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Result : Searchterm 'Diffusion' found in 8 terms [] and 36 definitions []
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Drug Information and Specification
T2, Predominantly negative enhancement
PHARMACOKINETIC
Intravascular
CONCENTRATION
29.8 mg Fe/mL
PREPARATION
Suspend in an isotonic glucose solution
INDICATION
Cardiovascular
DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE NOT A SUBSTITUTE FOR THE ACCOMPANYING
PACKAGE INSERT!
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Magnetic resonance imaging ( MRI) is based on the magnetic resonance phenomenon, and is used for medical diagnostic imaging since ca. 1977 (see also MRI History).
The first developed MRI devices were constructed as long narrow tunnels. In the meantime the magnets became shorter and wider. In addition to this short bore magnet design, open MRI machines were created. MRI machines with open design have commonly either horizontal or vertical opposite installed magnets and obtain more space and air around the patient during the MRI test.
The basic hardware components of all MRI systems are the magnet, producing a stable and very intense magnetic field, the gradient coils, creating a variable field and radio frequency (RF) coils which are used to transmit energy and to encode spatial positioning. A computer controls the MRI scanning operation and processes the information.
The range of used field strengths for medical imaging is from 0.15 to 3 T. The open MRI magnets have usually field strength in the range 0.2 Tesla to 0.35 Tesla. The higher field MRI devices are commonly solenoid with short bore superconducting magnets, which provide homogeneous fields of high stability.
There are this different types of magnets:
The majority of superconductive magnets are based on niobium-titanium (NbTi) alloys, which are very reliable and require extremely uniform fields and extreme stability over time, but require a liquid helium cryogenic system to keep the conductors at approximately 4.2 Kelvin (-268.8° Celsius). To maintain this temperature the magnet is enclosed and cooled by a cryogen containing liquid helium (sometimes also nitrogen).
The gradient coils are required to produce a linear variation in field along one direction, and to have high efficiency, low inductance and low resistance, in order to minimize the current requirements and heat deposition. A Maxwell coil usually produces linear variation in field along the z-axis; in the other two axes it is best done using a saddle coil, such as the Golay coil.
The radio frequency coils used to excite the nuclei fall into two main categories; surface coils and volume coils.
The essential element for spatial encoding, the gradient coil sub-system of the MRI scanner is responsible for the encoding of specialized contrast such as flow information, diffusion information, and modulation of magnetization for spatial tagging.
An analog to digital converter turns the nuclear magnetic resonance signal to a digital signal. The digital signal is then sent to an image processor for Fourier transformation and the image of the MRI scan is displayed on a monitor.
For Ultrasound Imaging (USI) see Ultrasound Machine at Medical-Ultrasound-Imaging.com.
See also the related poll results: ' In 2010 your scanner will probably work with a field strength of' and ' Most outages of your scanning system are caused by failure of' | | | | | | | | | • View the DATABASE results for 'Device' (141).
| | | • View the NEWS results for 'Device' (29).
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small-steps-can-yield-big-energy-savings-and-cut-emissions-mris Thursday, 27 April 2023 by www.itnonline.com | | |
Portable MRI can detect brain abnormalities at bedside Tuesday, 8 September 2020 by news.yale.edu | | |
Point-of-Care MRI Secures FDA 510(k) Clearance Thursday, 30 April 2020 by www.diagnosticimaging.com | | |
World's First Portable MRI Cleared by FDA Monday, 17 February 2020 by www.medgadget.com | | |
Low Power MRI Helps Image Lungs, Brings Costs Down Thursday, 10 October 2019 by www.medgadget.com | | |
Cheap, portable scanners could transform brain imaging. But how will scientists deliver the data? Tuesday, 16 April 2019 by www.sciencemag.org | | |
The world's strongest MRI machines are pushing human imaging to new limits Wednesday, 31 October 2018 by www.nature.com | | |
Kyoto University and Canon reduce cost of MRI scanner to one tenth Monday, 11 January 2016 by www.electronicsweekly.com | | |
A transportable MRI machine to speed up the diagnosis and treatment of stroke patients Wednesday, 22 April 2015 by medicalxpress.com | | |
Portable 'battlefield MRI' comes out of the lab Thursday, 30 April 2015 by physicsworld.com | | |
Chemists develop MRI technique for peeking inside battery-like devices Friday, 1 August 2014 by www.eurekalert.org | | |
New devices doubles down to detect and map brain signals Monday, 23 July 2012 by scienceblog.com |
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(EPI) Echo planar imaging is one of the early magnetic resonance imaging sequences (also known as Intascan), used in applications like diffusion, perfusion, and functional magnetic resonance imaging. Other sequences acquire one k-space line at each phase encoding step. When the echo planar imaging acquisition strategy is used, the complete image is formed from a single data sample (all k-space lines are measured in one repetition time) of a gradient echo or spin echo sequence (see single shot technique) with an acquisition time of about 20 to 100 ms.
The pulse sequence timing diagram illustrates an echo planar imaging sequence from spin echo type with eight echo train pulses. (See also Pulse Sequence Timing Diagram, for a description of the components.)
In case of a gradient echo based EPI sequence the initial part is very similar to a standard gradient echo sequence. By periodically fast reversing the readout or frequency encoding gradient, a train of echoes is generated.
EPI requires higher performance from the MRI scanner like much larger gradient amplitudes. The scan time is dependent on the spatial resolution required, the strength of the applied gradient fields and the time the machine needs to ramp the gradients.
In EPI, there is water fat shift in the phase encoding direction due to phase accumulations. To minimize water fat shift (WFS) in the phase direction fat suppression and a wide bandwidth (BW) are selected. On a typical EPI sequence, there is virtually no time at all for the flat top of the gradient waveform. The problem is solved by "ramp sampling" through most of the rise and fall time to improve image resolution.
The benefits of the fast imaging time are not without cost. EPI is relatively demanding on the scanner hardware, in particular on gradient strengths, gradient switching times, and receiver bandwidth. In addition, EPI is extremely sensitive to image artifacts and distortions. | | | | • View the DATABASE results for 'Echo Planar Imaging' (19).
| | | • View the NEWS results for 'Echo Planar Imaging' (1).
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From ISOL Technology
'Ultra high field MR system, it's right close to you.
FORTE 3.0T is the new standard for the future ultra high field MR system.
If you are pushing the limits of your existing clinical MR scanner, the FORTE will surely take you to the next level of diagnostic imaging.
FORTE is the core leader of the medical technology in the 21st century. Proving effects of fMRI that cannot be measured with MRI less than 2.0T.'
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Short bore compact
128 x 128, 256 x 256, 512 x 512, 1024 x 1024
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| | | | • View the DATABASE results for 'Hahn Echo' (2).
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