New Criteria Reduce Inter-Observer Variability in Chronic Cerebrospinal Venous Insufficiency: A Case Control Study.
http://openventio.org/Volume4-Issue1/New-Criteria-Reduce-Inter-Observer-Variability-in-Chronic-Cerebrospinal-Venous-Insufficiency-A-Case-Control-Study-NOJ-4-123.pdf

Looking at the Five Zamboni Criteria According to the Revised Protocol of the International Society for Neurovascular Disease. Revised protocol was in 2011.