Week 3 - Imaging of Circulatory Disturbances Flashcards
What questions do we want to know when imaging for vascular issues?
- What is the anatomy?
- is there a blockage?
- is it stenosis or occlusion, and it is significant?
- is there a rupture/leak?
What functional imaging methods are there?
- ultrasound,
- radionuclide imaging,
- MRI functional imaging
What is catheter angiography?
vessel punctured, catheterised. contrast injected and presents with series of images
What is lung scintigraphy?
shows ventilation/perfusion scans for defects
How do we visualise vessels?
contrast. high density iodine used, normally IV but sometimes oral or rectal.
What are problems with iodine contrast?
- can cause severe allergic reactions
- renal dysfunction in those with kidney issues
- disturb thyroid metabolism
- destroy blood clotting mechanism
What are some reactions to contrast?
nausea, itching, flushing, seizures, arrhythmia, anaphylaxis
How does ultrasound work?
piezoelectric crystal has electric power. produces waves and vibrations that become ultrasound waves, reflect off all internal layers of patients body and then is deflected, returning to piezoelectric crystal and converted back to electricity. provides picture. all to do with timing of signal return
How does a CT scan work?
many xray beams and detectors in giant dome. allows views from transverse or saggital views. more xrays more clear image will be. White is most dense - bone - and black is least dense - gas.
What are the phases of a CT scan?
before contrast, arterial phase, venous phase, nephrogenic phase and delay phase
What is the delay phase for in a CT scan?
contrast has washed out, except for fibrotic tissue. allows you to see fibrotic tissue, tumours, leaks, obstructions
What does the CT nephrogenic stage look at?
kidney tumours or trauma
What does the CT arterial phase look at?
when contrast is first inserted - bleeding, aneurysms, stenosis or occlusion
Which phase of a CT scan are urinary tract calculi (kidney stones) picked up?
non-contrast phase as they naturally contrast with surrounding soft tissue
How long do you wait for the arterial phase of a CT scan?
within 15 seconds of injecting contrast
