Simultaneous dual contrast weighting using double echo rapid acquisition with relaxation enhancement (RARE) imaging

2013 ◽  
Vol 72 (6) ◽  
pp. 1590-1598 ◽  
Author(s):  
Katharina Fuchs ◽  
Fabian Hezel ◽  
Sabrina Klix ◽  
Ralf Mekle ◽  
Jens Wuerfel ◽  
...  
Keyword(s):  
Rapid Acquisition ◽  
Contrast Weighting

Electron-beam damage of oxides at high current densities

1989 ◽  
Vol 47 ◽  
pp. 634-635
Author(s):  
M. R. McCartney ◽  
J. K. Weiss ◽  
David J. Smith
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Current Density ◽  
Transition Metal Oxides ◽  
Time Resolved ◽  
Rapid Acquisition ◽  
Resolution Electron ◽  
Current Densities ◽  
Electron Stimulated Desorption ◽  
Channel Analyzer

It is well-known that electron-beam irradiation within the electron microscope can induce a variety of surface reactions. In the particular case of maximally-valent transition-metal oxides (TMO), which are susceptible to electron-stimulated desorption (ESD) of oxygen, it is apparent that the final reduced product depends, amongst other things, upon the ionicity of the original oxide, the energy and current density of the incident electrons, and the residual microscope vacuum. For example, when TMO are irradiated in a high-resolution electron microscope (HREM) at current densities of 5-50 A/cm2, epitaxial layers of the monoxide phase are found. In contrast, when these oxides are exposed to the extreme current density probe of an EM equipped with a field emission gun (FEG), the irradiated area has been reported to develop either holes or regions almost completely depleted of oxygen. ’ In this paper, we describe the responses of three TMO (WO3, V2O5 and TiO2) when irradiated by the focussed probe of a Philips 400ST FEG TEM, also equipped with a Gatan 666 Parallel Electron Energy Loss Spectrometer (P-EELS). The multi-channel analyzer of the spectrometer was modified to take advantage of the extremely rapid acquisition capabilities of the P-EELS to obtain time-resolved spectra of the oxides during the irradiation period. After irradiation, the specimens were immediately removed to a JEM-4000EX HREM for imaging of the damaged regions.

The Improvement of Torsion Assessed by Cardiovascular Magnetic Resonance Feature Tracking after Coronary Artery Bypass Grafting: A Sensitive Index of Cardiac Function

2017 ◽  
Vol 20 (1) ◽  
pp. 026 ◽  
Author(s):  
Nan Cheng ◽  
Liuquan Cheng ◽  
Rong Wang ◽  
Lin Zhang ◽  
Changqing Gao
Keyword(s):  
Cardiovascular Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ejection Fraction ◽  
Cardiac Function ◽  
Feature Tracking ◽  
Artery Bypass ◽  
Left Ventricular ◽  
Rapid Acquisition ◽  
Left Ventricular Torsion ◽  
Ventricular Torsion

Objective: The aim of this study was to quantify left ventricular torsion by newly applied cardiovascular magnetic resonance feature tracking (CMR-FT), and to evaluate the clinical value of the ventricular torsion as a sensitive indicator of cardiac function by comparison of preoperative and postoperative torsion.Methods: A total of 54 volunteers and 36 patients with previous myocardial infarction (MI) and LV ejection fraction (EF) between 30%-50% were screened preoperatively or postoperatively by MRI. The patients’ short axis views of the whole heart were acquired, and all patients had a scar area >75% in at least one of the anterior or inferior segments. Their apical and basal rotation values were analyzed by feature tracking, and the correlation analysis was performed for the improvement of LV torsion and ejection fraction after CABG. The intra- and inter-observer reliabilities of torsion measured by CMR-FT were assessed.Results: In normal hearts, the apex rotated counterclockwise in the systolic period with the peak rotation as 10.2 ± 4.8°, and the base rotated clockwise as the peak value was 7.0 ± 3.3°. There was a timing hiatus between the apex and base untwisting, during which period the heart recoils and its suction sets the stage for the following rapid filling period. The postoperative torsion and rotation significantly improved compared with preoperative ones. However, the traditional indicator of cardiac function, ejection fraction, didn’t show significant improvement.Conclusion: Left ventricular torsion derived from CMR-FT, which does not require specialized CMR sequences, was sensitive to patients with low ejection fraction whose cardiac function significantly improved after CABG. The rapid acquisition of this measurement has potential for the assessment of cardiac function in clinical practice. 

scholarly journals Ca-Stimulated Type 8 Adenylyl Cyclase Is Required for Rapid Acquisition of Novel Spatial Information and for Working/Episodic-Like Memory

2008 ◽  
Vol 28 (18) ◽  
pp. 4736-4744 ◽  
Author(s):  
M. Zhang ◽  
C. Moon ◽  
G. C.-K. Chan ◽  
L. Yang ◽  
F. Zheng ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
Spatial Information ◽  
Rapid Acquisition
Sign in / Sign up

Export Citation Format

Share Document