What is the approximate velocity described for the posterior cerebral artery in this data?

• A. 47 cm/s
• B. 21 cm/s
• C. 55 cm/s
• D. 39 cm/s

Answer: (A)

Understanding Doppler velocities in cerebral arteries: the posterior cerebral artery generally has lower flow speeds than the middle cerebral artery, with mean velocities often in the 40–60 cm/s range in adults. If the data describe the PCA velocity as about 47 cm/s, that sits right in the typical PCA range and matches the described measurement, making it the best choice. A value like 21 cm/s would be unusually low for PCA and could suggest very low flow or a sampling issue; 55 cm/s is plausible but tends toward the higher end (more typical of MCA in many datasets); 39 cm/s is possible but slightly farther from the reported value than 47 cm/s.