Accuracy and Reproducibility of Lymphoscintigraphy for Sentinel Node Detection in Patients with Cutaneous Melanoma

Sentinel Lymph Node Biopsy in Breast Cancer with 99mTc-Tilmanocept: A Multicenter Study on Real-Life Use of a Novel Tracer

^99mTc-tilmanocept is a novel radiopharmaceutical for sentinel lymph node (SLN) biopsy in breast cancer. Our aim was to describe results with ^99mTc-tilmanocept in a heterogeneous group of breast cancer patients scheduled for SLN biopsy. Methods: Radiotracer preparation followed the manufacturer's indications. Local protocols for SLN detection within 9 participant centers were not changed for the entire duration of the study. In total, 344 patients with T1-T4, N0-N2 breast cancer (352 lesions) were included. Superficial (intradermal or periareolar) or deep (peritumoral or intratumoral) injections were performed. The doses were adjusted depending on the scheduled time for surgery. Results: Lymphoscintigraphy was able to depict at least 1 SLN in 339 of 352 breast lesions (96.3%), and the intraoperative SLN detection rate reached 97.2%. On univariable analysis, SLN detection rates did not differ by age, clinical T or N stage, tumor location, histologic subtype, or prior neoadjuvant therapy. Lymphoscintigraphy showed higher SLN detection in patients with a normal weight (body mass index < 25) than in those who were overweight or obese (body mass index ≥ 25), at 99.2% versus 94.6%, respectively (P = 0.031). The proportion of patients with preoperative lymphoscintigraphic detection or excised SLNs was higher with superficial than deep injections. Reinjected cases were significantly lower when superficial injection was chosen first (P < 0.001). Injection site and the tumor markers human epidermal growth factor receptor 2 and estrogen receptor had an impact on preoperative SLN visualization and intraoperative localization. In 80 cases, SLN biopsy resulted in a positive lymph node. During a mean follow-up of 19 mo, no axillary recurrences were observed. Conclusion: Whatever the protocol, ^99mTc-tilmanocept showed good results in a heterogeneous breast cancer population, although the best results were achieved when a superficial injection was chosen.

Next generation of radiotracers for sentinel lymph node biopsy: What is still necessary to establish new imaging paradigms?

Sentinel lymph node (SLN) biopsy is now the standard of care for regional staging in several solid tumors. The interstitial administration of a radiotracer around the primary tumor provide the possibility to sequentially obtain images with a gamma camera and visualize lymphatic mapping and the SLN. There is, however, a large geographical variability in those radiotracers and nanocolloids ranging from 15-100nm which are most widely employed in Europe, while filtered and unfiltered ^99mTc-sulfur colloid (range 20-1000nm) is usually used in the USA with different drawbacks in its use. The new radiotracer ^99mTc-Tilmanocept, designed specifically for the identification of SLNs and recently becoming commercially available in USA and Europe, appears to have the potency to overcome the shortcomings described for the conventional radiotracers used until now for SLN biopsy and at the same time to transform current imaging paradigms. After delineating the challenges for the next generation of radiotracers, this paper discusses the properties of ^99mTc-Tilmanocept, its validation process for SLN biopsy and its emerging clinical applications in various malignancies.

Melanoma & nuclear medicine: new insights & advances

The contribution of nuclear medicine to management of melanoma patients is increasing. In intermediate-thickness N0 melanomas, lymphoscintigraphy provides a roadmap for sentinel node biopsy. With the introduction of single-photon emission computed tomography images with integrated computed tomography (SPECT/CT), 3D anatomic environments for accurate surgical planning are now possible. Sentinel node identification in intricate anatomical areas (pelvic cavity, head/neck) has been improved using hybrid radioactive/fluorescent tracers, preoperative lymphoscintigraphy and SPECT/CT together with modern intraoperative portable imaging technologies for surgical navigation (free-hand SPECT, portable gamma cameras). Furthermore, PET/CT today provides 3D roadmaps to resect 18F-fluorodeoxyglucose-avid melanoma lesions. Simultaneously, in advanced-stage melanoma and recurrences, 18F-fluorodeoxyglucose-PET/CT is useful in clinical staging and treatment decision as well as in the evaluation of therapy response. In this article, we review new insights and recent nuclear medicine advances in the management of melanoma patients.

[Sentinel node in melanoma and breast cancer. Current considerations]

The main objectives of sentinel node (SN) biopsy is to avoid unnecessary lymphadenectomies and to identify the 20-25% of patients with occult regional metastatic involvement. This technique reduces the associated morbidity from lymphadenectomy and increases the occult lymphatic metastases identification rate by offering the pathologist the or those lymph nodes with the highest probability of containing metastatic cells. Pre-surgical lymphoscintigraphy is considered a "road map" to guide the surgeon towards the sentinel nodes and to localize unpredictable lymphatic drainage patterns. The SPECT/CT advantages include a better SN detection rate than planar images, the ability to detect SNs in difficult to interpret studies, better SN depiction, especially in sites closer to the injection site and better anatomic localization. These advantages may result in a change in the patient's clinical management both in melanoma and breast cancer. The correct SN evaluation by pathology implies a tumoral load stratification and further prognostic implication. The use of intraoperative imaging devices allows the surgeon a better surgical approach and precise SN localization. Several studies reports the added value of such devices for more sentinel nodes excision and a complete monitoring of the whole procedure. New techniques, by using fluorescent or hybrid tracers, are currently being developed.

Melanoma and nuclear medicine

Supported by a large body of published work, the contribution of nuclear medicine technologies to the assessment of melanoma has been increasing in recent years. Lymphoscintigraphy-assisted sentinel lymph node biopsy and PET are in continuous evolution with the aid of technological imaging advances, making it possible to fuse functional and anatomic images (e.g., with SPECT/CT, PET/CT and 3D rendering systems). The development of hybrid fluorescent-radioactive tracers that enable high-quality preoperative lymphoscintigraphy and SPECT/CT, and the optimization of modern intraoperative portable imaging technologies, such as free-hand SPECT and portable γ-cameras, are important innovations that have improved sentinel lymph node identification in complex anatomical areas, such as the pelvis and head and neck. Concurrently, ¹⁸F-fluorodeoxyglucose-PET has proved its usefulness in the clinical staging and treatment decision-making process, and there is also emerging evidence regarding its utility in the evaluation of therapeutic response. The potential uses of other novel PET radiotracers could open up a new field of use for this technique. In this article, we review the current and future role of nuclear medicine in the management of melanoma.

Reproducibility of lymphoscintigraphic evaluation of the upper limb

BACKGROUND

Although reproducibility studies are missing, a lymphoscintigraphic evaluation of the upper limb is often used in routine practice to diagnose lymphedema and in clinical research, for example, to investigate the effect of a physical treatment. Therefore, the aim of the present study was to investigate the reproducibility of the lymphoscintigraphic evaluation of the upper limb.

METHODS AND RESULTS

In breast cancer patients, 20 lymphoscintigraphic evaluations of the upper limb were performed on two test occasions with an interval of 1 week. (99m)Tc nanocol was injected subcutaneously in the hand. A standardized protocol was applied. In the early phase, two static images of the injection places were taken and in between dynamic images of both axilla during 40 min (15 min rest, 15 min squeezing a ball, and 15 min rest). After a break of 70 min, a static image of the injection places and of the axilla was made. At the end, a partial whole body image was acquired. A strong reproducibility was found for the following quantitative variables (ICC 0.75 to 0.85): change of uptake in axilla during the break; change of extraction from hands during the break; and extraction and uptake in the late phase. The other quantitative variables (i.e., extraction form the hands in the early phase, time of arrival, accumulation rate, and uptake in axilla in the early phase) had weak to moderatie reproducibility (ICC 0.07 to 0.70). All qualitative variables (i.e., number of lymph nodes in the axilla, upper arm and elbow/lower arm, gradation of lymph collectors in upper or lower arm and of dermal backflow, and presence of lymph collaterals) had strong to very strong reproducibility (ICC 0.76 to 1.00).

CONCLUSION

A lymphoscintigraphy of the upper limb is a reproducible imaging tool to assess lymph transport quantitatively and qualitatively.

The clinical use of PET/CT in the evaluation of melanoma

Positron emission tomography combined with computed tomography (PET/CT) has emerged in the last decade as a dominant imaging modality used for staging, monitoring response and surveillance of various cancers, including melanoma. Using 2-deoxy-2-((18)F)fluoro-D-glucose ((18)F-FDG) as the radiopharmaceutical, PET/CT has demonstrated its efficacy and its utility in the management of patients with advanced melanoma. Nonetheless, challenges remain in the early stage evaluation of melanoma and in the development of novel radiotracers to better characterize lesions found on PET/CT. This chapter focuses on the advantages and limitations of this imaging modality in melanoma. We also detail and describe the approach to perform (18)F-FDG PET/CT, the methods to accurately quantify lesions, as well as the pearls/pitfalls of image interpretation. Finally, an overview of preclinical and investigational clinical radiopharmaceuticals is presented.

Lymphoscintigraphy in clinical routine practice: reproducibility and accuracy in melanoma patients with a long-term follow-up

INTRODUCTION

The sentinel node status is the most important single factor determining overall survival for patients with localized melanoma. Preoperative lymphoscintigraphy (LS) is essential in locating the correct sentinel lymph node (SN) and the reproducibility of the method determines the accuracy of the sentinel node biopsy (SNB). This study aims at determining the reproducibility and accuracy of LS in routine clinical practice after long-term follow-up.

PATIENTS AND METHODS

One hundred and eight melanoma patients with clinically unpredictable lymphatic drainage were prospectively enrolled to undergo two LS. The first LS was performed to determine the site and number of the lymphatic basins to plan SNB anesthesia and the second preoperative LS was to allow SN localization intra-operatively.

RESULTS

Lymphatic drainage was demonstrated in all patients. In 84 of 108 cases, both LSs were concordant in terms of site and number of nodal basins visualized. After a median follow-up of 80 months, no nodal recurrence was observed in the five patients with a decreased number of lymph node basins. In the group with increased number of lymph node basins, one patient developed nodal metastases in the same regional lymph node basin visualized by both LS studies.

CONCLUSION

LS is an accurate and reproducible method to determine the localization of the sentinel node in the day-to-day routine to clinical practice when primary melanoma is also located in body sites with variable lymphatic drainage.