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Result : Searchterm 'Spatial Resolution' found in 1 term [] and 80 definitions []
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Searchterm 'Spatial Resolution' was also found in the following services: 
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Contrast Resolution
 
Low-contrast resolution: The ability to image objects with similar subjects contrast; contrast detectability.
High-contrast resolution: The ability to image small objects having high subject contrast and spatial resolution.
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Further Reading:
  Basics:
Image Characteristics and Quality
   by www.sprawls.org    
IMAGE CONTRAST IN MRI(.pdf)
   by www.assaftal.com    
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Ultrasound  (10) Open this link in a new window
DixonInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
The Dixon technique is a MRI method used for fat suppression and/or fat quantification. The difference in magnetic resonance frequencies between fat and water-bound protons allows the separation of water and fat images based on the chemical shift effect.
This imaging technique is named after Dixon, who published in 1984 the basic idea to use phase differences to calculate water and fat components in postprocessing. Dixon's method relies on acquiring an image when fat and water are 'in phase', and another in 'opposed phase' (out of phase). These images are then added together to get water-only images, and subtracted to get fat-only images. Therefore, this sequence type can deliver up to 4 contrasts in one measurement: in phase, opposed phase, water and fat images. An additional benefit of Dixon imaging is that source images and fat images are also available to the diagnosing physician.
The original two point Dixon sequence (number of points means the number of images acquired at different TE) had limited possibilities to optimize the echo time, spatial resolution, slice thickness, and scan time; but Dixon based fat suppression can be very effective in areas of high magnetic susceptibility, where other techniques fail. This insensitivity to magnetic field inhomogeneity and the possibility of direct image-based water and fat quantification have currently generated high research interests and improvements to the basic method (three point Dixon).
The combination of Dixon with gradient echo sequences allows for example liver imaging with 4 image types in one breath hold. With Dixon TSE/FSE an excellent fat suppression with high resolution can be achieved, particularly useful in imaging of the extremities.
For low bandwidth imaging, chemical shift correction of fat images can be made before recombination with water images to produce images free of chemical shift displacement artifacts. The need to acquire more echoes lengthens the minimum scan time, but the lack of fat saturation pulses extends the maximum slice coverage resulting in comparable scan time.
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Further Reading:
  Basics:
Separation of fat and water signal in magnetic resonanace imaging
2011   by www.diva-portal.org    
Direct Water and Fat Determination in Two-Point Dixon Imaging
April 2013   by scholarship.rice.edu    
MRI evaluation of fatty liver in day to day practice: Quantitative and qualitative methods
Wednesday, 3 September 2014   by www.sciencedirect.com    
Measurement of Fat/Water Ratios in Rat Liver Using 3DThree-Point Dixon MRI
2004   by www.civm.duhs.duke.edu    
  News & More:
The utility of texture analysis of kidney MRI for evaluating renal dysfunction with multiclass classification model
Tuesday, 30 August 2022   by www.nature.com    
Liver Imaging Today
Friday, 1 February 2013   by www.healthcare.siemens.it    
mDIXON being developed to simplify and accelerate liver MRI
September 2010   by incenter.medical.philips.com    
MRI Resources 
Pacemaker - Resources - Cochlear Implant - Image Quality - Pediatric and Fetal MRI - Implant and Prosthesis pool
 
Echelon™ 1.5TInfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.
 
www.hitachimed.com/contentindex.asp?ID=971 From Hitachi Medical Systems America Inc.;
Hitachi expanded its portfolio with the Echelon™ 1.5T. The MRI scanner combines a compact magnet and a scalable 8-channel RF system with high-performance gradients and slew rate to select short echo times, small field of views, high matrices and thin slices. Standard features of the Echelon MRI system include higher-order active shim, RAPID (parallel imaging for use on brain MRI, body, cardiovascular imaging, and orthopedic coils), multiple coil ports, and an advanced reconstruction engine.
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Short bore
Head, body coil, spine, breast, knee, shoulder, vascular multiple array coils.
SYNCHRONIZATION
Cardiac gating, ECG/peripheral, respiratory gating
PULSE SEQUENCES
SE, IR, FSE, FIR, GE, SG, BASG, PBSG, PCIR, DWI, Radial, Angiography: TOF, FLUTE (Fluoro-triggered bolus MRA), Time-resolved MRA
IMAGING MODES
Single, multislice, volume study
PIXEL INTENSITY
Level Range: -2,000 to +4,000
Sub millimeter
POWER REQUIREMENTS
208/220/240 V, single phase
CRYOGEN USE
Low cryogen boil-off
STRENGTH
30 mT/m
150 T/m/sec
Higher-order active shim
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Further Reading:
  Basics:
Echelon 1.5T
   by www.hitachimed.com    
Searchterm 'Spatial Resolution' was also found in the following services: 
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News  (8)  Resources  (1)  Forum  (1)  
 
Echo Planar ImagingInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
Echo Planar Imaging Timing Diagram (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.
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• View the NEWS results for 'Echo Planar Imaging' (1).Open this link in a new window.
 
Further Reading:
  Basics:
New Imaging Method Makes Brain Scans 7 Times Faster
Sunday, 9 January 2011   by www.dailytech.com    
Searchterm 'Spatial Resolution' was also found in the following service: 
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Ultrasound  (10) Open this link in a new window
Excelart AG™ with PianissimoInfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
http://www.medical.toshiba.com/clinical/radiology/15texcelart.htm From Toshiba America Medical Systems Inc.;
the EXCELART is a superconducting whole body MRI system with a short wide-bore magnet, operating at 1.5 T. It features powerful high-speed gradients with a revolutionary gradient acoustic noise reduction system: Pianissimo. The dramatic reduction of gradient acoustic noise by Pianissimo greatly enhances patient comfort during exams. The standard array platform and a wide range of array coils ensure excellent images. A powerful 64-bit RISC-based computer system and newly developed array processor realize high productivity.
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Cylindrical Wide Short Bore
Opt. (WIP) Single and Multi Voxel
SYNCHRONIZATION
ECG: standard; peripheral: optional, respiratory gating
PULSE SEQUENCES
SE, FE, IR, FastSE, FastIR, FastFLAIR, Fast STIR, FastFE, FASE, Hybrid EPI, Multi Shot EPI; Angiography: 2D(gate/non-gate)/3D TOF, SORS-STC
IMAGING MODES
Single, multislice, volume study
TR
3.5-30000 msec
TE
8 msec min. SE; 1.2 msec min. FE
SINGLE/MULTI SLICE
less than 0.015 (256x256)
FOV
2 cm
1.0 min. 2-DFT: 0.2 min. 3-DFT
Up to 1024
MEASURING MATRIX
32-1024, phase;; 64-1024, freq.
PIXEL INTENSITY
256 gray levels
BORE DIAMETER
or W x H
65.5 cm, patient aperture
MAGNET WEIGHT
4050 kg (bare magnet incl. L-He)
H*W*D
235 x 219 x 199 cm
COOLING SYSTEM TYPE
Closed-loop water-cooled
CRYOGEN USE
Liquid helium: approx. less than 0.05 L/hr
STRENGTH
25 mT/m
5-GAUSS FRINGE FIELD
2.5 m / 4.0 m
Passive, active, auto-active
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MRI Resources 
Pathology - Patient Information - Mobile MRI - Collections - Veterinary MRI - Education
 
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