Fig. 2.

Optoacoustic tomography provides a non-invasive assessment of the rim–core vascular phenotypes of both breast cancer models. a Rim data were taken from a region of interest drawn around the outside of the tumour, then shrunk by a radial distance of 1 mm. Significant differences in THb and SO₂^MSOT were seen between the rim and core of MDA-MB-231 tumours, though only THb showed a rim–core variation in MCF-7 tumours b, c. Extracting “large” (20–30 mm² OT area) tumours for a size matched analysis (d) showed similar THb values but different SO₂^MSOT between rims and cores e, f. Statistical significance was assessed by paired two-tailed t-test within a single-tumour type and by unpaired two-tailed t-test between tumour types. For (b) and (c) n^MCF−7 = 11; n²³¹ = 15, for (e) and (f) n^MCF−7 and n²³¹ = 4. All panels data are expressed as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001