Chapter 3 - Brain Imaging of Communication Functioning Flashcards
(98 cards)
1
Q
What method was historically used to understand brain organization?
A
Observations of patients with focal brain lesions
2
Q
Who identified left inferior frontal lesions as responsible for nonfluent aphasia?
A
Broca
3
Q
Who identified left superior temporal lesions as responsible for fluent aphasia?
A
Wernicke
4
Q
What imaging technology was introduced in the early 20th century for studying brain anatomy?
A
X-ray technology
5
Q
What technique uses air to study ventricular anatomy?
A
Pneumoencephalography
6
Q
What is the purpose of cerebral angiography?
A
To diagnose blockages and other vascular problems
7
Q
What are the two types of angiograms?
A
- Arteriogram
- Venogram
8
Q
What does a contrast agent do during angiography?
A
Makes blood vessels highly visible
9
Q
What risks are associated with angiography?
A
- Damage to blood vessels
- Allergic reactions to contrast
- Worsening renal impairment
10
Q
What is computed tomography (CT) based on?
A
X-ray images compiled into cross-sectional slices
11
Q
What does CT imaging primarily visualize?
A
Tissues with different densities
12
Q
What is a major advantage of CT scans?
A
Fast and easy to obtain
13
Q
What is a significant disadvantage of CT scans?
A
Moderate to high radiation exposure
14
Q
What does perfusion tomography assess?
A
Cerebral blood flow and volume
15
Q
What are the two main components of magnetic resonance imaging (MRI)?
A
- A powerful magnet
- Radio waves
16
Q
What property of the hydrogen atom is utilized in MRI?
A
The inherent spin of the proton
17
Q
What is the purpose of the strong magnetic field in MRI?
A
To align protons along the longitudinal axis
18
Q
What are the common MRI sequences used in clinical practice?
A
- T1-weighted
- T2-weighted
- Fluid-attenuated inversion recovery (FLAIR)
- Diffusion-weighted
19
Q
What does T1-weighted MRI reflect?
A
The time it takes protons to relax back to the longitudinal axis
20
Q
How does T1-weighted imaging differentiate between tissues?
A
- Water-filled tissue appears dark
- Fat-filled tissue appears white
21
Q
What major limitation does CT have in detecting ischemic stroke?
A
It may appear normal or show only subtle changes in early stages
22
Q
True or False: Angiography is considered a neuroimaging technique.
A
False
23
Q
Fill in the blank: The contrast agent used in angiography is usually a pharmaceutical compound containing _______.
A
iodine
24
Q
What did the introduction of advanced imaging techniques reduce in angiography?
A
Invasiveness and associated risks
25
What is T1-weighted MRI also called?
Spin-lattice relaxation time
## Footnote
T1-weighted MRI provides detailed anatomical information and differentiates between white and gray matter.
26
What does T1-weighted MRI show about water-filled and fat-filled tissues?
Water-filled tissues appear dark, and fat-filled tissues appear white
## Footnote
Gray matter is darker than white matter in T1-weighted images.
27
What happens to tissues in demyelinating diseases like multiple sclerosis on T1-weighted MRI?
Fat is stripped away and replaced by water, making tissues appear darker than normal.
28
What is T2-weighted MRI also known as?
Spin-spin relaxation time
## Footnote
T2-weighted MRI is sensitive to tissue pathology.
29
On T2-weighted scans, how do water- and fluid-filled tissues appear?
Bright
## Footnote
Fat-containing tissues appear less bright.
30
What type of lesions are best seen on T2-weighted MRI?
Abnormalities that appear bright, especially when damaged tissues develop edema.
31
What is the purpose of FLAIR sequences in MRI?
To suppress the signal from fluids
## Footnote
In brain imaging, it highlights hyperintense lesions like those in MS.
32
What does diffusion-weighted MRI (dMRI) measure?
The diffusion of water molecules in tissues.
33
What is the most important application of diffusion-weighted imaging (DWI)?
Detecting ischemic stroke within 5 to 10 minutes after onset of symptoms.
34
How do DWI and ADC images compare in a stroke area?
Bright on DWI images and dark on ADC images.
35
What does diffusion tensor imaging (DTI) help map?
Connectivity of white matter fibers.
36
What is the main advantage of T1-weighted MRI?
Provides detailed anatomical images.
37
What is a major disadvantage of MRI compared to CT?
Cost and longer scan times (15 to 60 minutes).
38
What is a common contrast agent used in MRI?
Gadolinium (Gd).
39
What is a significant safety advantage of MRI over CT?
MRI does not involve radiation.
40
What can affect the quality of an MRI scan?
Movement of the patient during the scan.
41
What is functional MRI (fMRI) primarily used for?
Mapping neural activity in the brain and spinal cord.
42
What principle does fMRI use to map brain activity?
Blood oxygen level dependent (BOLD) contrast.
43
What is the main disadvantage of fMRI?
Requires the subject to remain completely still.
44
What is the most frequently used tracer in PET scans?
Fluorine-18 fluorodeoxyglucose (FDG).
45
What does FDG uptake indicate in PET scans?
Tissue metabolic activity.
46
What are common clinical uses of F-FDG PET?
* Evaluation of brain tumors
* Presurgical evaluation of epilepsy
* Evaluation of early-stage Alzheimer’s disease.
47
What is a limitation of PET imaging?
Inherent limitation in resolution, resulting in blurry images.
48
What does a positron emission tomography (PET) scan using fluorodeoxyglucose (FDG) indicate in a patient evaluated for epilepsy surgery?
It indicated a left anterior temporal seizure focus with reduced metabolism in the left anterior temporal lobe.
## Footnote
The scan shows 20% less uptake than in the corresponding area of the right temporal lobe.
49
What can PET detect before structural changes occur?
Disease processes such as early stages of Alzheimer's disease (AD).
## Footnote
Hypometabolism is apparent in the parietal and temporal lobes on PET before clinical symptoms appear.
50
What is the purpose of the tracer F-DOPA in PET scans?
To measure dopamine receptor density and diagnose Parkinson’s disease.
## Footnote
Reduced uptake of F-DOPA in the putamen and caudate may signal early onset of Parkinson's disease.
51
What is a disadvantage of PET scans?
Exposure to radioactive tracers and high cost.
## Footnote
The production of positron-emitting tracers requires a cyclotron, which is expensive.
52
What is the primary function of Single-Photon Emission Computed Tomography (SPECT)?
To utilize gamma-emitting radioactive isotopes to measure blood flow in the brain.
## Footnote
SPECT does not require a cyclotron and can be performed quickly.
53
How does SPECT differ from PET in terms of tracer emission?
SPECT uses single photons while PET uses positron-emitting ligands.
## Footnote
This difference affects the equipment and methodology used.
54
What are the clinical applications of SPECT?
Evaluation of psychiatric and neurological diseases, including dementia, stroke, and traumatic brain injury.
## Footnote
It is also useful for presurgical evaluation of medically uncontrolled seizures.
55
What is the time efficiency of SPECT scans?
Less than an hour.
## Footnote
SPECT scans are faster and more cost-effective compared to PET scans.
56
What is the main principle behind Near-Infrared Spectroscopy (NIRS)?
It measures changes in cerebral oxygenation using near-infrared light absorbed by hemoglobin.
## Footnote
NIRS can map regions of increased oxygenation during specific tasks.
57
What is the primary advantage of NIRS compared to fMRI?
NIRS is more portable and less expensive than fMRI.
## Footnote
It is particularly useful in young children who cannot cooperate for fMRI.
58
What does Electroencephalography (EEG) measure?
Cortical voltage fluctuations from electrodes placed on the scalp.
## Footnote
These fluctuations reflect ionic current flows within the neurons of the cerebral cortex.
59
What is the most common clinical use of EEG?
To help confirm the clinical diagnosis of epilepsy.
## Footnote
EEG is also used to differentiate between epilepsy types and localize seizure activity.
60
What are the advantages of EEG?
* Ready availability in medical centers
* Relatively low cost
* Tolerance of patient movement
* Non-invasive with no radiation exposure
## Footnote
EEG has poor spatial sensitivity but high temporal resolution.
61
What are evoked potentials in EEG?
EEG waves resulting from the presentation of a stimulus.
## Footnote
Averaging multiple responses enhances the evoked potentials, allowing for two-dimensional mapping of their distribution.
62
What does Magnetoencephalography (MEG) measure?
Magnetic fields produced by electrical currents in the brain.
## Footnote
MEG uses superconducting quantum interference devices (SQUIDs) to detect these fields.
63
What is the temporal resolution of EEG and MEG?
Milliseconds.
## Footnote
This high temporal resolution makes them superior to fMRI, which has a one-second time resolution.
64
What are the limitations of EEG and MEG?
They record activity primarily on the surface of the brain and are less effective in deep structures.
## Footnote
Both techniques are also susceptible to signals being attenuated with distance from the source.
65
What is the purpose of combining EEG and MEG with MRI?
To localize sources of electrical or magnetic activity in the brain more accurately.
## Footnote
This combination enhances the utility of both EEG and MEG for functional imaging.
66
What is the Wada test also known as?
Intracarotid amobarbital procedure
## Footnote
Introduced in 1949 to determine cerebral dominance before brain surgery.
67
What is the main purpose of the Wada test?
To determine cerebral dominance prior to brain surgery.
68
How is the anesthetic injected in the Wada test?
Into one internal carotid artery at a time.
69
What happens to the contralateral arm during the Wada test?
It falls and the fingers cease wiggling.
70
What type of testing is performed before the anesthetic is applied in the Wada test?
Baseline language and memory testing.
71
What are some of the stimuli used during the Wada test?
* Object naming
* Verbal comprehension
* Repetition
* Automatic speech
* Presentation of memory items
72
What risks are associated with the Wada test?
* Dislodging plaque
* Arterial spasm
* Injury to the arterial wall
73
What is the main limitation of the Wada test?
It is strictly a test of lateralization and does not allow for further localization of language functions.
74
What is electrical stimulation mapping used for?
To localize language and other functions during cortical ablation.
75
When can electrical stimulation be performed?
* During surgery in the operating room
* Outside the operating room after electrode implantation
76
What does stimulation of the primary motor or sensory cortex produce?
Positive responses that can be seen or felt.
77
What must a patient do to evaluate the language cortex during electrical stimulation?
Perform a language task.
78
What is the significance of the basal temporal language area (BTLA)?
It may be important in speech perception.
79
What are the risks associated with cortical mapping?
Risks inherent to surgery, such as infection.
80
What are some cautions when generalizing findings from cortical mapping?
Individuals with early-onset epilepsy may have a language shift to the nondominant hemisphere or to adjacent areas.
81
What is being considered as a replacement for the Wada test and cortical stimulation?
fMRI.
82
What does fMRI identify that is different from cortical stimulation?
Cortex involved in, but not necessarily required for, a particular function.
83
Which imaging technique has the lowest resolution?
SPECT.
84
What technology allows safer and less invasive visualization of cerebral vasculature compared to cerebral angiography?
CTA and MRA.
85
What does electrical stimulation help to map?
Eloquent areas of the brain prior to cortical ablation.
86
Which functional imaging technique examines glucose metabolic rate directly?
PET.
87
What are some advantages of EEG?
* Excellent time resolution
* Detects changes in cortical electrical activity
* Can be recorded for prolonged periods of time
88
What is one disadvantage of MRI?
Movement artifact, contraindicated with metal implant.
89
What is the main function of electrical stimulation during cortical mapping?
To determine the function of a specific cortical region.
90
What correlates with functional outcome after aphasic stroke?
Anterior temporal lobe connectivity
## Footnote
Reference: Crinion JT, Lambon Ralph MA, Wise RJ. Anterior temporal lobe connectivity correlates with functional outcome after aphasic stroke. Brain 2009; 132(Pt 12): 3428‐3442
91
What are the types of damage associated with non-fluent speech?
Subcortical damage and white matter disconnection
## Footnote
Reference: Bonilha L, Fridriksson J. Subcortical damage and white matter disconnection associated with non-fluent speech. Brain 2009; 132(Pt 6): e108
92
What does functional MRI measure in stroke patients recovering from aphasia?
Cortical language activation
## Footnote
Reference: Cao Y, Vikingstad EM, George KP, Johnson AF, Welch KM. Cortical language activation in stroke patients recovering from aphasia with functional MRI. Stroke 1999; 30(11): 2331‐2340
93
What does neuroimaging quantify in aphasia treatment research?
Brain lesions after stroke
## Footnote
Reference: Crinion J, Holland AL, Copland DA, Thompson CK, Hillis AE. Neuroimaging in aphasia treatment research: quantifying brain lesions after stroke. Neuroimage 2013; 73: 208‐214
94
What predicts language recovery in chronic aphasia?
Functional re-recruitment of dysfunctional brain areas
## Footnote
Reference: Meinzer M, Flaisch T, Breitenstein C, Wienbruch C, Elbert T, Rockstroh B. Functional re-recruitment of dysfunctional brain areas predicts language recovery in chronic aphasia. Neuroimage 2008; 39(4): 2038‐2046
95
What is associated with the production and perception of speech movements?
Modulation of frontal lobe speech areas
## Footnote
Reference: Fridriksson J, Moser D, Ryalls J, Bonilha L, Rorden C, Baylis G. Modulation of frontal lobe speech areas associated with the production and perception of speech movements. J Speech Lang Hear Res 2009; 52(3): 812‐819
96
What is primary progressive aphasia?
A neurological syndrome that affects language abilities over time
## Footnote
Reference: Wilson SM, Ogar JM, Laluz V et al. Automated MRI-based classification of primary progressive aphasia variants. Neuroimage 2009; 47(4): 1558‐1567
97
What is a characteristic of acute ischaemic dysarthria?
Left-hemispheric dominance for articulation
## Footnote
Reference: Urban PP, Rolke R, Wicht S et al. Left-hemispheric dominance for articulation: a prospective study on acute ischaemic dysarthria at different localizations. Brain 2006; 129(Pt 3): 767‐777
98
What does functional neuroimaging assist with in traumatic brain injury?
Cognitive rehabilitation
## Footnote
Reference: Strangman G, O’Neil-Pirozzi TM, Burke D et al. Functional neuroimaging and cognitive rehabilitation for people with traumatic brain injury. Am J Phys Med Rehabil 2005; 84(1): 62‐75
