 Cardiac sonographers also may assist physicians who perform transesophageal echocardiography, which involves placing a tube in the patient's esophagus to obtain ultrasound images.Those who assist physicians in the diagnosis of disorders affecting the circulation are known as vascular technologists, vascular specialists or vascular sonographers.They obtain a medical history, evaluate pulses and assess blood flow in arteries and veins by listening to the vascular flow sounds for abnormalities.