Tissue site markers for in vivo imaging

Abstract

The invention is directed biopsy site markers and methods of marking a biopsy site, so that the location of the biopsy cavity is readily visible by conventional imaging methods, particularly by ultrasonic imaging. The biopsy site markers of the invention have high ultrasound reflectivity, presenting a substantial acoustic signature from a small marker, so as to avoid obscuring diagnostic tissue features in subsequent imaging studies, and can be readily distinguished from biological features. The several disclosed embodiments of the biopsy site marker of the invention have a high contrast of acoustic impedance as placed in a tissue site, so as to efficiently reflect and scatter ultrasonic energy, and preferably include gas-filled internal pores. The markers may have a non-uniform surface contour to enhance the acoustic signature. The markers have a characteristic form which is recognizably artificial during medical imaging. The biopsy site marker may be accurately fixed to the biopsy site so as to resist migration from the biopsy cavity when a placement instrument is withdrawn, and when the marked tissue is subsequently moved or manipulated.

1 . An intracorporeal site marker for marking a selected site within tissue of a patient's body, comprising:
 an ultrasound detectable body including boundaries that contrast in acoustical impedance with tissue of the selected site, so as to reflect ultrasound during ultrasound imaging, the ultrasound detectable body having a first end spaced apart from a second end; and   a first migration resistant tissue engaging element attached to the ultrasound detectable body, and configured with a first linear portion that cantilevers outwardly from the first end of the ultrasound detectable body in a first direction, and configured with a first curved end portion that extends from the first linear portion, the first curved end portion having a first terminating free end portion that extends in a second direction opposite to the first direction back toward the ultrasound detectable body, the first terminating free end portion being radially spaced apart from the ultrasound detectable body.   
     
     
         2 - 41 . (canceled) 
     
     
         42 . The intracorporeal site marker of  claim 1 , wherein the first terminating free end portion of the first curved end portion of the first migration resistant tissue engaging element is longitudinally spaced from the first end of the ultrasound detectable body. 
     
     
         43 . The intracorporeal site marker of  claim 1 , comprising a second migration resistant tissue engaging element attached to the ultrasound detectable body, and configured with a second linear portion that cantilevers outwardly from the second end of the ultrasound detectable body in the second direction, and configured with a second curved end portion that extends from the second linear portion, the second curved end portion having a second terminating free end portion that extends in the first direction opposite to the second direction back toward the ultrasound detectable body, and the second terminating free end portion being radially spaced apart from the ultrasound detectable body. 
     
     
         44 . The intracorporeal site marker of  claim 43 , wherein the second terminating free end portion of the second curved end portion of the second migration resistant tissue engaging element is longitudinally spaced from the second end of the ultrasound detectable body. 
     
     
         45 . An intracorporeal site marker for marking a selected site within tissue of a patient's body, comprising:
 a remotely detectable body; and   at least one migration resistant tissue engaging element attached to the remotely detectable body, and configured with a linear portion that cantilevers outwardly from the remotely detectable body and a curved end portion that extends from the linear portion, the curved end portion having a terminating free end portion that extends in a direction back toward the remotely detectable body and is radially spaced apart from the remotely detectable body.   
     
     
         46 . The intracorporeal site marker of  claim 45 , the at least one migration resistant tissue engaging element including a first migration resistant tissue engaging element having a first terminating free end portion and a second migration resistant tissue engaging element having a second terminating free end portion, the first terminating free end portion and the second terminating free end portion being oriented to face in opposite directions. 
     
     
         47 . The intracorporeal site marker of  claim 45 , the at least one migration resistant tissue engaging element including a first migration resistant tissue engaging element and a second migration resistant tissue engaging element, wherein each of a first linear portion of the first migration resistant tissue engaging element and a second linear portion of the second migration resistant tissue is attached to an external surface of the remotely detectable body. 
     
     
         48 . The intracorporeal site marker of  claim 47 , wherein the first linear portion of the first migration resistant tissue engaging element and the second linear portion of the second migration resistant tissue are non-coaxial. 
     
     
         49 . The intracorporeal site marker of  claim 45 , the remotely detectable body having a first end spaced apart from a second end, the at least one migration resistant tissue engaging element including:
 a first migration resistant tissue engaging element attached to the remotely detectable body, and configured with a first linear portion that cantilevers outwardly from the first end of the remotely detectable body in a first direction, and configured with a first curved end portion that extends from the first linear portion, the first curved end portion having a first terminating free end portion that extends in a second direction opposite to the first direction, and the first terminating free end portion being radially spaced apart from the remotely detectable body; and   a second migration resistant tissue engaging element attached to the remotely detectable body, and configured with a second linear portion that cantilevers outwardly from the second end of the remotely detectable body in the second direction, and configured with a second curved end portion that extends from the second linear portion, the second curved end portion having a second terminating free end portion that extends in the first direction opposite to the second direction, and the second terminating free end portion being radially spaced apart from the remotely detectable body.   
     
     
         50 . An intracorporeal site marker for marking a selected site within tissue of a patient's body, comprising:
 a cylindrical body having a first end spaced apart from a second end; and   a first migration resistant tissue engaging element attached to the cylindrical body, and configured with a first linear portion that cantilevers outwardly from the first end of the cylindrical body in a first direction, and configured with a first curved end portion that extends from the first linear portion, the first curved end portion having a first terminating free end portion that extends in a second direction opposite to the first direction, and the first terminating free end portion being radially spaced apart from the cylindrical body.   
     
     
         51 . The intracorporeal site marker of  claim 50 , wherein the first terminating free end portion of the first curved end portion of the first migration resistant tissue engaging element is longitudinally spaced from the first end of the cylindrical body. 
     
     
         52 . The intracorporeal site marker of  claim 50 , comprising a second migration resistant tissue engaging element attached to the cylindrical body, and configured with a second linear portion that cantilevers outwardly from the second end of the cylindrical body in the second direction, and configured with a second curved end portion that extends from the second linear portion, the second curved end portion having a second terminating free end portion that extends in the first direction opposite to the second direction, and the second terminating free end portion being radially spaced apart from the cylindrical body. 
     
     
         53 . The intracorporeal site marker of  claim 52 , wherein the second terminating free end portion of the second curved end portion of the second migration resistant tissue engaging element is longitudinally spaced from the second end of the cylindrical body.