A feasibility study of indocyanine green fluorescence mapping for sentinel lymph node detection in cutaneous melanoma

The Use of Indocyanine Green and Near-Infrared Fluorescence Imaging Versus Blue Dye in Sentinel Lymph Node Biopsy in Cutaneous Melanoma: A Retrospective, Cohort Study

BACKGROUND

The use of indocyanine green (ICG) and near-infrared fluorescence imaging is a promising option for sentinel lymph node (SLN) mapping in cutaneous melanoma. The study objective was to compare the performance of ICG and blue dye at detecting SLNs with radioisotope nanocolloid (technetium-99).

METHODS

Between April 2018 and June 2022, 293 consecutive patients with cutaneous melanoma (Breslow thickness ≥ 0.8 mm) underwent wide local excision and SLN biopsy. Patients were divided into group A (ICG; n = 122) and group B (blue dye; n = 163). All patients underwent SPECT/CT imaging preoperatively. SLN detection parameters and complications were compared between the groups.

RESULTS

A total of 285 patients had complete data and were included in the analysis. The median age was 62.0 (range 10-91) years, and 139 (48.8%) were female patients. The mean Breslow thickness was 2.6 mm, 89 (31.2%) patients had ulceration, and 179 (62.8%) patients had mitosis ≥ 1 mm2. The mean number of SLNs detected per patient in group A was 1.58 and group B was 1.48. In groups A and B, the SLN detection rate was 96.7% versus 89.6% (p = 0.022) and the pathological SLN detection rate was 92.3% versus 97.1% (p = 0.481), respectively.

CONCLUSIONS

ICG had a higher SLN detection rate and equal pathological SLN detection rate to blue dye. ICG may not be inferior to blue dye and is a useful adjunct to radioisotope in SLN biopsy in cutaneous melanoma.

Transcutaneous sentinel lymph node detection in cutaneous melanoma with indocyanine green and near-infrared fluorescence: A diagnostic sensitivity study

Sentinel lymph node (SLN) biopsy with preoperative radiocolloid-based lymphoscintigraphy and blue dye injection is considered the standard procedure for staging nodal metastases in early-stage cutaneous melanoma patients with clinically uninvolved lymph nodes. While this combination renders good accuracy in SLN detection, radiation exposure and the frequent allergic reactions to the blue dye are considered drawbacks of this technique. Indocyanine green (ICG) is a water-soluble fluorescent dye that can be identified through near-infrared fluorescence imaging (NIRFI). The aim of this prospective diagnostic sensitivity study was to assess the feasibility of ICG and NIRFI to identify SLNs in melanoma transcutaneously ("before skin incision") and to analyze the various factors influencing detection rate, in comparison to lymphoscintigraphy. This study included 93 patients undergoing SLN biopsy for cutaneous melanoma. The region and the number of the SLNs identified with lymphoscintigraphy and with ICG were recorded. Patients' characteristics, as well as tumor details were also recorded preoperatively. One hundred and ninety-four SLNs were identified through lymphoscintigraphy. The sensitivity of ICG for transcutaneous identification of the location of the SLNs was 96.1% overall, while the sensitivity rate for the number of SLNs was 79.4%. Gender and age did not seem to influence detection rate, but a body mass index >30 kg/m2 was associated with a lower identification rate of the number of SLNs (P = .045). Transcutaneous identification of SLNs through ICG and NIRFI technology is a feasible technique that could potentially replace in selected patients the standard SLN detection methodology in cutaneous melanoma.

Analysis of the Different Lymphatic Drainage Patterns during Sentinel Lymph Node Biopsy for Skin Melanoma

In the last two decades, studies of lymphoscintigraphy imaging in lymphatic mapping reported an extreme heterogeneity of skin lymphatic drainage of some skin area, in contrast with the previous scientific literature. The aim of this study was to investigate the presence of any correlations between the topographical location of cutaneous melanoma and the topographical location of sentinel lymph nodes. Data from 165 patients undergoing sentinel lymph node biopsy between January 2013 and May 2021 were analyzed, demonstrating that melanomas in the Lumbar region presented a significant more heterogeneous drainage by site than those in the Scapular region (p < 0.01) and that melanomas in the Subscapular region were significantly more heterogeneous by laterality (unilateral vs. bilateral) than those in the Scapular region (p < 0.05). Results of this study supported the evidence of multiple lymphatic drainage as regards the sentinel node biopsy performed in skin melanoma located on the dorsal subscapular region and lumbar region. For this reason, the association of preoperative lymphoscintigraphy with another imaging evaluation is needed in these critical cutaneous areas. Recent technical developments enabling fluorescence lymphography together with indocyanine green have significantly improved the visualization of lymphatic drainage patterns at a microscopic level. In the preoperative phase, any doubt can be resolved by associating the SPET-CT scan to lymphoscintigraphy, while during the intraoperative phase, an additional evaluation with indocyanine green can be performed in doubtful cases. The aim of the duplex lymphatic mapping (pre and/or intraoperative) is an accurate search of sentinel nodes, in order to reduce the rate of false negatives.

Indocyanine Green Fluorescence Imaging with Lymphoscintigraphy Improves the Accuracy of Sentinel Lymph Node Biopsy in Melanoma

BACKGROUND

Despite advances in melanoma management, there remains room for improvement in the accuracy of sentinel lymph node biopsy. The authors analyzed a prospective cohort of patients with primary cutaneous melanoma who underwent sentinel lymph node biopsy with lymphoscintigraphy and indocyanine green fluorescence to evaluate the quality and accuracy of this technique.

METHODS

Consecutive primary cutaneous melanoma patients who underwent sentinel lymph node biopsy with radioisotope lymphoscintigraphy and indocyanine green fluorescence from 2012 to 2018 were prospectively enrolled. Analysis was performed of melanoma characteristics, means of identifying sentinel lymph nodes, sentinel lymph node status, and recurrence.

RESULTS

Five hundred ninety-four melanomas and 1827 nodes were analyzed; 1556 nodes (85.2 percent) were identified by radioactivity/fluorescence, 255 (14 percent) by radioactivity only, and 16 (0.9 percent) with indocyanine green only. There were 163 positive sentinel nodes. One hundred forty-seven (90.2 percent) were identified by radioactivity/fluorescence, 13 (8 percent) by radioactivity only, and three (0.6 percent) with fluorescence only. Of the 128 patients with a positive biopsy, eight patients' (6.3 percent) nodes were identified by radioactivity only and four (3.4 percent) with fluorescence only. There were 128 patients with a positive biopsy, 454 with a negative biopsy, and 12 patients who had a negative biopsy with subsequent nodal recurrence. Mean follow-up was 2.8 years.

CONCLUSIONS

In the study of the largest cohort of patients with primary cutaneous melanoma who underwent a sentinel lymph node biopsy with radioisotope lymphoscintigraphy and indocyanine green-based technology, the quality and accuracy of this technique are demonstrated. This has important implications for melanoma patients, as the adoption of this approach with subsequent accurate staging, adjuvant workup, and treatment may improve survival outcomes. .

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Mapping sentinel lymph nodes in cutaneous melanoma: a vast array of perioperative imaging modalities

Sentinel lymph node biopsy (SLNB) is a decisive step in the staging process of melanoma, critically impacting patients' oncological outcome and driving the decision-making process. SLNB limits the extent of the dissection in cases where no metastases are found. Conversely, when metastases are detected, SLNB has the potential to improve regional control of the disease when complete lymphadenectomy or early administration of adjuvant treatment are indicated. Thus, accurately identifying sentinel lymph nodes represents an important prognostic factor. Several strategies have been studied, including novel procedures that are not commonly used in the clinical setting. This review highlights the different tracers, preoperative and intraoperative imaging modalities studied to perform SLNB in cutaneous melanoma. The development of innovative modalities has been fueled by a need to optimize current approaches, offering new alternatives that can overcome some of the limitations of the standard method.