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Flashcards in Neuroimaging Deck (23):
1

Event-related potentials

Brief changes in slow-wave EEG signal in response to a discrete sensory stimulus

2

Appearance of CT

White = dense (bone)
Black = less dense (air)
Dark gray (CSF)
Nearly black (fat tissue just outside skull)

Hyperdense = brighter areas
Hypodense = darker areas
Grey/isodense = intermediate density similar to brain tissue

3

Appearance of hemorrhage on CT

Hyperdense when fresh, becomes isodense after ~ a week, hypodense after ~ 2-3 weeks

4

MRI is better than CT in what situations?

Subtle tumor/infarct, brainstem lesion, old hemorrhage, anatomical detail

5

CT is better than MRI in what situations?

Head trauma, lower cost, fresh hemorrhage, speed, skull fracture, pacemaker

6

Appearance of MRI scans

Hyperintense = brighter areas

Hypointense = darker areas

7

Neuroangiography

The study of central nervous blood vessels & related cervicocerebral vasculature using radiographs during injection of IV contrast medium

8

UBO

Unidentifiable bright object

Refers to hyperintense white matter foci on MRIs (T2-weighted)

9

What might UBOs represent?

May be due to white matter pallor, infarction, ischemia, plaques or other causes

10

What is the differences between T1 and T2 MRI images?

T1 - white matter is brighter than gray matter

T2 = CSF is brighter than gray matter

11

Magnetic resonance spetroscopy (MRS)

Noninvasive technique used to measure chemical makeup of tissue (e.g., levels of neurotransmitters in the brain)

12

EEG changes in dementia

Nonspecific slowing is most common

13

Limitations of EEG

Unable to detect activity from deep cortical & subcortical structures

Uncertain localization

14

EEG - coherence

Degree to which respective regions' frequencies are correlated; often interpreted as a measure of "connectivity" between regions

15

What neuroimaging findings are most strongly related to AD severity?

Volumetric measures of medial temporal lobe & other cortical structures

Also has prognostic value for IDing progression from MCI to AD

16

How does IV contrast dye affect the appearance of CTs?

Contains iodine which is denser than brain & will appear hyperdense in areas of increased vascularity or breakdown of BBB

17

Myelography

Iodinated contrast dye is introduced into CSF, allows better visual of nerve roots & abnormal impingement on spinal CSF

18

Describe the appearance of intracranial hemorrhage on MRI

Acute may be hard to see b/c resembles CSF
Subacute contains hemosiderin & appears white
Chronic contains dark areas resulting from hemosiderin deposits

19

Which MRI sequence is better for identifying anatomy: T1 or T2?

T1

20

Which MRI sequence is better for clear differentiation of fluid: T1 or T2?

T2

21

Diffusion tensor imaging

Depicts the directionality of water diffusion which is associated with meylin integrity

22

How do brain tumors appear on PET?

High-grade neoplasms demonstrated increased metabolism, low-grade neoplasms demonstrate decreased activity; radiation necrosis shows decreased activity & tumor recurrence shows increased

23

Magnetic resonance spectroscopy (MRS)

Detects local concentrations of certain chemicals in the brain