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Aphasia > Exam #1: Neuroimaging > Flashcards

Exam #1: Neuroimaging Flashcards

1
Q

what are the most relevant neuroimaging techniques for aphasiologists to know about?

A
  • structural neuroimaging
  • functional neuroimaging
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2
Q

types of structural neuroimaging:

A
  • (CAT/CT) Computerized Axial Tomography
  • (MRI) Magnetic Resonance Imaging
  • (DTI) Difussion Tensor Imaging
  • Cerebral Angiography (arteriography)
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3
Q

types of functional neuroimaging:

A
  • (fMRI) Functional Magnetic Resonance Imaging
  • (PECT/PET) Positron Emission (Computed Tomography)
  • (EEG) Electroencephalography
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4
Q

structural neuroimaging

A

have a picture of the brain to see what is going on

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5
Q

functional neuroimaging

A

shows how your brain is functioning

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6
Q

Structural Neuroimaging:
Computerized Axial Tomography (CAT/CT) scan

A
  • takes x-rays of thin slices of the brain (1-2 mm thick)
  • bone and blood are high in density and absorb many x-rays, show up as light areas)
  • white and gray matter and the ventricles are low density areas that don’t absorb many x-rays and therefore show up as dark areas (e.g., cerebral infarctions, edema, cystic lesions)
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7
Q

CT is useful in detecting both…

A

focal and progressive pathologies

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8
Q

for a CT scan, infarct may not be visible on the scan in what stages?

A
  • acute
  • fails to reveal small lesions
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9
Q

CT scan is useful to rule out…

A
  • hemorrhages
  • it is an important screening factor for the administration of tPA
  • it is a quick and easy way of looking at the brain in the E.R.
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10
Q

what is tPA (thrombolytic plasminogen activator)?

A

a drug that acts as a clot buster when administered in the first hours following ischemic stroke onset

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11
Q

cost of CT scan:

A
  • $1,500 (cheaper than MRI)
  • available in most medical centers in the U.S.
    (will not reveal lacunae arteries because they are too small)
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12
Q

Structural Neuroimaging:
Magnetic Resonance Imaging (MRI)

A
  • capitalizes on the magnetic activities of hydrogen molecules contained in water in the body
  • does not use radiation
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13
Q

why does an MRI show excellent distinctions between gray and white matter?

A

because gray matter contains more water than with matter

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14
Q

Why is an MRI superior to a CT scan for spatial resolution and identifying ischemic storkes?

A
  • it detects small lesions missed by CT
  • however, it takes longer to obtain images, and it makes loud banging noises, which some patients are unable to tolerate
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15
Q

Some patients may be unable to have MRI scans if they have metals that stick to magnets (e.g., pacemaker)

A
  • damage device components
  • inhibit pacemaker function
  • trigger rapid pacing
  • deliver inappropriate shocks
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16
Q

cost of an MRI:

A

$2,000 to 4,000

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17
Q

Structural Neuroimaging:
MRI - Diffusion Tensor Imaging (DTI) / Tractography

A
  • method used to measure the directional flow of water molecules in the brain, thus mapping out white matter such as the corpus callosum and arcuate fasciculus as well as small fibers in the brain
18
Q

in an MRI - DTI, by quantifying white matter connections between gray matter areas…

A

it is possible to have a metric of dysfunctional or damaged white matter in the brain

19
Q

Structural Neuroimaging:
Cerebral Angiography

A

the arteries are infused with a radiopaque substance and then x-rays are taken of them

20
Q

What is a cerebral angiography good for identifying?

A

thromboses, aneurysms, hemorrhages, and irregularly displaced arteries (e.g., caused by tumors or hematomas)

21
Q

Cerebral Angiography:
x-ray radiopaque material shows…

A
  • variation in blood circulation that might suggest vascular occlusions
  • arterial sections beyond a clot that blocks the blood flow will not show up because the radiopaque materials is blocked
22
Q

Functional Neuroimaging:

A
  • functional magnetic resonance imaging (fMRI)
  • positron emission (computed) tomography (PECT, or PET)
  • electroencephalography (EEG)
23
Q

Functional Neuroimaging:

A

shows how your brain is functioning

24
Q

Functional Neuroimaging:
Functional Magnetic Resonance Imaging (fMRI)

A
  • this method helps to detect changes in cerebral blood flow as the patient performs different activities
  • shows the areas of the brain where the blood is flowing associating to the task they are doing - brain areas “light-up” when performing certain tasks
25
Q

Functional Neuroimaging:
Functional Magnetic Resonance Imaging (fMRI) detects…

A

increased blood flow that is typically associated with cerebral activity in the regions that are activated
- is usually used as a research tool

26
Q

Functional Neuroimaging:
Positron Emission Tomography (PET) scan

A

can measure vital functions such as blood flow, oxygen use, and glucose metabolism, which helps doctors identify abnormal from normal functioning organs and tissues

27
Q

A Positron Emission Tomography (PET) scan is also used to evaluate the effectiveness of a patient’s…

A

treatment plan

28
Q

Positron Emission Tomography (PET):
PET works on the assumption that…

A

areas of high radioactivity are correlated with increased brain function and blood flow
- hypometabolism (under-active)
- hypermetabolism (overly active)

29
Q

Positron Emission Tomography (PET):
is a unique type of imaging test that helps doctors see…

A

how the organs and tissues inside your body are actually functioning
- enables visualization of cerebral metabolic activity

30
Q

Positron Emission Tomography (PET):
is used together with what two scans? for improvement of?

A
  • MRI and CT, for improvement of localization
  • however, PET scan can often detect cellular level metabolic changes occurring in an organ or tissue in early stages of the disease
31
Q

PET scan can often detect what kind of changes occurring in an organ or tissue in early stages of the disease?

A

cellular level metabolic changes

32
Q

Positron Emission Tomography (PET):
the test involves injecting a very small dose of a radioactive chemical, called a _______, into the vein of your arm.

A
  • radiotracer
  • the tracer travels through the body and is absorbed by the organs and tissues being studied
33
Q

Positron Emission Tomography (PET):
how long does it take to administer the scan?
high or low radiation exposure?
cost?

A
  • 2-3 hours
  • low radiation exposure
  • expensive ($7,000 to 8,000)
34
Q

Functional Neuroimaging: FDG - PET
Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)

A

useful for detecting hypometabolism

35
Q

Functional Neuroimaging: FDG - PET
Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)

Why is a FDG - PET useful for detecting hypometabolism?

A
  • for increasing/decreasing suspicion of an underlying neurodegenerative disorder
  • for identifying signatory pattern of a neurodegenerative syndrome
  • for identifying abnormalities suggesting a non-degenerative disorder
36
Q

considerations for ordering PET:

A
  • when cognitive impairment/dementia is clearly present, but CT/MRI is normal
  • assist with differential diagnosis of dementia (especially AD vs FTD)
37
Q

Functional Neuroimaging: EEG - Electroencephalography

A

scalp provides real-time measure of brain activity (phsyiologic/pathologic) by recording the electrical potential (brain waves) of the cerebral cortex

38
Q

Functional Neuroimaging: EEG - Electroencephalography
Behavioral state:
Paroxysmal events:
Pathologic:

A

Behavioral state: wake, drowsy, sleep, coma
Paroxysmal events: seizure, psychogenic
Pathologic: epilepsy, encephalopathy, lesion

39
Q

Functional Neuroimaging: EEG - Electroencephalography:
EEG is primarily from what kind of currents?

A
  • synaptic currents (dendrites tree of pyramidal neurons)
  • done by neurologists specialized in EEG
40
Q

Functional Neuroimaging: EEG - Electroencephalography
Interpretation of EEG findings:

A
  • normal
  • abnormal
41
Q

Functional Neuroimaging: EEG - Electroencephalography
when EEG is likely to be most helpful:

A
  • seizure disorders
  • paroxysmal events (spells: pseudo-seizure red flags - no response to convulsants, very prolonged seizures, and history of or prior conversion symptoms)
  • disorder of consciousness (encephalopathy, coma)
42
Q

Functional Neuroimaging: EEG - Electroencephalography
How does an EEG work?

A
  • multiple electrodes are placed on the scalp to pick up electrical impulses the brain generates
  • these impulses are recorded on a moving paper
  • activity from several places on the cortex is recorded
  • different patterns of brain waves associated with different kinds of activities (e.g., listening, talking, thinking) are recorded

Aphasia (2 decks)

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