FIG. 4.

Spatial relatedness of cycling hypoxia obtained using phosphorescence lifetime imaging of a skin fold window chamber containing the R3230Ac mammary carcinoma. Watershed segmentation results are shown for 2.5-min intervals. Time increased from left to right, top to bottom, in 2.5-min increments. Watershed segmentation creates boundaries at sharp gradients in pO₂; segmented regions can be thought of as pO₂ isobars. Segments are color-coded by their deviations from the median pO₂ of the image. Red, high deviations from the median; blue, no deviation from the median. Figure adapted from Cardenas Navia et al. with permission from the author and publisher (51).