what are 5 common scans used in CT
- Head
- cervical spine
- abdomen and pelvis with contrast
- abdomen and pelvis without contrast
- CT angiography
how do low density object appear on CT? High?
low densities are dark, high densities are lighter
what are 4 complications in getting a good Ct
- patient movement
- pt size
- inability to lay flat
- metallic artifact
hounsfeld units
units of density, air is -1000, bone is +1000
image windowing
different computer adjustments to make structures on a CT more or less clear
what are 5 ways to introduce contrast for a CR
- Oral
- rectal
- IV
- arthrography
- myelography
what is the difference between these two pictures
the left is without contrast, the right is with contrast
what is the relevance of contrast timing to getting a good CT
if the contrast isnt in at the right time it won’t be in the structures you are trying to view
how long after oral contrast should a CT be taken
1-2 hours
what is necessary when introducing contrast by IV
a high quality IV that can take the pressure needed for injection
three CT protocols
- with IV contrast
- without contrast
- with and without contrast
what are three contraindications for contrast
- Iodine allergy
- compromised renal function
- recent adminstration of contrast
when is MRI indicated over Head CT
when there are suspected metastatic diseases or masses
what are three diagnoses that would indicate getting a CT head with contrast
- stroke
- hemorrhage
- hematoma
subarachnoid hemorrhage
hemorrhagic stroke
subdural hematoma
stroke
stroke
metastatic lesion
what are three indications to perform a CT angiograph
- stroke symptoms
- carotid occulsion/dissection/stenosis
- aneurysms
T/F it is necessary to get an MRI or CT before doing a CT angiogram
true
what view is this? what is missing
CT angiogram
the interal carotid is not visable because it is occluded
what would indicate a CT sinus screen
chronic sinusitis or post operative follow up
