TE (ECHO Time)
Patient
Scan Time
Contrast Media (e.g. Gadolinium)
TR (Repetition Time)
IR (Inversion Recovery)
Flip Angle
FOV (Field of View)
Slice Thickness
Bandwidth
Magnet Strength
Artifacts (e.g. Chemical Shift &Partial Volume)
SNR (Signal to Noise Ratio)
Magnetic Susceptibility
Voxel Size
Spatial Resolution (SR) and Contrast (CR)
NEX (Number of Excitations), FAT/SAT (FAT Saturation)
Echo Train Length
Coil Size/Location
FID (Free Induction Decay)
Amplitude
IT (Inversion Time)
3 Principle Parameters
PD (Proton Density)
T2 (Spin-Spin Relaxation Time)
Number Of Slices
Paramagnetic Materials
Motion
Matrix
Partial Saturation
An increase in field strength requires a decrease in TR, and a decrease in field strength requires an increase in TR.
As the Ratio is increased: ↑SNR, ↓IR, & ↑IT. And as the Ratio is decreased: ↓SNR,↑IR, & ↓IT
As TR is increased:↑SNR, ↓T1 CONTRAST, ↑# SLICES, ↑TIME, ↑PD, ,↑MOTION ARTIFACTS, ↑FLIP ANGLE. And as TR is decreased: ↓SNR, ↑T1 CONTRAST, ↓#SLICES, ↓TIME, ↓PD, ↓MOTION ARTIFACTS, ↓FLIP ANGLE
As TE is increased: ↑T2 CONTRAST, ↓SNR, ↓PD, ↑T2 CONTRAST, ↓# SLICES, ↑MAGNETIC SUSCEPTIBILITY And as TE is decreased: ↓T2 CONTRAST, ↑SNR, ↑PD, ↓T2 CONTRAST, ↑# SLICES, ↓MAGNETIC SUSCEPTIBILITY
As Flip Angle is increased: ↑T1 CONTRAST, ↓T2, ↑SNR, ↑Spins onto Transverse plane. And as Flip Angle is decreased: ↓T1 CONTRAST, ↑T2, ↓SNR, ↓Spins onto X & Y plane
As Matrix size is increased: ↑SNR (√²), ↑SNR/VOXEL, ↑SR, ↑CR, ↑TIME, ↓TRUNCATION. And as Matrix size is decreased: ↓SNR (√²), ↓SNR/VOXEL, ↓SR, ↓CR, ↓TIME, ↑TRUNCATION.
As FOV is increased: ↑IMAGED AREA, ↑SNR/VOXEL,↓SR, ↓ALIASING, ↑ARTIFACTS. And as FOV is decreased: ↓IMAGED AREA,↓SNR/VOXEL, ↑SR, ↑ALIASING, ↓ARTIFACTS
As NEX is increased: ↑TIME & ↑SNR (√²). And as NEX is decreased: ↓TIME & ↓SNR (√²)
As FID is increased: ↓FID & ↓MOTION ARTIFACTS. And as FID is decreased: ↑FID & ↑MOTION ARTIFACTS
As Slice Thickness increases: ↑SNR, ↑AREA IMAGED, ↓SR, ↑PARTIAL VOLUME AFFECT. And as Slice Thickness is decreased: ↓SNR, ↓AREA IMAGED, ↑SR,↓PARTIAL VOLUME AFFECT
As ETL is increased: ↓SNR, ↓TIME, ↓# SLICES, ↑CONTRAST MIX, ↑BLURRING. And as ETL decreases: ↑SNR, ↑TIME, ↑# SLICES, ↓CONTRAST MIX, ↓BLURRING
As Chemical Shift Artifact increases: ↑W/NARROW (low) Receiver BW. And as Chemical Shift Artifact decreases:↓W/WIDER (higher) W/- with Receiver BW
As Partial Volume Artifact Increases: ↑W/ SLICE THICKNESS, ↑VOXELS, ↓SR, ↑ SNR . And as Partial Volume Artifact decreases: ↓W/ SLICE THICKNESS, ↓VOXELS, ↑SR, ↓SNR
As Bandwidth is increased: ↓SNR, ↓Q (quality), ↓MINIMUM TE, ↓CHEMICAL SHIFT, ↑SNR SLICE THICKNESS. And as Bandwidth is decreased: ↑SNR, ↑Q, ↑MINIMUM TE, ↑CHEMICAL SHIFT, ↓SLICE THICKNESS
As Coil Size is increased: ↑FOV, ↑ARTIFACTS, ↑AREA IMAGED, ↓SNR. And as Coil Size is decreased: ↓FOV, ↓ARTIFACTS, ↓AREA IMAGED,↑SNR
As Amplitude is increased:↑# SLICES, ↓SLICE THICKNESS, ↓FOV, ↓TE, ↓SCAN TIME. And as Amplitude is decreased: ↓# SLICES, ↑SLICE THICKNESS, ↑FOV, ↑TE, ↑SCAN TIME
A long TR and short TE
A long TR and long TE
T1 (Spin-Lattice Relaxation Time)
A short TR and short TE
TR: <800
TE: <30
flip angle: 90°
TR: >1000
TE: <30
flip angle: 90°
TR: >2000
TE: >80
flip angle: 90°
The image looks like:
fluid (e.g. urine, CSF): low signal intensity (black)
muscle: intermediate signal intensity (grey)
fat: high signal intensity (white)
brain: grey matter: intermediate signal intensity (grey) And white matter: hyperintense compared to grey matter (white-ish)
The image looks like:
fluid (e.g. joint fluid, CSF): high signal intensity (white)
muscle: intermediate signal intensity (grey)
fat: high signal intensity (white)
hyaline cartilage: intermediate signal intensity (grey)
fibrocartilage: low signal intensity (black)
The image looks like:
fluid (e.g. urine, CSF): high signal intensity (white)
muscle: intermediate signal intensity (grey)
fat: high signal intensity (white)
brain: grey matter: intermediate signal intensity (grey). And white matter: hypointense compared to grey matter (dark-ish).
The time between the 180° inverting pulse and the 90°-pulse
Excitation technique applying repeated RF pulses in times comparable to or shorter than T1. Incomplete T1 relaxation leads to reduction of the signal amplitude;; there is the possibility of generating images with increased contrast between regions with different relaxation times.
Type of substance with a small but positive magnetic susceptibility; the addition of a small amount of paramagnetic substance may greatly reduce the relaxation times of a tissue; used as contrast agents
Measure of the ability of a substance to become magnetized
The time required to collect all data needed to generate the programmed images
Pulse sequence for MRI wherein the net magnetization is inverted and relaxes to equilibrium with the emission of an MR signal after a 90° RF pulse; a method similar to spin echo but each excitation is preceded by an inversion pulse time T1.
Volume element; or 3-D analog of a pixel
CR- It is the ability of an imaging system to distinguish between multiple densities in the radiographic image. And SR- the ability of an imaging system to differentiate between two near-by objects.