Graduate Echo Pulse Sequences

These flashcards cover key vocabulary and concepts related to gradient-echo pulse sequences in MRI, suitable for exam preparation.

Gradient-echo pulse sequences

MRI sequences that use gradients to rephase magnetic moments and typically involve variable RF flip angles.

Incoherent or spoiled gradient-echo

A type of gradient-echo sequence that spoils residual transverse magnetization to produce T1 and proton density weighted images.

Reverse-echo gradient-echo

A gradient-echo sequence that allows for longer effective TE to achieve true T2 weighting.

Balanced gradient-echo

A gradient-echo sequence that corrects for phase errors in moving fluids and enhances steady-state effects.

Fast gradient-echo

A rapid acquisition variant of the gradient-echo sequence that achieves very brief scanning times.

Echo planar imaging (EPI)

A rapid imaging technique that allows for the acquisition of images in one TR period using a sequence of gradient-echoes.

Variable flip angle

In gradient-echo sequences, a flip angle that is not fixed at 90°, allowing flexibility to optimize contrast.

Steady state

A stable magnetization condition maintained in gradient-echo sequences, where energy in equals energy out.

Residual transverse magnetization

Transverse magnetization that builds up over successive TR periods influencing image contrast.

T2* weighting

A form of image weighting in MRI that accounts for T2 decay influenced by magnetic field inhomogeneities.

Gradient rephasing

A technique in gradient-echo sequences where gradients are used instead of RF pulses to rephase the transverse magnetization.

Signal-to-noise ratio (SNR)

A measure of the signal level relative to the background noise, important for image quality in MRI.

T1 contrast

Contrast in MRI images mainly influenced by the T1 recovery times of different tissues.

T2 contrast

Contrast in MRI images mainly influenced by the T2 decay times of different tissues.

Proton density (PD) weighting

Image weighting in MRI that emphasizes differences in the density of protons in tissues.

SARGE (Steady Acquisition Rewound Gradient-Echo)

A type of gradient-echo sequence utilizing rewinding of gradients to rephase all transverse magnetization.

Flip angle (FA)

The angle through which the net magnetic vector is tilted during RF excitation in MRI.