The use of SPECT/CT for anatomical mapping of lymphatic drainage in vulvar cancer: possible implications for the extent of inguinal lymph node dissection

Molecular image-guided surgery in gynaecological cancer: where do we stand?

PURPOSE

The aim of this review is to give an overview of the current status of molecular image-guided surgery in gynaecological malignancies, from both clinical and technological points of view.

METHODS

A narrative approach was taken to describe the relevant literature, focusing on clinical applications of molecular image-guided surgery in gynaecology, preoperative imaging as surgical roadmap, and intraoperative devices.

RESULTS

The most common clinical application in gynaecology is sentinel node biopsy (SNB). Other promising approaches are receptor-target modalities and occult lesion localisation. Preoperative SPECT/CT and PET/CT permit a roadmap for adequate surgical planning. Intraoperative detection modalities span from 1D probes to 2D portable cameras and 3D freehand imaging.

CONCLUSION

After successful application of radio-guided SNB and SPECT, innovation is leaning towards hybrid modalities, such as hybrid tracer and fusion of imaging approaches including SPECT/CT and PET/CT. Robotic surgery, as well as augmented reality and virtual reality techniques, is leading to application of these innovative technologies to the clinical setting, guiding surgeons towards a precise, personalised, and minimally invasive approach.

Detection of sentinel lymph node in vulvar cancer using 99mTc-labeled colloid lymphoscintigraphy, blue dye, and indocyanine-green fluorescence: a meta-analysis of studies published in 2010-2020

OBJECTIVES

Sentinel lymph node (SLN) biopsy is widely accepted in the surgical staging of early vulvar cancer, although the most accurate method for its identification is not yet defined. This meta-analysis aimed to determine the technique with the highest pooled detection rate (DR) for the identification of SLN and compare the average number of SLNs detected by planar lymphoscintigraphy (PL), single-photon emission computed tomography/computed tomography (SPECT/CT), blue dye and indocyanine green (ICG) fluorescence.

METHODS

The meta-analysis was conducted according to the PRISMA guideline. The search string was: "sentinel" and "vulv*", with date restriction from 1st January 2010 until Dec 31st, 2020. Three investigators selected studies based on: (1) a study cohort or a subset of a minimum of 10 patients with vulvar cancer undergoing either PL, SPECT/CT, blue-dye, or ICG fluorescence for the identification of SLN; (2) the possibility to extrapolate the DR or the average number of SLNs detected by a single technique (3) no evidence of other malignancies in the patient history.

RESULTS

A total of 30 studies were selected. In a per-patient and a per-groin analysis, the DR for SLN of PL was respectively 96.13% and 92.57%; for the blue dye was 90.44% and 66.21%; for the ICG, the DR was 91.90% and 94.80%. The pooled DR of SPECT/CT was not calculated, since only two studies were performed in this setting. At a patient-based analysis, no significant difference was documented among PL, blue dye, and ICG (p = 0.28). At a per-groin analysis, PL and ICG demonstrated a significantly higher DR compared to blue dye (p < 0.05). The average number of SLNs, on a per-patient analysis, was available only for PL and ICG with a median number of 2.61 and 1.78 lymph nodes detected, respectively, and no significant statistical difference.

CONCLUSIONS

This meta-analysis favors the use of ICG and PL alone and in combination over blue dye for the identification of the SLN in vulvar cancer. Future studies may investigate whether the combined approach allows the highest DR of SLN in patients with vulvar cancer.

Lymphatic mapping and sentinel node biopsy in vulvar melanoma: the first multicenter study and systematic review

OBJECTIVE

This multicenter study aimed to investigate the role of preoperative lymphatic mapping and sentinel node biopsy (SNB) as well as the impact of negative SNB on loco-regional control and survival in vulvar melanoma patients with clinically negative nodes (cN0).

METHODS

Patients who had a proven vulvar melanoma with a Breslow thickness of 1-4 mm, cN0 and underwent a preoperative lymphatic mapping followed by SNB between July 2013 and March 2021 were retrospectively included. Groin recurrence and mortality rate were calculated as absolute and relative frequency. Disease-free survival (DFS) and overall survival (OS) were assessed by the Kaplan-Meier method. We provided a systematic review, searching among PubMed/Medline and Embase libraries. A total of 6 studies were identified (48 patients).

RESULTS

A total of 18 women were included. Preoperative planar images showed 51 SNs in 28 groins. Additional SPECT/CT images were acquired in 5/18 cases; SNs were identified pre- and intra-operatively in all cases. A total of 65 SNs were excised from 28 groins. A total of 13/18 (72.2%) patients (21/28 groins, 75%) had negative SNs with no groin recurrences and 12/13 (92.3%) were still alive at last follow-up. Five out of the 18 (27.8%) patients (7/28 groins, 25%) had positive SNs, 2/5 (40%) patients died of cancer after 26.2 and 33.8 months, respectively. The median DFS and OS for the entire cohort were 17.9 months (95% CI, 10.3-19.9) and 65.0 months (95% CI, 26.2-infinite), respectively. The probability of DFS and OS at 3 years were 15.5% (95% CI, 2.6-38.7) and 64.3% (95% CI, 15.5-90.2), respectively.

CONCLUSIONS

The use of preoperative lymphatic mapping followed by SNB permits a precise and minimally invasive surgical approach in cN0 vulvar melanoma patients. Negative SNB is associated with low risk of groin relapse and good survival.

Can late lymphoscintigraphy be omitted in the sentinel node procedure in early-stage vulvar cancer?

INTRODUCTION

In the Netherlands, the sentinel lymph node procedure protocol consists of preoperative lymphoscintigraphy combined with intraoperative blue dye for identifying sentinel lymph nodes in early vulvar squamous cell carcinoma. This study aimed at investigating the role of early and late lymphoscintigraphy.

MATERIAL AND METHODS

From January 2015 to January 2019, early and late lymphoscintigraphies of 52 women were retrospectively analyzed. Lymphoscintigraphy was performed 30 minutes (early) and 2.5-4 hours (late) after vulvar injection of ^99m Tc-labeled nanocolloid. We calculated the concordance correlation coefficient (CCC) between number of sentinel lymph nodes detected on both images using the Lins concordance coefficient and correlated with clinicopathological data.

RESULTS

Thirty-four women had a midline tumor and 18 had a lateral tumor. Detection rates with early and late scintigraphy were 88.5% and 98.1%, respectively. Median number of detected nodes was 1.0 (0-7) and 2.0 (0-7). Good statistical correlation between number of sentinel lymph nodes detected on early and late imaging was found (CCC = 0.76) in most patients. In 18 women (35%) a mismatch occurred: a higher number of nodes was detected on late imaging. In 11 of 18 women re-injection was performed because no sentinel lymph nodes were visualized on early images. Late imaging and intraoperative detection showed a good statistical correlation (CCC = 0.61). One woman showed an isolated groin recurrence despite negative sentinel lymph nodes.

CONCLUSIONS

This study showed good statistical correlations between early and late scintigraphy in most patients. However, in 35% of women late scintigraphy detected more nodes. In case of poor visualization after the first scintigraphy, re-injection should be considered. Late scintigraphy is probably helpful in confirming successful re-injection and in showing deviating lymph flow in women with failed mapping after the first injection and successful re-injection. Because missing metastatic sentinel lymph nodes often leads to a poor prognosis, we prefer optimal correlations between imaging and intraoperative identification. Hence, late scintigraphy cannot be safely omitted.

A Review of Nuclear Medicine Approaches in the Diagnosis and the Treatment of Gynecological Malignancies

Nuclear medicine is defined as the diagnosis and the treatment of disease using radiolabeled compounds known as radiopharmaceuticals. Single-photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computer tomography (PET/CT) based radiopharmaceuticals have proven reliable in diagnostic imaging in nuclear medicine and cancer treatment. One of the most critical cancers that also relies on an early diagnosis is gynecological cancer. Given that approximately 25% of all cancers in developing countries are a subset of gynecological cancer, investigating this cancer subtype is of significant clinical worth, particularly in light of its high rate of mortality. With accurate identification of high grade distant abdominal endometrial cancer as well as extra abdominal metastases, 18F-Fluorodeoxyglucose ([18F]FDG) PET/CT imaging is considered a valuable step forward in the investigation of gynecological cancer. Considering these factors, [18F]FDG PET/CT imaging can assist in making management of patient therapy more feasible. In this literature review, we will provide a short overview of the role of nuclear medicine in the diagnosis of obstetric and gynecological cancers.

Medial Inguino-Femoral Lymphadenectomy for Vulvar Cancer: An Approach to Decrease Lymphedema without Compromising Survival

Simple Summary

This prospective study has demonstrated that if the inguinal nodes medial to the lateral border of the femoral artery and the femoral nodes are negative in patients with vulvar cancer, the chances of having a positive node lateral to the artery are less than 1 in 10,000. About one-third of groin nodes are situated lateral to the femoral artery, so leaving these nodes in situ if the medial nodes are negative should significantly decrease the incidence and severity of lower limb lymphedema, without compromising survival.

Abstract

Background: Lower limb lymphedema is a long-term complication of inguino-femoral lymphadenectomy and is related to the number of lymph nodes removed. Our hypothesis was that lymph nodes lateral to the femoral artery could be left in situ if the medial nodes were negative, thereby decreasing this risk. Methods: We included patients with vulvar cancer of any histological type, even if the cancer extended medially to involve the urethra, anus, or vagina. We excluded patients whose tumor extended (i) laterally onto the thigh, (ii) posteriorly onto the buttocks, or (iii) anteriorly onto the mons pubis. After resection, the inguinal nodes were divided into a medial and a lateral group, based on the lateral border of the femoral artery. Results: Between December 2010 and July 2018, 76 patients underwent some form of groin node dissection, and data were obtained from 112 groins. Approximately one-third of nodes were located lateral to the femoral artery. Positive groin nodes were found in 29 patients (38.2%). All patients with positive nodes had positive nodes medial to the femoral artery. Five patients (6.6%) had positive lateral inguinal nodes. The probability of having a positive lateral node given a negative medial node was estimated to be 0.00002. Conclusion: Provided the medial nodes are negative, medial inguino-femoral lymphadenectomy may suffice and should reduce lower limb lymphedema without compromising survival.

MRI Staging in Locally Advanced Vulvar Cancer: From Anatomy to Clinico-Radiological Findings. A Multidisciplinary VulCan Team Point of View

MR imaging provides excellent spatial and contrast resolution to stage locally advanced vulvar cancer (LAVC) for tumor and nodal evaluation in order to facilitate the planning of treatment. Although there are no standard indications for how to estimate the clinical stage of International Federation of Gynecology and Obstetrics at diagnosis, MR imaging can depict the tumor and its extension to the vulvar region and adjacent organs, such as the vagina, urethra, and anus. Optimizing the MR imaging protocol and technique is fundamental for correct staging. The aim of this overview was to focus on the role of MR imaging in LAVC staging. We define vulvar anatomy and corresponding MR imaging findings, MR imaging protocol, and technique. Moreover, we describe the MR imaging findings of LAVC with example cases stage by stage. Key imaging findings based on signal intensity, diffusion restriction, and enhancement are portrayed to correctly identify and stage vulvar cancer. A structured report for LAVC staging is reported in order to give all necessary information to the clinicians and to facilitate MR imaging comprehension.

Safety and Benefit Of Sentinel Lymph Nodes Biopsy Compared to Regional Lymph Node Dissection in Primary Vulvar Cancer Patients Without Distant Metastasis and Adjacent Organ Invasion: A Retrospective Population Study

Background

The safety and benefit of sentinel lymph node biopsy (SLNB) compared with regional lymph node dissection (RLND) and no lymph nodes removed (NA) in patients with vulvar squamous cell cancer (VSCC) was not well studied.

Methods

A retrospective analysis on VSCC patients without distant metastasis and adjacent organ invasion from the Surveillance, Epidemiology, and End Results Program database between 2004 and 2016 was carried out. Within subgroups stratified by negative (LN−) or positive (LN+) regional lymph node findings, inverse probability weighting (IPW) adjusted multivariate Fine-Gray compete risk (CR) model and accelerated failure time (AFT) model was used to investigate the factors associated with and cancer-specific survival (CSS) and overall survival (OS).

Results

Of the 3,161 VSCC patients treated with surgery, 287 (9.1%) underwent SLNB, 1,716 (54.3%) underwent RLND, and 1,158 (36.6%) had no regional lymph nodes removed. As illustrated by IPW adjusted multivariate regressions, SLNB was significantly associated with prolonged CSS (LN−, adjusted sub-proportional hazard ratio [sHR] = 0.42; 95% confidence interval [CI], 0.19–0.93; P=0.032; LN+, adjusted sHR = 0.29; 95% CI, 0.16–0.54, P<0.001) and OS (LN−, adjusted time ratio [TR] = 1.38; 95% CI, 0.82–2.32; P=0.226; LN+, adjusted TR = 2.68; 95% CI, 1.73–4.14; P<0.001), although the effect of SLNB on OS was not significant within the LN− cohort. Moreover, SLNB led to improved CSS (adjusted sHR = 0.40; 95% CI, 0.23–0.70; P = 0.001) and OS (adjusted TR=1.15, 95% CI 0.76-1.73, P=0.279) compared with NA. Age was a significant prognostic factor of CSS and OS, whereas tumor size, surgery type, and invasion depth were not.

Conclusions

SLNB leads to significantly prolonged CSS and OS in VSCC surgery patients without distant metastasis and adjacent organ invasion than RLND, except for the similar OS in the LN− cohort. SLNB could be carried out preferentially for VSCC surgery patients without distant metastasis and adjacent organ invasion, irrespective of tumor size, surgery type, invasion depth, and regional lymph nodes metastasis. Further prospective clinical trials are warranted to confirm the findings of this study.

Lymphadenectomy in the Management of Gynecologic Cancer

Among nearly all gynecologic cancers, knowing whether the cancer has metastasized to lymph nodes impacts the ultimate management of the cancer. Lymph node status assists in cancer staging, prognostication, guidance of surgical intervention and adjuvant therapy, and removal of positive lymph nodes may be therapeutic in some cancers. Surgical staging through lymph node removal and pathologist assessment is standard of care for most gynecologic cancers. This section reviews the anatomic lymphatic drainage patterns of each gynecologic organ and the evolution and current practice of surgical lymph node assessment along the spectrum of gynecologic cancers.

Sentinel lymph node biopsy procedure in squamous vulvar cancer. 10 years follow-up analysis

AIM

Application of sentinel lymph node biopsy (SLNB) procedure in early-stage vulvar cancer and analysis of results, recurrences and complications.

MATERIAL AND METHODS

40 patients with vulvar cancer and SLNB between 2008 and 2018 were retrospectively reviewed. During the surgical procedure the inguinofemoral lymph nodes were checked with a gamma probe to identify the sentinel nodes that were removed and referred for intraoperative pathological assessment. Subsequently, long-term patient follow-up was performed with analysis of complications, relapse and mortality.

RESULTS

40 patients (mean age: 72 years [47-86], the overall detection rate per patient was 95% and a total of 129 Sentinel Lymph Nodes (SLNs) were removed (3.22 SLN/patient). In 3 out of 25 patients with lateral tumour lesions drainage was bilateral and in 2 out of 15 with midline lesions drainage was unilateral. On lymphoscintigraphy, 16 out of 40 had bilateral drainage and 24 unilateral. A total of 119 SLN- and 10 SLN+ were obtained, in 8 out of 10 an inguinofemoral lymphadenectomy was performed. In the SLN- group, one case of lymphatic blockage and one false negative were included. In 12 out of 40 patients there were post-surgical complications, 4 of them lymphoedemas. In the median follow-up (40 months), 6 out of 10 with SLN+ (40% mortality) and 7 out of 30 SLN- (16% mortality) had recurrences.

CONCLUSIONS

SLNB in vulvar cancer is the technique of choice for correct staging and locoregional therapy. Correct clinical lymph node staging is important before surgery in order to avoid potential blockage drainages which could induce a false negative SLN.

Lymphoscintigraphy and sentinel lymph node biopsy in vulvar carcinoma: update from a European expert panel

PURPOSE

This study aimed to update the clinical practice applications and technical procedures of sentinel lymph node (SLN) biopsy in vulvar cancer from European experts.

METHODS

A systematic data search using PubMed/MEDLINE database was performed up to May 29, 2019. Only original studies focused on SLN biopsy in vulvar cancer, published in the English language and with a minimum of nine patients were selected.

RESULTS

Among 280 citations, 65 studies fulfilled the inclusion criteria. On the basis of the published evidences and consensus of European experts, this study provides an updated overview on clinical applications and technical procedures of SLN biopsy in vulvar cancer.

CONCLUSIONS

SLN biopsy is nowadays the standard treatment for well-selected women with clinically negative lymph nodes. Negative SLN is associated with a low groin recurrence rate and a good 5-year disease-specific survival rate. SLN biopsy is the most cost-effective approach than lymphadenectomy in early-stage vulvar cancer. However, future trials should focus on the safe extension of the indication of SLN biopsy in vulvar cancer. Although radiotracers and optical agents are widely used in the clinical routine, there is an increasing interest for hybrid tracers like indocyanine-^99mTc-nanocolloid. Finally, it is essential to standardise the acquisition protocol including SPECT/CT images, and due to the low incidence of this type of malignancy to centralise this procedure in experienced centres for personalised approach.

Lower-Limb Lymphatic Drainage Pathways and Lymph Nodes: A CT Lymphangiography Cadaver Study

Background Most lymphatic imaging examinations of the lower limb require intradermal or subcutaneous injection of tracer material into the foot to demonstrate the lymphatic vessels; however, no standard protocol exists, and single or multiple injections are applied at different sites. Purpose To determine the three-dimensional relationships between each lymphatic group of the lower limb and corresponding regional lymph nodes. Materials and Methods A total of 130 lower limbs (55 from men and 75 from women) from 83 fresh human cadavers were studied. Lymphatic vessels were first visualized by using indocyanine green fluorescent lymphography with 19 injection sites in the foot, classified into four distinct lymphatic groups (anteromedial, anterolateral, posteromedial, and posterolateral); dilute oil-based contrast material was then injected. Next, specimens were scanned with CT and three-dimensional images were analyzed. Results The anteromedial and anterolateral lymphatic groups of the lower-leg lymphatic vessels were independent of each other and connected to different regional lymph nodes in the inguinal region. The posteromedial group and the anteromedial group in the lower leg drained to the same inguinal lymph nodes. Only the posterolateral group of lymphatic vessels in the lower leg drained to the popliteal lymph nodes. Leg lymphatic drainage pathways were independent of genital pathways. Conclusion Standard injection sites at the web spaces between the toes did not help visualize some lymph nodes of the lower leg. Additional injection sites in the medial, lateral, and posterior aspect of the foot would be better for evaluating the whole lymphatic pathways and regional lymph nodes and for improving understanding of leg lymphedema. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Weiss and Liddel in this issue.

Two decades of SPECT/CT - the coming of age of a technology: An updated review of literature evidence

PURPOSE

Single-photon emission computed tomography (SPECT) combined with computed tomography (CT) was introduced as a hybrid SPECT/CT imaging modality two decades ago. The main advantage of SPECT/CT is the increased specificity achieved through a more precise localization and characterization of functional findings. The improved diagnostic accuracy is also associated with greater diagnostic confidence and better inter-specialty communication.

METHODS

This review presents a critical assessment of the relevant literature published so far on the role of SPECT/CT in a variety of clinical conditions. It also includes an update on the established evidence demonstrating both the advantages and limitations of this modality.

CONCLUSIONS

For the majority of applications, SPECT/CT should be a routine imaging technique, fully integrated into the clinical decision-making process, including oncology, endocrinology, orthopaedics, paediatrics, and cardiology. Large-scale prospective studies are lacking, however, on the use of SPECT/CT in certain clinical domains such as neurology and lung disorders. The review also presents data on the complementary role of SPECT/CT with other imaging modalities and a comparative analysis, where available.

The sentinel node approach in gynaecological malignancies

This review discusses the state-of-the-art of sentinel lymph node mapping in gynaecological malignancies, including cervical cancer, endometrial cancer, and vulvar cancer, with an emphasis on new technological advances. For this objective, PubMed/MEDLINE was searched for relevant studies about the sentinel lymph node procedure in gynaecology. In particular, the use of preoperative lymphatic mapping with lymphoscintigraphy and single photon emission tomography/computed tomography (SPECT/CT) was identified in 18 studies. Other recent advances as hybrid tracers (e.g. ICG-^99mTc-nanocolloid) and intraoperative tools (portable γ-camera and 3D navigation devices) appear to also represent a useful guide for the surgeon during the operation. Concerning vulvar and cervical cancers, the sentinel lymph node procedure has been incorporated to the current guidelines in Europe and North America, whereas for endometrial cancer it is considered investigative.