Brain Imaging Lec10

Question 1

____ imaging invovles a rotating x ray beam

Answer 1

CT

Question 2

rate of attenuation with a CT varies by

Answer 2

tissue

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

Question 3

what is detected with a CT?

Answer 3

radiodensity information

used to reconstruct 3d image

Question 4

advantages to CT

Answer 4

bone imaging

hemorrhage detection

patient flexibility

Question 5

disadvantages to CT

Answer 5

1. ionizing radiation
2. not as good for soft tissue
3. lower spatial resolution

Question 6

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

Answer 6

RF pulse

Question 7

with MRI, Infrequent RF pulses enhance___

Answer 7

water signal

Question 8

advantages to MRI

Answer 8

1. high spatial resolution
2. no radiation
3. excellent contrast
4. functional/chemical imaing avail.

Question 9

disadvantages to MRI

Answer 9

1. long study duration
2. no ferromagnetic or electronic devices
3. small as hell – claustrophobia

Question 10

with Magnetic resosnance spectroscopy you look at the

Answer 10

chemical structure of the brain

Question 11

on MRS choline indicates

Answer 11

demyelination

Question 12

on MRS, creatine indciates

Answer 12

glial

Question 13

on MRS, lactate indicates

Answer 13

ischemia

Question 14

on MRS, NAA indicates

Answer 14

neuronal marker

Question 15

____ involves measuring water diffusion

Answer 15

DTI: Diffusion Tensor Imaging

Question 16

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

Answer 16

axes

Question 17

fMRI in vivo measures

Answer 17

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

Question 18

limitations of FMRI includes

Answer 18

spatial and temporal resolution

Question 19

what does PET involves?

Answer 19

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

Question 20

disadvantages of PET?

Answer 20

1. need a cyclotron to make radioisotope
2. radiation exposure

Question 21

what are 5 applications of imaging mdoalities?

Answer 21

1. map nml brain development
2. alzheimers disease
3. image guieded neurosurgery
4. schizopehnia
5. pain )in high vs. low sensitvity pts)

Question 22

advantages of pet?

Answer 22

functional imaging

physiological variables can be determined

Question 23

to study brain structure what could you use

Answer 23

CT or MRI

Question 24

what to use when looking at vascualture?

Answer 24

MRI

Question 25

what to use when looking at fiber tracts?

Answer 25

mri

Question 26

what to use when looking at brain perfusion?

Answer 26

pet

Question 27

what to use when looking at NT integrity?

Answer 27

PET

Question 28

what to use when looking at metabolism?

Answer 28

PET

Question 29

what to use when looking at chemical structure?

Answer 29

MRI

Question 30

elements of ___ atomic numbers show up better on CT

Answer 30

high (ca iron barium lead)

Question 31

on ct, hyodense areas can indicate

Answer 31

edema and infarction

Question 32

hyperdense structures on ct can indicate

Answer 32

calcifications and hemorrhage and bone trauma

Question 33

SPATIAL RESOLUTION OF ____ MILLIMETERS IN CT SCAN

Answer 33

SEVERAL

Question 34

SPATIAL RESOLUTION IS ___ MILLIMETER IN MRI

Answer 34

ONE

Question 35

with mri, ___ is used isntead of xrays

Answer 35

radiofrequency

Question 36

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

Answer 36

realign

Question 37

when RF pulse turns off the energy from each spinning proton absorbed from the RF \_\_\_

Answer 37

decays

Question 38

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

Answer 38

rf signal

Question 39

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

Answer 39

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

Question 40

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

Answer 40

gray scale level

Question 41

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

Answer 41

varying the timing of the rf pulse

Question 42

diag. applications of mri includr

Answer 42

inflammatory disease, neoplastic disease, epilepsy, stroke

Question 43

MRS can derive __ and \_\_

Answer 43

concentrations and ratios of chemicals

Question 44

a ___ is applied with MRS

Answer 44

RF pulse

Question 45

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

Answer 45

the size of peak

Question 46

on MRS ___ is raised in tumor tissue

Answer 46

choline

Question 47

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

Answer 47

density of fluids.

Question 48

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.

Answer 48

oxyhemoglobin

Question 49

in control condition of fmri the task is comprised of

Answer 49

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

Question 50

what imaging modalities have fairly poor spatial resolution

Answer 50

pet FMRI ct

Question 51

on an FMRI ___ was active during all emotions

Answer 51

amygdala

Question 52

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

Answer 52

prefrontal cortex

Question 53

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

Answer 53

PET

Question 54

what is APOE-4 allele related to?

Answer 54

genetic risk for alzheimers

Question 55

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

Answer 55

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

Question 56

which studies use ionizing radiation

Answer 56

ct and pet

Question 57

with studies can provide functional imaging

Answer 57

pet and mri

Question 58

disorders to study with ct

Answer 58

hemorrhages, generalized atrophy

Question 59

disorders to study with mri

Answer 59

tumor demyination degenerate disorders

Question 60

disorders to study with pet

Answer 60

psychiatric/addictive/degenerative disorders epilepsy