Chronic venous disease is a common disease of the lower limbs. Severe CVD can lead to lower limb swelling, pigmentation, and repeated skin ulceration, which seriously affects patients' quality of life. About 10.5% to 92.7% of CVD patients with recurrent varicose veins had insufficient perforating veins. Treatment of these IPVs can promote venous ulcer healing and reduce the recurrence rate of venous ulcers. Accurate assessment and positioning of insufficient perforating veins in the lower leg is a key step in developing a personalized treatment strategy. At present, Color Doppler ultrasonography performed in the upright position in combination with the Valsalva maneuver or local pressure of the limb is regarded as the "gold standard" for the diagnosis of perforating veins insufficiency. However, in China, a large number of perforating veins insufficiency are diagnosed by venography. Because the majority of Chinese vascular surgeons are not versatile in vascular ultrasound examination and venous ultrasound protocols vary from institution to institution. A non-functioning valve in an insufficient perforated vein allows blood to flow retrograde from a deep vein to a superficial vein. Some researchers have shown that the venous blood temperature of deep veins is higher than that of superficial veins. Thus, the retrograde flow of "warm blood" from the deep vein to the superficial vein increases the skin temperature located on the insufficient perforated vein. This study tested the feasibility of a smartphone and its compatible portable thermal imaging device as a tool for assessing insufficient perforated vein. The objective is to study the sensitivity and specificity of smartphone thermal imaging in diagnosing and locating the insufficient perforated vein in CVD patients.
