FVB mice (Charles River Laboratories, Inc.; sex, female; age, 9–10 weeks), were serially imaged using a PerkinElmer Quantum GX micro-CT scanner at different times after intraductal injection as described37 (link) with a solution containing 60 or 100 mM Tantalum oxide nanocrystals as contrast agent. Serial micro-CT was performed with: 2 minute acquisition; 90kVp/88μA; FOV, 36 mm; voxel resolution, 72 μm3.