Effectiveness of Infrared Thermography Combined With Ankle-Brachial Index in the Assessment of Patients With Below-the-Knee Periphery Artery Diseases

Abstract

Objective:

The prevalence of peripheral artery disease (PAD) is on the rise due to an aging population. This study aimed to gain insight into the clinical role of infrared thermography (IRT) as a diagnostic method and prognostic tool for below-the-knee (BTK) PAD patients.

Materials and Methods:

The study prospectively recruited 64 patients who received lower limb revascularization for symptomatic BTK PAD (ChiCTR2400083847). IRT was used to detect lower limb skin temperature. Locations on the lower extremity sampled with IRT were dorsal areas, plantar areas, and medial and lateral areas of the calves.

Results:

One hundred twenty-eight limbs of 64 patients were divided into normal (n=35), mild (n=22), moderate (n=55), and severe (n=16) groups based on the ankle-brachial index (ABI) testing. Limbs in the moderate and severe groups showed an obvious decrease in surface temperature when compared to the normal baseline measurements, particularly in the dorsal areas (all p values <0.01). Further analysis revealed IRT increased the sensitivity of ABI from 75.8% (69/91) to 96.7% (88/91) in PAD diagnosis. In addition, our results showed maximum temperature variations (ΔTEMP) on treated limbs decreased significantly after endovascular treatment. Further analysis revealed showed a negative correlation between maximum ΔTEMP on treated limbs and walking distance.

Conclusions:

Our findings showed the use of IRT increased the diagnostic efficacy of ABI in BTK PAD patients. This noninvasive technique has the potential to be applied in PAD diagnosis, preoperative, and postoperative evaluation.

Clinical Impact

An ankle-brachial index (ABI) is the most commonly used diagnostic method for evaluating vascular disorders in the lower limb. The high prevalence of medial sclerosis, which can render arteries incompressible upon cuff inflation, may lead to falsely elevated ABI values (ABI>1.4) in patients with diabetes mellitus. Infrared thermography (IRT) is a novel potential diagnostic method that does not require physical contact. The use of IRT may increase the diagnostic efficacy of ABI in BTK PAD patients. This non-invasive technique has the potential to be applied in PAD diagnosis, preoperative, and postoperative evaluation.