The results reported by Petusseau’s team suggest hypoxia imaging as an efficient approach to identifying tumors in cancer treatment
The technical challenge in detecting DF is due to its low intensity; background noise makes it difficult to detect without a single photon detector. The team overcame this problem using a highly sensitive time-gated imaging system, which allows signal detection within a specified time window only. This greatly reduces the background noise and enables a wide-field direct mapping of oxygen partial pressure (pO2) changes with the acquired DF signal. The result is real-time metabolic information, a useful map for surgical guidance.
Lead author Arthur Petusseau, a doctoral candidate in Engineering Sciences at Dartmouth College, explains: “Acquiring both prompt and delayed fluorescence in a rapid sequential cycle allowed for imaging oxygen levels in a way that was independent of the PpIX concentration.” Petusseau’s team demonstrated the efficacy of their technique using mice models of pancreatic cancer, which exhibited hypoxic tumors. The DF signal obtained from the cancerous cells was over five times stronger than that from surrounding healthy oxygenated tissues. The signal contrast was further enhanced when the tissues were palpated before imaging to further enhance transient hypoxia.
According to Frédéric Leblond, Professor of Engineering Physics at Polytechnique Montréal and JBO Associate Editor, “The results reported by Petusseau’s team suggest hypoxia imaging as an efficient approach to identifying tumors in cancer treatment. PpIX DF detection uses a known clinical dye and an already-approved in-human marker, with great potential for surgical guidance, and more.” Petusseau notes that the imaging of pO2 in tissues could also enable control of tissue metabolism. This, in turn, would help us better understand the biochemistry involved in oxygen supply and consumption.
Source: SPIE – The International Society for Optics and Photonics