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Enhanced optical imaging of rat gliomas and tumor margins
M M Haglund1, D W Hochman, A M Spence
1Department of Neurological Surgery, University of Washington School of Medicine, Seattle.
Abstract:
Current intraoperative methods used to maximize the extent of tumor removal are limited to intraoperative biopsies, ultrasound, and stereotactic volumetric resections. A new technique involving the optical imaging of an intravenously injected dye has the potential to localize tumors and their margins with a high degree of accuracy. In a rat glioma model, enhanced optical imaging was performed and indocyanine green was used as the contrast-enhancing agent. In all 22 animals, the peak optical change in the tumor was greater than in the ipsilateral brain around the tumor and the contralateral normal hemisphere. The clearance of the dye was significantly delayed to a greater extent in the tumor than in the brain around the tumor and the normal brain. After attempts were made at complete microscopic resection, enhanced optical imaging of the tumor margins and the histological samples demonstrated a specificity of 93% and a sensitivity of 89.5%. Enhanced optical imaging was capable of outlining the tumor even when the imaging was done through the cranium. The optical imaging of rat gliomas with a contrast-enhancing dye is able to differentiate between normal brain and tumor tissue both at the cortical surface and at the tumor margins. The application of these studies in an intraoperative clinical setting may allow for the more accurate determination of tumor margins and may increase the extent of tumor removal.
Insights
Enhanced optical imaging using indocyanine green effectively distinguishes glioma tumors from healthy brain tissue in rats. This technique accurately identifies tumor margins, potentially improving surgical tumor removal during operations.
Area of Science:
- Neuro-oncology
- Medical Imaging
- Surgical Oncology
Background:
- Current methods for determining tumor extent during surgery are limited.
- Accurate intraoperative margin detection is crucial for maximizing tumor removal and improving patient outcomes.
Purpose of the Study:
- To evaluate the efficacy of enhanced optical imaging with indocyanine green for intraoperative glioma margin localization in a rat model.
- To assess the accuracy of this technique in differentiating tumor tissue from normal brain tissue.
Main Methods:
- Enhanced optical imaging was performed on a rat glioma model following intravenous injection of indocyanine green.
- Optical changes and dye clearance in tumor tissue were compared to surrounding and contralateral brain tissue.
- Imaging accuracy was assessed against histological samples after attempted tumor resection.
Main Results:
- Indocyanine green showed significantly greater optical change and delayed clearance in tumors compared to normal brain tissue.
- Enhanced optical imaging accurately delineated tumor margins, achieving 93% specificity and 89.5% sensitivity.
- The technique successfully outlined tumors even through the cranial bone.
Conclusions:
- Enhanced optical imaging with indocyanine green can reliably differentiate rat gliomas from normal brain tissue.
- This imaging modality shows promise for improving intraoperative tumor margin definition and increasing the extent of tumor resection in clinical settings.