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Echo planar

Lin Cheng, Matthew D Blackledge, David J Collins, Matthew R Orton, Neil P Jerome, Thorsten Feiweier, Mihaela Rata, Veronica Morgan, Nina Tunariu, Martin O Leach, Dow-Mu Koh
PURPOSE: To introduce T2-adjusted computed DWI (T2-cDWI), a method that provides synthetic images at arbitrary b-values and echo times (TEs) that improve tissue contrast by removing or increasing T2 contrast in diffusion-weighted images. MATERIALS AND METHODS: In addition to the standard DWI acquisition protocol T2-weighted echo-planar images at multiple (≥2) echo times were acquired. This allows voxelwise estimation of apparent diffusion coefficient (ADC) and T2 values, permitting synthetic images to be generated at any chosen b-value and echo time...
October 1, 2016: Computers in Biology and Medicine
Bertram J Wilm, Christoph Barmet, Simon Gross, Lars Kasper, S Johanna Vannesjo, Max Haeberlin, Benjamin E Dietrich, David O Brunner, Thomas Schmid, Klaas P Pruessmann
PURPOSE: The purpose of this work was to improve the quality of single-shot spiral MRI and demonstrate its application for diffusion-weighted imaging. METHODS: Image formation is based on an expanded encoding model that accounts for dynamic magnetic fields up to third order in space, nonuniform static B0 , and coil sensitivity encoding. The encoding model is determined by B0 mapping, sensitivity mapping, and concurrent field monitoring. Reconstruction is performed by iterative inversion of the expanded signal equations...
October 21, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Zhe Zhang, Bing Zhang, Ming Li, Xue Liang, Xiaodong Chen, Renyuan Liu, Xin Zhang, Hua Guo
PURPOSE: To report a diffusion imaging technique insensitive to off-resonance artifacts and motion-induced ghost artifacts using mulitshot Cartesian turbo spin-echo (TSE) acquisition and iterative POCS-based reconstruction of multiplexed sensitivity encoded magnetic resonance imaging (MRI) (POCSMUSE) for phase correction. MATERIALS AND METHODS: Phase insensitive diffusion preparation was used to deal with the violation of the Carr-Purcell-Meiboom-Gill (CPMG) conditions of TSE diffusion-weighted imaging (DWI), followed by a mulitshot Cartesian TSE readout for data acquisition...
October 20, 2016: Journal of Magnetic Resonance Imaging: JMRI
Andreas Fehlner, Sebastian Hirsch, Martin Weygandt, Thomas Christophel, Eric Barnhill, Mykola Kadobianskyi, Jürgen Braun, Johannes Bernarding, Ralf Lützkendorf, Ingolf Sack, Stefan Hetzer
PURPOSE: To improve the resolution of elasticity maps by adapting motion and distortion correction methods for phase-based magnetic resonance imaging (MRI) contrasts such as magnetic resonance elastography (MRE), a technique for measuring mechanical tissue properties in vivo. MATERIALS AND METHODS: MRE data of the brain were acquired with echo-planar imaging (EPI) at 3T (n = 14) and 7T (n = 18). Motion and distortion correction parameters were estimated using the magnitude images...
October 20, 2016: Journal of Magnetic Resonance Imaging: JMRI
Daniel Stäb, Steffen Bollmann, Christian Langkammer, Kristian Bredies, Markus Barth
With the advent of ultra-high field MRI scanners in clinical research, susceptibility based MRI has recently gained increasing interest because of its potential to assess subtle tissue changes underlying neurological pathologies/disorders. Conventional, but rather slow, three-dimensional (3D) spoiled gradient-echo (GRE) sequences are typically employed to assess the susceptibility of tissue. 3D echo-planar imaging (EPI) represents a fast alternative but generally comes with echo-time restrictions, geometrical distortions and signal dropouts that can become severe at ultra-high fields...
October 20, 2016: NMR in Biomedicine
Hideaki Kaneko, Shuo Zhang, Miho Sekiguchi, Takuya Nikaido, Koshi Makita, Jiro Kurata, Shin-Ichi Konno
STUDY DESIGN: Cross-sectional study. OBJECTIVE: To evaluate activity of the nucleus accumbens (NAc) in response to lumbar mechanical stimulation in patients with chronic low back pain (cLBP) using functional magnetic resonance imaging (fMRI). SUMMARY OF BACKGROUND DATA: Although a modified activity of the NAc was characterized in cLBP patients, its pathological significance has yet to be determined. We hypothesized that NAc activation in response to pain might differ depending on the extent of psychiatric problems, which might be associated with the affective/motivational background of chronic pain...
October 17, 2016: Spine
Asanori Kiyuna, Norimoto Kise, Munehisa Hiratsuka, Shunsuke Kondo, Takayuki Uehara, Hiroyuki Maeda, Akira Ganaha, Mikio Suzuki
OBJECTIVES: Spasmodic dysphonia (SD) is considered a focal dystonia. However, the detailed pathophysiology of SD remains unclear, despite the detection of abnormal activity in several brain regions. The aim of this study was to clarify the pathophysiological background of SD. STUDY DESIGN: This is a case-control study. METHODS: Both task-related brain activity measured by functional magnetic resonance imaging by reading the five-digit numbers and resting-state functional connectivity (FC) measured by 150 T2-weighted echo planar images acquired without any task were investigated in 12 patients with adductor SD and in 16 healthy controls...
October 13, 2016: Journal of Voice: Official Journal of the Voice Foundation
Marios C Yiannakas, Francesco Grussu, Polymnia Louka, Ferran Prados, Rebecca S Samson, Marco Battiston, Daniel R Altmann, Sebastien Ourselin, David H Miller, Claudia A M Gandini Wheeler-Kingshott
Diffusion tensor imaging (DTI) has recently started to be adopted into clinical investigations of spinal cord (SC) diseases. However, DTI applications to the lower SC are limited due to a number of technical challenges, related mainly to the even smaller size of the SC structure at this level, its position relative to the receiver coil elements and the effects of motion during data acquisition. Developing methods to overcome these problems would offer new means to gain further insights into microstructural changes of neurological conditions involving the lower SC, and in turn could help explain symptoms such as bladder and sexual dysfunction...
2016: PloS One
B F Kjølby, A R Khan, A Chuhutin, L Pedersen, J B Jensen, S Jakobsen, D Zeidler, R Sangill, J R Nyengaard, S N Jespersen, B Hansen
Diffusion kurtosis imaging (DKI) is sensitive to tissue microstructure and may therefore be useful in the diagnosis and monitoring of disease in brain and body organs. Generally, diffusion magnetic resonance imaging (dMRI) in the body is challenging because of the heterogeneous body composition, which can cause image artefacts as a result of chemical shifts and susceptibility differences. In addition, the abdomen possesses physiological factors (e.g. breathing, heartbeat, blood flow) which may severely reduce image quality, especially when echo planar imaging is employed, as is typical in dMRI...
October 12, 2016: NMR in Biomedicine
Nicola Schieda, Christopher S Lim, Muhammad Idris, Robert S Lim, Christopher Morash, Rodney H Breau, Trevor A Flood, Matthew D F McInnes
PURPOSE: To evaluate magnetic resonance imaging (MRI) for assessment of extraprostatic extension (EPE) and positive surgical margins (PSM) in anterior prostate cancer (APC). MATERIALS AND METHODS: With Institutional Review Board approval, 25 APC (>2/3 of tumor anterior to urethra) were assessed using 3T MRI by two blinded radiologists for: size and maximal leading edge of tumor (relative to anterior fibromuscular stroma [AFMS]) on b ≥1000 sec/mm(2) echo-planar-MRI fused onto T2 -weighted-MRI, invasion of AFMS and EPE...
October 11, 2016: Journal of Magnetic Resonance Imaging: JMRI
Robert J Harris, Timothy F Cloughesy, Linda M Liau, Phioanh L Nghiemphu, Albert Lai, Whitney B Pope, Benjamin M Ellingson
Acidity within the extracellular milieu is a hallmark of cancer. There is a current need for fast, high spatial resolution pH imaging techniques for clinical evaluation of cancers, including gliomas. Chemical exchange saturation transfer (CEST) MRI targeting fast-exchanging amine protons can be used to obtain high-resolution pH-weighted images, but conventional CEST acquisition strategies are slow. There is also a need for more accurate MR simulations to better understand the effects of amine CEST pulse sequence parameters on pH-weighted image contrast...
September 15, 2016: NMR in Biomedicine
Suraj D Serai, Jonathan R Dillman, Andrew T Trout
Purpose To compare two-dimensional (2D) gradient-recalled echo (GRE) and 2D spin-echo (SE) echo-planar imaging (EPI) magnetic resonance (MR) elastography for measurement of hepatic stiffness in pediatric and young adult patients suspected of having liver disease. Materials and Methods In this institutional review board-approved, HIPAA-compliant study, 58 patients underwent both 2D GRE and 2D SE-EPI MR elastography at 1.5 T during separate breath holds. Liver stiffness (mean of means; in kilopascals) was measured by five blinded reviewers...
October 10, 2016: Radiology
Bruce A Bowser, Norbert G Campeau, Carrie M Carr, Felix E Diehn, Jennifer S McDonald, Gary M Miller, Timothy J Kaufmann
INTRODUCTION: Ferumoxytol (Feraheme) is a parenteral therapy approved for treatment of iron deficiency anemia. The product insert for ferumoxytol states that it may affect the diagnostic ability of MRI for up to 3 months. However, the expected effects may not be commonly recognized among clinical neuroradiologists. Our purpose is to describe the artifacts we have seen at our institution during routine clinical practice. METHODS: We reviewed the patients at our institution that had brain MRI performed within 90 days of receiving intravenous ferumoxytol...
October 4, 2016: Neuroradiology
Burak Akin, Hsu-Lei Lee, Jürgen Hennig, Pierre LeVan
Resting-state networks have become an important tool for the study of brain function. An ultra-fast imaging technique that allows to measure brain function, called Magnetic Resonance Encephalography (MREG), achieves an order of magnitude higher temporal resolution than standard echo-planar imaging (EPI). This new sequence helps to correct physiological artifacts and improves the sensitivity of the fMRI analysis. In this study, EPI is compared with MREG in terms of capability to extract resting-state networks...
October 3, 2016: Human Brain Mapping
H Sun, P Seres, A H Wilman
Standard functional MRI (fMRI), which includes resting-state or paradigm-driven designs, is widely used in studies of brain function, aging, and disease. These fMRI studies typically use two-dimensional gradient echo-planar imaging, which inherently contains phase data that enables quantitative susceptibility mapping (QSM). This work focuses on the dual value of QSM within fMRI studies, by providing both a localized analysis of functional changes in activated tissue, and iron-sensitive structural maps in deep grey matter (DGM)...
September 30, 2016: NMR in Biomedicine
T Bakaj, L Bakaj Zbrozkova, R Salzman, M Tedla, I Starek
OBJECTIVES: To investigate the correlation between preoperative non-echo planar diffusion-weighted (non-EPI DWI) MR imaging with surgical findings of recidivous middle ear cholesteatoma after canal wall up (CWU) and canal wall down (CWD) mastoidectomy. BACKGROUND: The detection of recidive cholesteatoma after CWU and after CWD procedures, when the trepanation cavity is spontaneously closed by soft tissue, is possible by second-look and revision surgery. However, many cases prove to be negative of the disease...
2016: Bratislavské Lekárske Listy
Chun-Chao Xia, Xi Liu, Wan-Lin Peng, Lei Li, Jin-Ge Zhang, Wen-Jian Meng, Xiang-Bing Deng, Pan-Li Zuo, Zhen-Lin Li
PURPOSE: To determine whether readout-segmented echo-planar imaging (rs-EPI) diffusion-weighted imaging (DWI) can improve the image quality in patients with rectal cancer compared with single-shot echo-planar imaging (ss-EPI) DWI using 3.0 T magnetic resonance (MR) imaging. MATERIALS AND METHODS: This study was approved by the Institutional Review Board, and informed consent was obtained from all patients. Seventy-one patients with rectal cancer were enrolled in this study...
October 2016: European Journal of Radiology
Yong-Lan He, Daniel Hausmann, John N Morelli, Ulrike I Attenberger, Stefan O Schoenberg, Philipp Riffel
PURPOSE: To evaluate the feasibility and clinical robustness of zoomed diffusion-weighted echo planar imaging (z-EPI) relative to conventional single-shot EPI (c-EPI) for DWI of the kidneys. MATERIALS AND METHODS: This retrospective study was approved by the institutional research ethics board. 66 patients (median age 58.5 years±13.4, range 23-83 years, 45 men, 21 women) undergoing 3T (Magnetom Skyra(®), Siemens Healthcare, Erlangen, Germany) using a dynamic parallel transmit array (TimTX TrueShape, Siemens Healthcare, Erlangen, Germany) for renal MRI were included in this study...
October 2016: European Journal of Radiology
Hiroyuki Morisaka, Utaroh Motosugi, Kevin J Glaser, Shintaro Ichikawa, Richard L Ehman, Katsuhiro Sano, Tomoaki Ichikawa, Hiroshi Onishi
PURPOSE: To evaluate the effect of imaging sequence (spin-echo echo-planar imaging [EPI] and gradient-echo [GRE]) and postprocessing method (two-dimensional [2D] and 3D inversion algorithms) on liver MR elastography (MRE) and to validate the diagnostic performance of EPI-MRE3D versus conventional GRE-MRE2D for liver fibrosis staging. MATERIALS AND METHODS: Three MRE methods (EPI-MRE3D , EPI-MRE2D , and GRE-MRE2D ) were performed on soft and mildly stiff phantoms and 58 patients with chronic liver disease using a 3 Tesla clinical MRI scanner, and stiffness values were compared among the three methods...
September 23, 2016: Journal of Magnetic Resonance Imaging: JMRI
David Kenkel, Borna K Barth, Marco Piccirelli, Lukas Filli, Tim Finkenstädt, Cäcilia S Reiner, Andreas Boss
OBJECTIVES: The aims of this study were to implement a protocol for simultaneous multislice (SMS) accelerated diffusion-weighted imaging (DWI) of the kidneys and to perform a systematic analysis of image quality of the data sets. MATERIALS AND METHODS: Ten healthy subjects and 5 patients with renal masses underwent DWI of the kidney in this prospective institutional review board-approved study on a 3 T magnetic resonance scanner. Simultaneous multislice DWI echo-planar sequences (acceleration factors [AFs] 2 and 3) were compared with conventional echo-planar DWI as reference standard for each acquisition scheme...
September 22, 2016: Investigative Radiology
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