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Proceedings Paper

Thermoacoustic imaging of prostate cancer: comparison to histology
Author(s): S. K. Patch; S. K. Griep; K. Jacobsohn; W. A. See; D. Hull
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Paper Abstract

Ex vivo imaging of fresh prostate specimens was performed to test the hypothesis that the thermoacoustic (TA) contrast mechanism generated with very high frequency electromagnetic (EM) irradiation is sensitive to prostate cancer. Ex vivo imaging was performed immediately after radical prostatectomy, performed as part of normal care. Irradiation pulsewidth was 700 ns and duty cycle was extremely low. Typical specific absorption rate (SAR) throughout the prostate was 70-90 kW/kg during pulsing, but time-averaged SAR was below 2 W/kg. TA pressure pulses generated by rapid heating due to EM energy deposition were detected using single element transducers. 15g/L glycine powder mixed into DI water served as acoustic couplant, which was chilled to prevent autolysis. Spatial encoding was performed by scanning in tomographic “step-and-shoot” mode, with 3 mm translation between slices and 1.8-degree rotation between tomographic views. Histology slides for 3 cases scanned with 2.25 MHz transducers were marked for comparison to TA reconstructions. These three cases showed little, moderate, and severe involvement in the histology levels surrounding the verumontanum. TA signal strength decreased with percent cancerous involvement. When VHF is used for tissue heating, the TA contrast mechanism is driven by ionic content and we observed suppressed TA signal from diseased prostate tissue in the peripheral zone. For the 45 regions of interest analyzed, a reconstruction value of 0.4 mV provides 100% sensitivity but only 29% specificity.

Paper Details

Date Published: 3 March 2014
PDF: 7 pages
Proc. SPIE 8943, Photons Plus Ultrasound: Imaging and Sensing 2014, 894305 (3 March 2014); doi: 10.1117/12.2036091
Show Author Affiliations
S. K. Patch, Univ. of Wisconsin-Milwaukee (United States)
S. K. Griep, The Univ. of Southern California (United States)
K. Jacobsohn, Medical College of Wisconsin (United States)
W. A. See, Medical College of Wisconsin (United States)
D. Hull, Bostwick Labs. (United States)

Published in SPIE Proceedings Vol. 8943:
Photons Plus Ultrasound: Imaging and Sensing 2014
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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