Flashcards in Sequence Parameters & Options Deck (240)

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1

## What is the difference in SNR between 2 adjacent pixels (eye's ability to detect difference)

### CNR

2

## Which parameter has the greatest influence on image quality

### CNR

3

## CNR is controlled by all the same factors as what

### SNR

4

## What is the ratio of signal amplitude to average noise amplitude called

### SNR

5

## Is signal predictable

### yes

6

## The induced voltage at the receiver coil is referred to as what

### signal

7

## Is noise predictible

### no, it's random

8

## What is noise dependent on

### body habitus & electrical noise of the system

9

## What parameter has the greatest influence on SNR

### size of FOV

10

## What is the ability of the imaging system to detect 2 points as separate

### spatial resolution

11

## Which pixel types give better spatial resolution: square or rectangular

### square

12

## What is the amount of tissue within a 3 D volume called

### voxel volume

13

## What determines voxel volume

### FOV, matrix & slice thickness

14

## What determines spatial resolution

### voxel volume only

15

## Formula for voxel volume

### pixel phase x pixel frequency x slice thickness

16

## What is the voxel volume when using a 24cm FOV, a 256x128 matrix & 3mm slices?

### (240mm/256) x (240mm/128) x 3 = 5.27mm³

17

## Which provide better spatial resolution - square or rectangular pixels

### square

18

## Which pixel type is better for reformatting 2D/3D images - square or rectangular

### square

19

## What is the amount of time it takes to fill k-space called

### acquisition time

20

## What has the greatest impact on the amount of patient motion detected on an image

### acquisition time

21

## What parameters affect acquisition time

### TR, NSA/NEX, phase matrix, ETL & # of slices (during 3D only)

22

## What is the formula to calculate 2D acquisition time for conventional sequences

###
TR x NSA x Phase encodings

(500ms x 1 x 256 = 128,000ms = 128sec = 2min 8 sec)

23

## What is the formula to calculate 2D acquisition time for fast sequences

###
(TR x NSA x Phase encodings)/ETL

(500ms x 1 x 256)/4 = 32,000ms = 32sec

24

## What is the formula to calculate 3D acquisition time for conventional sequences

###
TR x NSA x Phase encodings x slice #

(500ms x 1 x 256 x 24 = 3,072,000ms = 3,072sec = 51min 12sec)

25

## List the 7 intrinsic parameters

###
T1 recovery

T2 decay

proton density

flow

ADC

perfusion

diffusion

26

## List the 8 extrinsic parameters

###
TR

TE

flip angle

TI

ETL

b value

FOV

matrix

27

## What are the 3 types of image contrast

###
T1

T2

PD

28

## Which type of contrast appears as a difference in signal intensities between tissues with varying hydrogen proton concentrations

### proton density contrast

29

## What is the objective when trying to achieve T1 weighting

### prevent recovery and decay

30