Contrast Media Flashcards
Why do we use contrast media
To visualise soft tissues
Gastrogram
+ve cm barium is used to line the organ and then distended with -ve cm air
Cystogram
+ve cm iodine is used to line the bladder and then distended with the negative cm air
Positive contrast media
contains elements of a high atomic number that are radio opaque (i.e. appear white on xray film - whiter than bone)
Negative contrast media
Gases which because of thier low density are radiolucent and appear black on x-ray. Commonly used gases, O2, room air, CO2,
Examples of common +VE contrast media
Barium
Water soluble iodine
Barium
Micropaque - powder, paste or solution
Used in GI tract
Adv - inert, insoluble
Dis- may cause a foreign body reaction if leaks
Water soluble iodine - Most common
Conray
Gastro-conray
Urografin
Gastrogafin
Hypaque
Water soluble iodine - Features
Hypertonic
Soluble
Following IV - excreted via kidney
Can use direct into lower urinary tract
Can use direct into GIT (not as effective as barium but can use if GI rupture)
Water soluble iodine- side effects
IV may cause fall in blood pressure or anaphylactic reaction
If animal conscious may cause whining or retching
Lower osmolar ionic media
e.g. Hexabrix
Fewer side effects than water soluble iodine
Better contrast in GIT than water soluble iodine
Not good for myelogram - draws water in and causes pressure
Lower osmolar non-ionic media
E.g. Omnipaque
Safe for myelography
Contrast radiography methods
Myelography
Gastrogram
Cystogram
Retrograde urography
IV urography
Myelography
Used to indicate lesions that are not detectable on ordinary x-rays
Indications- spinal pain, neurological signs, prolapsed invertebral discs
Myelography preperation of patient and equipment
Anaesthetised
Clip area (caudal to skull or lumbar spine)
Spinal needle (20-22g)
Warmed contrast media
Check dose ( variations between cisternal tap and lumbar tap)
Syringe
Sample bottle for CSF
Aid to elevate head
Surgical scrub
Sterile gloves
Myelography method of restraint
GA essential
Myelography method
Cisterna Magna puncture (most common for myelogram)
Lumbar puncture