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633: Human Imaging II > Magnetic Resonance Imaging > Flashcards

Flashcards in Magnetic Resonance Imaging Deck (26):
1

How are coronal MRI images viewed?

from the front

2

How are axial MRI images viewed?

from below

3

How are sagittal MRI images viewed?

from left to right

4

Disease processes that give rise to low signal intensity on T1 imaging give rise to ___ signal intensity on T2

high

5

What gives rise to high signal intensity on a T1 image?

*light appearance

bone marrow

6

What gives rise to low signal intensity on a T1 image?

*dark appearance

IVDs

7

What gives rise to the lowest signal intensity on a T1 image?

*black appearance

CSF

8

What gives rise to high signal intensity on a T2 image?

*light appearance

CSF and IVDs

9

T1 images are made at ___ energy levels. Why?

High, so most of the energy from the radiofrequency remains in the tissues

10

T2 images are made at ___ energy levels.

low

11

Because T2 images are made at low energy levels, how does this effect the image?

They appear grainier and display less spatial resolution

12

What do T1 images measure energy from?

Structures such as fat, which give up energy rapidly

13

What do T2 images measure energy from?

Structures such as water, which does not readily give up energy

14

T1 imaging measures energy ___ in the process of longitudinal remagnetization

early

15

T2 imaging measures energy ___ in decay of transverse relaxation

late

16

T2 imaging is valuable in detecting what?

inflammation

17

In summary, ___ gives rise to high signal intensity on T1-weighted images and low to intermediate signal on T2

fat

18

In summary, ___ gives rise to high signal intensity on T2-weighted images and very low signal on T1

water

19

What structures show low signal intensity on all sequences?

Tendons, ligaments, menisci, and cortical bone

20

Does red or yellow marrow display a higher signal intensity on T1 images?

yellow

21

What type of signal intensity do muscles exhibit on T1 and T2 images?

intermediate signal intensity for both, although signal intensity slightly lower on T2

22

What also gives rise to intermediate signal intensity on T1 and T2 images?

cartilage

23

MRI is very sensitive for detecting changes and variations in bone marrow, which is important in the diagnosis of what?

- bone tumors
- stress fractures
- AVN

24

What is the best modality for differential diagnosis between disk herniations and other causes of nerve root impingement?

MRI

25

Is an MRI more sensitive than a bone scan for detecting bone metastases? Why or why not?

More, because it has the ability to stage neoplasms in bone and soft tissues along with extent of tissue invasion prior to surgery

26

What are the contraindications to MRI?

- ferrous metals
- pacemakers
- claustrophobia