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Elsa AACN > CH 6 Neuroimaging studies > Flashcards

CH 6 Neuroimaging studies Flashcards

1
Q

X Rays

A

rapid exam of skull injuries

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2
Q

CT stands for

A

computed tomography

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3
Q

What is CT

A

x-ray beam rotated around pt’s head to take many views
rays absorbed based on density
greatest absorption occurs for the densest structures (hyperdense) like bones, fresh blood, calcifications

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4
Q

Hyperdense structures are brighter or lighter in color?

A

lighter

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5
Q

Example of Hypodense structures on CT?

A

air and fat

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6
Q

Hypodense structures are brighter or lighter in color?

A

darker

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7
Q

Advantage of CT

A

detect gross abnormality in acute care

useful for skull fracture, hemorrhage, mass effect

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8
Q

Disadvantage of CT

A

less effective at detecting white matter changes (e.g. plaques in MS, microvascular ischemic changes) or refine differential diagnosis (e.g. tumor, mass)

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9
Q

Risks of CT

A

small amount of ionizing radiation

allergic reaction to iodine based contrast media

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10
Q

MRI stands for

A

Magnetic Resonance Imaging

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11
Q

How is MRI done

A

generate high resolution anatomic images of brain structure
radiofrequency pulses generate electromagnetic reaction of hydrogen protons in water molecules. When pulses stop, protons return to original alignment, then emission of signals detected by scanner to construct image

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12
Q

What do T1 and T2 stand for

A

time constants

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13
Q

T1

A

demonstrates greater anatomic detail but less tissue contrast

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14
Q

T2

A

enhanced contrast and more sensitive to detecting damaged vs intact tissue
more useful for lesion identification

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15
Q

FLAIR

A

fluid attenuated inversion recovery

allows for representation of even greater contrast between normal and pathological issue

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16
Q

Advantages of MRI

A

highly detailed images of brain anatomy

detection of low contrast or small lesions (e.g. MS, AVM, low grade astrocytoma)

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17
Q

Diffusion Weighted MRI (DWI)

A

using diffusion of water molecules to generate contrast in MR images

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18
Q

When is DWI used

A

stroke imaging, white matter diseases, oncology

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19
Q

Why is DWI used over conventional imaging?

A

allows collection of info about molecular activity and cellular function
sensitive to microstructural changes
detect abnormalities like white matter disease
(e.g. stroke during first few hours of onset prior to detectability on standard MRI)

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20
Q

Perfusion Weighted MRI

A

infer how blood travels through brain’s vasculature through the use of contrast medium or endogenous blood flow marker

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21
Q

When is Perfusion Weighted MRI used?

A

diagnosis and imaging of brain tumors which exhibit unusual diffusion due to mass effect, modulated metabolism, pathological leakage across blood brain barrier

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22
Q

What does Perfusion Weighted MRI assess?

A

assessment of hemodynamic parameters

e.g. cerebral blood volume, cerebral blood flow, mean transit time, and time to peak

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23
Q

Susceptibility Weighted imaging

A

sensitive to detecting small amounts of blood products and calcium that may be undectatable with other MRI sequences

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24
Q

Susceptibility weighted imaging advantage

A

useful for small lesion

ability to detect more subtle TBIs and hemorrhages in cerebral amyloid angiopathy

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25
Q

Diffusion Tensor Imaging (DTI)

A

examine white matter integrity and white matter tracts by detecting the directional movements of water molecules

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26
Q

How does DTI assess

A

generates fractional ansiotropy (FA) value

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27
Q

FA value in DTI (high vs low)

A

high FA value in very organized densely myelinated regions of the brain (e.g. corpus callosum, pyramidal tracts)

Low FA value in less organized, less myelinated, or state of edema, injury or inflammation

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28
Q

Magnetic Resonance Spectroscopy (MRS)

A

MRI method to localize and characterize brain based biomarkers

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29
Q

How is MRS different from conventional MRI

A

can image endogenous biological markers such as creatinine, NAA, glutamate
can detect brain cell loss in degenerative diseases such as AD and MS

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30
Q

Magnetic Resonance Angiography (MRA)

A

generate images of arteries to evaluate stenosis, occlusions, aneurysms

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31
Q

Advantages of MRA

A

non invasive nature

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32
Q

Disadvantages of MRA

A

poorer spatial resolution
less sensitivity to vessels with slower blood flow
lengthier procedure time than CT angiography

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33
Q

2 categories of Functional imaging

A

resting

activated

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34
Q

What is Single photon Emission computer tomography (SPECT)

A

examines regional changes in cerebral activity or brain chemistry through the use and detection of tracer flow or receptor binding isotopes

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35
Q

What is SPECT for

A

study regional blood flow (rCBF) which is correlated with brain activity

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36
Q

SPECT markers have been developed for specific types of neuropathology such as

A

beta amyloid and TAU

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37
Q

Advantages of SPECT

A

less extensive tech requirements

radio tracers are stable

38
Q

Position Emission Tomography (PET)

A

examines glucose utilization with radiostopes

examines metabolic activity in brain cells engaged in cognitive tasks

39
Q

How does PET assess

A

utilizes intravenous tracers (FDG) nad oxygen 15 ti characterize resting regional brain metabolism

40
Q

How is PET useful

A

differential diagnosis of dementia due to differing patterns of abnormal cerebral metabolism

41
Q

How does PET help with diagnosis of AD?

A

in AD, PET imaging reveals bilaterally reduced regional glucose metabolism in posterior temporoparietal cortices in addition to anterior and mesial temporal lobes

42
Q

How does PET help with diagnosis of FTD?

A

in FTD, PET imaging shows hypometabolism mostly in the frontal and anterior temporal cortices

43
Q

PET advantage

A

greater spatial resolution than SPECT

44
Q

PET disadvantage

A

expense

45
Q

fMRI

A
  • examines regional changes in brain activity
  • neural activity is associated with blood flow to that region and the localized surplus of oxyhemoglobin relative to deoxyhemoglobin results in signal intensity
46
Q

BOLD effect

A

blood oxygen level dependent effect

measures changes in blood flow by detecting changes in intravascular oxyhemoglobin concentration

47
Q

Use of fMRI mostly for?

A

presurgical mapping for epilepsy surgeries and tumor resections

48
Q

advantages of fMRI

A

no tracers, radiosotopes, contrast agents

superior to SPECT and PET

49
Q

Electrophysiological Studies

A

EEG

50
Q

EEG

A
  • monitor brain electrical activity along the scalp

- records the sum of rhythmical activitiy of thousands of neurons

51
Q

What is EEG used for

A

to differentiate epileptic seizures from other types of events (non epileptic, fainting, subcortical d/o)

dx of coma, determination of brain death, polysomnography, monitoring anesthesia depth

52
Q

Repetitive slow wave complexes over temporal lobe with cerebral dysfunction indicates

A

herpes simplex encephalitis

53
Q

EEG wave forms are classified according to what?

A

frequency
amplitude
shape
scalp region

54
Q

Alpha waves - how many Hz?

A

8-12 Hz waveforms

55
Q

Alpha waves are observed in which age groups?

A

all age groups, most common in adults

56
Q

When are alpha amplitude manifested?

A

patient relaxed with eyes closed and ablated by eye opening

57
Q

Where are alpha waves located?

A

bilateral posterior regions

58
Q

Beta waves - how many Hz?

A

12-30 Hz

59
Q

Beta waves are observed in which age groups?

A

all age groups

60
Q

When are beta waves manifested?

A

it is the dominant rhythm in patients who are alert, anxious, or have their eyes open

61
Q

Describe beta waves distribution

A

symmetrical distribution

most evident frontally

62
Q

Beta activity can be enhanced under what condition

A

sedating drugs (e.g. benzo, barbiturates)

63
Q

Theta waves - how many Hz?

A

4-7 Hz

64
Q

Theta waves are observed in which age groups?

A

children

any age group during sleep

65
Q

When are theta waves observed?

A

transiently observed during normal wakefulness

prominently observed during drowsiness

66
Q

Delta waves - how many Hz?

A

up to 4 Hz

67
Q

When are delta waves observed?

A

during sleep across all age groups

normally the dominant rhythm in infants

68
Q

Where are delta waves observed?

A

frontally in adults and posteriorly in children

69
Q

What are evoked potentials (EP)?

A

involves the noninvasive stimulation of afferent pathways

70
Q

Visual EP tests

A

present fixed visual pattern to each eye and record electrical activity

71
Q

Auditory EP tests

A

administer repetitive clicks to each ear

72
Q

Somatosensory EP test

A

use mechanical or brief electrical stimulation to skin

73
Q

EP is often used for what?

A

detect and localize lesions in the CNS

monitor prognosis after CNS trauma or hypoxia

74
Q

EMG

A

recording electrical activity in specific muscles and peripheral nerves

75
Q

Needle EMG

A

insert needle electrode into muscle

nerve conduction studies utilize electrodes taped to the skin to measures specific waveforms generated

76
Q

MEG/MSI

A

detect minute magnetic fields generated by neuronal activity
when neuronal synapse becomes active, there is current flow across membranes that can be recorded

77
Q

Cerebral Anteriography (angiography)

A

injection of iodine-based contrast into the cerebrovascular via catheter inserted into femoral or brachial artery and threaded up the aortic arch

78
Q

What is angiography best used for?

A

characterization of AVM, aneurysm, cerebral venous sinus thrombosis
differential dx of tumor that produce a stain as a result of neovascularization

79
Q

coil embolization of aneurysm

A

performed with angiography

80
Q

Wada testing

A

inject sodium amobarbital into cerebrovasculature via angiographically guided catheter to produce brief period of anesthsia of ipsilateral hemisphere

81
Q

purpose of Wada testing

A

Testing of language, memory, movement is conducted to determine capabilities of one hemisphere while the other is anesthetized

Testing performed for presurgical candidates with epilepsy to determine hemispheric dominance for language and potential post op loss

82
Q

CTA - computed tomographic angiography

A

visualize arterial and venous vessel

requires combo of IV injection of radiocontrast and CT scan

83
Q

Function of CTA

A

evaluate carotid stenosis, intra and extra cranial atheroschlerosis, aneurysms

84
Q

Advantage of CTA

A

high quality image in 5-10 sec
useful for dx and f/u of cerebrovascular disease
image less impacted by movement

85
Q

Disadvantages of CTA

A

reduced sensitivity for aneurysm smaller than 3mm

not reveal plaque ulceration or small vessel disease

86
Q

Lumbar punture

A

spinal tap
provides access to subacrachnoid space to obtain samples of CSF, CSF pressure, or remove CSF
detection of biomarkers (e.g. tau)

87
Q

How is lumbar puncture performed

A

insert needle below spinal cord (L4/L5)
inspect CSF fluid for blood or bacterial to assess infectious or inflammatory disorders, sub-arachnoid hemorrhage and abnormalities of intracranial pressure that affect CSF

88
Q

Awake and alert waves before falling asleep?

A

BATS
Beta
Alpha

89
Q

Waves observed in Non Rem Stage 3 sleep

A

Drink

- Delta

90
Q

Waves observed REM sleep

A

Blood = Beta

91
Q

Waves in non Rem sleep stage 1

A

baTS
Theta
sleep spindles/ k complex

Elsa AACN (35 decks)

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