Figure 6 | Scientific Reports

Figure 6

From: Macroscopic fluorescence-lifetime imaging of NADH and protoporphyrin IX improves the detection and grading of 5-aminolevulinic acid-stained brain tumors

Figure 6

Cumulated phasor plot for NADH and PPIX fluorescence for all 42 tissue samples—The point clouds show the distribution of fluorescence lifetimes compared to the universal circle (in red). Points lying on the universal circle indicate a single-exponential fluorescence decay. However, NADH and PPIX show an elongated cloud which is indicative for a multiexponential decay. For NADH, this is due to the mixture of free and bound NADH and is well known. On the other hand, PPIX shows a clear bi-exponential decay with a long component at 16 ns and a short component below 2 ns. This indicates that the measured PPIX fluorescence lifetime of our samples is a mixture between native PPIX and tissue autofluorescence. Hence, our PPIX fluorescence lifetimes measured would be dependent on the PPIX concentration in the tissue.

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