Abstract
Purpose: To differentiate PCA segments and cortical branches by means of transcranial color-coded
duplex sonography (TCCD) and to measure flow parameters at rest and during visual
stimulation.
Materials and Methods: 60 healthy subjects with a good acoustic temporal bone window were examined. The
main stem of the PCA (P1, P2 and P3) and 4 main cortical branches – the anterior temporal
artery (ATA), the occipital temporal artery (OTA), the parietooccipital artery (POA)
and the calcarine artery (CA) – were assessed using an axial transtemporal approach.
Systolic and diastolic blood flow velocities (BFVs) were recorded at rest and during
visual stimulation.
Results: Identification of the P1 segment of the PCA was successful in 97.5% (117/120) of
cases. The P2 and P3 segments were visualized in all cases. The 4 main cortical branches
could be identified to varying degrees: ATA in 88%, OTA in 96%, POA in 69% and CA
in 62%. There was an evoked flow response in the P2 main stem and in all cortical
branches. The most pronounced increase in diastolic/systolic BFV after visual stimulation
test was seen in the CA (42%/35%), followed by P2 (30%/24%), the POA (27%/27%), the
OTA (16%/13%) and the ATA (9%/8%).
Conclusion: Insonation through the temporal bone window with TCCD confidently allows the assessment
of the P1 to P3 segments of the PCA as well as the 2 proximal branches, the ATA and
the OTA. An ultrasound-based classification of PCA anatomy and its cortical branches
may be used as a noninvasive method for the evaluation of posterior circulation pathology.
Key words
brain - blood vessels - ultrasound