I just found out how to do this, so I thought I would report here:
string[] roles = Access.GetAccessingMembershipRoles(int.Parse(nodeID), nodeToCheck.Path);
or simpler if you do not want to manually check the assigned roles that you can check against user-user
bool hasAccess = Access.HasAccess(int.Parse(nodeID), nodeToCheck.Path, MembershipHelper.GetCurrentUser());
source share