Tissue markers

Abstract

The inventions provided herein relate to tissue markers and uses thereof, e.g., to mark a target tissue site (e.g., a biopsy site in a breast tissue) or to produce a cell scaffold. The tissue markers described herein are designed to be resistant to fast migration (e.g., immediate migration after implantation through a needle track) and slow migration (e.g., over an extended period of time) upon implantation at a target tissue site (e.g., a biopsy site in a breast tissue), without using an adhesive. Additionally or alternatively, the tissue markers described herein can be readily detectable by at least one imaging modality, e.g., but not limited to magnetic resonance imaging, X-ray imaging, ultrasound imaging, or a combination thereof.

What is claimed is: 
     
         1 . A tissue marker for implanting through a cannula into a target tissue at a target site, the tissue marker imagable by one or more imaging modalities and having a flexible polymer sheet, with a predetermined density, wherein the flexible polymer sheet is initially arranged within the cannula in a rolled configuration, constrained by the cannula from unrolling, and, upon the implantation of the tissue marker at the target site, the flexible polymer sheet at least partially unrolls, with the flexible polymer sheet maintaining the predetermined density in both rolled and at least partially unrolled configurations. 
     
     
         2 . The tissue marker of  claim 1  wherein the flexible polymer sheet defines a hollow cylinder in the rolled configuration. 
     
     
         3 . The tissue marker of  claim 1  wherein the flexible polymer sheet fully unrolls to form a planar shape. 
     
     
         4 . The tissue marker of  claim 1  wherein the flexible polymer sheet further comprises macropores. 
     
     
         5 . The tissue marker of  claim 4  wherein the macropores form a channel between two surfaces of the flexible polymer sheet. 
     
     
         6 . The tissue marker of  claim 1  wherein the one or more imaging modalities are selected from a group consisting of ultrasound imaging, X-ray-based imaging (including computed tomography), magnetic resonance imaging (MRI), fluorescent imaging, and any combinations thereof. 
     
     
         7 . The tissue marker of  claim 1  wherein the flexible polymer sheet in the at least partially unrolled configuration conforms to a void at the target site. 
     
     
         8 . The tissue marker of  claim 1  wherein the tissue marker further comprises a shape-memory element carried by the flexible polymer sheet. 
     
     
         9 . The tissue marker of  claim 8  wherein the shape-memory element comprises a curved wire. 
     
     
         10 . The tissue marker of  claim 8  wherein the shape-memory element comprises a coil. 
     
     
         11 . The tissue marker of  claim 8  wherein the flexible polymer sheet comprises first and second layers and the shape-memory element is located between the first and second layers. 
     
     
         12 . The tissue marker of  claim 8  wherein the shape-memory element includes one or more of copper-aluminum-nickel alloys, nickel-titanium alloys, or nitinol. 
     
     
         13 . The tissue marker of  claim 1  wherein the flexible polymer sheet comprises a contrast agent, detectable by at least one of the one or more imaging modalities. 
     
     
         14 . The tissue marker of  claim 13  wherein the contrast agent is selected from a group comprising metal oxide particles, metal materials, amorphous materials, crystalline materials, gas bubbles, paramagnetic substances, and any combinations thereof. 
     
     
         15 . The tissue marker of  claim 14  wherein the metal oxide particles comprise iron oxide particles, the gas bubbles comprise air-filled microbubbles, and the paramagnetic substance comprises Vitamin E. 
     
     
         16 . A tissue marker for implanting through a cannula into a target tissue at a target site, the tissue marker comprising a flexible polymer sheet, having first and second layers, and a shape-memory element, in the form of a curved wire, located between the first and second layers, with the flexible polymer sheet visible by a first imaging modality, and the curved wire visible by a second imaging modality, different from the first imaging modality, wherein the flexible polymer sheet is initially arranged within the cannula in a rolled configuration, constrained by the cannula from unrolling, and, upon the implantation of the tissue marker at the target site, the flexible polymer sheet at least partially unrolls, with the flexible polymer sheet maintaining a predetermined density in both rolled and at least partially unrolled configurations. 
     
     
         17 . The tissue marker of  claim 16  wherein the flexible polymer sheet further comprises a plurality of air-filled bubbles. 
     
     
         18 . The tissue marker of  claim 16  wherein the flexible polymer sheet further comprises beads. 
     
     
         19 . The tissue marker of  claim 16  wherein the curved wire is a coil. 
     
     
         20 . The tissue marker of  claim 16  wherein the tissue marker further comprises metal oxide particles. 
     
     
         21 . The tissue marker of  claim 20  wherein the metal oxide particles are iron oxide particles. 
     
     
         22 . The tissue marker of  claim 16  wherein the tissue marker further comprises a paramagnetic substance. 
     
     
         23 . The tissue marker of  claim 22  wherein the paramagnetic substance is Vitamin E. 
     
     
         24 . The tissue marker of  claim 16  wherein the flexible polymer sheet further comprises an active agent selected from a group comprising at least one of a therapeutic agent, an antimicrobial agent, an anesthetic, a cell growth factor, and any combinations thereof. 
     
     
         25 . The tissue marker of  claim 16  wherein the flexible polymer sheet defines a hollow cylinder in the rolled configuration. 
     
     
         26 . The tissue marker of  claim 25  wherein the flexible polymer sheet fully unrolls to form a planar shape. 
     
     
         27 . A tissue marker for implanting through a cannula into a target tissue at a target site, the tissue marker comprising:
 a flexible polymer sheet having a plurality of beads to enhance a first imaging modality, the flexible polymer sheet further having first and second layers,   a shape-memory element, in the form of a curved wire to enhance a second imaging modality, and located between the first and second layers, and   a paramagnetic element enhancing a third imaging modality, different from the first imaging modality and different from the second imaging modality;   wherein the flexible polymer sheet is initially arranged within the cannula in a rolled configuration, constrained by the cannula from unrolling, and, upon the implantation of the tissue marker at the target site, the flexible polymer sheet at least partially unrolls, with the flexible polymer sheet maintaining a predetermined density in both rolled and at least partially unrolled configurations.   
     
     
         28 . The tissue marker of  claim 27  wherein the plurality of beads are ceramic. 
     
     
         29 . The tissue marker of  claim 27  wherein the paramagnetic element comprises Vitamin E. 
     
     
         30 . The tissue marker of  claim 29  wherein the paramagnetic element further comprises iron oxide particles. 
     
     
         31 . The tissue marker of  claim 27  wherein the first imaging modality is ultrasound, the second imaging modality is X-ray, and the third imaging modality is magnetic resonance imaging (MRI). 
     
     
         32 . The tissue marker of  claim 27  wherein the flexible polymer sheet defines a hollow cylinder in the rolled configuration. 
     
     
         33 . The tissue marker of  claim 32  wherein the flexible polymer sheet fully unrolls to form a planar shape.