Imaging Flashcards
What does DSA stand for?
Digital subtraction angiography
What is considered the gold standard for visualizing the arteries in the brain
Digital subtraction angiography
What is TTE used for?
To see wall motion abnormalities, low left ventricular ejection fraction (<20-30%), valvular abnormalities, and PFO.
What can TEE show?
Atria, left atrial appendage clot, size of PFO, PFO associated with atrial septal aneurysm, aortic arch atheroma
Transcranial Doppler US (TCD) with bubble study is used to detect…
Right to left shunt
What is TCD used to detect?
Monitoring vasospasm in SAH
To detect occlusion, recanalization, and reocclusion of the large intracranial arteries in real time
What does a MRA show?
The cerebral arterial anatomy.
Diagnose intracranial and extracranial stenosis, aneurysms, or dissections.
What is CTP (CTperfusion) used for?
Shows a better definition of ischemic brain tissue earlier than a non-contrast CT.
Requires more contrast, 2-4 axial slices, more radiation, and patient cooperation.
Why are MRI/MRA done?
- To localize the lesion
- To understand the mechanism
+ small vessel lacunar infarcts
+ large artery atherosclerosis
+ embolism
+ hemodynamic
+ venous - To differentiate between old and new using diffusion weighted sequence
- To understand tissue physiology (perfusion imaging)
- To look for stenosis, dissection, aneurysm, AVM
- Incidental findings
In what situations is a repeat CT helpful?
To localize lesion in pts unable to have MRI
Evaluation of the deteriorating pt to assess
- mass effect/edema
- to look for hemorrhagic conversion
- to look for stroke reoccurrence
Why is a CTA head/neck done?
To look for arterial stenosis, dissection, aneurysm
Why is a TTE (w/bubble study) done
To assess embolic source - anterior wall or apical akinesis - clot - valvular disease - large PFO To detect a low EF (20-30%)
A TEE w/ bubble study can see what that a TTE cannot?
Aortic atheroma PFO Atrial septal aneurysm Spontaneous echo contrast Left atrial appendage clot
A carotid US is looking for
Carotid Artery stenosis or occlusion
Direction of vertebral artery flow
A TCD is used to detect
- Clot presence and lysis in the acute setting
- Confirmation of intracranial stenosis/occlusion of major arteries seen on MRA or CTA
- Emboli detection/ monitoring
- When used with bubble study it is the least expensive/invasive way to screen for R -> L shunting
- Hemodynamic reserve
- Evaluate collateral flow patterns
What is DSA used to detect?
- Gold standard for determining degree of stenosis
- Only way to definitively delineate and follow aneurysm or AVMs, dissection, vasculitis, or other arteriopathies
What can a CT detect?
Infarction Tumors Hemorrhage - location and extent of SAH, pattern of hemorrhage Calcification Bone trauma Hydrocephalus Midline shift
On a CT what do areas of dark and bright represent
Dark = hypodense - indicates infarction and brain edema Bright= hypersense - indicates calcifications and hemorrhage
What do CT perfusion studies measure?
Measures cerebral blood flow and ischemic tissue not yet infarcted.
What is the purpose of performing a CT perfusion study
To select pts for reprofusion therapy past the TPA window by identifying tissue at risk for infarction and
Why is a CT Angiogram performed?
It is the STANDARD for diagnosing cerebral aneurysms, AVMs, dissections and fistulas
What is and why is a CTA performed
Noninvasive 3D map of vessel anatomy.
Used to determine the presence of vessel abnormalities such as occlusions, AVM, and aneurysms
What does a MRI show
Contrast between different soft tissues
Can detect necrotic tissue, oxygen deprived tissue and degenerative diseases.
