Noncontact Ultrasound Applied to Osteroporosis Diagnostics Updated to Include Broadband Ultrasonic Attenuation and Offline Data Analysis
K Ganezer1*, I Neeson2, P Halcrow3, J Bulman4, (1) California State University, Carson, CA, (2) VN Instruments Ltd.,, Elizabethtown, Ontario K6T 1A9, (3) California State University Dominguez Hills, Los Angeles, California, (4) Loyola Marymount University, Los Angeles, CaliforniaWE-E-134-5 Wednesday 2:00PM - 3:50PM Room: 134
The purpose was to push forward our efforts on applying noncontact ultrasound to quantitative imaging of cortical bone as described in our recent paper on speed of sound and attenuation, and integrated response to ultrasound spectroscopy including Broadband ultrasound attenuation (BUA) and to replace our noisy piezoelectric transducers with much quieter velocity correcting capacitive transducers at frequencies of 500 kHz and 850kHz.
An NCU imaging system, a pair of broadband capacitive .500 and .850 MHz, non-contact transducers, and cortical bone phantoms were used to determine bone mineral density (BMD), speed of sound (SOS), integrated acoustical response (IR), and ultrasonic transmittance. Air gaps of greater than 3 cm, two transmission and reflection paths, and a digital signal processor were used to collect data from phantoms of nominal mass density and (BMD) from 1.17 g/cm3 to 2.25 g/cm3 and from 0 g/cm3 to 1.7 g/cm3. Spectra were analyzed offline using Matlab, including its signal processing and Simulink tool boxes as well as customized Matlab based files, therefore providing much more detailed methods then online approaches, as used in our initial paper.
Good correlations between known BMD and measured SOS, IR, and transmittance were obtained for all 14 phantoms obtained in the original studies were complimented with spectroscopic and BUA measurements obtained with capacitive transducers that had much better stability then the original measurements and provided strong correlations with the known BMD of phantoms.
The results suggest that the usage of capacitive transducers, offline analysis with Matlab including customized simulations and data analysis algorithms yields much better results than those in our original paper. The new results give us all the more impetus to extend the NCU methods to bone phantoms that more closely mimic human cortical bone and to subsequently apply our methods in vivo.
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