From the case:
Azygos anterior cerebral artery (illustration)
{"current_user":null,"step_through_annotations":true,"access":{"can_edit":false,"can_download":true,"can_toggle_annotations":true,"can_feature":false,"can_examine_pipeline_reports":false,"can_pin":false},"extraPropsURL":"/studies/11230/annotated_viewer_json?lang=us"}
In an azygous anterior cerebral artery, no anterior communicating artery (Acom) is present and the two A1 segments join to form a single A2 trunk.
Unable to process the form. Check for errors and try again.