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8 May 1997 Photodynamic-therapy-induced alterations of the blood-brain barrier transfer constant of a tracer molecule in normal brain
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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.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ivan Yeung, Lothar D. Lilge, Brian C. Wilson, Ting-Yim Lee, Laura Stevens, and Aleksa Cenic "Photodynamic-therapy-induced alterations of the blood-brain barrier transfer constant of a tracer molecule in normal brain", Proc. SPIE 2972, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy VI, (8 May 1997);

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