Intraoperative ICG Dye Monitoring for Identification of Pituitary Adenoma in Endoscopic Transsphenoidal Surgery: A Prospective Observational Study

Introduction: Histological and imaging studies have shown that pituitary adenomas possess a distinct capillary vascular density compared to adjacent anatomical structures. This has led to the hypothesis that intraoperative indocyanine green (ICG) fluorescence endoscopy may help visually differentiate tumors from surrounding normal tissues such as the pituitary gland and dura. Achieving accurate and complete tumor resection while preserving surrounding structures requires real-time intraoperative information on tumor location and margins. Aim of the Study: This study aimed to assess the utility of a novel intraoperative imaging technique—ICG fluorescence endoscopy—during transsphenoidal surgery (TSS) for pituitary tumors, with a focus on real-time visualization and differentiation of tumor tissue. Methodology: A conventional endoscopic endonasal approach was employed to access the sellar region. Following exposure of the sellar dura and tumor, a bolus of ICG (12.5–25 mg) was administered intravenously. Under near-infrared light, differences in fluorescence intensity between tumor tissue and adjacent normal structures were observed. These variations in intensity, temporal changes in fluorescence, and tissue-specific patterns allowed differentiation of tumor margins and identification of surrounding structures. Areas of dural invasion by tumor exhibited enhanced fluorescence compared to native dura. The fluorescence examination added approximately 15–20 minutes to the overall operative time under general anesthesia. No complications were noted due to ICG or the fluorescence imaging process. Patients were monitored postoperatively for up to three months, including follow-up MRI to assess for residual tumor or recurrence. Results: The use of ICG fluorescence provided valuable assistance in identifying tumor tissue, particularly in cases involving microadenomas. Among currently available fluorophores, ICG appears to be the most effective based on existing literature. However, the technique has certain limitations, such as blood pooling in the operative field and challenges in clearly distinguishing tumor from normal pituitary tissue. Further investigation is needed to better understand the fluorescence characteristics of various adenoma types and to refine the technique. Conclusion: ICG fluorescence endoscopy demonstrates potential as a real-time intraoperative tool for distinguishing pituitary tumors from surrounding tissues and for detecting dural invasion. This method may contribute to more complete tumor resections while reducing the risk of damage to adjacent normal structures.