Imaging of Head + Neck Flashcards
What imaging modalities are available for neurological imaging?
Radiography (X-Ray)
Fluoroscopy
Ultrasound
Computed Tomography (CT)
Magnetic Resonance (MRI)
What is the difference between radiography (X-ray) and fluoroscopy, and when is one preferred over the other?
X-Ray: Used for trauma (fractures)
Fluoroscopy: Continuous X-Ray (barium Swallow, Angiography, Myelography) *uses contrast*
What is angiography used for?
Evaluate blood vessels
It is invasive (go up through femoral), but you can intervene by dissolving a clot or imploying a stent right there.
What is Myelography?
uses fluoroscopy (contract) w/ cervical or lumbar puncture
cons = could cause CSF leak + invasive
What could we use an ultrasound for?
Carotid stenosis
What is a CT?
Series of X-Rays scanned axially and then digitally re-sliced in any plane
How is a CT measured?
Radiodensity measured in Hounsfield units
In CT, Hyperdense =
White/bright (ex. bone)
In CT, Hypodense =
Black/dark
In Hounsfield units what is a bone window vs soft tissue window?
bone = wide window (+1000)
soft tissue = narrow window (+30-40)
What do you typically get first from a patient w/ trauma or stroke?
Non-contrast CT
If symptoms last longer than 3 hrs or 1st CT wasen’t in enough detail, then what do you get?
CT w/ contrast (iodine)
Indicated in: neoplasm, Infection, vascular disease, inflammatory disease
In contrast, what does enhancement refelct?
Vascularity of the tissue
Wherever it is bright, blood goes
(Ex. enhancement in brain = BBB is absent)
What is a CT Angiography?
Non-invasive
Contrast though IV
Used for atherosclerosis, aneurysems
What is teh difference between contrast study and angiogram?
Contrast = evaluate breakdown in BBB and other things –> goes where blood goes
Angiograms = evaluate blood vessels
On an MRI, what does hyperintense + hypointense mean?
hyperintense = white/bright
hypointense = black/dark
When would you use an MRI?
To further evaluate a CT in way higher detail and also for ischema (cause no contrast would go in that area cause there is no blood)
Also, tumors, infections
In an MRI what do these mean?
T1 = CSF dark (hypointense)
T2 = CSF bright (hyperintense)
Flair = No CSF (good for edema/stroke)
How does an MRI work?
Patient lies in a large magnet, and the magnet aligns all the protons in the body. Radiowaves then pass through the patient and the returning signals are converted to an image.
