Specific thermographic changes during Walker 256 carcinoma development: Differential infrared imaging of tumour, inflammation and haematoma

Background: Infrared imaging measures spatial variations in the skin temperature aiming to determine pathological processes; hence possible use of this non-invasive analytical method in cancer detection is emerging. Methods: Infrared thermal imaging was used to detect changes in rat skin surface temperature associated with experimental cancer development (Walker 256 carcinoma), inflammation (upon s.c. Sephadex injection) and haematoma (provoked by s.c. blood coagulate injection). Infrared camera with a geometric resolution of 76,800 pixels, spectral range of 8–14 μm and the minimal detectable temperature resolution of 0.07 °C with spatial resolution of 0.48 mm at measuring distance of 30 cm was used to obtain computerised thermal scans. Genuine ThermoWEB software developed for remote internet control as open source software was used. Results: The raise of peripheral temperature was observed after induction of local inflammation or haematoma. Opposite to that, transient decrease of the skin surface temperature was observed after tumour transplantation. Progressive growth of tumour was associated with the raise of the skin surface temperature from the 10th day after tumour inoculation, when the tumours developed supportive neoangiogenic blood supply, as verified by histology. Conclusion: While the raise of peripheral temperature in advanced tumour was caused by neoangiogenesis, the reduction in skin surface temperature in an early period after tumour cell inoculation indicated a decay of transplanted tumour cells due to the immune response and the lack of blood supply. Thus, infrared thermal imaging may have considerable value in evaluation of the tumour development and discrimination of cancer from inflammation and haematoma.