If you are practicing physician, chiropractor, or medical professional you likely were exposed to thermal imaging at some point in your education or career. Just like with any other digital imaging technology, this technology has changed rapidly over the last 10 years or so. Cameras used to have very low resolution and could only temperature sense pixels in the 160 x 120 range. Current cameras can now image at the 1024 x 768 pixel level which is an almost 10x increase in resolution. With this higher resolution many more techniques have been identified to help access human function and provided deeper information concerning what a disease state or dysregulation might look like under thermal imaging.
The human body is always striving to maintain a “core” body temperature. Slight variations from the core temperature are normal as you move from the human core to the periphery. The periphery is, under normal circumstances cooler. Anomalies of heat and cool are readily apparent using thermal imaging and would indicate and point to areas where the body is more active (under hotter readings) and less active (under cooler readings). Areas of heat would indicate very active cells and more active mitochondria within cells (mitochondria are what produce heat). Mitochondria become more active under an immune response. While yet to be studied, logic would indicate that activated t and b cells would be more active and thereby warmer than surrounding blood or tissue.
Cancer, by definition, is an altered metabolic rate. Cancers (most) stick cellular metabolism in a mode which is called the Warburg effect. This forces cancer cells to be more active and thereby produce more heat than surrounding tissues. Further it is now looking like part of the pathology of a pathogenic infection is to also “stick” cells in a warburg like metabolic state (1). Cells that are stuck in a state where they are more active and producing more heat, depending on how close to the surface they are, will be detectable by thermography. This is the very reason thermal imaging is capable of diagnostically detecting breast cancer, but could not identify a deeper tissue cancer such as lung cancer. The lungs are to deep into tissue to be able to make determination from a heat signature, however the breasts are not. While the underlying study does not yet exists, it is logical to assume that a “hotter” lymphatic system, as evidenced by places where lymph would be near the surface, like lymphatic glands, the crooks of the arms, and between the fingers, would be indications of immune activation and chronic inflammation.
So what are the most well researched and established areas of interest that thermal imaging can address? Cancer detection, detecting areas of inflammation including arthritis and chronic inflammation, detecting vascular issues including varicose veins, identifying diabetes, and identify potential atherosclerosis issues are now all being explored via research.
In the areas of cancer detection, breast cancer has long been a target of thermal imaging and there is lot of literature on. One of the newer areas being studied is the ability to identify metastasizing oral cancers. A recent study found that: “The entropy-gradient support vector machine (EGSVM)-based infrared thermal imaging system showed a trend of higher sensitivity, whereas contrast-enhanced computed tomography (CT) showed a trend of higher specificity. The EGSVM-based infrared thermal imaging system is a promising non-radiating, noninvasive tool for the detection of lymph node metastasis from oral cavity cancer.” (2)
By far and away the easiest and most used application of thermal imaging is identifying areas of trauma and inflammation which likely are causal for pain and pain management. In the field of rheumatic arthritis (RA) the standard for accessing RA type inflammation in knees and joints has been power doppler ultrasound (PDUS). PDUS has several disadvantages including cost of equipment, steep learning curve and some variability in observations. Thermal imaging has emerged as a simple, powerful tool for mapping the heat distribution pattern and has the potential to document and quantify disease activity in RA. In this study, the objective was to study the thermal imaging pattern of inflamed knee joints in cases of RA and its correlation with PDUS. The study found that “There was a statistically significant difference in mean knee temperature as well as mean knee-thigh temperature differential of inflamed versus control knees. Thermal imaging has the potential to become simple, objective, cost-effective and reliable tool for diagnosis and assessment of disease activity in inflammatory arthritis.” (3).
Vascular issues are related to a variety of symptoms including pain. A recent animal study found “One innovative technology that has recently been incorporated into veterinary medicine for the specific purpose of studying pain in animals is called infrared thermography (IRT), a technique that works by detecting and measuring levels of thermal radiation at different points on the body's surface with high sensitivity. Changes in IRT images are associated mainly with blood perfusion, which is modulated by the mechanisms of vasodilatation and vasoconstriction. IRT is an efficient, noninvasive method for evaluating and controlling pain, two critical aspects of animal welfare in biomedical research. The aim of the present review is to compile and analyze studies of infrared thermographic changes associated with pain in laboratory research involving animals.”(4).
Diabetes in another disease state which is being researched for identification by thermal imaging. Identifying diabetes in the earliest of stages allow interventions which can result in never really clinically developing the disease and a reversal of symptoms. Intermittent fasting would be one of these interventions (5). Research from 2019 is indicating that an early detection method could be developed by thermal imaging of the tongue to identify early stages of diabetes (6).
Carotid artery stenosis is an issue where vessels become clogged with clots which can restrict blood flow to the brain. Carotid arteries are easily visible with thermal imaging due to their proximity to the surface. In a recent study its was found that: “Using the mean temperature as a threshold value, the resultant thermal image was processed and normalized. Between the two stenosis models, disruption in the thermal features corresponding to the presence of stenosis was observed. The method described in this study paves the path to experimentally study the thermal effect of the presence of stenosis in the carotid artery.” (7)
Thermal imaging is inexpensive and becoming increasly so. Clinics are beginning to appear which may be a good resources for physicians, chiropractors, and other medical professionals. It is non-invasive diagnostic and thereby very unthreatening to many patients. Further thermal images represent a way for a patient to visually “see” their pain/trauma/issues and also represents a way to gauge if they might be making progress reducing inflammation in an area or system. Thermal imaging is sexy and compelling feedback that has a bigger and broader place in medical sciences. The issue in the very near future will be building a competent population of radiologist (and other professionals) who are capable of interpreting these images. The technology has clearly now arrived.
(1) Proal, Amy D.; VanElzakker, Michael B. Pathogens Hijack Host Cell Metabolism: Intracellular Infection as a Driver of the Warburg Effect in Cancer and Other Chronic Inflammatory Conditions. Immunometabolism 3(1):e210003, January 2021. | DOI: 10.20900/immunometab20210003
(2) Dong F, Tao C, Wu J, Su Y, Wang Y, Wang Y, Guo C, Lyu P. Detection of cervical lymph node metastasis from oral cavity cancer using a non-radiating, noninvasive digital infrared thermal imaging system. Sci Rep. 2018 May 8;8(1):7219. doi: 10.1038/s41598-018-24195-4. Erratum in: Sci Rep. 2018 Jul 10;8(1):10624. PMID: 29739969; PMCID:
(3) Vasdev V, Singh R, Aggarwal V, Bhatt S, Kartik S, Hegde A, Kumar A, Bhaskar SV. Thermal imaging in rheumatoid arthritis knee joints and its correlation with power Doppler ultrasound. Med J Armed Forces India. 2023 Dec;79(Suppl 1):S189-S195. doi: 10.1016/j.mjafi.2022.05.011. Epub 2022 Sep 2. PMID: 38144611; PMCID: PMC10746829.
(4) Mota-Rojas D, Olmos-Hernández A, Verduzco-Mendoza A, Lecona-Butrón H, Martínez-Burnes J, Mora-Medina P, Gómez-Prado J, Orihuela A. Infrared thermal imaging associated with pain in laboratory animals. Exp Anim. 2021 Feb 6;70(1):1-12. doi: 10.1538/expanim.20-0052. Epub 2020 Aug 25. PMID: 32848100; PMCID: PMC7887630.
(5) Crupi AN, Haase J, Brandhorst S, Longo VD. Periodic and Intermittent Fasting in Diabetes and Cardiovascular Disease. Curr Diab Rep. 2020 Dec 10;20(12):83. doi: 10.1007/s11892-020-01362-4. PMID: 33301104.
(6) Selvarani A, Suresh GR. Infrared Thermal Imaging for Diabetes Detection and Measurement. J Med Syst. 2019 Jan 2;43(2):23. doi: 10.1007/s10916-018-1140-1. PMID: 30604094.
(7) Saxena A, Ng EYK, Canchi T, Tee JJ, Ng LK. Relation Between Neck Skin Temperature Measurement and Carotid Artery Stenosis: In-Vitro Evaluation. J Biomech Eng. 2020 Nov 1;142(11):114501. doi: 10.1115/1.4048423. PMID: 32914828.
