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Flashcards in Brain Imaging Lec10 Deck (60)
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1
Q

____ imaging invovles a rotating x ray beam

A

CT

2
Q

rate of attenuation with a CT varies by

A

tissue

Beam attenuates (ie weakens) as it passes through brain tissue

3
Q

what is detected with a CT?

A

radiodensity information

used to reconstruct 3d image

4
Q

advantages to CT

A

bone imaging

hemorrhage detection

patient flexibility

5
Q

disadvantages to CT

A

1. ionizing radiation

2. not as good for soft tissue

3. lower spatial resolution

6
Q

with MRI, Rapid repetitions of ___ enhance gray-white contrast

A

RF pulse 

7
Q

with MRI,  Infrequent RF pulses enhance___

A

 water signal

8
Q

advantages to MRI

A

1. high spatial resolution

2. no radiation

3. excellent contrast

4. functional/chemical imaing avail.

9
Q

disadvantages to MRI

A

1. long study duration

2. no ferromagnetic or electronic devices

3. small as hell -- claustrophobia

10
Q

with Magnetic resosnance spectroscopy you look at the

A

chemical structure of the brain

11
Q

on MRS choline indicates

A

demyelination

12
Q

on MRS, creatine indciates

A

glial

13
Q

on MRS, lactate indicates

A

ischemia

14
Q

on MRS, NAA indicates

A

neuronal marker

15
Q

____ involves measuring water diffusion

A

DTI: Diffusion Tensor Imaging

16
Q

DTI: Diffusion Tensor Imaging invovles measuring water diffusion along different orientatations within ___

A

axes

17
Q

fMRI in vivo measures 

A

BOLD, blood-oxygen-level dependent, signals at baseline vs.
! experimental conditions

18
Q

limitations of FMRI includes

A

spatial and temporal resolution

19
Q

what does PET involves?

A

PET: radioactive tracer incorporated into a biologically active molecule (ex. Glucose, oxygen, dopamine transporters)

20
Q

disadvantages of PET? 

A

 1. need a cyclotron to make radioisotope

2. radiation exposure

21
Q

what are 5 applications of imaging mdoalities?

A

1. map nml brain development

2. alzheimers disease

3. image guieded neurosurgery

4. schizopehnia

5. pain )in high vs. low sensitvity pts)

22
Q

advantages of pet?

A

functional imaging

physiological variables can be determined

23
Q

to study brain structure what could you use

A

CT or MRI

24
Q

what to use when looking at vascualture? 

A

MRI

25
Q

what to use when looking at fiber tracts? 

A

mri

26
Q

what to use when looking at brain perfusion? 

A

pet

27
Q

what to use when looking at NT integrity? 

A

PET

28
Q

what to use when looking at metabolism? 

A

PET

29
Q

what to use when looking at chemical structure? 

A

MRI

30
Q

elements of ___ atomic numbers show up better on CT

A

high (ca iron barium lead)

31
Q

on ct, hyodense areas can indicate

A

edema and infarction

32
Q

hyperdense structures on ct can indicate

A

calcifications and hemorrhage and bone trauma 

33
Q

SPATIAL RESOLUTION OF ____ MILLIMETERS IN CT SCAN

A

SEVERAL

 

34
Q

SPATIAL RESOLUTION IS ___ MILLIMETER IN MRI

A

ONE

35
Q

with mri, ___ is used isntead of xrays

A

radiofrequency

36
Q

when the rf pulse is turned off protons ___ with the external magnetic field

A

realign

37
Q

when RF pulse turns off

the energy from each spinning proton absorbed from the RF ___

A

decays

38
Q

as energy decays, an ___ is emitted which is picked up by an antennae

A

rf signal

39
Q

each pixel of an image on an mri is encoded with a nubmerical index that represents the 

A

relaive strength of the RF signal in the area of the brain

40
Q

each numerical index (which represents an RF signal) corresponds to a 

A

gray scale level

41
Q

how can a dr adjust an MRI to look at tissue he or she is most interested in?

A

varying the timing of the rf pulse

42
Q

diag. applications of mri includr

A

inflammatory disease, neoplastic disease, epilepsy, stroke

43
Q

MRS can derive __ and __

A

concentrations and ratios of chemicals

44
Q

a ___ is applied with MRS

A

RF pulse

45
Q

with MRS what represents the concentration of each chemical component of interest

A

the size of peak

46
Q

on MRS ___ is raised in tumor tissue

A

choline

47
Q

The difference between T1 and T2 weighted MRI images is due to ____

A

density of fluids.

48
Q

when a person is performing a task in the MRI scanner that results in increased neural activity, resulting changes in the concentration of _____ is represented by small changes in intensity values on the MR images. 

A

oxyhemoglobin

49
Q

in control condition of fmri the task is comprised of 

A

all features of experimental task except the specific cognitive variable of interest

50
Q

what imaging modalities have fairly poor spatial resolution

A

pet 

FMRI

ct

51
Q

on an FMRI ___ was active during all emotions

A

amygdala

52
Q

FMRI studies have shown ___ regions important for memory formation have prolonged maturational trajectory

A

prefrontal cortex 

53
Q

____ has been used in the management of AD, since hypometabolism in various brain regions have been associated with severity of clinical symptoms

A

PET

54
Q

what is APOE-4 allele related to?

A

genetic risk for alzheimers

55
Q

APOE-4 allele carriers had inc brain activation during __ tasks

A

memory

 

after 4 years the degree of brain activity correlated with memory decline

56
Q

which studies use ionizing radiation

A

ct and pet

57
Q

with studies can provide functional imaging

A

pet and mri

58
Q

disorders to study with ct

A

hemorrhages, generalized atrophy

59
Q

disorders to study with mri

A

tumor

demyination

degenerate disorders

60
Q

disorders to study with pet

A

psychiatric/addictive/degenerative disorders

epilepsy