Medical Dopers: Help me decipher this report, please?

Exam: US DPLX CAROTID BILAT
Indications: L HAND & ARM NUMBNESS, CLOT

Color duplex Doppler carotid sonography is performed. Multiple transferse and longitudinal scans were made.

On the right side, there is some plaquing at the origin of the internal and external carotid arteries. **On the right side, the peak systolic velocity in the internal is 63 cm per second with systolic ration of 1.1. The end diastolic velocity is 17. There is antegrade flow in the vertebral and biphasic flow in the right subclavian.
**
On the left side, again noted, is calcitic plaquing with posterior shadowing at the origin of the left internal carotid. Peak systolic velocity in the left internal carotid is 58 cm per second with systolic ration of .87. There is antegrade vertebral and biphasic left subclavian flow.

Impression: Plaquing involving both carotid bulbs resulting in less than 49% narrowing. Antegrade flow is seen in both vertebral arteries.

What I don’t get is the bolded text. I think I have a decent grasp on what systolic and diastolic velocities are. But what about the numbers? What is “normal?” And I’m thinking that antegrade flow is back flow. Is that correct?

Any input would be appreciated.

Seeker