Subtraction pitfalls in venous DSA of the renal arteries

Venous DSA of the renal arteries was performed in 32 patients for suspected renovascular hypertension who were considered for percutaneous transluminal angioplasty (PTA). To trace the causes of contradictory or divergent findings in our material, v-DSA and conventional angiography prior to PTA were compared. Superimposition of dense bone structures on the origins of the renal arteries was the most common cause of different findings. In 22 arteries with superimposition, 11 were not the same (50%). In 42 arteries without superimposition 7 were not comparable (16.5%). The difference between both groups is statistically significant (chi square test: p less than 0.05). Other possible factors of influence such as motion artifacts, superimposition of vessels and calcifications in the region of the renal arteries, had no measurable effect. The importance and the origin of subtraction artifacts caused by dense bone structures are discussed.