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Applications of acoustic microscopy to tissue analysis
ABSTRACTS, ULTRASONIC IMAGING AND TISSUE CHARACTERIZATION SYMPOSIUM
SESSION
5:
ACOUSTSC
PARAMETERS,
PHANTOMS,
AND CALIBRATION
APPLICATIONS OF ACOUSTIC MICROSCOPY TO TISSUE ANALYSIS, R. Silverman*, F. Lizzi", J. Hui', M. Rondeaul, D.J. Coleman*, E. Feleppa", LCornell University Medical Co1 lege, New and York, NY 10021 and "Riverside Research Institute, New York, NY 10036. A scanning-laser acoustic microscope (SLAM) has been used analyze the acoustic properties of various types of treated to untreated tumors and ocular structures. Most observations and have been conducted using 100 MHz ultrasound (15 micrometer have been and wavelength). Acoustic micrograms digitized to study several fundamental computer analysis has been used regarding the origin of ultrasonic echoes. The questions studies with digitized rf signals often involve d comparison obtained during in pulse-echo scanning prior to the __-__ !&X2 microscope examinations. In one series of studies, microscope images have been to provide maps that estimate acoustic impedance within used (1) melanomas derived from human tumors and implanted in mice; and (2) melanoma5 excised from human eyes. These images are analyzed in terms of Z-D spectra and 2-D autocorrelation functions which, in turn, are used to predict the power 5pectr-a measured with a clinical digital analysis system. These computations are then compared with actual presurgical spectra. Spectra computed for different subregions in these tumors are helping to improve our understanding of those tissue elements that are responsible for specific ocular tumor "signatures." A second series of studies uses single line traces through digitized acoustic micrograms to predict theoretically A-mode results that would be obtained for specific trancducers. The computer A-mode results resemble those observed clinically. These studies are providing unique insights into the origins of echoes seen in high-resolution examination5 of the retina, choroid, sclera. The and acoustically-heterogeneous internal structure of the sclera is special interest of because it can give rise to echoes that may complicate the interpretation of clinical data. This research was supported in part by NIH grants EY01212, EY-03173 and RR-05853. APPARATUS FOR MEASURING ULTRASOUND ATTENUATION AND SPEED IN BIOPSY SPECIMENS, P.D. Edmonds, M. Arditi, J.F. Jensen, W.C. Ross, W.J. Vinzant, and C.L. Mortensen, Bioengineeri ng Research Laboratory, SRI International, Menlo Park, CA 94025. Many ultrasonic attenuation measurements in tissues have made with been piezoelectric receiving transducers that are subject to phase cancellation over their aperture and consequent generat ion of erroneously-high results. Busse and Miller Cl3 have described a phase-insensitive acoustoelectric transducer (AET). With the advice and assistance of Miller's we have incorporated an AET receiver in new apparatus grow, to measure attenuation and sound speed in freshly-excised breast biopsy specimens. The apparatus is controlled by an HP-86 computer. Stepper motors are used to move the specimen holder in a programmed scanning pattern with 3 x 3 mm "pixel" size. Locations in the specimen are successively interrogated two focused transducers, one of which by transmits 4-us tonebursts amplitude modulated by a Blackman window function,
55
SESSION
5:
ACOUSTSC
PARAMETERS,
PHANTOMS,
AND CALIBRATION
APPLICATIONS OF ACOUSTIC MICROSCOPY TO TISSUE ANALYSIS, R. Silverman*, F. Lizzi", J. Hui', M. Rondeaul, D.J. Coleman*, E. Feleppa", LCornell University Medical Co1 lege, New and York, NY 10021 and "Riverside Research Institute, New York, NY 10036. A scanning-laser acoustic microscope (SLAM) has been used analyze the acoustic properties of various types of treated to untreated tumors and ocular structures. Most observations and have been conducted using 100 MHz ultrasound (15 micrometer have been and wavelength). Acoustic micrograms digitized to study several fundamental computer analysis has been used regarding the origin of ultrasonic echoes. The questions studies with digitized rf signals often involve d comparison obtained during in pulse-echo scanning prior to the __-__ !&X2 microscope examinations. In one series of studies, microscope images have been to provide maps that estimate acoustic impedance within used (1) melanomas derived from human tumors and implanted in mice; and (2) melanoma5 excised from human eyes. These images are analyzed in terms of Z-D spectra and 2-D autocorrelation functions which, in turn, are used to predict the power 5pectr-a measured with a clinical digital analysis system. These computations are then compared with actual presurgical spectra. Spectra computed for different subregions in these tumors are helping to improve our understanding of those tissue elements that are responsible for specific ocular tumor "signatures." A second series of studies uses single line traces through digitized acoustic micrograms to predict theoretically A-mode results that would be obtained for specific trancducers. The computer A-mode results resemble those observed clinically. These studies are providing unique insights into the origins of echoes seen in high-resolution examination5 of the retina, choroid, sclera. The and acoustically-heterogeneous internal structure of the sclera is special interest of because it can give rise to echoes that may complicate the interpretation of clinical data. This research was supported in part by NIH grants EY01212, EY-03173 and RR-05853. APPARATUS FOR MEASURING ULTRASOUND ATTENUATION AND SPEED IN BIOPSY SPECIMENS, P.D. Edmonds, M. Arditi, J.F. Jensen, W.C. Ross, W.J. Vinzant, and C.L. Mortensen, Bioengineeri ng Research Laboratory, SRI International, Menlo Park, CA 94025. Many ultrasonic attenuation measurements in tissues have made with been piezoelectric receiving transducers that are subject to phase cancellation over their aperture and consequent generat ion of erroneously-high results. Busse and Miller Cl3 have described a phase-insensitive acoustoelectric transducer (AET). With the advice and assistance of Miller's we have incorporated an AET receiver in new apparatus grow, to measure attenuation and sound speed in freshly-excised breast biopsy specimens. The apparatus is controlled by an HP-86 computer. Stepper motors are used to move the specimen holder in a programmed scanning pattern with 3 x 3 mm "pixel" size. Locations in the specimen are successively interrogated two focused transducers, one of which by transmits 4-us tonebursts amplitude modulated by a Blackman window function,
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