1) Pial AVM

This is mostly a pial AVM with a dural component (mixed AVM)

Q: What is the Spetzler-Martin grading system, what is it used for?

A: Published in 1986, it determines the risk of (open) surgical treatment. 

References:

Summary

http://radiopaedia.org/articles/spetzler-martin-avm-grading-system

Original article

http://www.ncbi.nlm.nih.gov/pubmed/3760956