Pulse Sequences and MRI Image Contrast

A series of radio frequency (RF) pulses and magnetic field gradients used to acquire MR images.

A pulse sequence using 90 and 180 degree RF pulses to create an image.

The initial weak signal detected, before rephasing occurs via 180-degree pulse in an MRI scan.

The time between successive 90-degree pulses in a pulse sequence.

Time from the 90-degree pulse to the signal echo.

A pulse sequence that uses gradients to refocus the magnetization and create an image, without 180-degree RF.

A pulse sequence that reverses the magnetization before acquiring an image, providing contrast.

A fast image acquisition technique commonly used in gradient echo sequences.

A fast MRI sequence acquiring all echoes in a single TR, using half-Fourier transformation for the other half of k-space.

An MRI sequence that uses magnetic field gradients to rephase magnetization instead of an 180-degree pulse, resulting in T2* relaxation.

The relaxation time in GRE sequence affected by magnetic field inhomogeneities.

MRI sequences where residual magnetization from previous TR is destroyed.

MRI sequence that uses fast echo to speed up image acquisition.

A mathematical representation of the spatial frequency components of an MRI image.

Time interval between successive 90-degree pulses in MRI pulse sequences.

Time between 90-degree pulse and signal echo.

Basic MRI sequence used in many exams; creates T1-weighted images for anatomy and T2-weighted images for pathology.

MRI image emphasizing tissue differences in relaxation time (T1).

MRI image highlighting differences in tissue relaxation times (T2), useful for pathology.

SE sequence with two 180-degree pulses per 90-degree pulse, producing two echoes per repetition time (TR).

Modified SE sequence using multiple 180-degree pulses per TR, creating more echoes to fill K-space quickly.

Number of 180-degree pulses; also called echo train length; affects image weighting and scan time.

2D mathematical representation of an MRI image; filling it faster increases scan speed.

Time interval between successive 90-degree pulses in MRI.

A GRE sequence where the residual transverse magnetization isn't destroyed, resulting in a steady signal strength over subsequent TRs.

In steady-state sequences, the time between pulses (TR) is shorter than the tissue's T1 and T2 relaxation times.

Another name for steady-state GRE sequences.

GRE sequences where residual transverse magnetization is spoiled, emphasizing T1 weighting.

An MRI pulse sequence that uses an initial 180-degree pulse to invert magnetization before further imaging.

The time between the inversion pulse (180 degrees) and the excitation pulse (90 degrees) in an inversion recovery sequence.

Flips the longitudinal magnetization by 180 degrees before the spin-echo or gradient echo sequence in an Inversion Recovery Sequence.

Different tissues have varied T1 values, and recovery of longitudinal magnetization is influenced by these values. This difference is used to create contrast in images.

Echo planar imaging technique utilizing multiple 180-degree pulses for rephasing.

EPI sequence using gradients for rephasing magnetization instead of 180-degree pulses.

Dynamic MRI technique using GRE or EPI sequences with contrast to study contrast uptake.

MRI technique highlighting areas with restricted water diffusion, often used in strokes.

Dynamic MRI technique comparing brain images during activity and rest.

MRI technique suppressing background tissue to highlight vessels and disease.

MRA technique using GRE sequences to show flowing blood.

MRA technique using GRE sequences, good background suppression but slower.

An MRI pulse sequence that inverts magnetization before acquiring an image, providing tissue contrast based on T1 relaxation times. Used to suppress specific tissues.

The time delay between the 180-degree inversion pulse and the subsequent 90-degree excitation pulse in an IR sequence. It determines which tissues are suppressed.

A type of IR sequence using a short TI to suppress fat signals in MRI scans, highlighting soft tissues.

An IR sequence that suppresses cerebrospinal fluid (CSF) signal, enhancing the visualization of brain structures.

An RF pulse in MRI that inverts the longitudinal magnetization of tissues, used in IR sequences to manipulate tissues.

Using Specific Inversion Times (TI), certain tissues are suppressed (nulled) in IR sequences, enhancing other tissue's visibility.

MRI technique to rapidly acquire images. Multiple K-space lines are collected per TR. Single-shot EPI fills all lines in one TR for ultra-fast imaging.

A type of EPI where all k-space lines are acquired in a single repetition time (TR), enabling extremely fast image acquisition.