Neurological Imaging and Neurointervention-Rangaswamy Flashcards
A characteristic X-ray is (blank) bremsstrahlung and (blank) percent characteristic x-ray
80%
20%
(Blank) xrays involve electrons going against tungsten atom, deviation due to nucleus ->loses energy, which comes out as x-ray
bremsstrahlung
(blank) xray uses a heated filament to produce an electron beam that hists a metal target (angstrom)
characteristic
• X-ray beam hits body and penetrates tissues
o (blank) blocks the beam, which is what produces image
o Bone appears bright
o Information limited due to lack of 3-D
Calcium (bone)
What is this:
inject iron dye that goes through blood vessels; uses same x-ray technology
o Iron blocks x-ray beam allowing us to view blood vessels
Can exam vessels in brain masses
ID aneurysms
catheter angiography
What is the physics behind an Ultrasound?
What color is fluid in an ultrasound?
send a sound signal, signal hits object and returns to localize object.
fluid is dark
IF something is hyperechoic, what does this mean?
it is reflected back (like dense tissues)
HyPOechoic is like blood (passes right through)
What does a doppler do?
gets velocity of flowing blood
High velocity indicates stenosis
What is the difference between angiogram and CT w/ contrast?
CT angiogram – instead of going into artery to inject dye we can just inject into vein
CT w/ contrast – ingestion of contrast; infiltrates everywhere, not just blood vessels
What is the physics behind a CT scan?
- Rotational x-ray source inside ring of detectors
- Possible to get whole body scan in 1-2 minutes
- Hyperdensities – bone; white
- Hypodensities – dark; fluid
What is this:
uses gamma rays sent from outside
Make radioisotopes and combine with some other elements
• Ex. Can mix with WBCs and inject back into patient
o Wherever WBCs go you get signal
nuclear medicine
What is this:
combined fluid isotope with deoxy-glucose (reaches every part of body); inject into body
• Anywhere with high metabolism (tumor) lights up
• Can detect hypometabolism
PET scan
What is the most commonly used modality in neuroimaging?
MRI
How does an MRI work?
How will blood and water present on a T1 image?
T2?
uses inherent signas in the body by detecting the rotation of hydrogen atoms within our body.
T1: water-> dark, Hemorrhage-> bright
T2: Water/tumor-> bright,
In an MRI, most pathologies will be bright on (blank)
T2
(blank) can get info on individual molecules in tumors, diagnosis can be based on this info. (blank) indicates high turnover. (blank) is only seen in neurons
spectroscopy
choline
NAA
(blank) identifies what areas using more oxygen during specific patients movement in real time (or language etc.)
Functional MRI
(blank) is a 3D modeling technique used to visually represent neural tracts using data collected by diffusion tensor imaging (DTI). It uses special techniques of magnetic resonance imaging (MRI), and computer-based image analysis.
diffusion tractography
What is this:
practioners insert a catheter into groin and thread it through vessels to probems site. Physician can deliver meds or ustilize medical devices to accomplish treatment
Neurointerventional radiology
Is neurointerventional radiology invasive?
no it is minimally invasive!
What are common neurointerventional surgeries?
- angioplasty
- stent placement
- thrombolysis and thrombectomy
- coiling
- embolization
How does an angioplasty work and where do you commonly put them?
- stenosed (narrowed) vessel
- place balloon and dilate it
- common in heart
What is this:
metal device places at site of stenosis
stent placement
What is an aneurysm?
Why are they worrisome?
bulges in vessels
-high potential for bleed and if in the brain can cause increased ICP
Do people survive aneurysms often?
no, 50% of patients never make it to hospital and there is a high chance of rebleed w/in a month
What is coiling?
fills weak areas that have aneurysms.
What is thrombolysis and thrombectomy?
blood clot lysis and surgical removal of clots too large to lyse
What are 2 image-guided treatments?
- endovascular treatments
- percutaneous image-guided treatments
What are the principles of imaging?
- Anatomy
- Pathology
- Clinical info
- Look for altered anatomy and signal changes
- Secondary effects
- Primary cause (differential diagnosis, diagnosis)
What are you looking for with anatomy?
-symmetry, morphology (blood vessels, ventricles, buds, masses)
What are you looking for with altered anatomy and signal changes?
o Radiodense vs. radiolucent (x-ray, CT)
o Hyperechoic vs. hypoechoic (US)
o Increased activity (nuclear medicine)
o Hyperintense vs. hypointense (MRI)
Imaging is mainly used as a (blank) modality.
It is used to mainly do what?
Imaging is also used to do what?
screening
rule out uncommon diseases
confirm clinical diagnosis and further characterization (e.g acute stroke, advanced tumor imaging)
What is this:
neurologic deficit that lasts more than 24 hours.
acute ischemic stroke
A major stroke is defined as a neurological deficit with the NIH stroke scale score of greater than or equal to (blank) and sustained for longer than (blank) days
4
7
In acute ischemic stroke what imaging should you get to see immediate findings?
What should you use to look for occluded vessels?
What imaging is less accurate but can be used to look at clots or hemmorhage and what is its downside?
MRI
angiogram
CT scan-> need to wait 24 hours to see ischemic stroke
When someone has head trauma, what is the first thing you do and why?
you get a head CT so you can check for hemmorhage
What is the difference between ischemia and infarct?
ischemia-> syndrome, but brain is still viable (loss of function, but potential to treat and reverse)
infarct-> brain tissue is dead
What is the sign that is subtle and an early sign of infarct?
insular ribbon sign
If you are doing a CT and you see a hyperdense artery what does this mean? What does a hemorrhage look like?
fresh clot and it will be bright (vessels shouldnt be seen)
Bright also
What is the order of imaging you should do with someone that has a stroke?
CT-> make sure no hemmorhage
CT angiogram-> check vessels
MRI-> check for infarct
What is this:
bleeding into subarachnoid space (area between arachnoid membrane and pia mater surrounding the brain, space that contains blood vessels)
acute subarachnoid hemorrhage
What is the approach to treating a subarachnoid hemorrhage?
Preventing further bleeding because primary bleed has already stopped
An aneurysm is a dilation of any vascular structure, usually located where?
at the base of the brain (not actually within the brain)
What imaging should you use for an acute subarachnoid hemorrhage?
What is sad about these bleeds?
1st: non-contrast CT scan
2nd : CTA (identify bulge location)
-> very complicated surgery (30% mortality)
What is a bleed within the parenchyma?
an acute intraparenchymal hemorrhage
What are intraparenchymal hemorrhages due to? How do you treat this?
hypertension or vascular malformation
- surgery
Why will you use a MRI for acute intraparenchymal hemorrhages?
to look for AV malformations
How do you treat an acute intraparenchymal hemorrhage?
ONYX embolization
very difficult and it is a 6 month process
Why will a hemorrhage appear bright on a CT scan?
hemoglobin
What is most sensitive for stroke?
diffusion weight sequence
What will a subdural hemorrhage appear like on a CT scan?
crescent shaped
What will a epidural hemorrhage appear like on a CT scan?
usually biconvex shaped
When you have a brain tumor, what should you use to look at it? What four things should you look for?
Contrast CT (look at meninges)
- surrounding edema
- necrosis
- enhancement
- hemorrhage
If the BBB is intact, what tumor grade is it?
I
What grade is a GBM?
grade 4
enhancement, necrosis and edema
What is this:
• Looks similar to GBM
• Look at capsule; well-defined lesion
• Diffusion weight sequence – bright; no movement
brain abscess
(blank) is used to make certain structures appear brighter on MRI (i.e. contrast agent)
Gadolinium
o Gray matter is brighter than white matter b/c gray matter is more (blank)
dense
What is this:
Dawson finger morphology
• Along the ventricles
Demyelinating disorder
MS
