Combined radio- and fluorescence guided sentinel node biopsy in a large cohort of melanoma patients

Objectives Indocyanine green (ICG)-99mTc-nanocolloid is a novel hybrid tracer for sentinel node (SN) biopsy allowing for combined preoperative SN mapping and intraoperative SN tracing of the radioactive component with a gamma ray detection probe, while ICG enables intraoperative optical detection of lymph vessels and SNs using near-infrared fluorescence imaging. In the present study the SN identification rate of this hybrid racer was evaluated in a large population of melanoma patients with different regions of lymphatic drainage.

Methods 102 Patients with melanoma of the head and neck (n=49), trunk (n=35) or extremities (n=18) were included and intradermally injected with ICG-99mTc-nanocolloid followed by lymphoscintigraphy and subsequent SPECT/CT imaging. Patent blue dye was used in all patients except those with a melanoma in the face. Intraoperatively, SNs were pursued using the blue dye and the probe, followed by optical verification with a fluorescence camera. A mobile gamma camera was used to confirm complete removal of all SNs.

Results At least one SN was preoperatively identified in 101 out of the 102 patients (total: 222 SNs). Intraoperatively, in 11 patients a SN was finally localized using fluorescence imaging, mainly because it was located close to the injection site (9 cases). The other SNs were harvested using a combination of blue dye detection, gamma tracing and fluorescence imaging. In the 74 patients in whom blue dye was used, only 57% of SNs had stained blue (p<0.0001). 25 Patients had a tumor-positive SN (25%).

Conclusions ICG-99mTc-nanocolloid enabled combined preoperative imaging and intraoperative radio- and fluorescence-guided SN biopsy in all 102 patients. It was found to be particularly useful for the detection of SNs in the neck near the injection site, and for SNs that failed to accumulate blue dye.

Research Support A KWF translational research award (Grant No. PGF 2009-4344) and a VIDI grant (Grant No. STW11272).