GI imaging Flashcards Preview

Hugh's MD1 Abdominal > GI imaging > Flashcards

Flashcards in GI imaging Deck (20):
1

Who invented X-rays?

 

Wilhelm Roentgen

 

2

What determines the absorption of X-ray beams?

Thickness of tissue

Density of tissue

Atomic number

3

How much affect does the atomic number of the substance have?

The 4th power

4

Which absorbs more X-rays, fluids or fat?

Fluids

5

How do you improve X-ray sensitivity?

Add contrast

Use a more sensitive method (CT)

6

What is a barium enema?

Retrograde introduction of barium into the system

7

What is an endoscopic retrograde cholangio-pancreatography?

Insert an endoscope down the GIT until you reach the major duodenal papilla then squirt contrast fluid up it

8

What is a percutaneous transhepatic cholangiography?

Procedure where a needle is inserted, goes through the liver and into the bile duct where contrast is injected

9

Which compound do you use for intravenous/intra-arterial contrast?

Iodine (53) 

10

How long after intravascular contrast administration will it be seen in the kidneys?

30 minutes

11

What happens when contrast is tagged with a bilirubin like compound?

It is metabolised in the liver

12

What is a houndsfield unit used for?

CTs

13

What is radioisotope imaging?

Intravenous administration of tagged molecules that target a certain organs and emit gamma rays, these are recorded using a camera 

14

What is the frequency and wavelength of ultrasounds?

High frequency

Short wavelengths

15

Why is gel required in ultrasounds?

Exclude air

16

How do ultrasounds create an image?

Beams of sound are reflected by tissue and sensed

17

What is shadowing in ultrasounds?

Where a substance completely reflects the sound

18

What is the doppler effect used for?

Measuring blood flow - RBCs reflect sound

19

What is the principle of MRI's?

Sends pulses of strong magnetic field and measures the resulting differences in radiowaves that return. Works due to the spin of H molecules

20

What percentage of blood is supplied to the liver via the portal veins?

75% (25% from hepatic arteries)