A PICC is defined as a tunneled where the venipuncture site (typically in the yellow zone) does not coincide with the exit site (typically, in the green zone).
It is possible to tunnel any PICC, with an anterograde tunnelization (if the catheter is designed for a distal 'trimming') or with a retrograde tunnelization (only for catheters designed for a proximal 'trimming').
The benefit of tunneling in terms of infectious risk will be twofold: directly (protection against extraluminal contamination, since the exit site is distant from the actual entrance of the catheter into the vein) but also indirectly (because it allows to move the exit site to an area with less bacterial contamination.
In terms of safety and cost-effectiveness it will always be advisable to choose PICC power injectable in polyurethane, non-valved, open-ended.