Imaging of Circulatory Disorders Flashcards
What are the 5 anatomical vascular imaging methods?
1 Plain radiograph
- Catheter angiography
- Ultrasound
- CT
- MRI
What are the 5 functional vascular imaging methods?
- Radionuclide imaging
- MRI functional imaging
- Ultrasound
- CT pulmonary angiogram
- Normal lung scintigraphy
Are blood vessels and lumen easy to visualise using imaging modalities?
No
Briefly explain the principal of radiographic contrast
Used to show bleeds and blockages. the denser a substance/structure is, the brighter it will appear
What are the advantages of spiral CT with contrast over other imaging modalities? (6)
- Better coordination with contrast
- Less time for the patient to hold their breath
- Less motion artefacts
- Multi-planar images
- Reduced radiation dosing
- Quicker scan times
What are the 7 ideal properties of a contrast agent?
- Inexpensive
- Inert
- Attenuation similair to soft tissues
- Stable
- must be distributed evenly between body compartments?
- Painless
- Easy to use/store
What is the ideal contrast agent?
Iodine
How is contrast agent administered?
Usually IV
Oral/Rectal/Stoma administration can be carried out depending upon the circumstances
What are the biggest problems associated with contrast? (7)
- major allergic reactions
- Renal dysfunction
- Disturbance of thyroid metabolism
- Disturbance of clotting mechanisms
- Seizures
- Pulmonary oedema
- Uncomfortable feelings
- Dose related (chemotoxic) reactions can include;
List the 4 Important Considerations before using Contrast
- Has the patient had a previous contrast allergy?
- Does the patient have asthma/atopy (allergies)?
- Does the patient have impaired renal function?
- Is the patient a diabetic taking metformin?
What is the significance of metaformin when giving contrast?
This is a rare complication in which the contrast + the metformin causes renal failure
Taking metformin after contrast can cause lactic acidosis
Name the crystal that is the basis of ultrasound
The Piezoelectric crystal
Briefly explain how ultrasonography works
- Electricity goes into the piezoelectric crystal causing it to produce vibrations and waveforms
- The ultrasound waves travel through the patient’s body
- The waves reflect off each surface that they encounter at a different frequency (the frequency is determined by the impendence of each tissue type)
- The waves return to the crystal and are converted into electricity
What is the most commonly used ultrasound mode?
B-Mode
What does the “B” stand for in B-Mode?
Brightness
