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Published on: September 19, 2014
Evaluating the utility of ICG-based NIR imaging for small intestine neuroendocrine tumors: Challenges and the need
Sebastiaan W R Dalmeijer1, Bo E Zweedijk2, Danielle F Boldewijn2
1Department of Surgical Oncology and Gastrointestinal Surgery, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Doctor Molewaterplein 40, Rotterdam, 3015 GD, the Netherlands; Department of Otorhinolaryngology and Head and Neck Surgery, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Doctor Molewaterplein 40, Rotterdam, 3015 GD, the Netherlands; Department of Surgery, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333 ZA, the Netherlands.
Purpose:
Accurate intraoperative localization of small intestinal neuroendocrine tumors (SI-NETs) remains a surgical challenge, with standard staging protocols frequently missing small primary or metastatic lesions. ICG has shown utility in other highly vascularized tumors, including pituitary and pancreatic neuroendocrine tumors and non-small cell lung cancer. We conducted a prospective feasibility study to evaluate the potential of near-infrared (NIR) fluorescence imaging (FI) using indocyanine green (ICG) to enhance intraoperative detection of SI-NETs.
Methods:
The initial aim was to include at least 26 patients; however, after analysis of the first two patients, we decided to terminate the study prematurely. Therefore, we present data from two patients who underwent abdominal surgery. Each patient received 2.5 mg/kg of ICG intravenously 18 h before surgery, utilizing the second-window ICG (SWIG) technique. Intraoperative imaging was performed using the Quest Spectrum V2 camera system. The primary endpoint was fluorescence positivity of primary tumors, defined as a tumor-to-background ratio (TBR) ≥ 1.5.
Results:
All primary tumors (n = 2) were identified via palpation and inspection, but none were fluorescence positive (median TBR 0.67, range 0.47-0.87). No occult primary or metastatic lesions were detected by fluorescence imaging. Metastatic lymph nodes and peritoneal nodules (n = 3, confirmed malignant) were also fluorescence negative. Strong non-specific background signal was observed in bowel and liver tissue, reflecting non-tumor-specific ICG uptake. Based on low tumor contrast and expert consensus, the study was terminated early without dose escalation.
Conclusion:
These findings demonstrate that ICG-based NIR FI did not enhance intraoperative detection of SI-NETs or metastases in this feasibility cohort and is limited by non-specific background fluorescence. Our data suggest that passive EPR-based accumulation may not be sufficient for reliable visualization of SI-NETs. Our results underscore the need for tumor-specific tracers targeting neuroendocrine markers to improve surgical precision in SI-NETs.
