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Phase contrast Magnetic

Sven Haller, Meike W Vernooij, Joost P A Kuijer, Elna-Marie Larsson, Hans Rolf Jäger, Frederik Barkhof
Cerebral microbleeds (CMBs), also referred to as microhemorrhages, appear on magnetic resonance (MR) images as hypointense foci notably at T2*-weighted or susceptibility-weighted (SW) imaging. CMBs are detected with increasing frequency because of the more widespread use of high magnetic field strength and of newer dedicated MR imaging techniques such as three-dimensional gradient-echo T2*-weighted and SW imaging. The imaging appearance of CMBs is mainly because of changes in local magnetic susceptibility and reflects the pathologic iron accumulation, most often in perivascular macrophages, because of vasculopathy...
April 2018: Radiology
Olivier Villemain, Mafalda Correia, Elie Mousseaux, Jérome Baranger, Samuel Zarka, Ilya Podetti, Gilles Soulat, Thibaud Damy, Albert Hagège, Mickael Tanter, Mathieu Pernot, Emmanuel Messas
OBJECTIVES: The goal of our study was to investigate the potential of myocardial shear wave imaging (SWI) to quantify the diastolic myocardial stiffness (MS) (kPa) noninvasively in adult healthy volunteers (HVs) and its physiological variation with age, and in hypertrophic cardiomyopathy (HCM) populations with heart failure and preserved ejection function (HFpEF). BACKGROUND: MS is an important prognostic and diagnostic parameter of the diastolic function. MS is affected by physiological changes but also by pathological alterations of extracellular and cellular tissues...
March 9, 2018: JACC. Cardiovascular Imaging
Mårten Unnerbäck, Eric L Bloomfield, Sven Söderström, Peter Reinstrup
Current methods to measure cerebral blood flow (CBF) in the neuro critical care setting cannot monitor the CBF continuously. In contrast, continuous measurement of intracranial pressure (ICP) is readily accomplished, and there is a component of ICP that correlates with arterial inflow of blood into the cranial cavity. This property may have utility in using continuous ICP curve analysis to continuously estimate CBF. We examined the data from 13 patients, monitored with an intraventricular ICP device determining the pulsatile amplitude ICPamp as well as the area under the ICP curve (AUCICP )...
March 16, 2018: Journal of Clinical Monitoring and Computing
Shelley HuaLei Zhang, Stephan E Maier, Lawrence P Panych
PURPOSE: Magnetic resonance spectroscopic imaging (MRSI), under low-spatial resolution settings, often suffers signal contamination from neighboring voxels due to ringing artifacts. Spatial localization can be improved by constraining the point-spread-function (PSF). Here the effectiveness of the two-dimensional PSF-Choice technique in providing improved spatial localization for MRSI is demonstrated. THEORY AND METHODS: The PSF-Choice technique constrains the PSF to a desired shape by manipulating the weighting of RF excitation pulse throughout phase-encode steps...
March 3, 2018: Journal of Magnetic Resonance
Abhishek Juyal, Amit Agarwal, Soumik Mukhopadhyay
The ground state of nanowires of single-crystalline pyrochlore Y_{2}Ir_{2}O_{7} is a density wave. The application of a transverse magnetic field increases the threshold electric field for the collective depinning of the density wave state at a low temperature, leading to colossal magnetoresistance for voltages around the depinning threshold. This is in striking contrast to the case where even a vanishingly small longitudinal magnetic field sharply reduces the depinning threshold voltage, resulting in negative magnetoresistance...
March 2, 2018: Physical Review Letters
Edmund Burke, Sanjeev A Datar
PURPOSE OF REVIEW: The essential role of the lymphatic system in fluid homeostasis, nutrient transport, and immune trafficking is well recognized; however, there is limited understanding of the mechanisms that regulate lymphatic function, particularly in the setting of critical illness. The lymphatics likely affect disease severity and progression in every condition, from severe systemic inflammatory states to respiratory failure. Here, we review structural and functional disorders of the lymphatic system, both congenital and acquired, as they relate to care of the pediatric patient in the intensive care setting, including novel areas of research into medical and procedural therapeutic interventions...
March 13, 2018: Current Opinion in Pediatrics
Misun Hwang, Matthew A Thimm, Anthony L Guerrerio
PURPOSE: Cavernous transformation of the portal vein can be missed on color Doppler exam or arterial phase cross-sectional imaging due to their slow flow and delayed enhancement. Contrast-enhanced ultrasound (CEUS) offers many advantages over other imaging techniques and can be used to successfully detect cavernous transformations of the portal vein. METHODS: A 10-month-old female was followed for repeat episodes of hematemesis. Computed tomography angiography (CTA) and magnetic resonance arteriogram (MRA) and portal venography were performed...
March 13, 2018: Journal of Ultrasound
Vrishank Raghav, Sudeep Sastry, Neelakantan Saikrishnan
Experimental flow field characterization is a critical component of the assessment of the hemolytic and thrombogenic potential of heart valve substitutes, thus it is important to identify best practices for these experimental techniques. This paper presents a brief review of commonly used flow assessment techniques such as Particle image velocimetry (PIV), Laser doppler velocimetry, and Phase contrast magnetic resonance imaging and a comparison of these methodologies. In particular, recommendations for setting up planar PIV experiments such as recommended imaging instrumentation, acquisition and data processing are discussed in the context of heart valve flows...
March 12, 2018: Cardiovascular Engineering and Technology
Wataru Jomoto, Masao Tanooka, Hiroshi Doi, Keisuke Kikuchi, Chiemi Mitsuie, Yusuke Yamada, Toru Suzuki, Toshiko Yamano, Reiichi Ishikura, Noriko Kotoura, Shingo Yamamoto
We sought to develop a surgical navigation system using magnetic resonance angiography (MRA) and a three-dimensional (3D) printer for robot-assisted radical prostatectomy (RARP). Six patients with pathologically proven localized prostate cancer were prospectively enrolled in this study. Prostate magnetic resonance imaging (MRI), consisting of T2-weighted sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) and true fast imaging with steady-state precession (true FISP), reconstructed by volume rendering, was followed by dynamic contrast-enhanced MRA performed with a volumetric interpolated breath-hold examination (VIBE) during intravenous bolus injection of gadobutrol...
January 2, 2018: Curēus
Tracy Ssali, Udunna C Anazodo, Jonathan D Thiessen, Frank S Prato, Keith St Lawrence
While positron emission tomography (PET) with15 O-water is the gold standard for imaging cerebral blood flow (CBF), quantification requires measuring the arterial input function (AIF), which is an invasive and noisy procedure. To circumvent this problem, we propose a non-invasive PET/ magnetic resonance (MR) approach that eliminates the need to measure the AIF by using global CBF determined by phase-contrast (PC) magnetic resonance imaging (MRI) as a reference region. Not only is this approach non-invasive, it adds no additional imaging time as PC MRI and15 O-water PET are acquired simultaneously...
March 9, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Tomoya Watanabe, Haruo Isoda, Yasuo Takehara, Masaki Terada, Takehiro Naito, Takafumi Kosugi, Yuki Onishi, Chiharu Tanoi, Takashi Izumi
PURPOSE: We performed computational fluid dynamics (CFD) for patients with and without paraclinoid internal carotid artery (ICA) aneurysms to evaluate the distribution of vascular biomarkers at the aneurysm initiation sites of the paraclinoid ICA. METHODS: This study included 35 patients who were followed up for aneurysms using 3D time of flight (TOF) magnetic resonance angiography (MRA) and 3D cine phase-contrast MR imaging. Fifteen affected ICAs were included in group A with the 15 unaffected contralateral ICAs in group B...
March 8, 2018: Neuroradiology
Da Wang, Aichi Chien, Jiaxin Shao, Fadil Abbas Ali, Peng Hu
The aim of this work was to develop and evaluate a fast phase contrast magnetic resonance imaging (PC-MRI) technique with hybrid one- and two-sided flow encodings only (HOTFEO) for accurate blood flow and velocity measurements of three-directional velocity encoding PC-MRI. Four-dimensional (4D) PC-MRI acquires flow-compensated (FC) and three-directional flow-encoded (FE) echoes in an interleaved fashion. We hypothesize that the blood flow velocity direction (not magnitude) has minimal change between two consecutive cardiac phases...
March 8, 2018: NMR in Biomedicine
Sarah Keller, Annette Aigner, Roman Zenouzi, Anne C Kim, Arnoud Meijer, Sören A Weidemann, Till Krech, Ansgar W Lohse, Gerhard Adam, Christoph Schramm, Jin Yamamura
OBJECTIVE: To evaluate magnetic resonance imaging (MRI) parameters T2 signal, contrast enhancement (CE), and relative liver enhancement (RLE) of extracellular gadolinium-based contrast agent (GBCA)-enhanced MRI as a marker for hepatic fibrosis and inflammation in patients with primary sclerosing cholangitis (PSC). METHODS: 3.0-Tesla MRI scans and liver biopsies of 40 patients (41.2 ± 17.1 years) were retrospectively reviewed. Biopsies were obtained within a mean time of 54 ± 55 days to MRI scans and specimens were categorized according to Ishak modified hepatic activity index (mHAI) and Scheuer staging of fibrosis...
2018: PloS One
Yasuhiro Fujiwara, Hirotoshi Maruyama, Kanako Toyomaru, Yuri Nishizaka, Masahiro Fukamatsu
Magnetic resonance imaging (MRI) is widely used to detect carotid atherosclerotic plaques. Although it is important to evaluate vulnerable carotid plaques containing lipids and intra-plaque hemorrhages (IPHs) using T1 -weighted images, the image contrast changes depending on the imaging settings. Moreover, to distinguish between a thrombus and a hemorrhage, it is useful to evaluate the iron content of the plaque using both T1 -weighted and T2 *-weighted images. Therefore, a quantitative evaluation of carotid atherosclerotic plaques using T1 and T2 * values may be necessary for the accurate evaluation of plaque components...
March 6, 2018: Radiological Physics and Technology
David Campos-Correia, João Cruz, António P Matos, Filipa Figueiredo, Miguel Ramalho
Hepatocellular carcinoma (HCC) usually develops in the setting of chronic liver disease. In the adequate clinical context, both multiphasic contrast-enhanced CT and magnetic resonance imaging are non-invasive modalities that allow accurate diagnosis and staging of HCC, although the latter demonstrates greater sensitivity and specificity. Imaging criteria for HCC diagnosis rely on hemodynamic features such as hyperenhancement in the arterial phase and washout in the portal or equilibrium phase. However, imaging performance drops considerably for small (< 20 mm) nodules because their tendency to exhibit atypical enhancement patterns...
February 28, 2018: World Journal of Radiology
Armin Fashi, Amir Ahmad Salarian, Abbasali Zamani
A novel and efficient device of solvent stir-bar microextraction (SSBME) system coupled with GC-FID detection was introduced for the pre-concentration and determination of malondialdehyde (MDA) in different biological matrices. In the proposed device, a piece of porous hollow fiber was located on a magnetic rotor by using a stainless steel-wire (as a mechanical support) and the whole device could stir with the magnetic rotor in sample solution cell. The device provided higher pre-concentration factor and better precision in comparison with conventional SBME due to the reproducible, stable and high contact area between the stirred sample and the hollow fiber...
May 15, 2018: Talanta
Victoria M Stoll, Margaret Loudon, Jonatan Eriksson, Malenka M Bissell, Petter Dyverfeldt, Tino Ebbers, Saul G Myerson, Stefan Neubauer, Carl- Johan Carlhäll, Aaron T Hess
BACKGROUND: Quantification and visualisation of left ventricular (LV) blood flow is afforded by three-dimensional, time resolved phase contrast cardiovascular magnetic resonance (CMR 4D flow). However, few data exist upon the repeatability and variability of these parameters in a healthy population. We aimed to assess the repeatability and variability over time of LV 4D CMR flow measurements. METHODS: Forty five controls underwent CMR 4D flow data acquisition...
March 2, 2018: Journal of Cardiovascular Magnetic Resonance
Francesco Pichi, K Bailey Freund, Antonio Ciardella, Mariachiara Morara, Emad B Abboud, Nicola Ghazi, Christine Dackiw, Netan Choudhry, Eduardo Cunha Souza, Leonardo Provetti Cunha, J Fernando Arevalo, T Y Alvin Liu, Adam Wenick, Lingmin He, Guadalupe Villarreal, Piergiorgio Neri, David Sarraf
Importance: Congenital retinal macrovessel (CRM) is a rarely reported venous malformation of the retina that is associated with venous anomalies of the brain. Objective: To study the multimodal imaging findings of a series of eyes with congenital retinal macrovessel and describe the systemic associations. Design, Setting, and Participants: In this cross-sectional multicenter study, medical records were retrospectively reviewed from 7 different retina clinics worldwide over a 10-year period (2007-2017)...
March 1, 2018: JAMA Ophthalmology
Jakob Weiss, Mike Notohamiprodjo, Jana Taron, Petros Martirosian, Dominik Nickel, Fabian Bamberg, Konstantin Nikolaou, Ahmed E Othman
PURPOSE: The aim of this study was to evaluate the feasibility of a prototype volume-interpolated breath-hold examination (VIBE) sequence using compressed sensing (VIBECS) for rapid multiphase arterial magnetic resonance imaging (MRI) at different temporal resolution during free-breathing in comparison with a conventional breath-hold approach (VIBESTD). MATERIAL AND METHODS: A total of 40 patients with liver malignancies were prospectively included in this study and underwent contrast-enhanced liver MRI at 1...
February 28, 2018: Investigative Radiology
A Lokossou, O Balédent, S Garnotel, G Page, L Balardy, Z Czosnyka, P Payoux, E A Schmidt
OBJECTIVE: The amplitude of intracranial pressure (ICP) can be measured by ICP monitoring. Phase-contrast magnetic resonance imaging (PCMRI) can quantify blood and cerebrospinal fluid (CSF) flows. The aim of this work was to investigate intracranial compliance at rest by combining baseline ICP monitoring and PCMRI in hydrocephalus patients. MATERIALS AND METHODS: ICP monitoring was performed before infusion testing to quantify ΔICP_rest at the basal condition in 33 suspected hydrocephalus patients (74 years)...
2018: Acta Neurochirurgica. Supplement
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