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Proceedings Paper

Monitoring tissue response to photodynamic therapy: the potential of minimally invasive electrical impedance spectroscopy and high-frequency ultrasound
Author(s): Brian C. Wilson; Andrea Molckovsky; G. J. Czarnota; Michael D. Sherar; Mike C. Kolios; Lothar D. Lilge; R. S. Dattani; Kendra Sunshine Osterman; Keith D. Paulsen; P. Jack Hoopes
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Paper Abstract

Electrical impedance spectroscopy (EIS) and high-frequency ultrasound (HFU) have been evaluated in various in vivo and in vitro models as potential methods to monitor biological changes induced by photodynamic therapy (PDT). EIS was assessed in tumor-bearing rat leg in vivo, in multicell tumor spheroids in vitro, and in normal rat liver tissue in vivo. HFU measurements, both imaging and backscatter frequency scanning, were tested in normal rat brain and skin treated in vivo. Marked changes in the EIS spectra were seen in all 3 models following PDT, depending on the photosensitizer and treatment parameters. With HFU, significant increases in echogenicity of the PDT-treated tissues were observed, with evidence of dose dependency and correlation with apoptotic cell death in vivo. While the results are encouraging for both modalities, a number of technical problems remain, particularly in the case of EIS, before these methods can be used reliably in mechanistic and clinical PDT applications.

Paper Details

Date Published: 6 July 1999
PDF: 10 pages
Proc. SPIE 3592, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VIII, (6 July 1999); doi: 10.1117/12.351508
Show Author Affiliations
Brian C. Wilson, Ontario Cancer Institute/Univ. of Toronto (Canada)
Andrea Molckovsky, Ontario Cancer Institute/Univ. of Toronto (Canada)
G. J. Czarnota, Ontario Cancer Institute/Univ. of Toronto (Canada)
Michael D. Sherar, Ontario Cancer Institute/Univ. of Toronto (Canada)
Mike C. Kolios, Ontario Cancer Institute/Univ. of Toronto (Canada)
Lothar D. Lilge, Ontario Cancer Institute/Univ. of Toronto (Canada)
R. S. Dattani, Ontario Cancer Institute/Univ. of Toronto (Canada)
Kendra Sunshine Osterman, Dartmouth College (United States)
Keith D. Paulsen, Dartmouth College (United States)
P. Jack Hoopes, Dartmouth College (United States)


Published in SPIE Proceedings Vol. 3592:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VIII
Thomas J. Dougherty, Editor(s)

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