In one embodiment, a method is provided. It discloses transgenic mice with inactivating mutations in the endogenous gene for the acetyl-CoA carboxylase 2 isoform of acetyl-CoA carboxylase. A section Ld of the length L of the conductor is provided with an Ni coating. The invention also provides methods of improving MR-imageability of polymers and medical devices by encapsulating the polymers and medical devices with hydrogels.