55 karma · joined April 3, 2018
To answer your specific points - I would go for MRI over CT - CTs tend to have high radiation doses, especially if you plan to do a full-body scan. I can't recommend it. MRIs are much less harmful. There are private clinics where you can pay for a full body "preventive" MRI - this will set you back a nice sum, >€1000 in the Netherlands, IIRC. Segmenting the resulting DICOM file is difficult. It will require a fair bit of work. Look into ITK / VTK / 3Dslicer. You will absolutely have to clean up and probably remesh any resulting stl/obj, I recommend using meshlab for that. From there, 3D printing can be done with any personal printer that has a large enough volume to not take forever. Using an external service, e.g. shapeways will be very expensive. If you don't have your own printer, you should probably look into an inexpensive FDM printer, I personally use an original prusa i3 Mk2.5.
All in all, it will be a very expensive journey if you're not already in the field and have connections. Maybe try to connect with local universities to find observational studies.
edit because I realised I sound very negative. I actually think you have a really cool idea. Please do go ahead if you have the time and money, and for the love of all that is holy, blog it for posterity!