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Flashcards in Neuroimaging Deck (20):
1

Skull Xray:
-indications

Indications:
-when not otherwise getting a CT scan & suspect skull fx, sinusitis, facial bone tumors, nose pathology, foreign body

-eval for fx of mandible and maxilla

-eval of skull for lytic lesions such as in Multiple Myeloma

-looking for scalp full thickness laceration or boggy hematoma

-eval for foreign body such as glass

2

Skull Xray
-drawbacks

-lack detail
-unable to see fx in skull base, if basilar skull fx
-cannot evaluate intracranial contents

3

CT scan:
-indications
-what is commonly missed on CT?

Indications:
-evaluate skull, skull base, vertebrae
-eval ventricles (hydrocephalus, shunt placement)
-suspicion of intracranial masses, mass effect
-looking for acute hemorrhage, ischemia

Tumors are commonly missed on CT

4

If patient is acutely ill, needs LP, and youre not sure if they have increased ICP you get what type of scan? Why?

When patient comes into ER with stroke like symptoms what test do we get? why?

You get CT scan, looking for things that would increase ICP such as mass. If there is increased ICP you might see midline shift, then you CANNOT get LP, this will cause brain herniation and death.

Pt coming into ER needs immediate CT scan, this is used to R/O hemorrhagic stroke. It cannot tell us acutely if the pt is having an ischemic stroke.

5

CT scan:
-Circumstances in which you would use contrast? no contrast?

WITH Contrast:
- neoplasm, infection, vascular dz, inflamm dz

WITHOUT contrast:
-trauma, R/O stroke, hemorrhagae, hydrocephalus, dementia, epilepsy, congenital malformation

6

When interpreting CT scan of the Head what 4 things should we be looking for?

-fluid
-mass
-shift
-look at each side and compare

7

CTs have two different technniques for evaluation, what are they?

Brain window for looking at soft tissue

Bone window for looking at bone.

8

WHat appears bright or dark on CT?

Bright: the more dense the tissue, any calcified structures (bone), new hemorrhage

Dark: water or CSF

9

Explain the three types of Hemorrhages of the brain

Subarachnoid Hemorrhage: arterial bleeding on the surface of the brain, between pia mater and arachnoid mater.
*usually from the circle of WIllis*

SUbdural Hematoma: venous bleeding between arachnoid and dura

Epidural Hematoma: dural artery or venous sinus bleeding between skull and dura; associated with skull fx

10

Causes of :
-subarachnoid hemorrhage
-subdural hematoma
-epidural hematoma

Subarachnoid: trauma, ruptured cerebral aneurysm

Subdural: tearing of bridging veins from deceleration, acceleration, or rotational forces (ex. elderly fall)

-epidural: associated with skull fx, fx bone lacerates a dural artery or venous sinus (high velocity trauma)

11

Describe what each of the following look like on CT
-subarachnoid
-subdural
-epidural

Subarachnoid: high density blood fills the sulci

Subdural: crescent shaped, midline shift
-the longer the blood has been sitting there the darker its appearance.

Epidural: biconvex mass, bleeding into the brain and soft tissue

12

Presentation of each:
-Subarachnoid
-subdural
-epidural

Subarachnoid: acute, thunderclap HA

Subdural: may be insidious, worsening HA over days

Epidural: acute presentation

13

Indications for CT angiography?

Atherosclerosis

Thromboembolism

Vascular dissection of carotids

Aneurysms

Vascular Malformations

Penetrating Trauma

Evaluation of carotids

14

MRI
- Whats the difference between T1 and T2 weighted images?
-what bright/dark on T1? T2?

T1 looks at normal brain anatomy, T2 looks at abnormal processes in the brain

T1:
-Bright= fat, white matter
-dark=CSF

T2:
-Bright= water, blood
-Dark: white matter

15

Indications for MRI

-subacute and chronic hemorrhages
-cerebral infarcts (Stroke, not acute; get the day after)
-primary and metastatic brain tumors
-intracranial abscess
-multiple sclerosis and other demyelinating dz
-new onset or refractory seizures
-vasculitis

16

MRI is superior to CT in every pathology except for?

except for skull fx and acute subarachnoid hemorrhage (b/c its slower than CT and costs more)

17

What are the advantages/disadvantages of CT/MRI?

Advantage of CT:
-simple, cheap, fast
-tolerated by claustrophobes
-no absolute CI
-better than MRI for bone detail

Disadvantages of CT:
-IV contrast complication
-Ionizing radiation

Advantage MRI :
-much broader palette of tissue contrasts
-no ionizing radiation
-IV contrast better tolerated
-better for tumor evaluation

Disadvantages MRI:
-higher cost
-difficult for unstable patients
-several absolute CI (cardiac pacemaker, aneurysm clips)
-claustrophobes need sedation
-image interpretation more challenging
-lacks bone detail

18

What is MR Angiography used for?

Useful for evaluation of intracerebral vessels

19

Cerebral Angiography (CT)
-gold standard imaging for what?
-other indications

gold standard for imaging the carotid arteries and evaluating cerebral aneurysms after subarachnoid hemorrhage.

OTHERS:
-cerebral vasculitis
-small aneurysm
-AVM
-Intraarterial tx of verebral vasospasm

20

WHat imaging study is most appropriate for acute stroke?

WHat imaging study is most appropriate in pt with a full thickness scalp laceration and GCS of 15?

If there is a concern for a tumor what is the most appropriate study?

Is there a concern for aneurysm what is the most appropriate study(s) to order?

In a patient with new onset seizures what is the diagnostic test of choice and what is the initial imaging test of choice?

-CT

Skull Xray

MRI

MRI w/ contrast b/c its blood vessels and then potentially cerebral angiography

Test of choice is MRI but the initial imaging test of choice is CT.