(a) High-resolution 3D MRI brain vascular map using SAIO. Various blood vessels in the rat brain can be visualized. In addition to clinically important brain vessels including anterior cerebral artery, middle cerebral artery, posterior cerebral artery, fine vessel structures as thin as ~ 100 microns in diameter can be clearly visualized. (b) 3D MRI brain vascular map using Dotarem (gadolinium-based contrast agent). Resolution is low and microvessels are not visible. (c) For 3D reconstruction, multiple slices of MRI images of the rat heart were obtained after injection of SAIO. Rat coronary arteries (180 microns) which are 10 times thinner than human coronary arteries were successfully visualized. Coronary arteries supply blood to the heart muscle and the blockage or narrowing of such arteries causes myocardial infarction or angina, but visualizing these arteries was impossible due to the limited resolution of current MRI contrast agents.