Long-Wave Infrared Imaging for Intraoperative Cancer Detection-What is the True Temperature of a Cancer?

BACKGROUND During cancer operations, the cancer itself is often hard to delineate-buried beneath healthy tissue and lacking discernable differences from the surrounding healthy organ. Long-wave infrared, or thermal, imaging poses a unique solution to this problem, allowing for the real-time label-free visualization of temperature deviations within the depth of tissues. The current study evaluated this technology for intraoperative cancer detection. METHODS In this diagnostic study, patients with gastrointestinal, hepatobiliary, and renal cancers underwent long-wave infrared imaging of the malignancy during routine operations. RESULTS It was found that 74% were clearly identifiable as hypothermic anomalies. The average temperature difference was 2.4°C (range 0.7 to 5.0) relative to the surrounding tissue. Cancers as deep as 3.3 cm from the surgical surface were visualized. Yet, 79% of the images had clinically relevant false positive signals [median 3 per image (range 0 to 10)] establishing an accuracy of 47%. Analysis suggests that the degree of temperature difference was primarily determined by features within the cancer and not peritumoral changes in the surrounding tissue. CONCLUSION These findings provide important information on the unexpected hypothermal properties of intra-abdominal cancers, directions for future use of intraoperative long-wave infrared imaging, and new knowledge about the in vivo thermal energy expenditure of cancers and peritumoral tissue.