Angiography

Question 1

what is angiography?

Answer 1

angiography is way of imaging BVs or organs within the body

Question 2

what is DSA?

Answer 2

it digital subtraction angiography in which there is removal of unwanted portions of image (soft tissue) and leaving the relevant parts (vessels)

Question 3

Explain the process involved in DSA?

Answer 3

1. Catheter insertion and placed at the right place
2. test injection with small amount of contrast to confirm the catheter positioning in area to be images under fluoroscopy
3. series of radiographs taken in which first mask image is acquired followed by a series of images
4. Mask image automatically subtracted from the subsequent images and resulting image viewed in real time
5. Series reviewed by radiologist to decide the diagnosis and end diagnosis, whether further series need to be taken of arterial supply and whether intervention procedure needs to be undertaken

Question 4

name six interventional radiography

Answer 4

1. Angioplasty
2. Stenting
3. IV filters
4. Thrombus and thrombolytic treatment
5. Embolisation using quils or gels
6. Ablation

Question 5

what is AVM?

Answer 5

AVM - malfunctioning b/w artery and vein system

Question 6

explain angioplasty procedure

Answer 6

• After diagnostic procure, another catheter is inserted
• A ballon is attached to the catheter and is placed across the stenosis (caused by the build up of plaques across arteries)
• The ballon is infected leading to expansion of arteries and results in improved blood flow. however, the plaque is not removed
• Angioplasty catheter consists of a gauge to ensure the ballon does not burst and different length and width of ballon to be appropriate for the stenosis size
• A short procedure, patient does not need to go theatre however, there are risks as well

Question 7

explain the stenting procedure

Answer 7

• Of the vessels is too weak and needs more than a ballon insertion then we can do stent insertion
• Stent is a metal scaffold that supports the blood vessels
• 1. A guide wire with a deflated ballon is passed through the catheter in narrow artery
• 2. The ballon is then inflated to open the artery and the stent expands around the ballon
• 3. The ballon is then removed and the stent in left in place to keep the artery open
• This is a permanent opening and done for patients with weak vessels or when stenosis is severe
• Lilac artery occlusions stetted to reduce the risk of distal embolisation
• Renal artery stenosis - stetted rather than angioplasty because of elastic recoil of vessels

Question 8

explain thrombolysis procedure

Answer 8

• For some occluded vessels
• Infusion of anti-thromoblytic drugs/ anti-coagulation drugs e.g. streptokinase, urokinase
• Different protocols used
• 1. Low dose infusion (over a period of time)
• 2. Bolus followed by low dose infusion
• 3. Bolus followed by high dose infusion

Question 9

when is embolisms used?

Answer 9

• Used for occluding vessels for
• 1. Vessels supplying a tumour
• 2. Vessels supplying an AVM
• 3. Vessels supplying an aneurysm
• 4. To stop internal bleeding

Question 10

what are the 3 types of emobilsation?

Answer 10

• 1. Coils - permanent insertion into the patient, used for barricade stent
• 2. PVA (polyvinyl alcohol particles) - permanent, medical version of super glue, need to make sure they applied in the right place. If applied in wrong place, it can occlude the vessels. Used to treat varicose veins.
• 3. Gel foam - temporary, used when there is a bleed until the vessel can heal itself

Question 11

explain when and how vena cava filter is used?

Answer 11

• Used for calcified veins or plaques
• Inserted into the inferior vena cava
• If any particle or plaque is loose within blood stream, gets trapped in the filter therefore, cannot enter the pulmonary system or heart and prevent occlusion in heart and embolism in lungs
• The filter prevents the emboli from the lower limbs reaching the pulmonary circulation
• May be permanent or temporary
• Used when patient have
• 1. recurrent pulmonary embolism (PE) despite the adequate anticoagulation
• Or 2. PE when the patient cannot have anticoagulation

Question 12

what is ablation?

Answer 12

Ablation

• Kill off unwanted tissues wherever that may be
• Often cardiac ablation in heart for patients with erythema

Question 13

what are the three types of ablation used and in which cases?

Answer 13

1. Radiofrequency - most commonly used, where high frequency radio waves is used to kill off tissues. Used for patients suffering from high menstural cycle to kill off the endometrium by inserting the catheter. However, cannot be perfumed for women who want to gt pregnant as RF ablation prevents the feotus to be viable
2. Hydrothermal - heating of tissue
3. Cryoablation - freezing of tissue, used in killing off tumour cells usually, cranial tumours. Catheter is inserted under fluoroscopy and once we know its in place, a lot of nitrogen is been sent to kill off the tissue by freezing it

Question 14

what are advantages and disadcnatges of CTA?

Answer 14

Advantage of CTA
- Look at vessels in more detail
- Can construct 3D images where as CATH in 2D
Disadvantage of CTA
- If any occlusion or stenosis is seen, they need to go into CATH lab for intervention

Question 15

what is digital subtraction angiography?

Answer 15

• it is used in fluoroscopy imaging

- the contrast outline structure is highlighted by removing the background anatomical structures from the images.

Question 16

outline the steps involved in DSA?

Answer 16

1. Acquire mask image (IM) to record anatomical background
2. Contrast injected - Series of images acquired which show arrival and run-off of contrast (contrast medium enhanced image, IC)
3. Image frames subtracted via digital processor. Any structures that are common to set 1 and set 2 are subtracted (i.e. all background anatomy but not the contrast filled structures)
4. Amplify contrast signal to boost displayed contrast of the vessels

Question 17

what are the artefacts in DSA?

Answer 17

most common is misregistration