Exam 3 Imaging Intro, CT, & PET Flashcards
Anatomical purpose of imaging
Location of masses or lesions within CNS
Functional purpose of imaging
Describe the location of brain activity associated with specific brain functions or dysfunction
Limitations of functional neuroimaging
- Physical properties of the recording system
- Physiological constraints of the brain
Only way meaning can be derived from images of brain activity
when acquired using the correct method and interpreted using the correct analyses
Two constraint based on resolution
Spatial resolution Temporal resolution
What is temporal resolution?
How close the timing between change in structure and behavior can be assessed
What is spatial resolution?
How accurate or specific can the neural structure or area associated with a behavior be located
Anatomical versus Functional constraints of imaging
- -Most techniques give insight into anatomical relationships but not function.
- -In those cases Function has to be derived from anatomical relationships.
- -Some techniques do function measures such as measures of metabolic activity within the brain
Types of Imaging (9)
- Radiologic: Radiographs, Angiography, Computed Tomography (CT) scanning
- Positron Emission Tomography (PET scans)
- Single-photon emission computerized tomography (SPECT)
- Magnetic Resonance Imaging (MRI)
- Functional MRI (fMRI)
- Electroencephalography (EEG)
- Event related potentials (ERPs) & Evoked potentials (EPs)
- Magnetoencephalography (MEG)
- Near-infrared Spectroscopy
Disadvantage using of radiograph for the head
Check skull only
Advantages to using radiographs for skull (4)
- -Find fractures
- -Diseases that affect bones of the skull
- -Find a metallic foreign object stuck in the skull.
- -Check problems on a baby’s head, such as an odd shaped skull
What is radiograph of skull being replaced by
CT scans
What’s so great about Cerebral Angiography?
- Images of the vessels of the brain using a contrast medium
- Allowing detection of abnormalities such as arteriovenous (AV) malformations, occlusions and aneurysms
- Fluoroscopic angiography used for placement of endovascular coils for the treatment of aneurysms
What sucks about Cerebral Angiography?
Replaced by computed tomographic (CT) angiography for general diagnostics
What is Computed tomography (CT)? (3)
- -Computed Axial Tomography (CAT) scanning
- -Uses a series of x-rays of the head taken from many different directions
- -Typically used for quickly viewing brain injuries
Types of views seen in CT
Horizontal, sagittal & coronal views
Advantages of the CT
Useful for evaluating
- Abnormal structures (tumors)
- Swelling from tissue damage in the brain
- Bleeding
- Assessment of ventricle size
Modern CT scanning can provide reasonable images in minutes
Example of brain bleed
Another example of CT of brain bleed
Disadvantages of CT
relatively poor anatomical location
These structures are:
- Septum pellucidum
- Internal capsule (anterior limb)
- Longitudinal fissure
- Caudate nucleus
- Putamen
- Thalamus
- Temporal horn of the lateral ventricle
- Internal capsule (posterior limb)
What is Computed tomography angiography (CTA)?
–Enhancement of blood vessels of brain with contrast medium with ability of viewing vessels from horizontal, sagittal and coronal views
–Allows for precise localization of vascular lesions
–Allows for 3-D reconstruction
–Allows for 4-D assessment of blood flow in the brain
Comparison of CTA with standard angiography
(just pic to look at)
Advantages of Computed tomography angiography (CTA)
- Multidimensional perspective
- enhanced detail with 3-D CTA where you can remove other brain tissue to enhance the vessels
- Spot the aneurysm
- Ability to rotate image with 3-D CTA
- Ability to do precise measurement with 3-D CTA
My advice to you about this power point (CT ppt)
Difficulty getting all the pics in, probably want to pull up the power point so that it makes more sense.
What is Positron Emission Tomography (PET)?
- -Produces a 3-D image of sites of elevated metabolism in the brain
- -Detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is infused attached to fludeoxyglucose (FDG), a glucose analogue
- Differences in brain activity can be assessed by differences in accumulation of FDG in different brain regions
Tracers found in PET?
Specific radioligands for dopamine, serotonin & acetylcholine receptors & transporters for neurological and psychiatric disorder assessment
What can PETs also detect?
Specific ligands for amyloid plaques – in vivo assessment in Alzheimer’s disease
