Analysis of vascular remodeling in vivo is a major challenge both for the study of the regulatory mechanisms of its initiation and inhibition, and for clinical evaluation of pathological processes. In vivo assays for the study of angiogenesis and tissue perfusion are essential for the study of cancer, wound healing, tissue regeneration and reproduction. Angiogenesis is being assessed today by immunohistological staining of biopsy specimens, an invasive procedure that gives only local information. Application of MRI as a non-invasive detection tool can provide full 3 dimensional information about vessel density functionality and maturation. Most of the previous approaches for the study of angiogenesis by MRI relied on the use of exogenous contrast agents. In my research vascular development is followed by functional-MRI using hypercapnic and hyperoxic challenges.