SPECT/CT Adds Distinct Lymph Node Basins and Influences Radiologic Findings and Surgical Approach for Sentinel Lymph Node Biopsy in Head and Neck Melanoma

Localization of sentinel lymph nodes using augmented-reality system: a cadaveric feasibility study

PURPOSE

Sentinel lymph node biopsy (SLNB) helps stage melanoma. Pre-surgical single-photon emission computed tomography/computed tomography (SPECT/CT) visualizes draining lymph nodes, but intraoperative gamma probe detection only estimates SLN location. This study evaluates augmented reality (AR) for projecting pre-surgical SLN imaging onto patients to aid precise localization and extraction.

METHODS

Molecular sieves (8 mm) incubated in fluorine-18 simulated lymph nodes and were implanted in the head and neck region of cadavers. Positron emission tomography/magnetic resonance imaging (PET/MRI) replaced SPECT/CT due to institutional restriction on cadavers. Virtual PET/MRI renderings were projected using the HoloLens 2 and custom software. Five cadavers underwent surgeries with standard, AR, and AR with head movement compensation methods.

RESULTS

AR achieved a mean surface localization error of 2.5±2.0 mm (range, 0-8 mm) and a depth error of 2.3±1.7 mm (range, 1-7 mm), both within PET voxel resolution. For more challenging level V nodes, the mean surface error slightly increased to 2.9 mm. Compared to manual surface marking, which had an average error of 18.6±13.0 mm (range, 6-62 mm), the AR system significantly reduced errors both in the head-straight and rotated positions (p <.001). Additionally, the AR system reduced the task completion time by 74% (35.1/47.4 s), with an average time of 12.3 s compared to 47.4 s for manual methods.

CONCLUSION

The AR system demonstrated high accuracy and efficiency in SLN localization, integrating head-movement compensation and 3D visualization to improve precision and reduce operating room time.

CLINICAL TRIAL NUMBER

Not applicable.

Single-Photon Emission Computed Tomography/Computed Tomography Utilization for Extremity Melanomas at a High-Volume Center

INTRODUCTION

Planar lymphoscintigraphy (PL) is commonly used in mapping before sentinel lymph node biopsy (SLNB) for invasive cutaneous melanoma. Recently, single-photon emission computed tomography (SPECT)/ computed tomography (CT) has been utilized, in addition to PL, for detailed anatomic information and detection of sentinel lymph nodes (SLNs) outside of the primary nodal basin in truncal and head and neck melanoma. Following a protocol change due to COVID-19, our institution began routinely obtaining both PL and SPECT-CT imaging for all melanoma SLN mapping. We hypothesized that SPECT-CT is associated with higher instances of SLNBs from "nontraditional" nodal basins (NTNB) for extremity melanomas.

METHODS

Patients with extremity melanoma (2017-2022) who underwent SLNB were grouped into SPECT-CT with PL versus PL alone. Outcomes were total SLNs removed, + or-SLN status, total NTNB sampled, and postoperative complication rate. Poisson regression and logistic regression models were used to assess association of SPECT-CT with patient outcomes.

RESULTS

Of 380 patients with extremity melanoma, 42.11% had SPECT-CT. There were no differences between the groups with regards to age at diagnosis or sex. From 2020 to 2022, all patients underwent SPECT-CT. SPECT-CT was associated with increased odds of SLNB from an NTNB, (odds ratio = 2.39 [95% confidence interval: 1.25-4.67]). There was no difference in odds of number of SLNs sampled, SLN positivity rate, or postoperative complication rate with SPECT-CT.

CONCLUSIONS

Routine SPECT-CT was associated with higher incidence of SLNB in NTNB but did not increase number of SLNs removed or SLN positivity rate. The added value of routine SPECT-CT in cutaneous melanoma of the extremities remains to be defined.

Phantom study of SPECT/CT augmented reality for intraoperative localization of sentinel lymph nodes in head and neck melanoma

OBJECTIVE

To show that augmented reality (AR) visualization of single-photon emission computed tomography (SPECT)/computed tomography (CT) data in 3D can be used to accurately localize targets in the head and neck region.

MATERIALS AND METHODS

Eight head and neck styrofoam phantoms were painted with a mixture of radioactive solution (Tc-99m) detectable with a handheld gamma probe and fluorescent ink visible only under ultraviolet (UV) light to create 10-20 simulated lymph nodes on their surface. After obtaining SPECT/CT images of these phantoms, virtual renderings of the nodes were generated from the SPECT/CT data and displayed using a commercially available AR headset. For each of three physician evaluators, the time required to localize lymph node targets was recorded (1) using the gamma probe alone and (2) using the gamma probe while wearing the AR headset. In addition, the surface localization accuracy when using the AR headset was evaluated by measuring the misalignment between the locations visually marked by the evaluators and the ground truth locations identified using UV stimulation of the ink at the site of the nodes.

RESULTS

For all three evaluators, using the AR headset significantly reduced the time to detect targets (P = 0.012, respectively) compared to using the gamma probe alone. The average misalignment between the location marked by the evaluators and the ground truth location was 8.6 mm.

CONCLUSION

AR visualization of SPECT/CT data in 3D allows for accurate localization of targets in the head and neck region, and may reduce the localization time of targets.

Effectiveness of SPECT/CT Imaging for Sentinel Node Biopsy Staging of Primary Cutaneous Melanoma and Patient Outcomes

Purpose

Coregistered SPECT/CT can improve accuracy of sentinel node biopsy (SNB) for staging melanoma. This benefit has implications for pathology services and surgical practice with increased diagnostic and surgical workload. The purpose of this study was to investigate the effectiveness of SPECT/CT imaging.

Methods

SNB data were collected over a 10-year period. Preoperative SLN mapping was performed by using planar lymphoscintigraphy (LSG) for all patients (n = 1522) and after October 2015, patients underwent a second co-registered SPECT/CT scan (n = 559). The patients were stratified according to the imaging protocol. The number of nodes and nodal basins were assessed. The reasons for cancellation also were assessed.

Results

A total of 95% (1446/1522) of patients underwent a successful SNB procedure. Significantly more sentinel nodes were identified by the SPECT/CT protocol (3 vs. 2; p < 0.0001). More patients were cancelled in the SPECT/CT cohort (9.3% vs. 2.5%; p < 0.0001). Head & neck, lower limb, and AJCC IB primaries were significantly less likely to proceed to SNB. SPECT/CT identified significantly more positive SNBs (20.9% vs. 16.5%; p = 0.038). SPECT/CT imaging was associated with improved disease-free (hazard ratio [HR] = 0.74; 95% confidence interval [CI]: 0.54–1.0); p = 0.048) and disease-specific survival (HR = 0.48; 95% CI: 0.3–0.78; p = 0.003). Patients who did not proceed to SNB had a significantly increased nodal relapse rate (23.5% vs. 6.8%; HR = 3.4; 95% CI: 1.9–6.2; p < 0.0001) compared with those who underwent SNB.

Conclusions

This large cohort study confirms the increased accuracy of SPECT/CT for identifying SLN metastases, which would appear to have a significant therapeutic benefit, although an increased risk of cancellation of the SNB procedure on the day of surgery.

Prognostic Role of Non-Identification of Sentinel Lymph Node in Cutaneous Melanoma Patients: An Observational Retrospective Study

Simple Summary

Sentinel lymph node status is the most important prognostic factor for patients with cutaneous melanoma, but occasionally it is not possible to identify the sentinel lymph node. Little is known in cutaneous melanoma literature about the phenomenon of non-identification of sentinel lymph node and its prognostic implications. In this study we observed that not identifying the sentinel lymph node involves a worse nodal disease-free survival, but not a worse melanoma-specific survival than a negative sentinel lymph node. Potentially, patients with non-identified SLN should receive a follow-up schedule like that of patients with positive SLN.

Abstract

Background: Sentinel lymph node (SLN) status is recognized as the most important prognostic factor for patients with cutaneous melanoma. However, sometimes it is not possible to identify SLN. The phenomenon of non-identification of SLN and its prognostic role have not been thoroughly evaluated in melanoma literature. The objective of this study was to identify which patient or tumor variables may be associated to non-identification of SLN and to evaluate the prognostic role of non-identification of SLN. Methods: Observational retrospective study of 834 cutaneous melanoma patients who underwent SLN biopsy at Instituto Valenciano de Oncología. Results: Forty-two patients (5%) presented non-identification of SLN. Patients with age at diagnosis of ≥ 64 years, obesity (BMI ≥ 30), and head and neck localization were at higher risk of non-identification of SLN. Non-identified SLN patients had worse nodal disease-free survival with respect to negative SLN patients, but not worse melanoma-specific survival. Conclusions: Our findings suggest a need to follow-up patients with non-identified SLN in the same way as patients with positive SLN.

Cranial nerve outcomes in regionally recurrent head & neck melanoma after sentinel lymph node biopsy

OBJECTIVE

Characterize long-term cranial nerve (CN) outcomes following sentinel lymph node biopsy (SLNB) based management for head and neck cutaneous melanoma (HNCM).

METHODS

Longitudinal review of HNCM patients undergoing SLNB from 1997-2007.

RESULTS

Three hundred fifty-six patients were identified, with mean age 53.5 ± 19.0 years, mean Breslow depth 2.52 ± 1.87 mm, and 4.9 years median follow-up. One hundred five (29.4%) patients had SLNB mapping to the parotid basin. Eighteen patients had positive parotid SLNs and underwent immediate parotidectomy / immediate completion lymph node dissection (iCLND), with six possessing positive parotid non-sentinel lymph nodes (NSLNs). Fifty-two of 356 (14.6%) patients developed delayed regional recurrences, including 20 total intraparotid recurrences: five following false negative (FN) parotid SLNB, three following prior immediate superficial parotidectomy, two following iCLND without parotidectomy, and the remaining 12 parotid recurrences had negative extraparotid SLNBs. Parotid recurrences were multiple (4.9 mean recurrent nodes) and advanced (n = 4 extracapsular extension), and all required salvage dissection including parotidectomy. Immediate parotidectomy/iCLND led to no permanent CN injuries. Delayed regional HNCM macrometastasis precipitated 16 total permanent CN injuries in 13 patients: 10 CN VII, five CN XI, and one CN XII deficits. Fifty percent (n = 10) of parotid recurrences caused ≥1 permanent CN deficits.

CONCLUSIONS

Regional HNCM macrometastases and salvage dissection confer marked CN injury risk, whereas early surgical intervention via SLNB ± iCLND ± immediate parotidectomy yielded no CN injuries. Further, superficial parotidectomy performed in parotid-mapping HNCM does not obviate delayed intraparotid recurrences, which increase risk of CN VII injury. Despite lack of a published disease-specific survival advantage in melanoma, early disease control in cervical and parotid basins is paramount to minimize CN complications.

LEVEL OF EVIDENCE

4 (retrospective case series) Laryngoscope, 130:1707-1714, 2020.

Comparison of 99mTc-Labeled Colloid SPECT/CT and Planar Lymphoscintigraphy in Sentinel Lymph Node Detection in Patients with Melanoma: A Meta-Analysis

We compared the detection rate (DR) for sentinel lymph nodes (SLN), the number of SLNs and the subjects with additional SLNs of single-photon emission computed tomography (SPECT/CT) and planar lymphoscintigraphy (PL) in patients with melanoma. Furthermore, we evaluated the impact of SPECT/CT on surgical plans. Articles containing head-to-head comparisons between SPECT/CT and PL were searched in Pubmed/MEDLINE and Scopus. The literature search was updated until December 31st, 2019. DR was calculated on a per patient-based analysis; the studies were pooled by their odds ratios (ORs) with a random effects model to assess the significance of difference (p < 0.05). The number of additional SLNs (calculated as the relative risk) and pooled proportion of patients with additional SLNs were investigated. The pooled ratio of surgical procedures influenced by the SPECT/CT findings was calculated. Seventeen studies with 1438 patients were eligible for the calculation of DR of SPECT/CT and PL. The average DR was 98.28% (95% confidence interval (95% CI): 97.94-99.19%) for the SPECT/CT and 95.53% (95% CI: 92.55-97.77%) for the PL; OR of 2.31 (95% CI: 1.66-4.18, p < 0.001) in favor of the SPECT/CT. There was a relative risk of a higher number of SLNs (1.13) for the SPECT/CT and 17.87% of patients with additional SLNs were detected by SPECT/CT. The average impact of SPECT/CT on surgery resulted in 37.43% of cases. This meta-analysis favored SPECT/CT over PL for the identification of SLNs in patients with melanoma due to a higher DR, reproducibility, number of SLNs depicted, proportion of patients with additional SLNs and the impact on the surgical plan. However, PL remains a good option due to the high values of the DR for SLNs.

The Lymphoscintigraphic Study of Unpredictable Head and Neck Cutaneous Melanoma Lymphatic Drainage

Head and neck cutaneous melanoma (HNCM) does not always follow standard lymphatic drainage; typical expected lymphatic pathways are associated with unexpected ones. The aim of this study was to investigate the relation between the primary HNCM sites and all possible lymphatic drainage pathways by lymphoscintigraphy with a special focus on the unexpected sentinel lymph node (SLNs) detection. We retrospectively analyzed 67 patients (46 M, 21 F; mean age 63 years) who underwent lymphoscintigraphy from January 2004 to November 2018. 99mTc-serum albumin was injected intra-dermally at the dose of 18–37 MBq in 0.2–0.4 mL. All patients underwent dynamic and static image acquisition. For all patients, the relation between the expected and unexpected SLNs was performed using the “Sidney Melanoma Unit Database” as our reference. The relation was performed also according to the primary HNCM localization. Cohens’ kappa was calculated. In 61/67 (91%) of patients, SLNs were detected only in predictable sites, while in six/67 (9%), unexpected SLNs were revealed. In all patients, the agreement proportion was 91% (95% confidence interval CI 0.8–0.96) and Cohen’s K was 0.11 (95% CI 0–0.43). Regarding the primary melanoma sites, the nasolabial field HNCM showed the highest rate of concordance (K = 0.60; 95%, CI 0.32–0.89) while the preauricular region HNCM revealed the highest rate of discordance with the clinically predictable drainage. The HNCM lymphatic drainage is extremely variable in regard to both the sites and the number of involved SLNs. The lymphoscintigraphic study is highly recommended to identify all possible SLNs in order to perform an accurate staging for all patients and to avoid missing unexpected SLNs.

Sentinel Lymph Node Biopsy in Head and Neck Melanoma: Long-term Outcomes, Prognostic Value, Accuracy, and Safety

OBJECTIVE

To evaluate the long-term outcomes of sentinel lymph node biopsy (SLNB) for head and neck cutaneous melanoma (HNCM).

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary academic medical center.

SUBJECTS AND METHODS

Longitudinal review of a 356-patient cohort with HNCM undergoing SLNB from 1997 to 2007.

RESULTS

Descriptive characteristics included the following: age, 53.5 ± 19 years (mean ± SD); sex, 26.8% female; median follow-up, 4.9 years; and Breslow depth, 2.52 ± 1.87 mm. Overall, 75 (21.1%) patients had a positive SLNB. Among patients undergoing completion lymph node dissection following positive SLNB, 20 (27.4%) had at least 1 additional positive nonsentinel lymph node. Eighteen patients with local control and negative SLNB developed regional disease, indicating a false omission rate of 6.4%, including 10 recurrences in previously unsampled basins. Ten-year overall survival (OS) and melanoma-specific survival (MSS) were significantly greater in the negative sentinel lymph node (SLN) cohort (OS, 61% [95% CI, 0.549-0.677]; MSS, 81.9% [95% CI, 0.769-0.873]) than the positive SLN cohort (OS, 31% [95% CI, 0.162-0.677]; MSS, 60.3% [95% CI, 0.464-0.785]) and positive SLN/positive nonsentinel lymph node cohort (OS, 8.4% [95% CI, 0.015-0.474]; MSS, 9.6% [95% CI, 0.017-0.536]). OS was significantly associated with SLN positivity (hazard ratio [HR], 2.39; P < .01), immunosuppression (HR, 2.37; P < .01), angiolymphatic invasion (HR, 1.91; P < .01), and ulceration (HR, 1.86; P < .01). SLN positivity (HR, 3.13; P < .01), angiolymphatic invasion (HR, 3.19; P < .01), and number of mitoses (P = .0002) were significantly associated with MSS. Immunosuppression (HR, 3.01; P < .01) and SLN status (HR, 2.84; P < .01) were associated with recurrence-free survival, and immunosuppression was the only factor significantly associated with regional recurrence (HR, 6.59; P < .01).

CONCLUSIONS

Long-term follow up indicates that SLNB showcases durable accuracy, safety, and prognostic importance for cutaneous HNCM.

Sentinel lymph node biopsy in cutaneous melanoma of the head and neck using the indocyanine green SPY Elite system

PURPOSE

Lymph node status is the single most important prognostic factor for patients with early-stage cutaneous melanoma. Sentinel lymph node biopsy (SLNB) has become the standard of care for intermediate depth melanomas. Modern SLNB implementation includes technetium-99 lymphoscintigraphy combined with local administration of a vital blue dye. However, sentinel lymph nodes may fail to localize in some cases and false-negative rates range from 0 to 34%. Here we demonstrate the feasibility of a new sentinel lymph node biopsy technique using indocyanine green (ICG) and the SPY Elite near-infrared imaging system.

MATERIALS AND METHODS

Cases of primary cutaneous melanoma of the head and neck without locoregional metastasis, underwent SLNB at a single quaternary care institution between May 2016 and June 2017. Intraoperatively, 0.25 mL of ICG was injected intradermal in 4 quadrants around the primary lesion. 10-15 minute circulation time was permitted. SPY Elite identified the sentinel lymph node within the nodal basin marked by lymphoscintigraphy. Target first echelon lymph nodes were confirmed with a gamma probe and ICG fluorescence.

RESULTS

14 patients were included with T1a to T4b cutaneous melanomas. Success rates for sentinel lymph node identification using lymphoscintigraphy and the SPY Elite system were both 86%. Zero false negatives occurred. Median length of follow-up was 323 days.

CONCLUSIONS

In this pilot study, Indocyanine green near-infrared fluorescence demonstrates a safe, and facile method of sentinel lymph node biopsy for cutaneous melanoma of the head and neck compared with lymphoscintigraphy and vital blue dyes.