Feasibility of sentinel node biopsy in head and neck melanoma using a hybrid radioactive and fluorescent tracer

Abstract

Purpose: This study was designed to examine the feasibility of combining lymphoscintigraphy and intraoperative sentinel node identification in patients with head and neck melanoma by using a hybrid protein colloid that is both radioactive and fluorescent.

Methods: Eleven patients scheduled for sentinel node biopsy in the head and neck region were studied. Approximately 5 h before surgery, the hybrid nanocolloid labeled with indocyanine green (ICG) and technetium-99m ((99m)Tc) was injected intradermally in four deposits around the scar of the primary melanoma excision. Subsequent lymphoscintigraphy and single photon emission computed tomography with computed tomography (SPECT/CT) were performed to identify the sentinel nodes preoperatively. In the operating room, patent blue dye was injected in 7 of the 11 patients. Intraoperatively, sentinel nodes were acoustically localized with a gamma ray detection probe and visualized by using patent blue dye and/or fluorescence-based tracing with a dedicated near-infrared light camera. A portable gamma camera was used before and after sentinel node excision to confirm excision of all sentinel nodes.

Results: A total of 27 sentinel nodes were preoperatively identified on the lymphoscintigraphy and SPECT/CT images. All sentinel nodes could be localized intraoperatively. In the seven patients in whom blue dye was used, 43% of the sentinel nodes stained blue, whereas all were fluorescent. The portable gamma camera identified additional sentinel nodes in two patients. Ex vivo, all radioactive lymph nodes were fluorescent and vice versa, indicating the stability of the hybrid tracer.

Conclusions: ICG-(99m)Tc-nanocolloid allows for preoperative sentinel node visualization and concomitant intraoperative radio- and fluorescence guidance to the same sentinel nodes in head and neck melanoma patients.

Fig. 1

Schematic overview of the study set-up. a After injection of ICG–^99mTc-nanocolloid, preoperative imaging of the sentinel nodes is performed. Intraoperatively, sentinel node localization is guided by the gamma ray detection probe, the portable gamma camera and the near-infrared (NIR) fluorescence camera. Postexcision gamma camera imaging confirms complete excision of all sentinel nodes. b In the patients with melanoma outside the facial region, patent blue was intraoperatively injected for optical detection of blue-stained sentinel nodes and a comparison with fluorescence imaging was made

Fig. 2

Combined preoperative lymphatic mapping and intraoperative radio- and fluorescence-guided sentinel node biopsy (patient 3, Table 1). a Early static anterior preoperative lymphoscintigram at 10 min after infraorbital peritumoral injection of ICG–^99mTc-nanocolloid showing the injection site (T) with lymphatic drainage to two sentinel nodes in the neck on the right (R) side and a third one on the left (L) side (arrows). b 3D SPECT/CT image 2 h postinjection providing additional anatomical information with visualization of a lymphatic duct (arrow) originating from the injection site (T). c, d Intraoperatively, the radioactive component of the hybrid tracer in the left sentinel node is visualized using a portable gamma camera, and its laser pointer guides placement of the incision. e, f A near-infrared fluorescence camera is used to visualize the fluorescent component of the hybrid tracer in the same (non-blue) sentinel node