I have 2 blood flow studies, both of which are represented by CPT93970. Both studies are done on the lower extremity deep veins. Both, also have a dx of Limb edema(729.81). One study is done to "rule out" DVT. The other study is done to "rule out" venous insufficiency. It is my understanding that these 2 studies cannot be performed simultaneously. One payor continues to deny these as duplicates. There are 2 separate reports interpreted. Is there any reason that I should not be billing 93970 X 2 ?