Mri Physicsweek 3 Part 2

Front 1

Sequential –

Back 1

all the lines of k-space are field for slice one, then slice 2, 3…)

Front 2

the three ways of acquiring data:

Back 2

Sequential
Two – dimensional volumetric
Three dimensional volumetric

Front 3

Acquisition Matrix -

Back 3

The total number of independent data samples in the frequency and phase directions (number of pixels in the frequency encoding - and phase encoding direction).

Front 4

an array of numbers in rows and columns is what makes up -

Back 4

A matrix size

Front 5

 A matrix with m rows and n columns is called an _ __ _ ____ and _ ___ _ ___ _____ ___ _______

Back 5

m-by-n matrix (or m×n matrix) - and -
.m and n are called its dimensions.

Front 6

A matrix with m rows and n columns is called an m-by-n matrix (or m×n matrix) and m and n are called its dimensions.

Horizontal =

Vertical =

Back 6

Horizontal = frequency direction
Vertical = phase direction

Front 7

FOV (field of view) – relates to

Back 7

the amount of anatomy covered

Front 8

Matrix -

Back 8

Matrix - system maps each individual signal.

Front 9

Receive bandwidth -

Back 9

The range of frequencies sampled and encoded within the FOV

Front 10

Resolution –

Back 10

the ability to distinguish two points as separate

Front 11

K space is

Back 11

an area where data collected from the signal are stored

Front 12

Scan time formula for single spin echo:

Back 12

ST = TR * NEX * PE
or
ST = TR * NEX or NSA * MATRIX
or
ST = TR * NEX or NSA * (FE) x(PE)
or
ST = TR * NEX or NSA * (PE ONLY)
THEN DIVIDE ANSWER BY 1000 AND THEN DIVIDE THAT BY 60 TO GET THE ANSWER IN MINUTES.

Front 13

The amplitude of the frequency encoding gradient determines how far to the left and right K space is traversed and this in turn determines

Back 13

the size of the FOV in the frequency direction of the image.

Front 14

The signal can be sampled more than once with the same slope of phase encoding gradient. Doing so will

Back 14

fill each line of K space more than once.

Front 15

The number of times each signal is sampled with the same slope of phase encoding gradient is usually called the

Back 15

number of signal averages (NSA) or the number of excitations (NEX)

Front 16

The way in which K space is traversed and filled depends on a combination of the

Back 16

polarity and amplitude of both the frequency and phase encoding gradients.

Front 17

The AMPLITUDE of the PHASE ENCODING GRADIENT determines how far UP AND DOWN K space is filled and in turn determines

Back 17

the size of the FOV in the PHASE DIRECTION of the image (or the SPACIAL RESOLUTION WHEN the FOV is SQUARE)

Front 18

The amplitude of the FREQUENCY ENCODING GRADIENT determines how far to the left and right K space is traversed and this in turn determines

Back 18

the size of the FOV in the frequency direction of the image.

Front 19

Depends on how the data are acquired and can be manipulated to suit the circumstances of the scan.
(different pulse sequences)

Alternative k – space filling:

Back 19

Partial echo imaging
Partial or averaging or half Fourier

Front 20

Partial echo imaging exploits

Back 20

the conjugate symmetry of K space.

Front 21

It is performed when only part of the signal is read by the frequency encoding gradient.

Back 21

Partial or fractional EI ( ECHO IMAGING)

Front 22

Partial or fractional EI (ECHO IMAGING IS ALSO CALLED

Back 22

Mirror image