Imaging Techniques Flashcards

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1
Q

What does CAT Scan stand for?

A

Computed-ASSISTED tomography

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2
Q

What are the four imaging techniques?

A

CAT scan
MRI
PET
fMRI

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3
Q

What does a CAT scan visualize?

A

It creates images of the brain and other internal structures of the body.

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4
Q

What type of image does a CAT scan produce?

A

A series of two-dimensional horizontal sections called tomograms.

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5
Q

What is the main disadvantage of CAT scans?

A

They can only take horizontal slices.

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6
Q

What is the resolution of a CAT scan?

A

It identifies subcortical structures at a resolution of 1 mm.

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7
Q

When are CAT scans commonly used?

A

In cases where pathological brain conditions are suspected, such as tumors, lesions, blood clots, hydrocephalus, and degenerative diseases.

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8
Q

How can a CAT scan assist physicians?

A

It helps determine if brain surgery is required.

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9
Q

What are the benefits of a CAT scan in terms of invasiveness and safety?

A

It is noninvasive and does not damage the subject, as the exposure to X-ray radiation is relatively small and short.

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10
Q

How do CAT scans capture images of the brain?

A

X-rays pass through the head and are picked up by detectors on the opposite side of the scanner.

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11
Q

How does brain tissue density affect the CAT scan?

A

The amount of radiation passing through the patient’s head varies based on the density of the brain tissue.

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12
Q

What happens after the initial X-ray passes through the head?

A

The radiation source and detectors are rotated by a few degrees, and the measurement is repeated.

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13
Q

What does “MRI” stand for?

A

Magnetic Resonance Imaging

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14
Q

What technology was the MRI developed from?

A

The CT (CAT) scan

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15
Q

How does MRI create images?

A

It measures waves emitted by hydrogen atoms activated by radio-frequency waves in a magnetic field.

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16
Q

What is one advantage of MRI over CT scans?

A

MRI provides higher-resolution, clearer images of the brain.

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17
Q

What type of brain images can MRI scans produce?

A

Extremely detailed brain images with precision close to that of actual brain sections.

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18
Q

For what purposes are MRI scans often used?

A

Studying brain structure and identifying tumors and lesions.

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19
Q

How is MRI scanning more versatile than CT scanning?

A

MRI can produce images in the sagittal, coronal, and horizontal planes, while CT is limited to horizontal.

20
Q

Is MRI invasive or harmful to the subject?

A

No, MRI is noninvasive and does not cause damage.

21
Q

Describe the process that generates MRI images.

A

The head enters a magnetic field, then radio waves excite hydrogen atoms in the brain, emitting signals that form images.

22
Q

What is one disadvantage of MRI?

A

It is expensive and not available in all hospitals.

23
Q

What does “PET” in PET scan stand for?

A

Positron Emission Tomography

24
Q

What does a PET scan primarily show?

A

Images of brain activity rather than brain structure.

25
Q

What substance is injected into the patient during a PET scan?

A

Radioactive 2-deoxyglucose (2-DG), injected into the carotid artery.

26
Q

Why is 2-deoxyglucose (2-DG) used in PET scans?

A

It’s similar to glucose and taken up by active neurons, but it cannot be metabolized quickly, allowing activity levels to be measured.

27
Q

How does a PET scan detect brain activity?

A

A computer measures radiation levels in each brain region and creates a color-coded image.

28
Q

What colors indicate high and low activity on a PET scan?

A

High activity appears as red or yellow, while low activity appears as blue or purple.

29
Q

What is the spatial resolution of PET scans?

A

Approximately 4 to 8 mm.

30
Q

How does the temporal resolution of PET scans compare to fMRI and EEG?

A

PET scans have lower temporal resolution than fMRI and EEG.

31
Q

What types of brain activities can PET scans image?

A

Activities like sensory perception, motor planning, verbal behavior, learning, and decision making.

32
Q

In what medical scenarios are PET scans helpful?

A

Detecting lesions and tumors in the brain.

33
Q

What are some disadvantages of PET scans?

A

Hard to define exact structures, limited to horizontal sections, and the analysis can be unconvincing.

34
Q

What does fMRI measure to produce images of brain activity?

A

The increase in oxygen flow to active areas of the brain.

35
Q

How does fMRI build on traditional MRI technology?

A

It combines MRI’s precision with functionality, allowing it to measure brain activity as well as structure.

36
Q

What are the advantages of fMRI over PET scans?

A

No injections are needed, it provides both structural and functional information, has better spatial resolution, and can produce 3D images of the entire brain.

37
Q

What is one limitation of fMRI in analyzing results?

A

It uses a subtraction method, making it hard to verify the accuracy of the baseline used.

38
Q

What is a limitation of fMRI related to timing?

A

Blood flow to active regions takes about 5 seconds, which makes it hard to measure specific neuron activity.

39
Q

What does EEG stand for?

A

Electroencephalography

40
Q

What does EEG measure?

A

The brain’s electrical activity through electrodes on the scalp.

41
Q

What is one primary advantage of EEG for sleep studies?

A

It can track sleep patterns and stages throughout day and night.

42
Q

Why is EEG commonly used in hospitals for epilepsy patients?

A

To detect seizure activity and monitor brain electrical activity during seizures.

43
Q

How does the cost of EEG compare to other brain imaging techniques?

A

EEG is relatively inexpensive and cost-effective.

44
Q

What is a disadvantage of EEG in terms of brain coverage?

A

EEG only measures surface-level brain activity and cannot assess deeper brain structures.

45
Q

What does “ERP” stand for in EEG studies?

A

Event-Related Potential

46
Q

What are ERPs?

A

ERPs are specific EEG wave patterns that occur in response to psychological events or stimuli.