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Proceedings Paper

Photodynamic-therapy-induced alterations of the blood-brain barrier transfer constant of a tracer molecule in normal brain
Author(s): Ivan Yeung; Lothar D. Lilge; Brian C. Wilson; Ting-Yim Lee; Laura Stevens; Aleksa Cenic
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Paper Abstract

Photofrin uptake studies in brain tissues using bulk sampling techniques have demonstrated up to a 10-fold higher concentration in intracranial tumors compared to normal brain structures. This selective uptake is in part attributed to the leaky blood-brain barrier (BBB) in brain tumors while intact BBB in normal brain excludes Photofrin from the extravascular space. However, in vivo preclinical studies have shown a very high sensitivity in normal brain to photodynamic therapy (PDT) despite this selective uptake. In vivo computed tomography (CT) measurement of the blood- brain transfer constant (K) and cerebral plasma volume using an x-ray dye as a tracer was used to monitor the degradation process of the BBB in normal brain during and post PDT. In these experiments, it was observed that K increased as early as 15 minutes after the onset of PDT, peaking at approximately 3 hr post PDT treatment followed by a drop close to baseline values for 3 out of 4 animals. On the other hand, the cerebral plasma volume showed a decrease also as early as 15 min post PDT onset, but its decrease continued up to 6 hrs with no apparent vascular stasis at the end of the time period. The results suggested a continuous process of BBB breakdown and vascular shutdown shortly after start of PDT.

Paper Details

Date Published: 8 May 1997
PDF: 10 pages
Proc. SPIE 2972, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VI, (8 May 1997); doi: 10.1117/12.273487
Show Author Affiliations
Ivan Yeung, Princess Margaret Hospital/Univ. of Toronto (Canada)
Lothar D. Lilge, Ontario Laser and Lightwave Research Ctr. (Canada) and Univ. of Toronto (Canada)
Brian C. Wilson, Ontario Cancer Institute/Univ. of Toronto (Canada), Ontario Laser and Lightwave Research C (Canada)
Ting-Yim Lee, John P. Robarts Research Institute (Canada)
Laura Stevens, John P. Robarts Research Institute (Canada)
Aleksa Cenic, John P. Robarts Research Institute (Canada)


Published in SPIE Proceedings Vol. 2972:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VI
Thomas J. Dougherty, Editor(s)

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