Vascular Interventional Radiology Flashcards
Give 3 common vascular diseases?
1) Acute lower limb ischaemia
2) Chronic ischaemia
3) Aneurysm disease
What are the 2 broad ways of imaging the vascular system?
Invasive (involves needles/scalpels)
Non invasive
Give 3 non invasive modalities of imaging the vascular system?
1) Duplex scanning (US Doppler)
2) MR Angiography (MRI of vessels)
3) CT angiography
Give an invasive way of imaging the vascular system?
Catheter/Contrast angiography
What are the 3 advantages and 1 disadvantage of duplex scanning (USS)?
Advantages:
1) No ionising radiation (good for use in pregnancy)
2) Readily available
3) Velocity and volume measurements can be obtained
Disadvantages:
1) Operator dependent - ie. can only be interpreted by the operator then and there, do not produce an image which can be interpreted by others
What is the major advantage of CT angiography and one disadvantage?
Advantage = readily available Disadvantage = uses x-rays
Give 3 uses of CT angiography in vascular disease?
1) Assessment of aortic aneurysms
2) Assessment of bleeding
3) Assessment of peripheral vessels
What is multiplanar formatting sometimes used in CTA (CT angiography)?
CT scans traditionally taken in axial plane, computers can now reformat the image to give an image in coronal plane, saggital plane etc.
What are the 2 advantages and 3 disadvantages of MR Angiography (MRA)?
Advantages: 1) Non invasive 2) No ionising radiation Disadvantages: 1) Not as readily available 2) Overestimates stenosis 3) Not suitable for all patients
Name 3 groups of patients for which MRA would not be suitable?
1) Claustrophobia
2) Pacemakers
3) Prostheses/ metal work
Which imaging technique is gold standard for vascular imaging?
Contrast/ catheter angiography
Contrast/ Catheter angiography is deemed an invasive procedure for what 2 reasons?
1) Procedure related: ie have to gain access to body
2) Contrast related: injecting contrast into someones blood stream
Why is the common femoral artery over the femoral head a good point of access for catheter angiography?
It is a relatively superficial artery
In its position over femoral head, the bone provides a hard surface to compress the artery against in order to achieve haemostasis
What are the 2 possible access complications in catheter angiography?
1) Haematoma at point of access
2) Pseudoaneurysm
What is a pseudoaneurysm?
A hematoma which forms as a result of a leaking hole in an artery. The haematoma forms outside of the arterial wall so to be considered a pseudoaneurysm the haematoma must continue to communicate with the artery
What are the 2 possible contrast mediums used in catheter angiography?
1) Iodinated contrast
2) CO2
When would CO2 be used as a contrast medium and what is the disadvantage?
Can be used in patients with renal impairment (iodinated contrast is nephrotoxic) and possible those who are allergic
Disadvantage is that it is quite painful for the patient
What is interventional radiology?
The use of imaging techniques to effect treatment rather than simply diagnose, it is a minimally invasive alternative to surgery
How can interventional radiology be used to treat haemorrhage?
Through embolization of the vessels which are bleeding using a catheter. Embolisation can be achieved using different mediums such as metal coils or glue.
What is subtraction angiography?
Take images without contrast. Add contrast and take further images then subtract the image without contrast from the image with contrast. Are left with an image showing only the vessels
Give 4 situations in which interventional radiography could be used to stop haemorrhage?
1) Trauma
2) GI bleeding
3) Post-partum haemorrhage
4) Haemoptysis (embolise the bronchial arteries, a lot of respiratory pts die due to choking on blood so this prevents that)
Interventional radiology can also use embolization in non-haemorrhagic conditions, name 3 non-haemorrhagic uses of embolization?
1) Chemoembolization
2) Selective internal radiotherapy (SIRT)
3) Uterine artery embolization (to treat fibroids and stop symptoms of menorrhagia and pain)
What is meant by chemoembolization and selective internal radiotherapy?
Used in oncology, palliative treatments, not yet curative, used in patients where there is no option of surgical resection. Catheter is used to inject chemotherapy or radiotherapy beads directly into the small vessels recruited by the tumour to supply it. The vessels are then embolized.
Other than SIRT of chemoembolization, name another use of interventional radiology in oncology?
Tumour stenting - ie. stenting a structure such as the oesophagus or GI tract to prevent occlusion by a tumour
Give the 2 main causes of acute limb ischaemia?
1) Thrombosis
2) Embolism
What 2 types of embolism can cause acute ischaemia?
1) Cardiac
2) Non-cardiac
80% of cardiac emboli are caused by what?
AF
Aswell as emboli and thrombosis, give the 6 other causes of ischaemia?
1) Intrinsic clotting abnormality
2) Arterial dissection
3) Surgery
4) Trauma
5) Extrinsic compression
6) Compartment syndrome
What are the 4 classifications of acute limb ischaemia, what is the classification system based on and is the tissue deemed viable in each?
Based on the appearance of the tissue, the sensory loss, muscle weakness and Doppler signal (whether it is audible or not - a pulse may be unpalpable but audible) I - tissue viable IIa - tissue marginally threatened IIb - tissue immediately threatened III - irreversible injury
Which stages of acute limb ischemia require imaging and which require immediate treatment?
Category I and IIa - require imaging
Category IIb and III - require immediate treatment
In an acute ischaemic limb what is the advantage of duplex scan?
Gives you a good overview of the sight and extent of obstruction
What are the pros and cons of using MRA to image an acute ischaemic limb?
Pros - non invasive and gives a comprehensive over view
Cons - low availability and possibility of motion artefact
What are the pros and cons of using CTA to image acute ischaemic limb?
Pros - acute imaging OOH, can show an in stent thrombosis, aneurysm and dissection and has a rapid scanning time
Cons - can get artefact so can give false positives
What are the 3 possible endovascular and 2 possible surgical treatment options for acute ischaemic limb?
Endovascular: 1) Thrombolysis 2) Aspiration/ mechanical thrombectomy (suck it out with a catheter) 3) Angioplasty +/- stent Surgical: 1) Surgical thrombectomy/ embolectomy 2) Bypass
How is thrombolysis carried?
Injection of TPA (converts plasminogen to plasmin)
How is chronic limb ischaemia treated?
Risk reduction - stop smoking etc.
Then treatment depends on symptoms, patient circumstances and extent of the disease
How is chronic ischaemia managed?
Have multidisciplinary discussions
Use interventional radiology
Surgical options include: endarterectomy, bypass graft and amputation
How is an aneurysm defined?
Expansion of an artery by more than 50%
What 4 arteries does aneurysmal disease commonly occur in?
1) Thoracic aorta
2) Abdominal aorta
3) Iliac, femoral and popliteal
4) Visceral arteries
Who is AAA screening carried out in?
Men over 60 years old
When is treatment for AAA carried out and what are the 2 main types of options?
Carried out when >5.5cm
Elective treatment
Options are surgical or endovascular
What is the endovascular option to treat aneurysmal disease?
Stent graft - a metal cage with fabric wrapped around it creates a lumen which excludes the aneurysm
(NB different from a metal stent used to open up narrowed arteries)
