This is an open-label pilot study including 10 GIST patients scheduled for an elective open or laparoscopic resection at Leiden University Medical Center (LUMC) and Erasmus Medical Center (EMC), Rotterdam. Patients will receive a single dose injection of 10mg ICG at a given moment during the 24 hours prior to surgery or during surgery. The timing of administration will be determined according to a step-up, step-down procedure. Standard of care surgery will be performed and a NIR fluorescence imaging system will be used to record the GIST under fluorescence.

Inclusion Criteria:

• Patients diagnosed with GIST by histology or cytology, localized or metastasized, scheduled to undergo an elective open or laparoscopic resection.
• 18 years

Exclusion Criteria:

• History of an allergy or hypersensitivity to sodium iodide, iodine or ICG
• Patients with hyperthyroidism and patients with an autonomous thyroid adenoma
• Patients pregnant or breastfeeding
• Patients with severe renal insufficiency (eGFR <30)

On request anonymized data can be shared with other researchers