Lymphoscintigraphy and intraoperative lymphatic mapping of sentinel lymph nodes in melanoma patients

Identification of sentinel lymph nodes (SLNs) using lymphoscintigraphy, the blue dye technique and intraoperative lymphatic mapping with a gamma-detecting probe has become the standard of care in diagnosing and treating melanoma. Numerous clinical studies have proven the reliability of predicting the histology of remaining lymph nodes in the lymphatic basin from the histologic evaluation of the SLNs. Technical and clinical factors presented in this paper have been shown to increase the accuracy of localization of SLNs. The nuclear medicine technologist shares a vital role in the radiopharmaceutical preparation and administration for preoperative lymphoscintigraphy and intraoperative lymphatic mapping in patients with melanoma.     

Direct lymphatic drainage from a melanoma on the back to paravertebral lymph nodes in the thorax.

Preoperative lymphoscintigraphy with Tc-99m antimony sulfide colloid was performed in a patient with cutaneous melanoma on the lower back just to the right of the midline. There was direct lymphatic drainage to paravertebral nodes in the chest on the right side at the level of the sixth and seventh thoracic vertebrae. There was also drainage directly to the right groin and via a series of interval nodes to the right axilla. Knowledge of the presence of such drainage may influence the surgical management of patients.     

Identification of bilateral breast sentinel lymph nodes draining primary melanoma of the back by preoperative lymphoscintigraphy and intraoperative mapping.

A 30-year-old white woman with a primary malignant melanoma of her right back at the Sappey line, 4 cm from the midline at the L2 level, underwent preoperative lymphoscintigraphy and intraoperative mapping of the sentinel lymph node using lymphazurin injection at the primary site and a hand-held gamma probe. Lymphoscintigraphy showed one sentinel lymph node in each breast and another one in the right axilla. These three sentinel lymph nodes were accurately identified using a hand-held gamma probe during operation. An additional sentinel and one nonsentinel lymph node from the right axilla were harvested. All four sentinel lymph nodes were blue and showed significantly elevated radioactivity compared with background. Histologic analysis showed that all these lymph nodes were negative for metastatic melanoma. She has been followed for a period of 26.7 months since her selective sentinel lymphadenectomy and has been free of disease to date. This case illustrates the importance of preoperative lymphoscintigraphy in identifying in-transit sentinel lymph nodes in both breasts in addition to the clinically predictable sentinel lymph node(s) in the right axilla.     

Evaluation and localization of lymphatic drainage and sentinel lymph nodes in patients with head and neck melanomas by hybrid SPECT/CT lymphoscintigraphic imaging

In patients with head and neck tumors, preoperative lymphoscintigraphy can be used to map lymphatic drainage patterns and identify sentinel lymph nodes. However, it is very difficult to determine the exact locations of head and neck sentinel nodes on preoperative lymphoscintigraphy without the use of anatomic landmarks. Lymph nodes in the head and neck are grouped into 7 regions, or levels, on the basis of anatomic landmarks. In patients undergoing standard lymphoscintigraphy, obtaining lateral marker images that show important anatomic landmarks can help with the localization of sentinel nodes. However, technical problems often render marker images of little or no use. Hybrid SPECT/CT lymphoscintigraphic imaging facilitates the localization of sentinel nodes by reliably showing the relationships between sentinel nodes and important anatomic structures. After reading this article, the reader should understand the lymph node level classification system for head and neck melanomas, be able to describe the technique used for the imaging of sentinel nodes in the head and neck region, and be able to demonstrate how SPECT/CT lymphoscintigraphic imaging can enable precise sentinel node localization and thus help to ensure minimal dissection.     

进一步开展前哨淋巴结的核医学探测

前哨淋巴结（sentinel lymph node,SLN）活组织检查（SLNB）是对恶性肿瘤患者实行个体化治疗的一个组成部分,在国内已有很多单位开展,主要针对乳腺、胃、宫颈、结直肠、口腔、皮肤等部位的恶性肿瘤。本期多篇SLN探测的论文,体现了核医学、外科和病理科的多学科协作,但从中也引出了进一步思考和商榷的问题。     

Non-visualization of sentinel lymph nodes in penile carcinoma

Purpose The purpose of this study was to analyse the incidence and cause of non-visualization of sentinel lymph nodes on preoperative lymphoscintigrams for penile cancer and its implications for further management.Methods Preoperative lymphoscintigraphy was performed after injection of ^99mTc-labelled nanocolloid in 123 clinically node-negative penile carcinoma patients. Anterior dynamic lymphoscintigraphy was performed during 20 min immediately after tracer injection. Subsequently, 5-min anterior and lateral static images were obtained 30 min and 2 h post injection.Results Lymphatic drainage to both groins was seen in 98 patients (79%), unilateral drainage in 23 patients (19%) and no drainage at all in two patients (2%). Thus, in 27 (11%) of 246 groins, no sentinel node was visualized. The amount of administered tracer dose was associated with non-visualization (p=0.01). Unilateral drainage was initially interpreted as a normal physiological phenomenon. After the occurrence of a tumour-positive node in a non-visualized groin, we explore non-visualized groins by blue dye mapping and intraoperative palpation. Sentinel nodes were retrieved in four out of eight such groins, of which one contained metastasis.Conclusion In penile carcinoma patients, preoperative lymphoscintigraphy visualizes a sentinel node in 89% of groins. Visualization depends on the administered tracer dose. It is worthwhile to explore non-visualized groins. Sentinel nodes can be intraoperatively identified in more than half of these cases.     

Elastography in the assessment of sentinel lymph nodes prior to dissection

Objective

Breast cancer starts as a local tumor but can become metastatic and spread via the lymph nodes. When the pre-operative assessment of the axillary lymph nodes is negative patients generally undergo sentinel node biopsy (SNB), followed by a secondary surgical axillary lymph node dissection (ALND) if the SNB is positive. The extemporaneous anatomo-pathological analysis of the sentinel lymph node enables metastases to be detected and an ALND at the same time of the SNB. The goal of this study was to evaluate the added value of ShearWave Elastography (SWE), compared with the conventional pre-operative assessment, in the screening of sentinel lymph nodes with a high metastatic risk, which could then benefit from an extemporaneous anatomo-pathological analysis.

Patients and methods

Women undergoing breast surgery with SNB were prospectively enrolled. Before surgery, they underwent ultrasound and elastography imaging of axillary lymph nodes using the SuperSonic Imagine device and its ShearWave™ elastography mode (SWE™). The results obtained were compared to the immunohistochemical results for the removed lymph nodes.

Results

65 patients were enrolled. From the 103 lymph nodes examined by elastography and the 185 lymph nodes removed we were able to pair 81; 70 were healthy and 11 were malignant. The stiffness measurements (mean and maximal values) were significantly different between the healthy and metastatic lymph nodes, (p < 0.05). The areas under the ROC curves were 0.76 (95% confidence interval (CI): 0.58–0.94) and 0.75 (95%CI: 0.55–0.95) for the mean and the maximal stiffness, respectively.

Conclusion

These encouraging results show a correlation between the metastatic risk of lymph nodes and their increased mean stiffness. Elasticity variables and potential thresholds that seem to predict the metastatic status of axillary lymph nodes were identified. If confirmed by further larger studies, these results could be useful in clinical practice for the identification of lymph nodes at high metastatic risk that could benefit from a intra-operative analysis to reduce the number of secondary surgical procedures.     

The role of interval nodes in sentinel lymph node mapping and dissection for melanoma patients.

In sentinel node (SN) biopsy, an interval SN is defined as a lymph node or group of lymph nodes located between the primary melanoma and an anatomically well-defined lymph node group directly draining the skin. As shown in previous reports, these interval SNs seem to be at the same metastatic risk as are SNs in the usual, classic areas. This study aimed to review the incidence, lymphatic anatomy, and metastatic risk of interval SNs. METHODS: SN biopsy was performed at a tertiary center by a single surgical team on a cohort of 402 consecutive patients with primary melanoma. The triple technique of localization was used-that is, lymphoscintigraphy, blue dye, and gamma-probe. Otolaryngologic melanoma and mucosal melanoma were excluded from this analysis. SNs were examined by serial sectioning and immunohistochemistry. All patients with metastatic SNs were recommended to undergo a radical selective lymph node dissection. RESULTS: The primary locations of the melanomas included the trunk (188), an upper limb (67), or a lower limb (147). Overall, 97 (24.1%) of the 402 SNs were metastatic. Interval SNs were observed in 18 patients, in all but 2 of whom classic SNs were also found. The location of the primary was truncal in 11 (61%) of the 18, upper limb in 5, and lower limb in 2. One patient with a dorsal melanoma had drainage exclusively in a cervicoscapular area that was shown on removal to contain not lymph node tissue but only a blue lymph channel without tumor cells. Apart from the interval SN, 13 patients had 1 classic SN area and 3 patients 2 classic SN areas. Of the 18 patients, 2 had at least 1 metastatic interval SN and 2 had a classic SN that was metastatic; overall, 4 (22.2%) of 18 patients were node-positive. CONCLUSION: We found that 2 of 18 interval SNs were metastatic: This study showed that preoperative lymphoscintigraphy must review all known lymphatic areas in order to exclude an interval SN.     

99mTc-human serum albumin: an effective radiotracer for identifying sentinel lymph nodes in melanoma.

Sentinel lymph node (SLN) biopsy has emerged as a novel approach for identifying patients with melanoma and regional nodal micrometastasis who may benefit from full nodal basin resection. To identify the pattern of tumor lymphatic drainage and the SLN, lymphoscintigraphy has been performed using primarily 99mTc-sulfur colloid (SC). In this study, we compare the efficacy of SLN biopsy using 99mTc-human serum albumin (HSA) with SLN biopsy after SC-based lymphoscintigraphy. METHODS: One hundred and six patients with localized cutaneous melanoma were studied. Lymphoscintigraphy was performed after intradermal injection of HSA in 85 patients and SC in 21 patients. Four patients underwent lymphoscintigraphy twice, once with SC and once with HSA. Dynamic images were acquired for up to 1 h, followed by high-count images of the SLN in various projections so that the most likely site was marked on the skin for biopsy. Intraoperatively, blue dye was injected around the primary site. Twenty-four patients underwent SLN dissection directed by preoperative lymphoscintigraphy and vital blue dye mapping; in the remaining 80 patients, a gamma probe was added intraoperatively to the localization procedure. Two patients underwent mapping with gamma probe alone. RESULTS: Draining lymphatic basins and nodes were identified by lymphoscintigraphy in all patients. The SLN was identified in 95% of patients when both blue dye and intraoperative gamma probe were used. When 99mTc-HSA was used for imaging, 98% of the SLNs ultimately identified were radiolabeled, and 82% were both hot and blue. Of the SLN recovered with SC, all the nodes were radiolabeled; however, there was only 58% hot and blue concordance. Greater numbers of SLNs were removed in the SC group (median 2.0 versus 1.0, P = 0.02); however, the incidence of micrometastasis was statistically similar in both HSA and SC cohorts. In the 4 patients examined with both tracers, SLN mapping was similar. CONCLUSION: Although SC has been the radiotracer of choice for SLN mapping in melanoma, HSA appears to be a suitable alternative, with identical success rates. In fact, the higher concordance between hot and blue nodes using HSA suggests superiority of this tracer for this purpose.