1. Clinical Application: Brain Function Measures
Perry C. Hanavan, Au.D.

2. Question
Which shows imaging plus blood flow assesses correlates function with structure?
EEG
PET
MRI
Ct Scan
MEG

3. Brain Structure Vs. Function
Imaging technologies assess structure
MRI
Ct Scan
Electrophysiologic technologies assess function
EEG EP
auditory, visual, tactile, vestibular
Imaging plus blood flow assesses correlates function with structure
SPECT
IB-PET & lorbetapir -F18 PET
PET
fMRI
Imaging (MRI) plus EEG
Magnetoencephalography (MEG)

4. Computerized Tomography Ct Scan
x-ray technology
sensitive to tissue densities
relatively quick procedure
detects calcification, hemorrhages, tumors, cerebrovascular disease, head trauma, cerebral atrophy
potential health risk due to x-ray

5. Magnetic Resonance Imaging
MRI technology able to assess differences in water and hydrogen atom distribution in various tissues combined with radio frequency signals
no radiation
easily detects fine differences between soft tissues such as grey and white matter, cerebrospinal fluid, vascular structures
detects plaque occurring with MS
clearly identifies cranial nerves and subcortical structures
diagnosis various brain diseases and disorders
imaging times longer than CT, thus more costly
Metal devices prevent MRI such as CI, clips, pacemakers

6. Diffusion-tensor MRI (DTMRI)
Used to visualize white matter tracts connecting different parts of neural networks in the brain
Used in pre-surgical planning for removal of a brain tumor to ensure tracts are spared during surgery.
Used to the study of 14 neurological conditions such ADHD and other developmental disorders, thought to arise from problems in white matter connections

7. Diffusion-weighted (DWMRI)
Shows whether brain tissue damage due to insufficient blood flow to the tissue
Can visualize tissue within minutes after damage by an “ischemic” injury (such as a stroke-producing blood clot)
Thus, allows early identification of damage

8. Perfusion-weighted MRI
Show areas of brain blood flow has been altered based on time course of regional signal changes induced by exogenously administered MRI contrast agent

9. Diffusion-Perfusion-weighted MRI
Used together to estimate “ischemic penumbra,” tissue damaged from reduced blood flow but not yet dead.
This tissue is target of intensive therapy for patients who have had ischemic stroke
Brain or pituitary gland tumor
Pituitary disease
Brainstem or cerebellum abnormalities
Multiple sclerosis

10. Magnetic Resonance Spectroscopy
MRS provides biochemical information about tissues of body (without the need for a biopsy)
MRI gives structure informationof the body
Whereas MRI shows tumour (cancer) location, MRS, in theory, tells aggressiveness of (malignant) tumour

11. EEG
Electroencephalography measures and records the electrical activity of the brain from multiple scalp electrodes.
Special sensors (electrodes) are attached to the scalp and connected to a computer to record and store the electrical activity of the brain.

12. Quantitative Electroencephalography (qEEG)
The digital EEG data is statistically analyzed, sometimes comparing values with “normative” database reference values and is converted into color maps or “Brain maps”.
Measure of various aspects of cognitive function
qEEG (quantitative)
qEEG

13. Evoked Potentials Measure event related activity
visual
auditory
tactile
Auditory Evoked Potentials
ABR, middle, slow, late
Mismatch negativity (MMG)
odd ball paradigm

14. Auditory Evoked Potentials
Auditory evoked potential analyzed on logarithmic time-base to reveal the component potentials with approximately equal weighting and categorized in arbitrary but commonly used time windows of short- (SLR), middle- (MLR), and long- (LLR) latency responses. (Figure modified and redrawn from Michelini et al., 1982.)

15. ABR

16. fMRI hemodynamic response indirect measure of brain function
increase in blood flow to region is related to amount of neural activity in region of the brain
indirect measure of brain function
assess cognitive function
safe noninvasive technology
assess brain function over time
assess effects of brain damage
assess recovery from damage
Intro to fMRI

17. fMRI Shows brain in action
Elucidate processes involved in higher cognitive functioning
Highly sensitive - can detect small changes
Method of choice for identifying areas of brain
activated with specific cognitive or motor task.
Indirect measure as dynamic changes in blood flow is much longer than neurons to fire electrochemical messages.
Used to study the reorganization of function following injury to a single brain area.

18. Positron Emission Tomography
Uses radioactive tracer combining with human chemical element (oxygen, nitrogen, etc.) to measure hemodynamic response
Disintegration of radioactive tracer emits positrons (positively charge particles) which collide with electrons producing gamma rays that are detected and measured by computers
PET scans displayed in 3D with various colors representative of hemodynamic response

19. Positron emission tomography (PET)
Radiation or nuclear medicine imaging
Produces 3-dimensional color images of functional processes
Detects pairs of gamma rays emitted indirectly by a tracer (positron-emitting radionuclide) placed in body on biologically active molecule.
Images are reconstructed by computer analysis.

20. PIB-PET & lorbetapir -F18 PET
PIB-PET (Pittsburgh Compound B”) and “florbetapir -F18 PET”
Tracers developed that bind solely to beta amyloid proteins
These proteins accumulate in the brains of people with
presymptomatic mild cognitive impairment (MCI),
overt MCI, and Alzheimer’s disease,
Not in the brains of cognitively healthy adults

21. Single Photon Emission Computed Tomography
SPECT scan is a type of nuclear imaging test that shows how blood flows to tissues and organs through arteries and veins in the brain
Integrates two technologies: computed tomography (CT) and a radioactive material (tracer).
 gamma photon–emitting radionuclides are administered and then detected by one or more gamma cameras 

26. Uses in Communication Disorders
ADD
ADHD
Alzheimer’s
Arteriovenous Malformation
Auditory processing
Developmental Delays
Epilepsy Epilepsy
Hearing assessment
MS MS
Parkinson’s
Stroke
Stuttering
Vestibular
TBI