Sentinel Node Identification in Melanoma: Current Clinical Impact, New Emerging SPECT Radiotracers and Technological Advancements. An Update of the Last Decade

Abstract

Background: Melanoma is the most lethal skin cancer with a mortality rate of 262 cases per 100.000 cases. The sentinel lymph node (SLN) is the first lymph node draining the tumor. SLN biopsy is a widely accepted procedure in the clinical setting since it provides important prognostic information, which helps patient management, and avoids the side effects of complete lymph node dissection. The rationale of identifying and removing the SLN relies on the low probability of subsequent metastatic nodes in case of a negative histological exam performed in the SLN. Discussion: Recently, new analytical approaches, based on the evaluation of scintigraphic images are also exploring the possibility to predict the metastatic involvement of the SLN. 99mTc-labeled colloids are still the most commonly used radiotracers but new promising radiotracers, such as 99mTc- Tilmanocept, are now on the market. In the last decades, single photon emission computed tomography- computerized tomography (SPECT/CT) has gained wider diffusion in clinical departments and there is large evidence about its superior diagnostic accuracy over planar lymphoscintigraphy (PL) in the detection of SLN in patients with melanoma. Scientists are also investigating new hybrid techniques combining functional and anatomical images for the depiction of SLN but further evidence about their value is needed. Conclusion: This review examined the predictive and prognostic factors of lymphoscintigraphy for metastatic involvement of SLN, the currently available and emerging radiotracers and the evidence of the additional value of SPECT/CT over PL for the identification of SLN in patients with melanoma. Finally, the review discussed the most recent technical advances in the field.

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

“…A higher DR and the larger number of SLNs identified by the SPECT/CT on a head-to-head comparison with PL can theoretically also determine a meaningful impact in surgical decision making. Nevertheless, the preoperative use of SPECT/CT for the identification of SLNs is not only important for the additional number of SLNs but also for the capability of providing anatomical information [21,53]. Furthermore, SPECT/CT may also localize unspecific hot spots that could be mistaken as additional SLNs using only PL [54].…”

“…Despite the recent introduction in the clinical setting of a new receptor-specific radiotracer ( 99m Tc-tilmanocept) which binds the CD 206 macrophage receptor, 99m Tc-labeled colloids are still the most widely used radiotracers for the identification of SLNs [20]. All 99m Tc-labeled colloids encompass particles with variable sizes, ranging from 5 to 5000 nm, and share the mechanism of accumulation mediated by the particle size at the level of the SLN, where the particles are phagocytized by the macrophages [21].…”

Breast Cancer-Related Lymphedema: Recent Updates on Diagnosis, Severity and Available Treatments

“…Some centers have reported also quantitative analysis based on decay-adjusted uptake and lymphatic transport index; however these are not commonly performed [ 39 , 40 ]. Recently, single photon emission computed tomography-computed tomography (SPECT-CT) lymphoscintigraphy has been used for the diagnosis of lymphedema providing 3-D live images of lymph flow [ 38 , 41 , 42 ]. A recent study reported significant association between the type of dermal backflow, the lymph flow pathways, and the visualization of lymph nodes around the clavicle [ 42 ].…”

The Efficacy of Radionuclide Imaging Techniques at Sentinel Node Identification in Patients with Cutaneous Melanoma

“…Наибольшее клиническое распространение получили радионуклидные методы диагностики с РФП, меченными 99m Tc, путь элиминации которых прослеживается с помощью планарной сцинтиграфии с использованием диагностической гамма-камеры и/или портативного ручного гамма-детектора для интраоперационной радиометрии [9]. На сегодняшний день доступные и наиболее часто используемые РФП для идентификации СЛУ могут быть выделены в две группы: наноколлоиды и рецептор-связывающие агенты [10]. Первая группа РФП широко распространена в странах Европы, США, Австралии и Канаде, а также в РФ (доступны 99m Тс-технефит, 99m Тс-алотех, 99m Тс-нанотоп) [11].…”

“…Основные преимущества метода по сравнению с указанным выше исследованы и определены на пациентах с меланомой кожи различной локализации. Способность лучше отображать пути лимфодренажа (в особенности нетипичные локализации СЛУ) и бóльшая чувствительность в обнаружении были неоднократно продемонстрированы [10][11][12][13][14][15].…”