METHODS Controlled interventional trial. Group 1 (10 subjects) will be healthy subjects with no clinical venous disease. Subjects with venous incompetence to be recruited into one of three groups. Group 2 (10 subjects) will have superficial venous incompetence; Group 3 (10 subjects) will have deep venous incompetence; Group 4 (10 subjects) will have deep vein occlusion. These will be clinical diagnoses confirmed with duplex ultrasound.