Intraoperative Use of I.V. Sodium Fluorescein in Suspected CNS Tumors

This clinical study investigates the intraoperative use of intravenous sodium fluorescein as a fluorescent tracer to assist in the surgical resection of aggressive tumors of the central nervous system (CNS). These tumors typically present as contrast-enhancing masses on pre-operative MRI or CT scans. The study is conducted at the IRCCS Foundation Neurological Institute "Carlo Besta" in Milan and follows a prospective observational design.

Malignant CNS tumors are often difficult to completely remove due to the challenge of distinguishing tumor margins from healthy brain tissue. This limitation affects prognosis, especially in high-grade gliomas. Sodium fluorescein, a dye historically used in ophthalmology, accumulates in areas where the blood-brain barrier is disrupted-such as in aggressive brain tumors-making it a potentially ideal agent for enhancing intraoperative visualization. When used with a surgical microscope equipped with a dedicated fluorescence filter, fluorescein allows surgeons to better identify tumor tissue during resection.

The study includes approximately 800 patients of any age and gender, all presenting with suspected aggressive CNS lesions based on contrast-enhanced imaging. Each patient receives 5 mg/kg of sodium fluorescein intravenously at the induction of anesthesia. Surgery is performed using fluorescence-guided techniques, and patients undergo pre- and post-operative imaging to assess the extent of resection. Clinical and neurological evaluations are conducted before and after surgery, with follow-up extending to the third post-operative day.

The primary objective is to qualitatively assess the intraoperative fluorescence characteristics of CNS tumors. Secondary objectives include evaluating the extent of tumor resection based on early post-operative imaging, monitoring neurological outcomes, and documenting any adverse reactions to fluorescein. Safety parameters such as blood pressure, heart rate, oxygen saturation, temperature, and renal function are monitored according to guidelines from the Italian Medicines Agency (AIFA).

Ethical approval is obtained from the appropriate Ethics Committee, and all patients provide informed consent prior to participation. The study complies with Good Clinical Practice (GCP) and the Declaration of Helsinki. Data are anonymized and stored securely, and results may be published following review and approval by the involved parties.

Inclusion criteria

• Patients of both genders, at any age.
• Patients with suspected aggressive lesion of the CNS, as suggested by pre-operative MRI or CT with i.v. contrast agent administration.

Exclusion criteria

• Impossibility to give consent due to cognitive deficits or language disorder.
• Known allergy to contrast agents and/or history of previous anaphylactic shocks.
• Known severe previous adverse reactions to Fluorescein
• Acute myocardial infarction or stroke in the last 90 days.
• Severe renal failure;
• Severe hepatic failure;
• Women in their first trimester of pregnancy or lactation.