared to 3D-FSE imaging with only PI in evaluating ankle joint pathologies. MATERIALS AND METHODS: Twenty consecutive patients underwent ankle magnetic resonance imaging (MRI), including acquisition of image sets of 2D-FSE sequences, and 3D-FSE sequences without and with CS, between June 2016 and November 2017...
March 2019: European Journal of Radiology
Gilbert Hangel, Saurabh Jain, Elisabeth Springer, Eva Hečková, Bernhard Strasser, Michal Považan, Stephan Gruber, Georg Widhalm, Barbara Kiesel, Julia Furtner, Matthias Preusser, Thomas Roetzer, Siegfried Trattnig, Diana M Sima, Dirk Smeets, Wolfgang Bogner
OBJECTIVES: To demonstrate the feasibility of 7 T magnetic resonance spectroscopic imaging (MRSI), combined with patch-based super-resolution (PBSR) reconstruction, for high-resolution multi-metabolite mapping of gliomas. MATERIALS AND METHODS: Ten patients with WHO grade II, III and IV gliomas (6/4, male/female; 45 ± 9 years old) were prospectively measured between 2014 and 2018 on a 7 T whole-body MR imager after routine 3 T magnetic resonance imaging (MRI) and positron emission tomography (PET)...
February 14, 2019: NeuroImage
Vineeta Das, Samarendra Dandapat, Prabin Kumar Bora
Advancements in tele-medicine have led to the development of portable and cheap hand-held retinal imaging devices. However, the images obtained from these devices have low resolution (LR) and poor quality that may not be suitable for retinal disease diagnosis. Therefore, this paper proposes a novel framework for the super-resolution (SR) of the LR fundus images. The method takes into consideration the diagnostic information in the fundus images during the SR process. In this work, SR is performed on the zone of interest of the fundus images...
February 1, 2019: Computerized Medical Imaging and Graphics: the Official Journal of the Computerized Medical Imaging Society
Sean Iain Docking, Jill Cook, Stephanie Chen, Jennie Scarvell, Wes Cormick, Paul Smith, Angela Fearon
BACKGROUND: It has been suggested that imaging findings play a role in directing treatment for Greater Trochanteric Pain Syndrome. Structural diagnoses associated with Greater Trochanter Pain Syndrome include gluteal tendinosis, and partial- or full-thickness gluteal tendon tears. However, few studies have compared imaging to confirmed tendon pathology observed during surgery. OBJECTIVE: To investigate the ability of magnetic resonance and ultrasound imaging to identify the presence of a pathological gluteus medius tendon in comparison to surgical and histological findings...
February 7, 2019: Musculoskeletal Science & Practice
Martin Lyngby Lassen, Thomas Beyer, Alexander Berger, Dietrich Beitzke, Sazan Rasul, Florian Büther, Marcus Hacker, Jacobo Cal-González
BACKGROUND: Respiratory patient motion causes blurring of the PET images that may impact accurate quantification of perfusion and infarction extents in PET myocardial viability studies. In this study, we investigate the feasibility of correcting for respiratory motion directly in the PET-listmode data prior to image reconstruction using a data-driven, projection-based, respiratory motion compensation (DPR-MoCo) technique. METHODS: The DPR-MoCo method was validated using simulations of a XCAT phantom (Biograph mMR PET/MR) as well as experimental phantom acquisitions (Biograph mCT PET/CT)...
February 13, 2019: Journal of Nuclear Cardiology: Official Publication of the American Society of Nuclear Cardiology
Soraya Gavazzi, Cornelis A T van den Berg, Alessandro Sbrizzi, H Petra Kok, Lukas J A Stalpers, Jan J W Lagendijk, Hans Crezee, Astrid L H M W van Lier
PURPOSE: To investigate the sequence-specific impact of <mml:math xmlns:mml=""> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> amplitude mapping on the accuracy and precision of permittivity reconstruction at 3T in the pelvic region. METHODS: <mml:math xmlns:mml=""> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> maps obtained with actual flip angle imaging (AFI), Bloch-Siegert (BS), and dual refocusing echo acquisition mode (DREAM) sequences, set to a clinically feasible scan time of 5 minutes, were compared in terms of accuracy and precision with electromagnetic and Bloch simulations and MR measurements...
February 8, 2019: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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