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 'Driven Equilibrium' 
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Result : Searchterm 'Driven Equilibrium' found in 5 terms [] and 3 definitions []
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Contrast Enhanced Gradient Echo SequenceInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
Contrast enhanced GRE sequences provide T2 contrast but have a relatively poor SNR. Repetitive RF pulses with small flip angles together with appropriate gradient profiles lead to the superposition of two resonance signals.
The first signal is due to the free induction decay FID observed after the first and all ensuing RF excitations.
The second is a resonance signal obtained as a result of a spin echo generated by the second and all addicted RF-pulses.
Hence it is absent after the first excitation, it is a result of the free induction decay of the second to last RF-excitation and has a TE, which is almost 2TR. For this echo to occur the gradients have to be completely symmetrical relative to the half time between two RF-pulses, a condition that makes it difficult to integrate this pulse sequence into a multiple slice imaging technique. The second signal not only contains echo contributions from free induction decay, but obviously weakened by T2-decay. Since the echo is generated by a RF-pulse, it is truly T2 rather than T2* weighted. Correspondingly it is also less sensitive to susceptibility changes and field inhomogeneities.
Companies use different acronyms to describe certain techniques.
Different terms (see also acronyms) for these gradient echo pulse sequences:
CE-FAST Contrast Enhanced Fourier Acquired Steady State,
CE-FFE Contrast Enhanced Fast Field Echo,
CE-GRE Contrast Enhanced Gradient-Echo,
DE-FGR Driven Equilibrium FGR,
FADE FASE Acquisition Double Echo,
PSIF Reverse Fast Imaging with Steady State Precession,
SSFP Steady State Free Precession,
T2 FFE Contrast Enhanced Fast Field Echo (T2 weighted).

In this context, 'contrast enhanced' refers to the pulse sequence, it does not mean enhancement with a contrast agent.
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MRI Resources 
Musculoskeletal and Joint MRI - - Sequences - Liver Imaging - Blood Flow Imaging - Pathology
 
Fast Relaxation Fast Spin EchoInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
(FRFSE, FR-FSE) The fast relaxation fast spin echo sequence provides high signal intensity of fluids even with short repetition times, and can be used with parallel imaging techniques for short breath hold imaging or respiratory gating for free-breathing, high isotropic resolution MR imaging. After signal decay at the end of the echo train, a negative 90° pulse align spins with long T2 from the transverse plane to the longitudinal plane, leading to a much faster recovery of tissues with long T2 time to the equilibrium and thus better contrast between tissues with long and short T2.
Fast relaxation FSE has advantages also for volumetric imaging as the TR can be substantially reduced and thus the scan time. The sequence can be post processed with maximum intensity projection, surface or volume rendering algorithms to visualize anatomical details in brain or spine MRI. Cerebro spinal fluid pulsation artifacts, often problematic in the cervical or thoracic spine may be reduced by radial sampling, in particular when combined with acquisitions of the PROPELLER type.

See also Fast spin echo, Driven Equilibrium.
 
Images, Movies, Sliders:
 Shoulder Sagittal T2 FatSat FRFSE  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 Shoulder Axial T2 FatSat FRFSE  Open this link in a new window
 Shoulder Coronal T2 FatSat FRFSE  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 
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MRI Resources 
MRI Technician and Technologist Jobs - Devices - Coils - Non-English - Health - Education
 
MSK-Extremeâ„¢InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.onicorp.com/ From ONI Medical Systems, Inc.;
MSK-Extremeâ„¢MRI system is a dedicated high field extremity imaging device, designed to provide orthopedic surgeons and other physicians with detailed diagnostic images of the foot, ankle, knee, hand, wrist and elbow, all with the clinical confidence and advantages derived from high field, whole body MRI units. The light weight (less than 650 kg) of the OrthOne System performs rapid patient studies, is easy to operate, has a patient friendly open environment and can be installed in a practice office or hospital, all at a cost similar to a low field extremity machine.
New features include a more powerful operating system that offers increased scan speed as well as a 160-mm knee coil with higher signal to noise ratio, and the option of a CD burner.
Device Information and Specification
CLINICAL APPLICATION
Dedicated extremity imaging
CONFIGURATION
16 cm knee, 18 cm lower extremity;; 12.3 cm upper extremity, additional high resolution v-SPEC Coils: 80 mm, 100 mm, or 145 mm.
SYNCHRONIZATION
No
PULSE SEQUENCES
SE, FSE, GE2D, GE3D, Inversion recovery (IR), Driven Equilibrium, Fat Saturation (FS), STIR, MT, PD, Flow Compensation (FC), RF spoiling, MTE, No Phase Wrap (NPW)
IMAGING MODES
Scout, single, multislice, volume
TR
10-10,000ms; 1ms steps
TE
5-150ms; 1 ms steps
SINGLE/MULTI SLICE
2D less than 200 msec/image
4cm-16cm
2D: 2mm-10mm/.1mm incr.
Up to 1,000x1,000
MEASURING MATRIX
X/Y: 64-512; 2 pixel steps
PIXEL INTENSITY
4,096 grey lvls; 256 lvls in 3D
28cm ID x 50cm L
MAGNET WEIGHT
635 kg
H*W*D
146 x 69 x 84 cm
POWER REQUIREMENTS
115VAC, 1phase, 20A; 208VAC, 3 phase, 30A
COOLING SYSTEM TYPE
LHe with 2 stage cold head
Negligible
STRENGTH
15 mT/m
5-GAUSS FRINGE FIELD
1.25m radial x 1.8m axial
Passive
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Further Reading:
  Basics:
MSK Extreme Brochure(.pdf)
   by www.nova-logic.ch    
MSK Extreme Specifications(.pdf)
   by www.nova-logic.ch    
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