Neuroimaging Flashcards
1
Q
Indications for skull xray?
A
- when they are not otherwise getting a CT scan (A&Ox3, GCS 15) and:
you suspect skull fracture, sinusitis, facial bone tumors, nose pathology, fb - eval for fractures of mandible and maxilla
- eval of skull for lytic lesions: MM
- scalp has full thickness laceration or boggy hematoma (looking for skull fracture)
- to eval for scalp fbs such as glass
2
Q
What are the drawbacks to skull X-rays?
A
- lack detail
- no reassurance if negative in setting of trauma as unable to eval in intracranial contents
- unable to see fractures in skull base, if *basilar skull fracture suspected - get CT
3
Q
Difference b/t vessels and fractures on skull xray?
A
- vascular indentations branch and taper, and are curvy, and fractures are usually straight and don’t branch
4
Q
What is a CT?
A
uses X-rays to create images with the aid of compute to generate cross sectional views of anatomy
- iodine contrast is sometimes used (may cause acute tubular necrosis in pts with compromised renal fxn)
- fast
5
Q
Indications for CT?
A
- eval of skull and skull base, vertebrae (trauma, bone lesions)
- eval of ventricles (hydrocephalus, shunt placement)
- suspicion of intracranial mass, mass effects (HA, N/V, visual sxs) - not as detailed as MRI, just a screening test
- looking for acute hemorrhage, ischemia: stroke, mental status change (ischemia isn’t evident on CT until 24 hrs post onset of sxs)
6
Q
Why should you get a CT scan when a pt is having a stroke?
A
- to differentiate b/t hemorrhagic and ischemic
- if hemorrhagic - bleeding will show up on CT
7
Q
When do you use a CT w/o contrast?
A
- trauma
- r/o stroke
- r/o hemorrhage
- hydrocephalus
- dementia
- epilepsy
- congenital malformations
8
Q
When should you order a CT w/ contrast?
A
- neoplasm (neovascularization)
- infection
- vascular disease
- inflammatory disease
9
Q
What are the main things you should look at in a CT?
A
- fluid
- mass
- shift
- at each side, and compare
10
Q
Difference windows on CT?
A
- Brain (detailed image of brain) vs Bone (brain detail taken out, focus on bone)
11
Q
The density of the tissue related to the brightness on CT?
A
- more dense the tissue - brighter it is on CT
- any calcified structure (bone) - bright
- new hemorrhage is also bright
- water (CSF) will be dark
12
Q
Difference in location of hemorrhage?
A
- subarachnoid hemorrhage: arterial bleeding on surface of brain, b/t pia mater and arachnoid mater (layer out over brain)
- subdural hematoma: venous bleeding b/t arachnoid and dura mater (contained bleed)
- epidural hematoma: dural artery or venous sinus bleeding b/t skull and dura, assoc with skull fracture (usually trauma involved)
13
Q
Subarachnoid hemorrhage, causes?
A
- injury of small arteries or veins on surface of brain, ruptured vessel bleeds into space b/t pia and arachnoid mater
- usually arterial (circle of willis)
- causes: trauma (most common), ruptured cerebral aneurysm
- show up bright (high density blood)
- no respect for anything, going into fissures and sulci and sella (death-star)
- ACUTE presentation
14
Q
What is a subdural hematoma?
A
- tearing of bridging veins from deceleration and acceleration or rotational forces
- blood collects in space b/t arachnoid mater and dura mater
- below dura, doesn’t respect suture lines
- low force trauma
- ** Venous (venous plexus)
- may be insidious (worsening HA over days)
- crescent shaped
- ex: old person falling
15
Q
Characteristics of a subdural hematoma on CT?
A
- crescent shaped
- hyperdense, may contain hypodense foci due to serum, CSF, or active bleeding
- doesn’t cross dural reflections
- if it is subacute - hematoma may not be as bright on CT (old blood)
- if chronic: will be darker due to reabsorbtion of hemorrhage over time
