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Skeletal Radiology A > MRI > Flashcards

Flashcards in MRI Deck (49)
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1

Why do patients and physicians favor MRI?

Noninvasive

Non-ionizing

2

T/F: MRI is considered a true multiplanar imaging

True

3

With soft tissue imaging, what is preferred, MRI or CT?

MRI

4

What is the first responder to bone pathology ?

Bone Marrow

5

Bone marrow activity is important for bone pathology, what imaging system is used to see bone marrow?

MRI

6

What percentage of sensitivity to change in the bone can MRI detect?

1% but is only regional

7

What two things interact with MRI processing?

Hydrogen protons (has magnetic charge)

External Magnetic field

8

Atomic nuclei have to have what characteristics to be manipulated by MRI?

Odd number of proton and neutrons

9

In which plane or direction of magnetic fields can hydrogen ions align?

Parallel or Anti-parallel

10

MRI magnets range of strength ?

.2-1.5 to 3 Tesla

11

MAgnetic field of earth

.25G(equator)

.6G(poles)

G=Gauss

12

10,000G= ___Tesla

1 Tesla

13

At what frequency and angle does the radio frequency have to be in order misalign the hydrogen to 90 or 180 degrees on its axis

Lamor-Frequency (42.58 MHz/T)

90 degrees

14

In which tissue do the proton orient the fastest in order?

1. Fat

2. Water

3. Bone barely has H-looks black

15

Pulse Sequence:

Time between each RF pulse varying from 500-4000msec

Time Repitition

16

Pulse sequence:

Time from RF to listening for signal generated by patient varying from <40 to 100msec or >

Time echo

17

Pulse sequence:

Determining factor of type of image created

TR + TE

18

Pulse sequence:

Weighted image w/ short TR and short TE

T1/ fat image

19

Pulse sequence:

Appearance of water and fat with T1

Fat=bright

Water=dark

20

Pulse sequence:

Weighted image w/ long TR and Long TE

T2- waterimage

21

Pulse sequence:

How does fat and water appear on T2

Water=bright

22

Pulse sequence:

Why do the hydrogen’s align quicker in fat?

Hydrogen is less tightly bound to fat than it is to water substances

23

Pulse sequence:

Image type is determined by TR and TE and what else?

Angle flip: Angle of deflection /flip of hydrogen proton

24

Pulse sequence:

Spin echo

90 degree flip angle

25

Pulse sequence:

Gradient echo

<90 degrees flip angle

26

MRI Image Type:

Fat image-structures containing fat appear brighter/whiter (bone marrow,
subcutaneous fat)

Water-containing structures (edema, neoplasm, inflammation, CSF,
large amounts of Fe) appear dark

long TR, short TE

Spin Echo T1

*standard*

27

MRI image Type:

Proton density

Good anatomical detail, has properties of both T1 and T2

Spin T2 first Echo

28

MRI Image type:

Water image

Loosely bound water (neoplasms, edema,
CSF) appear bright/white

Tightly bound or low water content (ligaments, sclerosis, cortical bone) or
large amounts of Fe appear dark/black

Spin T2 second echo

*Classic/Standard*

29

MRI Image Types:

Multiple echoes/TR

Faster exam time

Very sensitive to edema

90-180 degree flip angle

Fast Spin Echo

30

MRI IMAGE type:

Fast MRI using short TR and TE w/ flip angle < 90degrees,

Provides a T2 image in less time but does sacrifice some signal

Gradient Echo

(GRE, GRASS, FLASH, FISP, MPGR, SPGR)