Intrinsic tissue fluorescence corrected for absorption and scattering improves 2-NBDG contrast between 4T1 tumors and normal tissue.

Abstract

<p><b>A</b>. Measured 2-NBDG₆₀ from the 4T1 and 4T07 tumors is distorted by hemoglobin absorption, and is on par with fluorescence from normal tissue. A normal tissue data-point and representative tumors with similar measured fluorescence values were selected to illustrate the effect of correction. <b>B</b>. Normalized spectra of measured 2-NBDG₆₀ illustrate the distortion in better detail. <b>C</b>. Measured 2-NBDG₆₀ is not significantly different between the different groups. <b>D</b>. Correction with the MC fluorescence model removes hemoglobin-induced distortions and improves contrast between normal and tumor. <b>E</b>. Corrected 2-NBDG₆₀ spectra from normal tissue, a 4T1 tumor, and a 4T07 tumor shown in 2D, normalized to their respective maxima are presented along with a true 2-NBDG fluorescence measurement, illustrating good agreement between the extracted in vivo spectral line shapes and native 2-NBDG. <b>F</b>. Corrected 2-NBDG₆₀ is significantly higher in 4T1 tumors compared with normal tissue (p = 0.02). Although mean 2-NBDG₆₀ in 4T07 tumors is higher compared with normal tissue, this is not statistically significant. <b>G</b>. The extracellular acidification rate (ECAR) of 4T1 and 4T07 cells, as calculated with a Seahorse Glycolysis stress test, is not significantly different. Data represent n = 12 cell samples from 3 distinct assays. Error bars represent standard error of the mean.</p