Echo time
The echo time (TE) refers to the time between the application of the radiofrequency excitation pulse and the peak of the signal induced in the coil. It is measured in milliseconds. The amount of T2 relaxation is controlled by the TE.
Related Radiopaedia articles
Physics and Imaging Technology: MRI
- MRI (introduction)
-
MRI physics
- B0
- chemical shift
- dependence of magnetization (proton density, field strength and temperature)
- echo time
- eddy currents
- electromagnetic induction
- Ernst angle
- flip angle
- Larmor frequency
- magnetic dipole magnetic field gradient
- magnetic susceptibility
- magnetism
- molecular tumbling rate effects on T1 and T2
- net magnetization vector (NMV)
- relaxation
- repetition time
- resonance and radiofrequency (RF)
- units of magnetism
- MRI hardware
- signal processing
-
MRI pulse sequences (basics | abbreviations | parameters)
- CSF flow studies
- diffusion weighted sequences (DWI)
- echo-planar pulse sequences
- fat-suppressed imaging sequences
- gradient echo sequences
- inversion recovery sequences
- metal artifact reduction sequence (MARS)
-
perfusion-weighted imaging
- techniques
- derived values
- saturation recovery sequences
- spin echo sequences
- spiral pulse sequences
- susceptibility-weighted imaging (SWI)
- T1 rho
- MR angiography (and venography)
-
MR spectroscopy (MRS)
- 2-hydroxyglutarate peak: resonates at 2.25 ppm
- alanine peak: resonates at 1.48 ppm
- choline peak: resonates at 3.2 ppm
- citrate peak: resonates at 2.6 ppm
- creatine peak: resonates at 3.0 ppm
- functional MRI (fMRI)
- gamma-aminobutyric acid (GABA) peak: resonates at 2.2-2.4 ppm
- glutamine-glutamate peak: resonates at 2.2-2.4 ppm
- Hunter's angle
- lactate peak: resonates at 1.3 ppm
- lipids peak: resonates at 1.3 ppm
- myoinositol peak: resonates at 3.5 ppm
- MR fingerprinting
- N-acetylaspartate (NAA) peak: resonates at 2.0 ppm
-
MRI artifacts
- MRI hardware and room shielding
- MRI software
- patient and physiologic motion
- tissue heterogeneity and foreign bodies
- Fourier transform and Nyquist sampling theorem
- MRI contrast agents
- MRI safety
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