Neuroimaging Flashcards
What is a technical challenge with diffusion tensor imaging?
The presence of crossing fibers and therefore susceptible to false positives and negatives
Increased diffusivity of fiber tracts is associated with what?
Poorer verbal but not nonverbal performance
Is gadolinium necessary in epilepsy MRI protocols?
No
Can low grade tumors be detected using epilepsy protocols?
Yes, on intermediate T2/FLAIR
What sequences on MRI are needed for epilepsy?
FLAIR, T-2, T-1, hemosiderin/calcification. Slice thickness should not exceed 3 mm
How should the T1 sequence be acquired?
A three dimensional technique at a 1 mm isotopic voxel size
How should the hippocampus be viewed?
At least 2 slice orientations
Diffusion tensor imaging abnormalities predict focal seizures?
No, although diffusion changes maybe more prominent on the side of seizure onset but there are also remote and contralateral diffusion abnormalities.
In ictal SPECT studies is there a difference between right temporal lobe seizures and left temporal lobe seizure onst?
Yes, there is a lesser degree of hyperperfusion in the midbrain of patients with right temporal lobe epilepsy.
Why are Cavernoma with hemorrhage easily visualized on routine MRI?
Due to susceptibility.
What measurement can be derived from diffusion tensor imaging?
Fractional anisotropic
How is gray matter density derived?
Voxel-base morphometry
Are there anatomical abnormalities other than hippocampal sclerosis in TLE?
Yes, quantatitive structural neoroimaging has shown anatomical abnormalities in cortical and subcritical regions. Both ipsilateral and contralateral.
Lissencephaly is caused by a neuronal migration during what time period in gestation?
12 any 24 weeks after conception
What is the default network seen on fMRI?
A nateork that shows increased activity during rest compared to during cognitive tasks
What syndrome sows MRI evidence of progressive atrophy in widespread neocortex all regions?
Drug-resistant temporal lobe epilepsy
What MRI findings were found in temporal lobe epilepsy?
Cortical thinning in the frontocentral, temporal, and cingulate regions
What epileptogenic lesion is there diagnostic evidence that post-processing is superior to visual analysis
Class II evidence that imagine processing accurately identified focal cortical dysphasia type II with extratemporal epilepsy
What are the characteristics of bottom of the sulcus dysphasia?
Infant or early onset of diurnal focal seizures, chronic nocturnal seizures, high frequency of seizure in clusters, often with prolonged remissions
Is early development normal in bottom of the sulcus dysphasia?
Yes unless seizures begin during infancy. There can be executive dysfunction, and/or language defects
What is the sign of retinal toxicity on ERG?
Decreased amplitude
What is the most frequent location of poly micro gyrus?
Perisylvian- bilateral and symmetric
Pathological findings of medial temporal lobe sclerosis?
Gloss’s and loss of neurons in CA1 and CA3 regions as well as Hulu’s and dent are.
