What is the circle of Willis?
It is a network of vessels that distributes flow to all regions of the RT ad LT hemispheres of the brain.
What is the most important source of cerebral blood supply and collateral circulation?
Circle of Willis
Where is the circle of Willis?
It is located at the base of the brain.
How many people have a complete Circle of Willis?
Only 20% of the population.
What is the criteria for vessel identification?
What are the characterisitics of transcranial doppler?
What are the pitfalls and trouble spots of TCD?
What should you set the equipment prior to an exam?
How should you position the patient pior to an exam?
What window can the MCA be seen in?
Transtemporal window
What is the M1 segment depth range?
40-60mm
What is the M2 segment depth range?
30-40mm
What is the flow direction of the MCA?
Towards the transducer
How should you sample the MCA?
In 2mm increments
Can the MCA change direction?
No, it will never change direction.
Where can the MCA/ACA bifurcation?
In the transtemporal window
What is the depth range of the MCA/ACA bifurcation?
60-70 mm
What is the flow pattern in the MCA/ACA bifurcation?
Bidirectional
What is the flow direction in the ACA?
Away from the transducer
What window can the ACA be seen in?
Transtemporal window
What is the segment depth of the ACA?
60-80 mm
What is the normal flow direction of the ACA?
Away from the transducer
When can the ACA flow direction change?
It can change direction with the presence of disease
Where can the PCA be seen?
It can be seen in the transtemporal window