Vascular Imaging

Question 1

What are the anatomical forms of vascular imaging (4)?

Answer 1

Plan radiograph
Catheter angiography
Ultrasound
CT/MRI

Question 2

What is a catheter angiography

Answer 2

Vessel punctured and catheterised
A contrast is injected using pump injector
Rapid series of images acquired

Question 3

What are the functional vascular imaging?

Answer 3

Radionuclide imaging
MRI functional imaging
Ultrasound

Question 4

What are the challenges of vascular imaging?

Answer 4

Soft tissue contrast:

- can’t see important structures (blood vessels, lumen of hollow viscera) very well

Question 5

What questions are we asking when examining the vessels (3)?

Answer 5

What is the anatomy?
Is there a blockade?
	- is the occlusion/stenosis clinically significant?
		- e.g. thrombus in stroke 
Is there a leak?
	- e.g. aortic aneurysm rupture

Question 6

What are the limitations of CT scans (3)?

Answer 6

Leaks:
- Wont identify small volume leaks
- snapshot image - can’t exclude intermittent bleeding
Blockages:
- can’t always differentiate between acute and chronic thrombosis
Anatomy:
- can be difficult to convey the anatomy to non-radiologists

Question 7

What are the pros for high density contrast (iodine) (6)?

Answer 7

Inert
Stable in different body compartments
Painless
Cheap
Easy to use
Differential x-ray attenuation

Question 8

What are the problems with ionated contrast (7)?

Answer 8

Allergic reactions 
Renal dysfunction 
Disturbance of thyroid metabolism 
Disturbance of clotting mechanism 
Seizures 
Pulmonary oedema 
Discomfort

Question 9

How does an ultrasound work?

Answer 9

Electricity —> ultrasound waves (piezoelectric effect) —> reflects back off boundaries in tissues (related to acoustic impedance) —> turned back into electricity —> converted back into pictorial form (related to timing of signal return)

Question 10

What is B-mode on ultrasound? What is it used for?

Answer 10

Brightness/2D mode

Scans anatomical plane giving anatomical representation of structures
Used in almost all types of ultrasound scans

Question 11

What is M-mode on ultrasound? What is it used for?

Answer 11

Motion mode

Less common
Shows a fixed plane over time
Good for assessing heart valve movement as well as heart chamber dimension and function

Question 12

What is doppler imaging on ultrasound? What is it used for?

Answer 12

The flow of blood alters the frequency of the ultrasound waves returning to the probe
Shows velocity/direction of blood
Common clinical use in detection of DVT