40. Imaging of Circulatory Disturbances Flashcards
What to look for in vascular imaging? (4)
- what is the anatomy?
- is there a leak?
- is there a blockage? (occlusion or stenosis?)
- can it be fixed
What are anatomical vascular imaging techniques? (4)
- plain films
- contrast angiography
- ultrasound
- CT/MRI
What are functional vascular imaging techniques? (3)
- radionuclide imaging
- MRI functional imaging
- ultrasound
What do we look for in vascular imaging? (3)
- soft tissue contrast?
- functional significance of lesions
- is treatment effective?
From bone, metal, soft tissue e.g. muscle, fat and air, name them from most to least dense.
- metal (most dense)
- bone
- soft tissue e.g. muscle
- fat
- air
What are the ideal properties of a man-made contrast agent used in radiology? e.g. iodinated contrast (6)
- has attenuation different as the surrounding tissues (ability for a structure to weaken and soak up x rays = attenuation), differential x ray attenuation
- inert (chemically inactive)
- not equal distribution in and out of selected body compartments (stable in selected body compartments)
- painless
- easy to use
- cheap
What are problems with iodinated contrast? (6)
- major reactions can occur
- renal dysfunction (since big macromolecules found within iodine)
- disfunction of thyroid metabolism (if under active)
- disturbance of clotting
- seizures
- pulmonary oedema
What are side effects of paranteral (through IV) iodinated contrast? (4)
- metallic taste
- feeling of warmth
- arterial injections: micturition, discomfort
- rarely nausea
What always needs to be discussed with patient and evaluated prior to paranteral iodinated contrast is administered?
- previous contrast allergies
- asthma/atopy (genetic tendency to develop conditions)
- poor renal function; nephropathy can be a problem
- ALWAYS ask if patient is on Meformin for diabetes (SERIOUS reaction can occur)
What happens during catheter angiography?
- vessel is punctured and catherised (catheter inserted into skin through vessel)
- sterile procedure
- iodine contrast injected using pump injector
- rapid series of images taken
What are some interventional radiology procedures which are minimally invasive treatments? (6)
- angiography/ angioplasty
- embolisation
- catheter thrombolysis
- drainage of abscesses
- nephrostomy
- vertebroplasty
When to use angioplasty?
- short stenoses or occlusions
- sessile/concentric plaques
- iliac> s.femoral artery> popliteal > crural
The bigger the vessel, the better the function result following angioplasty.
What is the main benefit of angioplasty?
Not as dangerous as surgery (however its effects not as long lasting)
What is inserted mainly though angioplasty?
Stents: to restore blood flow to the vessel
What is an example of a negative contrast agent?
carbon dioxide
When is CO2 used as contrast agent? (2)
- if patient has poor renal function
- if patient is sensitive to iodinated contrast agents
What is an example of a positive contrast agent?
iodine
What is angioplasty used for? (5)
- occlusion
- dissection
- embolisation
- rupture
- infection
What are main pros for ultrasound use? (6)
- no radiation dose
- quick
- non-invasive
- resolution vs penetration
- good for physiological findings
- operator dependent
On an ultrasound probe, when does image appear red and when does it appear blue?
Red; when blood flowing towards the probe
Blue: when blood is flowing away from the probe
What is radionuclide imaging used for? (2)
- to check perfusion (and ventilation)
- to check blood loss
(sequential imaging)
What can be easily seen on a V:Q scan?
Pulmonary embolism (perfusion abnormal but ventilation is normal)
For which conditions is radionuclide imaging beneficial for? (2)
- perfusion of transplant kidneys (or any organs)
- blood loss into GI tract
What are pros for nuclear medicine? (3)
- IV injection only
- good patient compliance
- easy to arrange
What are cons for nuclear medicine? (3)
- radiation dose
- very insensitive
- very non- specific
What are pros or CT angiogram? (3)
- gives information about other structures
- sensitive
- IV injection only
What are cons for CT angiogram? (3)
- radiation dose
- high contrast dose
- expensive
What are pros for magnetic resonance angiography (MRA)? (4)
- sensitive
- specific
- no radiation
- no nephrotoxic contrast
What are cons for magnetic resonance angiography? (3)
- very expensive
- needs state of the art machinery
- high contrast cost
Define consent in radiology.
A process in which a patient learns key facts about an investigation/ treatment, including potential risks and benefits, before deciding whether or not to proceed.
Informed consent continues throughout the procedure.
Who should obtain consent for interventional radiology purposes?
- only the person doing the procedure
- new graduates should not obtain consent for procedures they don’t fully understand
Who should not administer contrast media to patients?
Students/staff who cannot recognise and treat any potential reactions
When can a newly qualified doctor gain informed consent from patients?
Only when they have detailed knowledge from active involvement and experience in interventional studies.
