Researchers are using a saline filled, human body-shaped fish tank to test MRI-safe implants.

The University of Waikato-led research aims to design implants such as pace makers and cochlear implants that can safely go through an MRI machine.

Engineering Professor Jonathan Scott says they're using a transparent, human shaped piece of plastic filled with jelly to simulate a body.

"Basically a saline jelly which simulates a piece of person and you put the thing you want to test, the piece of wire or the implant in the fish tank and you push the fish tank in the MRI machine."

Scott says people wearing implants like pacemakers, cochlear and spinal cord pain relief implants can't have MRI scans.

"What we're aiming to do is devise a new implant lead that can safely go into an MRI machine."