Imaging Of The Head And Neck Flashcards
How is an x ray produced?
What can you use it for?
What types are there?
Produced by sudden deceleration of electrons hitting anode with different tissues absorbing radiation differently
Use for trauma, degenerative disease, post op
PA, AP, lateral
What is fluoroscopy?
When can you use this?
Continuous x ray radiation passing thru body onto a fluorescent screen creating a moving x ray image
Swallow study
Interventional radiology
Arthography
Cardiac catheterization
What is an angiography?
What can is be used for?
Fluoroscopy with injection of contrast into vasculature intending to evaluate peripheral vasculature
Aneurysms, vascular malformation, fistulae, stenosis, thrombosis, dissection, stenting, thrombolysis
Contrast: barium or iodine
What are the pros to angiography?
Cons?
Pros: fast, diagnostic and therapeutic
Cons: invasive, contrast, radiation
What is myelography?
When can you use it?
Uses fluoroscopy
Intrathecal injection of contract
Spinal stenosis, nerve root compression, CSF leak
What are the pros for myelography?
Cons?
Defines subarachnoid space
Identifies spinal block
Invasive
could cause CSF leak, headache
Uses radiation
Uses contrast
What is computed tomography?
What is the radio density measured in?
Series of x-Rays scanned axially.
Hounsfield units
What is the Hounsfield unit of water?
What will appear white? What will appear black?
0 HU
Hyper dense (>0) = white
Hypodense (<0) = black
How are CTs read?
As if looking at the patient from the feet
What is the HU of
Air
Bone
Water/CSF
Air: -1000
Bone: +1000
Water/CSF: 0
What can CTs be used for?
Skull, skull base and vertebrae Ventricles Intracranial masses, mass effect Hemorrhage, ischemia Calcification
What are the pros to CTs?
Cons?
Pros: fast, relatively inexpensive, good at detecting large pathology
Cons: less detailed than MRI, radiation exposure, low sensitivity in posterior fossa
When would contrast be indicated?
Neoplasm Infection Vascular disease Inflammatory disease More than 3 hours after onset of symptoms
When would contrast be contraindicated?
Trauma Hemorrhage Hydrocephalus Dementia Epilepsy Within 3 hours of symptoms
What keeps IV contrast out of brain?
Blood brain barrier
Enhancement of brain parenchyma w/ contrast would indicate absent BBB or pathology
What are structures that will enhance with IV contrast?
Cerebral blood vessel Meninges - dura, arachnoid, pia Pineal glands Pituitary gland Choroid plexus
What would you use a CT angiography for?
Atherosclerosis, dissection, aneurysm, trauam
What are the pros and cons to CT angiography?
Pros: non-invasive, examine vessels from origin
Cons: contrast, radiation, lower resolution
What is MRI?
Hyperintense radiodensity will appear?
Hypo-intense radiodensity will appear?
Large magnet aligns all the protons in the body, then radio waves pass thru patient and returning signals are converted into an image
Hyper-intense: white
Hypo-intense: black
What are the uses to mri?
Pros?
COns?
Further evaluate ct, tumors, infection, joint imaging
Pros: high level of detail, safe in pregnancy, vessel imaging w/o contrast
Cons: time consuming, cant use if metal devices, expensive, claustrophobia
How will fluid appear in T1 weighted MRI?
Water/CSF = black (hypo-intense)
White matter: white
Good for visualizing normal anatomy
How will fluid appear in a T2 weighted MRI?
Water/CSF = bright (hyper-intense)
White matter: dark
Good for visualizing pathology
What is T2 FLAIR?
Removes CSF from a T2 mri
England fluid with high protein content that would then indicate edema/abscesses
(FLAIR: fluid attenuated inversion recovery)
What is an ultrasound?
Pros?
Cons?
Noninvasive imaging technique using ultrasound waves
Used to evaluated carotid arteries, placement of central lines
Pros: non-invasive, cheap, no radiation
Cons: learning curve
