A method of marking a biopsy site within a patients body includes providing a delivery tube having a plunger carrying a quantity of an ultrasound-detectable bio-resorbable particulate material in the delivery tube distal to the plunger, the ultrasound-detectable bio-resorbable particulate material having a particle size between about 200 microns and about 500 microns and having internal bubble cavities having a size of at least 50 microns and depressing the plunger for depositing the quantity of the ultrasound-detectable bio-resorbable particulate material at the biopsy site.
