Self-contained, self-piercing, side-expelling marking apparatus

A marking apparatus for the percutaneous placement of an imaging marker in a tissue mass, comprising:

• a handle configured to be grasped by a user, the handle having a rear opening;
• a cannula having:
• a peripheral wall forming a lumen that carries the imaging marker,
• a proximal end coupled to the handle,
• a lateral opening in the peripheral wall that is open to the lumen,
• a closed-off distal portion having a distal void and a pointed tip, wherein the distal void is distal to the lateral opening and is proximal to the pointed tip, and
• a resilient end wall proximal to the distal void;
• a stylet having a distal end with an angled surface, the stylet being disposed in the lumen and movable in the lumen between a ready position and an expelled position, the stylet being configured to advance through the lumen to the expelled position, the resilient end wall being configured to deflect distally and beneath the resilient end wall and into the distal void as the stylet advances through the lumen into the expelled position, the angled surface of the stylet being configured to drive the imaging marker out of the lumen through the lateral opening of the cannula as the stylet advances into the expelled position;
• and
• a plunger received in the rear opening of the handle and configured to move relative to the handle, the plunger being connected to the stylet.

A marking apparatus for the percutaneous placement of an imaging marker in a tissue mass, the marking apparatus comprising:

• a handle having a rear opening;
• a cannula having:
• a peripheral wall forming a lumen that carries the imaging marker,
• a proximal end carried by the handle,
• a closed-off distal portion terminating in a self-piercing tip,
• a lateral opening in the peripheral wall, wherein the lateral opening extends in a region between the proximal end of the cannula and the closed-off distal portion of the cannula, the lateral opening having a proximal extent and a distal extent, and
• a cantilever end wall extending into the lumen from the peripheral wall at the distal extent of the lateral opening, the cantilever end wall having a distal free end that is suspended in the lumen above the peripheral wall;
• a stylet having a proximal end and a distal end, the stylet being slidably received within the lumen for movement between a ready position, wherein the distal end of the stylet is spaced inwardly from the self-piercing tip to form a marker recess in communication with the lateral opening, and an expelled position, wherein the distal end of the stylet is advanced a sufficient distance into the marker recess to expel the imaging marker contained in the lumen through the lateral opening of the cannula, the cantilever end wall of the cannula being configured to deflect upon engagement of the distal end of the stylet such that the distal end of the stylet passes beneath the cantilever end wall and into the closed-off distal portion;
• and
• a plunger received in the rear opening of the handle and configured to move relative to the handle, the plunger being connected to the proximal end of the stylet.