Instrument having enhanced ultrasound visibility

Abstract

An instrument ( 10 ) for ultrasonic imaging comprises a probe ( 12 ) for insertion into a material ( 62 ) containing a liquid. The probe ( 12 ) has a coating comprising a carrier material ( 30 ) and a quantity of reactive material ( 32 ) which, upon contacting a reactant produce a quantity of bubbles ( 62 ) adjacent the coating for reflecting ultrasonic energy. In one application the probe ( 12 ) comprises a biopsy needle and the coating is positioned towards a sharp distal end thereof ( 14 a ) thereby to facilitate the guiding and positioning thereof. Alternatively, the coating can be provided along the entire length of the instrument ( 10 ) or at descrete portions along its length.

1 . An instrument insertable into a medium and capable of being detected with sonic imaging equipment comprises: 
 an elongate member, for insertion into said medium and having a region the position of which it is desirable to monitor; and    bubble generating means, for generating a plurality of discrete mobile bubbles at said desired region, whereby said discrete mobile bubbles are detectable by sonic imaging equipment thereby to give an accurate indication of the position of said region.    
     
     
         2 . An instrument as claimed in  claim 1  further including a coating at said region and in which said bubble generating means is contained within said coating thereby to generate said bubbles within said coating and release them for passage therethrough.  
     
     
         3 . An instrument as claimed in  claim 1  or  claim 2  in which said bubble generating means comprises a reactive substance which upon interaction with a reactant acts to produce said bubbles.  
     
     
         4 . An instrument as claimed in any one of  claims 1  to  3  in which said bubble generating means comprises an effervescent material which, upon contacting fluid effervesces thereby to create said bubbles.  
     
     
         5 . An instrument as claimed in  claim 4  in which said effervescent material comprises a mixture of sodium hydrogen carbonate and citric powder.  
     
     
         6 . An instrument as claimed in any one of  claims 2  to  5  further including an outer layer of fluid permeable-gas impermeable material for allowing fluid to enter the coating and retaining any gas bubbles created therein within said coating.  
     
     
         7 . An instrument as claimed in any one of  claims 2  to  6  in which the coating comprises a fluid permeable-gas impermeable polymer.  
     
     
         8 . An instrument as claimed in any one of  claims 2  to  5  including an outer gas impermeable layer and a plurality of openings for allowing fluid to contact the reactant but limiting the escape of any gas bubbles from the carrier material.  
     
     
         9 . An instrument as claimed in one of  claims 2  to  5  in which said coating comprises a matrix of interconnecting passages having a pore size through which fluid may permeate but in which gas bubbles of a size larger than a predetermined size are retained.  
     
     
         10 . An instrument as claimed in any one of  claims 2  to  7  in which the coating comprises a hydrophilic material.  
     
     
         11 . An instrument as claimed in any one of  claims 2  to  10  in which said coating forms a carrier material throughout which said bubble generating means is dispensed.  
     
     
         12 . An instrument as claimed in any one of  claims 1  to  9  in which the coating comprises an epoxy based resin.  
     
     
         13 . An instrument as claimed in  claim 12  in which the coating comprises EPOTEC epoxy  353  ND resin.  
     
     
         14 . An instrument as claimed in any one of  claims 1  to  13  in which said instrument includes a distal end and said coating lies adjacent said distal end.  
     
     
         15 . An instrument as claimed in any one of  claims 1  to  13  in which said coating is provided at a plurality of discrete positions along said elongate member.  
     
     
         16 . An instrument as claimed in any one of  claims 1  to  15  in which said elongate member comprises a biopsy needle assembly.  
     
     
         17 . A method of determining the position of an instrument as claimed in any one of  claims 1  to  16  including the steps of: 
 (a) inserting the instrument into a material;  
 (b) creating a plurality of discrete mobile bubbles at the desired region; and  
 (c) positioning an ultrasound transducer on a surface of the material and transmitting an ultrasonic signal in a direction substantially towards said instrument thereby to cause at least some of said signals to be reflected by said bubbles and collecting said reflected signal in said transducer;  
 (d) converting the reflected ultrasound signal into an electrical signal suitable for creating a display on a video monitor; and  
 (e) displaying a video image from said signal, thereby to provide a visual representation of the position of said instrument.