Arterial Doppler studies involve a pain free circulation test that can be performed in the office. Dr Gavin offers this service at the Woodstock location only. The test involves the use of ultrasound to listen to and measure the bloodflow in your feet. In some cases, circulation problems are identified and further testing is necessary. Peripheral Vascular Disease and Diabetes are the two main causes of gangrene and amputations in the U.S. Signs of PVD can include discoloration/blue feet or toes, cold feet, pain in the feet or toes, calf cramps- especially while walking, and night pain.