Marker materials and forms for magnetic marker localization (MML)
A magnetic marker for marking a site in tissue in the body. In one embodiment, the marker comprises a magnetic metallic glass. In another embodiment, the marker is in a non-spherical configuration having an anisotropy ratio less than 9. In yet another embodiment, the marker is in a non-spherical configuration having an anisotropy ratio less than 6. In yet another embodiment, the marker is in a non-spherical configuration having an anisotropy ratio less than 3.
1 . An implantable marker for marking a tissue site, the implantable marker comprising:
a structure having at least a portion thereof formed of at least one magnetic material with a mass susceptibility of greater than 0.05 m 3 /kg,
wherein the structure is configured to change between a packed configuration and a deployed configuration,
wherein the packed configuration has a first anisotropy of magnetic susceptibility,
wherein the deployed configuration has a second anisotropy of magnetic susceptibility,
wherein the first anisotropy of magnetic susceptibility is greater than the second anisotropy of magnetic susceptibility.
2 . The implantable magnetic marker of claim 1 , wherein the first anisotropy of magnetic susceptibility is less than or equal to 5.
3 . The implantable magnetic marker of claim 1 , wherein the first anisotropy of magnetic susceptibility is greater than 5.
4 . The implantable magnetic marker of claim 1 , wherein the first anisotropy of magnetic susceptibility is less than or equal to 9.
5 . The implantable magnetic marker of claim 1 , wherein the first anisotropy of magnetic susceptibility is greater than or equal to 9.
6 . The implantable magnetic marker of claim 1 , wherein the at least one magnetic material has a magnetic coercivity of less than about 79.6 kAm-1 (1000 Oe).
7 . The implantable magnetic marker of claim 1 , wherein the at least one magnetic material has a magnetic coercivity of less than about 500 Oe.
8 . The implantable magnetic marker of claim 1 , wherein the at least one magnetic material has a magnetic coercivity of less than about 100 Oe.
9 . The marker of claim 1 , wherein the structure comprises a first segment and a second segment.
10 . The marker of claim 9 , wherein the first segment comprises a solid material, wherein the second segment comprises a second material.
11 . The marker of claim 1 , wherein the deployed configuration has one or more shapes or combinations of one or more shapes.
12 . The marker of claim 11 , wherein the one or more shapes are selected from the group consisting of: a bead, a dumbbell, dumbbell-like forms, a cable, a ball of yarn, a cylinder, a wire, and a multi-stranded cable.
13 . The marker of claim 1 , wherein the structure is deployable using a needle.
14 . A method comprising:
providing an implantable marker for marking a tissue site in a packed configuration, wherein the packed configuration has a first anisotropy of magnetic susceptibility; and
changing the packed configuration of the implantable marker to a deployed configuration, wherein the deployed configuration has a second anisotropy of magnetic susceptibility,
wherein the first anisotropy of magnetic susceptibility is greater than the second anisotropy of magnetic susceptibility,
wherein the implantable marker comprises at least one magnetic material with a mass susceptibility of greater than 0.05 m 3 /kg.
15 . The method of claim 14 further comprising localizing the implantable marker after implantation, using a hand-held probe, wherein the implantable marker is in the deployed configuration.
16 . The method of claim 14 , wherein the first anisotropy of magnetic susceptibility is less than or equal to 5.
17 . The method of claim 14 , wherein the first anisotropy of magnetic susceptibility is greater than 5.
18 . The method of claim 14 , wherein the first anisotropy of magnetic susceptibility is less than or equal to 9.
19 . The method of claim 14 , wherein the first anisotropy of magnetic susceptibility is greater than or equal to 9.