Piezo micro-markers for ultrasound medical diagnostics

Abstract

An imaging system is disclosed that uses piezoelectric markers. The piezoelectric fields in combination with ultrasound reflections can be used to construct an image of an otherwise difficult to detect feature within a subject's body. In one embodiment, the invention includes a piezoelectric marker, including at least one piece of piezoelectric material, an ultrasound transducer connected to an ultrasound pulser and a receiver, a computer sequencing control connected to the receiver and the ultrasound pulser, a display connected to the computer sequencing control and electrodes connected to the computer sequencing control via amplification circuitry.

What is claimed is: 
     
         1 . An imaging system comprising:
 a piezoelectric marker embedded in a subject's body, wherein the piezoelectric marker comprises at least one piece of piezoelectric material;   an ultrasound transducer configured to excite the piezoelectric marker with an ultrasound signal; and   electrodes configured to detect an electric field generated by the piezoelectric marker.   
     
     
         2 . The imaging system of  claim 1 , wherein the piezoelectric marker comprises a material selected from the group consisting of PVDF, PVDF-TRFE, PZT, lithium niobate, quartz, lead metaniobate, lead titanate, and tourmaline. 
     
     
         3 . The imaging system of  claim 1 , wherein the piezoelectric marker comprises a plurality of pieces of piezoelectric material connected in electrical series. 
     
     
         4 . The imaging system of  claim 1 , wherein the piezoelectric material in the piezoelectric marker is coated with a biocompatible layer. 
     
     
         5 . The imaging system of  claim 4 , where the biocompatible layer has an acoustic impedance that is less than the acoustic impedance of the piezoelectric marker. 
     
     
         6 . The imaging system of  claim 4 , where the thickness of the biocompatible layer is equal to about one quarter of a wavelength of the ultrasound signal. 
     
     
         7 . The imaging system of  claim 1 , where the piezoelectric material has a thickness equal to about half of a wavelength of the ultrasound signal. 
     
     
         8 . The imaging system of  claim 1 , where the piezoelectric material is curved. 
     
     
         9 . The imaging system of  claim 8 , where the piezoelectric material is curved with a radius of curvature that is larger than one half wavelength of the ultrasound signal. 
     
     
         10 . A method of detecting an object embedded in a subject's body, comprising:
 exciting a piezoelectric marker embedded in a subject's body with an ultrasound signal;   generating electric fields in the piezoelectric marker in response to the ultrasound signal; and   detecting the electric fields using electrodes.   
     
     
         11 . The method of  claim 10 , further comprising detecting an ultrasound signal reflected by the piezoelectric marker. 
     
     
         12 . The method of  claim 11 , wherein the electric fields are detected before the reflected ultrasound. 
     
     
         13 . The method of  claim 10 , wherein the piezoelectric marker comprises a material selected from the group consisting of PVDF, PVDF-TRFE, PZT, lithium niobate, quartz, lead metaniobate, lead titanate, and tourmaline. 
     
     
         14 . The method of  claim 10 , wherein the piezoelectric marker comprises a plurality of pieces of piezoelectric material connected in electrical series. 
     
     
         15 . The method of  claim 10 , wherein the piezoelectric marker is coated with a biocompatible layer. 
     
     
         16 . The method of  claim 13 , where the biocompatible layer has an acoustic impedance that is less than the acoustic impedance of the piezoelectric marker. 
     
     
         17 . The method of  claim 15 , where the thickness of the biocompatible layer is equal to about one quarter of a wavelength of the ultrasound signal. 
     
     
         18 . The method of  claim 10 , where the piezoelectric material has a thickness equal to about half of a wavelength of the ultrasound signal.