This was vaguely touched upon in several questions, but never directly assessed:
Question 13 from the first paper of 2006 (regarding brain death)
Question 2 from the first paper of 2008 (regarding the use of ultrasound in general)
Question 8 from the first paper of 2008 (regarding the diagnosis of vasospasm)
Question 5 from the first paper of 2013 (regarding the diagnosis of brain death)
Question 2 from the second paper of 2013 (again about the vasospasm)
2MHz low frequency probe on temporal bone to measure flow in MCA.
Non-invasive and easily repeatable.
ANZICS Death and Organ Donation Committee, THE ANZICS STATEMENT ON DEATH AND ORGAN DONATION Edition 3.2 2013
Sloan, M. A., et al. "Sensitivity and specificity of transcranial Doppler ultrasonography in the diagnosis of vasospasm following subarachnoid hemorrhage." Neurology 39.11 (1989): 1514-1514.