Commercially available guidewires, designed for X-ray-guided endovascular interventions, are built from stainless steel or nitinol core wires, usually coated by a polymer jacket. The metal wire makes the guidewire inherently X-ray visible. In the RF fields prevailing during MRI metal parts longer than 10 - 15 cm heat up and conduct electricity. This leads to burns and electric shocks primarily for the patient but also for the attending physician. Therefore conventional guidewires are MR unsafe and must not be used in MR scanners. As a consequence, the lack of MR safe guidewires so far has prevented development and clinical implementation of MRI-guided endovascular interventions.
Removal of the metal core from a conventional guidewire makes the product unusable. Purely polymer-based MR guidewires have proven to be not comparable to conventional guidewires as they do not possess sufficiently good mechanical properties. Therefore, more powerful materials need to be employed to achieve the necessary mechanical properties for high quality MR safe guidewires.