Brain Imaging & Cross Sections

CT Image Acquisition

Computed Tomography, a bunch of x-rays showing structues

CT Radiation/Magnets

Yes radiation (x-ray), no magnets

CT Advantages

quicker and comfier than MRI, less sensitive to movement, quieter

CT Disadvantages

not as finely detailed, worse spatial resolution, hard to see lesions

MRI Image Acquisition

Magnetic Resonance Imagine, spins protons from applying a magnetic field around them, shows structures

MRI Radiation/Magents

No radiation, Yes magnets

MRI Advantages

High spatial resolution, easy to compare slices since thinner

MRI Disadvantages

Long time to record, confined space, louder, sensitive to movement

MRI T1

CSF dark, white matter light, lesions dark

MRI T2

CSF bright, white matter dark grey, lesions bright

MRI Flair

CSF dark, white matter dark grey, lesions bright
most common to read lesions

PET Image Acquisition

positron emission tomography, radioactive tracer injected into patient and detected by gamma ray detectors, shows metabolic activity

PET Radiation/Magnets

Yes radiation (positron), no magnets

Reading PET scans

Green = low activity, red = high activity

PET advantages

different tracers image different things

PET disadvantages

poor spatial resolution when used alone

18FDG Tracer

most commonly used, shows glucose metabolism

SPECT Image Acquistion

Single Photon Emission Computed Tomography, gamma-emitting radioisotopes used as tracers, show activity

SPECT Radiation/Magnets

Yes radiation (gamma), no magnets

SPECT advantages

can use different tracers, can detect problems earlier than MRI, CT, X-rays

SPECT Disadvantages

radiation exposure

PET v SPECT

Pet uses positron-emitting radioisotopes, SPECT uses gamma-emitting radioisotopes & a 2 panel machine that spins around the patient

Surface EEG

electroencephalogram, uses electrodes to indirectly (on surface of skull) measure electrical activity of brain

Surface EEG Advantages

less invasive

Surface EEG disadvantages

lower accuracy since skull, skin, and hair obstruct signals, lots of pre- and post-processing

Intracranial EEG

electroencephalogram reserved for epileptic patients, electrodes directly on brain to measure electrical activity

Intracranial EEG Advantages

Increased accuracy since directly only brain

Intracranial EEG Disadvantages

Invasive, lots of pre- and post-processing

MEG Image Acquisition

Magnetoencephalogram, uses magnets to measure electrical activity in the brain, based on right hand rule

MEG Output

look for synced activity that correlated with a change

MEG Advantages

less invasive, “mobile” options available

Axial Section View

cut to let us see top & bottom

Axial Section Advantages

see left and right differences to compare hemispheres

Axial Section - what is visible

basal ganglia, ventricles, anterior-posterior white matter tracts

Axial Section - Head of Caudate Nucleus

Axial Section - Putamen

Axial Section - Globus Pallidus

Axial Section - Thalamus

Axial Section - Tail of Caudate Nucleus

Coronal Section View

cut to divide into anterior/posterior slices

Coronal Section Advantages

see left and right differences, whole lobes, subcortical structures, and brainstem

Coronal Section - what is visible

Medial-lateral white tracts, corpus callosum, lobes, deep nuclei, brainstem

Sagittal Section View

cuts to let us see left and right

Sagittal Section - what is viewable

rostro-caudal size, structure, anterior-posterior structures and white-matter tracts, cerebellar and brainstem

Sagittal Section Disadvantages

not able to view left and right differences

Axial Section - Caudate Nucleus (Scans)

Seen in red

Axial Section - Putamen (Scan)

seen in purple

Axial Section - Globus Pallidus (Scans)

seen in yellow

Axial Section - Thalamus (Scans)

seen in green

Coronal Section - Caudate Nucleus

seen in red

Coronal Section - Putamen

seen in purple

Coronal Section - Globus Pallidus

seen in yellow

Coronal Section - Thalamus

seen in green

Sagittal Section - Caudate Nucleus

seen in red

Sagittal Section - Putamen

seen in purple

Sagittal Section - Globus Pallidus

seen in yellow

Sagittal Section - thalamus

seen in green

Sagittal Section - corpus callosum

seen in magenta

Sagittal Section - Cingulum

highlighted in yellow

Sagittal Section - fornix

highlighted in blue

Sagittal Section - hippocampus

highlighted in green

Layers of Grey Matter

not uniform, certain things clustered in certain areas

Cerebral Cortex Grey Matter Layers

molecular layer (superficial), external pyramidal layer, multiform cell layer (deep)