Interestingly, despite the high differences of CXCR4 expression reported in the literature [33, 55], there were no significant differences in the perfusion parameters between the two tumor models used, which may be due to unsuitability of our targeted-MB to provide efficient readouts on CXCR4, or insufficient differences in receptor expression between the vasculature of these models. Here, CXCR4 is linked to neoplasm.