As demonstrated by histological and neuroimaging studies, pituitary neuroendocrine tumors have a capillary vascular density that differs significantly from that of surrounding structures.

Data show that intraoperative indocyanine green videoangiography (ICG VA) can be a useful and easily applicable additional diagnostic tool for visualization of pituitary lesions using the microscopic approach ¹⁾.

The ICG endoscope is also very useful during endoscopic endonasal transsphenoidal surgery (ETSS). Hide et al. suggest that the real-time observation of the blood supply to the optic nerves and pituitary helps to predict the preservation of their function ²⁾.

22 patients with pituitary neuroendocrine tumors were treated with transsphenoidal microsurgery. Intraoperatively 25 mg ICG was administered intravenously and visualized via the fluorescence mode of the operation microscope (Pentero/Zeiss).

22 patients qualified for transsphenoidal approach presenting with different clinical symptoms (13 patients with acromegaly, 6 with Cushing's syndrome and 3 with other symptoms like vision disorder or dizziness) and identification of a pituitary lesion (21 of 22 patients) in preoperative MR-imaging (mean diameter: 9 mm; SD 3.6; 6 macroadenomas, 15 microadenomas, 1 MR-negative). In all 22 patients ICG VA was performed during surgery. No technical failures or adverse events after drug administration occurred. Visualization was optimal approximately 2.4 min after intravenous application. In all patients the adenoma could be detected via two different types of visualization: direct visualization by fluorophore emission versus indirect detection of the adenoma by a lower ICG fluorescence compared to the surrounding tissue.

The data show that intraoperative ICG VA can be a useful and easily applicable additional diagnostic tool for visualization of pituitary lesions using the microscopic approach ³⁾.

Hide et al. included 38 patients with pituitary neuroendocrine tumors (n = 26), tuberculum sellae meningiomas (n = 4), craniopharyngiomas (n = 3), chordomas (n = 2), Rathke's cleft cyst (n = 1), dermoid cyst (n = 1), or fibrous dysplasia (n = 1). After opening the sphenoid sinus and placing the ICG endoscope, the authors injected 12.5 mg of ICG into a peripheral vein as a bolus and observed the internal carotid arteries (ICAs), cavernous sinus, intercavernous sinus, and pituitary.

The ICA was clearly identified by a strong fluorescence signal through the dura mater and the covering thin bone. The intercavernous and cavernous sinuses were visualized a few seconds later. In patients with tuberculum sellae meningiomas, the abnormal tumor arteries in the dura were seen and the vague outline of the attachment was identified. At the final inspection after tumor removal, perforators to the brain, optic nerves, chiasm, and pituitary stalk were visualized. ICG fluorescence signals from the hypophyseal arteries were strong enough to see and spread to the area of perfusion with the passage of time.

The ICA and the patent cavernous sinus were detected with the ICG endoscope in real-time and at high resolution. The ICG endoscope is very useful during endoscopic endonasal transsphenoidal surgery (ETSS). Hide et al. suggest that the real-time observation of the blood supply to the optic nerves and pituitary helps to predict the preservation of their function ⁴⁾.

16 patients undergoing endoscopic transsphenoidal surgery for benign pituitary lesions were prospectively enrolled in the study. A standard endoscopic endonasal approach to the sella was completed. Each patient then underwent endoscopic examination of the sellar dura and then the exposed pituitary neuroendocrine tumor after ICG bolus injection (12.5-25 mg). This examination was performed using a custom endoscope with a near-infrared light source and excitation wavelength filter.

The authors successfully recorded ICG fluorescence from sellar dura, pituitary, and surrounding structures in 12 of 16 patients enrolled. There were 3 technical failures of intraoperative ICG endoscopy, and 1 patient was excluded following discovery of a dye cross-allergy. A standard dose of 25 mg of ICG in 10 ml of aqueous solution optimized visualization of sellar region microvasculature within 45 seconds of peripheral bolus injection. Adenoma was less fluorescent than normal pituitary gland. Dural invasion by tumor was identifiable by a marked increase in fluorescence compared with native dura. The ICG endoscopic examination added 15-20 minutes of operative time under general anesthesia. There were no complications that resulted from use of ICG or the fluorescent light source.

Indocyanine green fluorescence endoscopy shows promise as an intraoperative modality to visually distinguish pituitary tumors from normal tissue and to visually identify areas of dural invasion, thereby facilitating complete tumor resection and minimizing injury to surrounding structures. These results support the continued development of fluorescence endoscopic resection techniques ⁵⁾.