Abstract
<p>A 47-year-old man presented with recurrent varicose veins in his right leg. There were varicose veins over his shin, but of note, a lateral thigh that swelled and was tender after exercise (Panel A-1). He was asked to lie supine and then to stand. On standing, an infrared thermographic (IRT) image (Panel A-2) was taken with a TOPDON Thermal Camera TC002C (TOPDON UK Ltd, Pangbourne, Reading) attached to an iPhone (Apple, Cupertino, California, USA). This image shows a “hot spot) (bright yellow) at the point of passive reflux through an isolated incompetent perforating vein (IPV) in the upper lateral thigh. As the refluxing blood refluxes down the incompetent varicose vein, the colour fades from yellow to orange, indicating cooling. There are also other incompetent veins visible on IRT over the lateral knee and upper shin. Panel A-3 shows the duplex ultrasound report, with the lateral thigh IPV indicated with an arrow. This also shows that he has reflux in the stump of his small saphenous vein, refluxing into the surface veins visible in panel A-2.IRT is a useful, non-invasive tool for visualising venous reflux in the legs, exploiting the temperature gradient between warmer blood within the deep muscular compartment refluxing into the cooler superficial venous system. As it captures dynamic thermal signatures in real time, IRT can complement duplex ultrasonography by providing a visual reflux map that can correlate with clinical findings. The use of IRT in the diagnosis of chronic venous insufficiency has been noted several times,1 and more recently we have used IRT to confirm active (systolic) reflux through a below-knee IPV during plantar and dorsiflexion movements.2 Moreover, experimental findings have quantified this deep-to-superficial temperature differential within a region of interest (ROI), enabling classification of reflux severity into no, mild, moderate and severe - a novel framework that may extend beyond conventional duplex criteria.3</p>