Neuro Imaging Flashcards
what is the standard slice orientation for neuro imaging
transaxial or axial where the L is shown as R as if you’re standing at the patient’s feet
what is an xray
short-wavelength EM vibrations that can produce a 2D image
what are x rays used for
bony changes, stenosis, and subluxation of the spine
what are the three advantages of an xray
- inexpensive
- readily available
- quick to obtain
what are the 2 disadvantages of xray
- ionizing radiation
2. nonsensitive with many pathologies missing on plain film
what is CT
commuted tomography is multiple x rays collected by a computer
what are cardinal signs of an abnormal head CT (3)
- abnormal tissue density
- mass effect from edema/hemorrhage/tumor
- ventricular enlargement
what are the two BIGGEST indications for CT
highly sensitive for intracranial hemorrhage and acute head trauma/skull fracture
how does a hemorrhage show up on a CT
white due to Hb
what is another, but lesser indication for a CT
certain brain tumors (meningiomas and gliomas) and cysts
what are the four major advantages of CT
- more accurate visualization than xray
- widely available at low cost
- critical care monitoring devices are allowed
- excellent bone imaging
what are the three major disadvantages of CT
- ionizing radiation
- acute phase head injuries may be negative for diffuse axonal injury and ischemic CVA
- poor resolution and contrast compared to MRI
what can CT not image?
diffuse axonal injury and ischemic CVA, especially during acute phase head injury
how can the CT disadvantages apply to PT
PT can educate family on inconclusivity of a negative CT result
what is the most commonly evaluated element in MRI
hydrogen
what does a T1 weighted MRI tell you
anatomic detail typically used to identify lesions (gray matter is gray and white matter is white)
when is a T2 MRI typically used
typically used to identify contusions, brain bleeds, changes in CSF, and ventricular volume
how does fluid show up on a T2 MRI
bright white
what are the two advantages of MRI
- no ionizing radiation
2. excellent soft tissue contrast and high resolution
what are the four disadvantages of MRI
- longer scan times
- susceptible to patient movement
- will dislodge implants
- limited availability and higher cost
what is cerebral angiography (CTA) used for
used to detect blockages or narrowing or arteries/veins in the brain, head, or neck with the best visualization of the vascular system
how long does a CTA take
takes up to 3 hours
how does CTA work
small capsule containing radiopaque dye released into cerebrum followed by a series of xrays in order to note any obstruction
how can a CTA be applied to a patient’s condition
it is used to determine stroke extent, size of a tumor, presence of aneurysms, AVMs, and blood flow
what are the PT implications for CTA (2)
- bedrest for approximately 8 hours to ensure proper healing of catheter site
- no movement of the catheter site, usually femoral artery
what is magnetic resonance angiography (MRA)
used to asses vascular anatomy in medium to large vessels without the use of a contrast agent
what is an EEG
recording of brain activity using electrodes fixed to the scalp
where does the electrical activity come from for EEG?
inhibitory and excitatory postsynaptic potential of pyramidal cells
what are the advantages of an EEG
noninvasive, painless, and inexpensive
what four things can an EEG assist in diagnosing
- seizure disorders involving tumors and head injury
- psych and sleep disorders
- metabolic/degenerative disorders of the brain
- CONFIRM DEATH
what is the sole PT implication for EEGs
activity may be withheld or performed based on orders
what is myelography
injection of contrast into subarachnoid to enhance dx of spinal nerve injury, vertebral displacement, herniation, cord compression, or cord tumor
what are the PT implications for myelography
complaint of headache, back spasm, and N/V
what does nuclear imaging do
images the spatial distribution of radioactive isotopes
what are types of nuclear imaging
bone scan, PET, SPECT scans
what are examples of things that will elicit an image on nuclear imaging
cell swelling, edema, and tumor growth
what does a PET scan tell you
brain hemodynamics and metabolic activity
also the most common nuclear imaging device for neuro patients
T/F: a PET scan can tell if a tumor is benign or malignant
true
what is PET mainly used for
dx, staging, and evaluation of treatment of brain tumors
what is the advantage of a PET scan
can perform hemodynamic, chemical, and thus functional imaging of cerebral blood flow and glucose metabolism
what are the three disadvantages of a PET scan
- high cost
- radiation
- limited access
what does ultrasound imaging do
assesses blood flow direction, velocity, and magnitude using the doppler effect against RBCs
what are the advantages of ultrasound doppler
noninvasive, portable, cheap, and high intrinsic spatial resolution
what is the disadvantage of ultrasound doppler
poor soft tissue contrast
what are the two types of ultrasound doppler
- transcranial doppler sonography
2. carotid noninvasives
what is transcranial doppler sonography
determines velocity of blood in cerebral or basilar arteries - over thin cranial bones or their gaps
what is carotid noninvasives
assesses severity of carotid occlusion and stenosis - over the common, internal, and external carotids
what is the order of imaging for a spinal trauma
- plain film x ray
- CT if fracture is suspected
- MRI if ligamentous/disc/soft tissue involvement suspicion
what imaging is best for progressive loss of neuro function
MRI has the greatest ability to differentiate spinal cord primary disorder and extradural defect - but we may also see spinal myelography
what is the best imaging for brain/skull trauma
non contrast CT or MRI in the first 24 hours, but CT is imaging of choice due to compatibility with medical equipment and sensitivity for skull fractures
what is the best imaging for a CVA
- CT very sensitive for acute ICH
2. MRI is more accurate for acute ischemic infarct
what is the best imaging for a brain tumor
- MRI
- CT with contrast (if MRI not available/indicated)
- PET scan
