Heart surgeries could be so much safer if surgeons can see and feel an actual representation of the patient's organ before the procedure itself. A system developed by a group of researchers from MIT and Boston Children's Hospital might make that a viable option. By using MRI scans as a blueprint, it allows doctors to print out a model of the patient's heart within just three hours. When you do an MRI scan, the machine takes hundreds of cross-sectional images of your organs. In order to create an accurate 3D-printable model, though, the boundaries between each part of the organ must be determined. It's critical for each part to look distinct, especially if the patient needs surgery due to an unusual anatomy.