The Utility of Infrared Thermography and Hyperspectral Imaging in Peripheral Artery Disease: A Systematic Review

BACKGROUND: Peripheral artery disease (PAD) is a prevalent vascular disorder that reduces blood flow and tissue oxygenation. Early detection is crucial to optimise treatment outcomes and minimise ulceration or gangrene and possible subsequent amputations. This systematic review evaluated the diagnostic significance and clinical utility of infrared thermography (IRT) and hyperspectral imaging (HSI) as non-invasive, contactless techniques for PAD and chronic limb-threatening ischaemia assessment. Infrared thermography assesses blood perfusion by detecting temperature changes in limbs and HSI can be utilised to evaluate oxygen saturation, and deoxyhaemoglobin and oxyhaemoglobin concentrations in superficial tissue. METHODS: After a comprehensive PubMed literature search, a total of 15 articles were included in the final analysis: eight studies utilising IRT for circulation assessment, six studies employing HSI, and one study combining the two. A total 607 participants with PAD were included. RESULTS: In the IRT studies, varying levels of correlations were found between established assessment modalities and temperature changes. Significant, but mostly modest, correlations were discovered in the HSI studies-particularly with deoxyhaemoglobin, oxyhaemoglobin, and the ankle-brachial index-making the clinical significance of the results unclear, but still suggesting that HSI has potential for assessing and screening PAD. Head-to-head, HSI accurately detected immediate perfusion changes after PAD treatment, while IRT did not, suggesting that HSI-derived parameters may be more precise for perfusion assessment. CONCLUSIONS: The results indicate that both IRT and HSI hold promise for assessing circulation, oxygenation, and perfusion in participants with vascular deficiency. Further research with larger sample sizes and standardised measurement protocols is needed to validate the clinical utility of IRT and HSI.