An interventional or a non-interventional instrument like a catheter, a surgical device, a biopsy needle, a pointer, a stent or another invasive or non-invasive device, like a position marker, or a surface or local coil like a head coil is disclosed, wherein these instruments are provided with an MR-safe RF transmission line or cable (2, 3) for connecting the instrument with related RF transmit/MR receive units or other signal processing units for operating the instrument during an MR imaging or MR examination of an examination object. Basically, MR safety is obtained or increased by means of a plurality of fuses (6) which are serially connected into the transmission line or cable (2, 3).