Functional Neuroimaging Flashcards
In T1 weighted images, liquids are (white/black) and (more/less) intense than solid tissues.
Liquids are black and less intense
In T2 weighted images, liquids are (white/black) and (more/less) intense than solid tissues.
Liquids are white and more intense
Gadolinium is a paramagnetic dye used to enhance images taken in MRI. It has a very strong MR intensity and (does/does not) cross the blood brain barrier.
Does not
___________ is a technique used in MRI to enhance blood intensity in order to map and image blood vessels.
MRA (Magnetic resonance angiography)
(T/F) MRA may be conducted without the use of an exogenous agent by magnetic excitation (labeling) of blood.
True.
____________ is a technique used in T2 weighted images that suppresses the bright white intensity of CSF and allows for the imaging of abnormalities that would otherwise be hidden by the CSF.
FLAIR
(FLuid Attenuation Inversion Recovery)
___________ refers to equal probability of movement by a substance in all directions.
Isotropy
___________ refers to unequal probability of movement by a substance in all directions.
Anisotropy
____________ is a technique used in white matter imaging that compares the anisotropy of a substance to its isotropy. This method is commonly used to note the diffusion of water in a region of the brain.
Apparent Diffusion Coefficient (ADC)
___________ is a technique that allows for detection of the density and direction of white matter.
Diffusion Tensor (or Weighted) Imaging (DTI or DWI)
In DTI, red tracts represent (right to left/front to back/top to bottom).
Right to left
In DTI, blue tracts represent (right to left/front to back/top to bottom).
Top to bottom
In DTI, green tracts represent (right to left/front to back/top to bottom).
Front to back
(MRI/CT) gives much better spatial resolution.
MRI
(MRI/CT) displays calcifications better.
CT
(MRI/CT) is cheaper and more widely available.
CT
(MRI/CT) uses small doses of ionizing radiation.
CT
(MRI/CT) uses strong magnetic fields.
MRI
In an MRI, images of a number of brain “slices” are acquired as a function of ________.
Time
Stimulation followed by neuronal activity (increases/decreases) regional cerebral blood flow (rCBF) and (increases/decreases) regional cerebral blood oxygenation (rCBO).
Increases rCBF
Increases rCBO
-
BOLD Signal = Blood Oxygen Level Dependent
- fMRI relies on BOLD Signal
____________ is an imaging technique in which radioisotopes are generated in a cyclotron by a bombardment of energy. This bombardment causes an atom to transform into an unstable isotope. These isotopes are introduced into the patient, and over time, will revert back into a stable molecule, emitting a positron in the process. The emitted positron will collide with an electron, subsequently emitting two gamma particles in opposite directions. The gamma particles may then be spatially localized to determine the gamma particles’ origin.
Positron Emission Tomography (PET)
The most common radioisotope used in PET is ______________.
Fluoro-2-deoxy-D-glucose (18F)
(T/F) FDG molecules are used because they may be metabolized in the same way normal glucose is within the body.
False. FDG molecules may enter tissue, but once phosphorylated in the first step of glycolysis as normal glucose is, they become “trapped” within the tissue and are unable to proceed further into metabolism. These radioisotopes may then be detected, highlighting which tissues take up glucose for energy in the presence of different stimuli.
___% of PET examinations use FDG to measure glucose metabolism.
90%
(PET/MRI/CT) is better for detecting increased or decreased amounts of metabolism, such as in cancers or other abnormalities.
PET
__________ is a variation of the PET exam that uses a special tracer. This allows for direct detection once the tracer is within the patient, as opposed to a radioisotope that needs to degrade before detection is possible.
Single Photon Emission Computed Tomography (SPECT)
___________ is characterized by global reduction in brain gray matter volume, but is not specific to any particular lobe.
Dementia
___________ is characterized by an increased number of commonly occurring abnormalities and increased ventricle size in the brain.
Schizophrenia
In medicated major depressive disorder (MDD), the amygdala size is (increased/decreased).
Increased
In non-medicated major depressive disorder (MDD), the amygdala size is (increased/decreased).
Decreased
