A medical device assembly for use in a magnetic field environment, comprising a medical device, said medical device comprising: an elongate shaft having a proximal end portion and a distal end portion; a positioning sensor disposed at said distal end portion of said shaft and comprising first and second leads (32 1, 32 2) arranged in a twisted pair pattern and extending from a sensing element of said sensor to said proximal end portion of said shaft; and an electromechanical connector having a first end, a second end, and a plurality of pins disposed at said first end thereof, wherein a first pin and a second pin of said plurality of pins are electrically connected to said first and second leads (32 1, 32 2) of said sensor, respectively, thereby forming a first partial magnetic loop (59 1) between said first and second pins, said connector further comprising a first electrical jumper electrically connecting said first pin with a third pin of said plurality of pins, and a second electrical jumper electrically connecting said second pin with a fourth pin of said plurality of pins, said connection of said first and second electrical jumpers between said first and third and said second and fourth pins, respectively, forming a second partial magnetic loop (59 2) between said third and fourth pins, wherein said first and second partial magnetic loops (59 1, 59 2) are configured to combine with respective first and second partial magnetic loops of a complementary electromechanical connector configured to be mated with said second end of said electromechanical connector of said medical device to form first and second magnetic noise cancellation loops that are substantially equal in area and opposite in orientation. an elongate shaft having a proximal end portion and a distal end portion; a positioning sensor disposed at said distal end portion of said shaft and comprising first and second leads (32 1, 32 2) arranged in a twisted pair pattern and extending from a sensing element of said sensor to said proximal end portion of said shaft; and an electromechanical connector having a first end, a second end, and a plurality of pins disposed at said first end thereof, wherein a first pin and a second pin of said plurality of pins are electrically connected to said first and second leads (32 1, 32 2) of said sensor, respectively, thereby forming a first partial magnetic loop (59 1) between said first and second pins, said connector further comprising a first electrical jumper electrically connecting said first pin with a third pin of said plurality of pins, and a second electrical jumper electrically connecting said second pin with a fourth pin of said plurality of pins, said connection of said first and second electrical jumpers between said first and third and said second and fourth pins, respectively, forming a second partial magnetic loop (59 2) between said third and fourth pins, a first electrical jumper electrically connecting said first pin with a third pin of said plurality of pins, and a second electrical jumper electrically connecting said second pin with a fourth pin of said plurality of pins, said connection of said first and second electrical jumpers between said first and third and said second and fourth pins, respectively, forming a second partial magnetic loop (59 2) between said third and fourth pins,