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MR elastography

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https://www.readbyqxmd.com/read/28612163/repeatability-and-reproducibility-of-2d-and-3d-hepatic-mr-elastography-with-rigid-and-flexible-drivers-at-end-expiration-and-end-inspiration-in-healthy-volunteers
#1
Kang Wang, Paul Manning, Nikolaus Szeverenyi, Tanya Wolfson, Gavin Hamilton, Michael S Middleton, Florin Vaida, Meng Yin, Kevin Glaser, Richard L Ehman, Claude B Sirlin
PURPOSE: To evaluate the repeatability and reproducibility of 2D and 3D hepatic MRE with rigid and flexible drivers at end-expiration and end-inspiration in healthy volunteers. MATERIALS AND METHODS: Nine healthy volunteers underwent two same-day MRE exams separated by a 5- to 10-min break. In each exam, 2D and 3D MRE scans were performed, each under four conditions (2 driver types [rigid, flexible] × 2 breath-hold phases [end-expiration, end-inspiration]). Repeatability (measurements under identical conditions) and reproducibility (measurements under different conditions) were analyzed by calculating bias, limit of agreement, repeatability coefficient (RC), reproducibility coefficient (RDC), intraclass correlation coefficient (ICC), and concordance correlation coefficient (CCC), as appropriate...
June 13, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28604279/diffusion-and-intravoxel-incoherent-motion-mr-imaging-based-virtual-elastography-a-hypothesis-generating-study-in-the-liver
#2
Denis Le Bihan, Shintaro Ichikawa, Utaroh Motosugi
Purpose To investigate the potential of diffusion magnetic resonance (MR) imaging to provide quantitative estimates of tissue stiffness without using mechanical vibrations in patients with chronic liver diseases and to generate a new elasticity-driven intravoxel incoherent motion (IVIM) contrast. Materials and Methods This retrospective study, conducted from January to April 2016, was approved by an institutional review board that waived the requirement for informed consent. Fifteen subjects were included (13 men and two women; mean age ± standard deviation, 73 years ± 8)...
June 12, 2017: Radiology
https://www.readbyqxmd.com/read/28585229/tomoelastography-of-the-prostate-using-multifrequency-mr-elastography-and-externally-placed-pressurized-air-drivers
#3
Florian Dittmann, Rolf Reiter, Jing Guo, Matthias Haas, Patrick Asbach, Thomas Fischer, Jürgen Braun, Ingolf Sack
PURPOSE: To demonstrate the feasibility of in vivo multifrequency magnetic resonance elastography (MRE) of the prostate using externally placed drivers. METHODS: Three pressurized-air drivers were used to excite shear waves within the prostate at vibration frequencies of 60, 70, and 80 Hz. Full 3D wave fields were acquired by multislice spin-echo echo-planar imaging in conjunction with tomoelastography wave speed recovery for generating full field-of-view stiffness maps...
June 6, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28583636/metabolic-profile-of-liver-damage-in-non-cirrhotic-virus-c-and-autoimmune-hepatitis-a-proton-decoupled-31-p-mrs-study
#4
Antti Hakkarainen, Lauri Puustinen, Reetta Kivisaari, Sonja Boyd, Urpo Nieminen, Perttu Arkkila, Nina Lundbom
PURPOSE: To study liver (31)P MRS, histology, transient elastography, and liver function tests in patients with virus C hepatitis (HCV) or autoimmune hepatitis (AIH) to test the hypothesis that (31)P MR metabolic profile of these diseases differ. MATERIALS AND METHODS: 25 patients with HCV (n=12) or AIH (n=13) underwent proton decoupled (31)P MRS spectroscopy performed on a 3.0T MR imager. Intensities of phosphomonoesters (PME) of phosphoethanolamine (PE) and phosphocholine (PC), phosphodiesters (PDE) of glycerophosphoethanolamine (GPE) and glycerophosphocholine (GPC), and γ, α and β resonances of adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH) were determined...
May 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28570101/mr-elastography-demonstrates-unique-regional-brain-stiffness-patterns-in-dementias
#5
Mona ElSheikh, Arvin Arani, Avital Perry, Bradley F Boeve, Fredric B Meyer, Rodolfo Savica, Richard L Ehman, John Huston
OBJECTIVE: The purpose of this study was to investigate age-corrected brain MR elastography (MRE) findings in four dementia cohorts (Alzheimer disease, dementia with Lewy bodies, frontotemporal dementia, and normal pressure hydrocephalus) and determine the potential use as a differentiating biomarker in dementia subtypes. SUBJECTS AND METHODS: Institutional review board approval and written informed consent were obtained to perform MRE on 84 subjects: 20 patients with normal pressure hydrocephalus, eight with Alzheimer disease, five with dementia with Lewy bodies, five with frontotemporal dementia, and 46 cognitively normal control subjects...
June 1, 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28558274/active-control-of-the-spatial-mri-phase-distribution-with-optimal-control-theory
#6
Pauline M Lefebvre, Eric Van Reeth, Hélène Ratiney, Olivier Beuf, Elisabeth Brusseau, Simon A Lambert, Steffen J Glaser, Dominique Sugny, Denis Grenier, Kevin Tse Ve Koon
This paper investigates the use of Optimal Control (OC) theory to design Radio-Frequency (RF) pulses that actively control the spatial distribution of the MRI magnetization phase. The RF pulses are generated through the application of the Pontryagin Maximum Principle and optimized so that the resulting transverse magnetization reproduces various non-trivial and spatial phase patterns. Two different phase patterns are defined and the resulting optimal pulses are tested both numerically with the ODIN MRI simulator and experimentally with an agar gel phantom on a 4...
May 22, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28530847/repeatability-of-mr-elastography-of-liver-a-meta-analysis
#7
Suraj D Serai, Nancy A Obuchowski, Sudhakar K Venkatesh, Claude B Sirlin, Frank H Miller, Edward Ashton, Patricia E Cole, Richard L Ehman
Purpose To perform a meta-analysis to generate an estimate of the repeatability coefficient (RC) for magnetic resonance (MR) elastography of the liver. Materials and Methods A systematic search of databases was performed for publications on MR elastography during the 10-year period between 2006 and 2015. The identified studies were screened independently and were verified reciprocally by all authors. Two reviewers independently determined the percentage RC and effective sample size from each article. A forest plot was constructed of the percentage RC estimates from the 12 studies...
May 22, 2017: Radiology
https://www.readbyqxmd.com/read/28493802/placental-imaging-normal-appearance-with-review-of-pathologic-findings
#8
Shaimaa Fadl, Mariam Moshiri, Corinne L Fligner, Douglas S Katz, Manjiri Dighe
The placenta plays a crucial role throughout pregnancy, and its importance may be overlooked during routine antenatal imaging evaluation. Detailed systematic assessment of the placenta at ultrasonography (US), the standard imaging examination during pregnancy, is important. Familiarity with the normal and abnormal imaging appearance of the placenta along with the multimodality and methodical approach for evaluation of its related abnormalities is necessary, so that radiologists can alert clinicians regarding appropriate prompt management decisions...
May 2017: Radiographics: a Review Publication of the Radiological Society of North America, Inc
https://www.readbyqxmd.com/read/28493388/magnetic-resonance-elastography-measured-shear-stiffness-as-a-biomarker-of-fibrosis-in-pediatric-nonalcoholic-fatty-liver-disease
#9
Jeffrey B Schwimmer, Cynthia Behling, Jorge Eduardo Angeles, Melissa Paiz, Janis Durelle, Jonathan Africa, Kimberly P Newton, Elizabeth M Brunt, Joel E Lavine, Stephanie H Abrams, Prakash Masand, Rajesh Krishnamurthy, Kelvin Wong, Richard L Ehman, Meng Yin, Kevin J Glaser, Bogdan Dzyubak, Tanya Wolfson, Anthony C Gamst, Jonathan Hooker, William Haufe, Alexandra Schlein, Gavin Hamilton, Michael S Middleton, Claude B Sirlin
Magnetic Resonance Elastography (MRE) is promising for non-invasive assessment of fibrosis, a major determinant of outcome in nonalcoholic fatty liver disease (NAFLD). However, data in children are limited. Study aims were to determine accuracy of MRE for detection of fibrosis and advanced fibrosis in children with NAFLD, and to assess agreement between manual and novel automated reading methods. We performed a prospective, multi-center study of 2D-MRE in children with NAFLD. MR-elastograms were analyzed manually at 2 reading centers and using a new automated technique...
May 11, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28488326/acute-pressure-changes-in-the-brain-are-correlated-with-mr-elastography-stiffness-measurements-initial-feasibility-in-an-in-vivo-large-animal-model
#10
Arvin Arani, Hoon-Ki Min, Nikoo Fattahi, Nicholas M Wetjen, Joshua D Trzasko, Armando Manduca, Clifford R Jack, Kendall H Lee, Richard L Ehman, John Huston
PURPOSE: The homeostasis of intracranial pressure (ICP) is of paramount importance for maintaining normal brain function. A noninvasive technique capable of making direct measurements of ICP currently does not exist. MR elastography (MRE) is capable of noninvasively measuring brain tissue stiffness in vivo, and may act as a surrogate to measure ICP. The objective of this study was to investigate the impact of changing ICP on brain stiffness using MRE in a swine model. METHODS: Baseline MRE measurements were obtained, and then catheters were surgically placed into the left and right lateral ventricles of three animals...
May 9, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28473066/acr-appropriateness-criteria-%C3%A2-chronic-liver%C3%A2-disease
#11
Jeanne M Horowitz, Ihab R Kamel, Hina Arif-Tiwari, Sumeet K Asrani, Nicole M Hindman, Harmeet Kaur, Michelle M McNamara, Richard B Noto, Aliya Qayyum, Tasneem Lalani
Because liver fibrosis can be treated, it is important to diagnose liver fibrosis noninvasively and monitor response to treatment. Although ultrasound (grayscale and Doppler) can diagnose cirrhosis, it does so unreliably using morphologic and sonographic features and cannot diagnose the earlier, treatable stages of hepatic fibrosis. Transient elastography, ultrasound elastography with acoustic radiation force impulse, and MR elastography are modalities that can assess for hepatic fibrosis. Although all international organizations recommend ultrasound for screening for hepatocellular carcinoma, ultrasound is particularly limited for identifying hepatocellular carcinoma in patients with obesity, nonalcoholic fatty liver disease, and nodular cirrhotic livers...
May 2017: Journal of the American College of Radiology: JACR
https://www.readbyqxmd.com/read/28471737/mr-elastography-derived-stiffness-a-biomarker-for-intervertebral-disc-degeneration
#12
Benjamin A Walter, Prasath Mageswaran, Xiaokui Mo, Daniel J Boulter, Hazem Mashaly, Xuan V Nguyen, Luciano M Prevedello, William Thoman, Brian D Raterman, Prateek Kalra, Ehud Mendel, William S Marras, Arunark Kolipaka
Purpose To determine the repeatability of magnetic resonance (MR) elastography-derived shear stiffness measurements of the intervertebral disc (IVD) taken throughout the day and their relationship with IVD degeneration and subject age. Materials and Methods In a cross-sectional study, in vivo lumbar MR elastography was performed once in the morning and once in the afternoon in 47 subjects without current low back pain (IVDs = 230; age range, 20-71 years) after obtaining written consent under approval of the institutional review board...
May 4, 2017: Radiology
https://www.readbyqxmd.com/read/28426437/supersonic-transient-magnetic-resonance-elastography-for-quantitative-assessment-of-tissue-elasticity
#13
Yu Liu, Jingfei Liu, Brett Z Fite, Josquin Foiret, Asaf Ilovitsh, J Kent Leach, Erik Dumont, Charles F Caskey, Katherine W Ferrara
Non-invasive, quantitative methods to assess the properties of biological tissues are needed for many therapeutic and tissue engineering applications. Magnetic resonance elastography (MRE) has historically relied on external vibration to generate periodic shear waves. In order to focally assess a biomaterial or to monitor the response to ablative therapy, the interrogation of a specific region of interest by a focused beam is desirable and transient MRE (t-MRE) techniques have previously been developed to accomplish this goal...
May 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28425401/mre-in-nafld-promising-but-further-validation-is-required
#14
John D Ryan, Emmanuel A Tsochatzis
MR elastography is a novel method for non-invasive fibrosis assessment, not yet sufficiently validated. In a recent study in 104 patients Park, Gastroenterology 2017; 152: 598-602), MRE was compared to transient elastography for the diagnosis of fibrosis is nonalcoholic fatty liver disease. The current viewpoint critically appraises this study.
May 2017: Annals of Hepatology
https://www.readbyqxmd.com/read/28422391/mr-elastography-detection-of-early-viscoelastic-response-of-the-murine-hippocampus-to-amyloid-%C3%AE-accumulation-and-neuronal-cell-loss-due-to-alzheimer-s-disease
#15
Tonia Munder, Anna Pfeffer, Stefanie Schreyer, Jing Guo, Juergen Braun, Ingolf Sack, Barbara Steiner, Charlotte Klein
PURPOSE: To investigate in vivo viscoelastic parameters related to early histopathological changes in the hippocampus and the cortex in early, preclinical Alzheimer's disease (AD) stages. MATERIALS AND METHODS: Magnetic resonance elastography (MRE) was applied to female APP23 mice, an established transgenic mouse model of AD, at three different stages early in disease progression. To investigate the potential therapeutic effects of physical, cognitive, and social stimulation on brain viscoelasticity and histopathological characteristics, MRE was also applied after exposing young APP23 mice to environmentally enriched cage conditions (ENR), for 1, 12, or 24 weeks, which corresponds to adolescent, young-adult, and adult age at the time of analysis...
April 19, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28367603/mr-elastography-high-rate-of-technical-success-in-pediatric-and-young-adult-patients
#16
Madalsa Joshi, Jonathan R Dillman, Alexander J Towbin, Suraj D Serai, Andrew T Trout
BACKGROUND: Magnetic resonance (MR) elastography allows the noninvasive assessment of liver stiffness, which is a surrogate for fibrosis. OBJECTIVE: The purpose of this study was to describe our experience using liver MR elastography in a large pediatric population with attention to the frequency and causes of exam failure. MATERIALS AND METHODS: Imaging records were searched for patients ≤18 years of age who underwent 2-D gradient recalled echo (GRE) MR elastography of the liver between September 2011 and August 2015 on one of two 1...
April 3, 2017: Pediatric Radiology
https://www.readbyqxmd.com/read/28344811/the-role-of-imaging-in-the-diagnosis-of-primary-prostate-cancer
#17
Hugh Harvey, Nandita M deSouza
Ultrasound and magnetic resonance imaging (MRI) are key imaging modalities in prostate cancer diagnosis. MRI offers a range of intrinsic contrast mechanisms (T2, diffusion-weighted imaging (DWI), MR spectroscopy (MRS)) and extrinsic contrast-generating options based on tumour vascular state following injection of weakly paramagnetic agents such as gadolinium. Together these parameters are referred to as multiparametric (mp)MRI and are used for detecting and guiding biopsy and staging prostate cancer. Although sensitivity of mpMRI is <75% for disease detection, specificity is >90% and a standardised reporting system together with MR-guided targeted biopsy is the optimal diagnostic pathway...
December 2016: Journal of Clinical Urology
https://www.readbyqxmd.com/read/28333623/a-comparison-of-fem-based-inversion-algorithms-local-frequency-estimation-and-direct-inversion-approach-used-in-mr-elastography
#18
Mohammad Honarvar, Ramin Sahebjavaher, Robert Rohling, Septimiu Salcudean
In quantitative elastography, maps of the mechanical properties of soft tissue, or elastograms, are calculated from the measured displacement data by solving an inverse problem. The model assumptions have a significant effect on elastograms. Motivated by the high sensitivity of imaging results to the model assumptions for in-vivo Magnetic Resonance Elastography (MRE) of the prostate, we compared elastograms obtained with four different methods. Two FEM-based methods developed by our group were compared with two other commonly used methods, Local Frequency Estimator (LFE) and curl-based Direct Inversion (c-DI)...
March 22, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28321914/a-compact-0-5%C3%A2-t-mr-elastography-device-and-its-application-for-studying-viscoelasticity-changes-in-biological-tissues-during-progressive-formalin-fixation
#19
Jürgen Braun, Heiko Tzschätzsch, Clara Körting, Angela Ariza de Schellenberger, Marika Jenderka, Toni Drießle, Michael Ledwig, Ingolf Sack
PURPOSE: To develop a method of compact tabletop magnetic resonance elastography (MRE) for rheological tests of tissue samples and to measure changes in viscoelastic powerlaw constants of liver and brain tissue during progressive fixation. METHODS: A 10-mm bore, 0.5-T permanent-magnet-based MRI system was equipped with a gradient-amplifier-controlled piezo-actuator and motion-sensitive spin echo sequence for inducing and measuring harmonic shear vibrations in cylindrical samples...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28289936/comparison-of-spin-echo-echoplanar-imaging-and-gradient-recalled-echo-based-mr-elastography-at-3-tesla-with-and-without-gadoxetic-acid-administration
#20
Yong Seek Kim, Ji Soo Song, Stephan Kannengiesser, Seung Young Seo
OBJECTIVE: To compare spin-echo echoplanar imaging (SE-EPI) and gradient recalled echo (GRE) MR elastography (MRE) at 3 T with and without gadoxetic acid administration. METHODS: We included 84 patients who underwent MRE before and after gadoxetic acid administration, each time using SE-EPI and GRE sequences. Diagnostic performance for predicting clinical liver cirrhosis and high-risk oesophageal varices was assessed using the area under the receiver-operating characteristic curve (AUC)...
March 13, 2017: European Radiology
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