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Indium-111-Photofrin-II scintillation scan
T C Origitano1, S M Karesh, O H Reichman
1Department of Surgery, Loyola University Medical Center, Maywood, Illinois.
Neurosurgery
|April 1, 1989
Summary
Photodynamic therapy uses Photofrin-II (HpD-II) for brain tumors. A new scan using 111indium-labeled HpD-II shows optimal tumor treatment timing occurs 72 hours post-injection.
Area of Science:
- Oncology
- Medical Imaging
- Radiochemistry
Background:
- Photodynamic therapy (PDT) is a promising adjuvant treatment for malignant glial tumors.
- Photofrin-II (HpD-II) is a key photosensitizing agent in PDT.
- Determining optimal timing for HpD-II photoactivation is crucial for maximizing tumor destruction while minimizing normal brain damage.
Purpose of the Study:
- To develop and validate a noninvasive radionuclide imaging method to assess HpD-II pharmacokinetics in brain tumors.
- To determine the optimal time for photoactivation of HpD-II in an experimental gliosarcoma model.
Main Methods:
- Synthesis of 111indium (111In)-labeled HpD-II with high yield and purity.
- Serial scintillation scanning in a canine gliosarcoma model to track 111In-HpD-II biodistribution.
- Verification of tumor localization using contrast-enhanced CT and histological examination.
Main Results:
- Successful synthesis of 111In-HpD-II with >90% yield and verified radiochemical purity.
- Demonstrated noninvasive tracking of 111In-HpD-II uptake and clearance in canine brain tumors.
- The optimal ratio of tumor-to-normal brain uptake of 111In-HpD-II was observed at 72 hours post-injection.
Conclusions:
- 111In-labeled HpD-II enables noninvasive evaluation of photosensitizer kinetics in brain tumors.
- The 72-hour time point represents the optimal window for photoactivation in this gliosarcoma model.
- This imaging approach can guide personalized PDT treatment timing for improved efficacy and safety.