This document discusses, among other things, a stiffening stylet for use with a peel-away or other sheath. The stylet includes an MR-compatible ceramic core and an MR-compatible tubular covering, such as a polyester heat shrink tubing. The ceramic core and the tubular covering together provide a step to engage a stop feature of the sheath to inhibit overextension of the stylet beyond a distal end of the sheath.
