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Result : Searchterm 'DRIVen Equilibrium' found in 5 terms [] and 3 definitions []
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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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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 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. 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 2D less than 200 msec/image X/Y: 64-512; 2 pixel steps 4,096 grey lvls; 256 lvls in 3D POWER REQUIREMENTS 115VAC, 1phase, 20A; 208VAC, 3 phase, 30A COOLING SYSTEM TYPE LHe with 2 stage cold head 1.25m radial x 1.8m axial
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