CT Flashcards
(20 cards)
On a brain CT, what does white matter look like vs dark matter?
White matter looks darker than gray matter
(T/F) CSF has a hounsfield value of 1 since it has a similar density to water
FALSE; value of 0!
What’s the difference b/w intra-axial and extra-axial collection in the brain?
intra-axial: within substance, brain, or spinal cord
extra-axial: within meningeal layers (aka: outside brain or spinal cord)
What’s the diff. b/w presentation of a hematoma and a tumor on CT?
Hematoma: will normally stay confined to space it’s filling and may push out a lil
Tumor: pushes soft tissues out of the way aggressively and causes noticeable mass effect
Do extra-axial collections appear hyperdense or hypodense on CT?
hyper-dense bc they’re normally hematomas which contain clotted blood
- only will be darker if hematoma is older
What is it called when the hematoma pushes on the brain?
Mass effect
What is a type of mass effect that has led to stuff shifting around in the brain?
midline shift
What some key characteristics of an intra-axial mass?
- surrounding edema
- mass effect
- hydrocephalus
What are CT scout images?
X-ray that gives you a big picture/overview that should be looked at before looking at CT slice images
(not diagnostic, uses lowest dose)
(T/F) A CT angio scan is taken when the bolus is in the vein of interest, not artery
FALSE; taken during arterial phase!!!
What can CT angio evaluate?
- Aorta
- Pulmonary arteries
- Carotid arteries
- Peripheral vascular system
- Circle of Willis
What kind of pathologic condition can CT angio be used to evaluate?
aortic dissection
EKG gating uses the pt’s cardiac rhythm to predict what?
to predict next Diastole happens
EKG gating is contraindicated in:
Afib or tachycardiac pts
____ is a multi detector w/ 64 slice scanners and can slice super thin (0.635 mm)
Cardiac CT
The more a coronary artery has calcified, the ___
the higher the risk of atherosclerotic plaque
- wont give a degree of vessel stenosis!
In a CTA, the calcium appears ___ in the blood vessel and the ____ is the white stuff going around it
dark in BV; iodine is white stuff
(T/F) CTA is more blurry than conventional angio
FALSE; not as blurry
guided biopsies:
use CT to get into correct area of lesion
A guided drainage can be used for a..?
“rim enhancing fluid collection containing air (most consistent w/ an abscess)”
