Best advantage of doing transcranial Doppler ultrasound?

- Transcranial Doppler ultrasound It uses low frequency probe as it has higher penetration Using low frequency probe and a proper acoustic window the vessels of Circle of Willis can be evaluated. The acoustic windows are: 1. Transtemporal 2.Submandibular 3.Transorbital 4.Suboccipital window It is very sensitive and the first line investigation to know the flow dynamics in middle cerebral aery It is used to detect vasospasm especially in SAH as during vasospasm there is increased flow velocity in the MCA Acoustic windows of Skull