Computed tomography lymphography by transbronchial injection of iopamidol to identify sentinel nodes in preoperative patients with non–small cell lung cancer: A pilot study

Pulmonary interstitial lymphography: A prospective trial with potential impact on stereotactic ablative radiotherapy planning for early-stage lung cancer

This prospective feasibility trial investigated pulmonary interstitial lymphography to identify thoracic primary nodal drainage (PND). A post-hoc analysis of nodal recurrences was compared with PND for patients with early-stage lung cancer; larger studies are needed to establish correlation. Exploratory PND-inclusive stereotactic ablative radiotherapy plans were assessed for dosimetric feasibility.

Diversity of lymphatic flow in patients with lung cancer revealed by computed tomography lymphography

OBJECTIVES

This study was conducted to verify the optimal extent of lymph node dissection or sampling during lung cancer surgery based on the sentinel node (SN) map created by computed tomography (CT) lymphography.

METHODS

From April 2010 to January 2015, patients with clinical stage I non-small-cell lung cancer, who were candidates for lobectomy or segmentectomy with standard hilar and mediastinal lymph node dissection, and in whom bronchus reached the tumour, were enrolled. An ultrathin bronchoscope was inserted to the target bronchus under the guidance of virtual bronchoscopic navigation images. CT images of the chest were obtained 30 s after 2.5 ml of iopamidol was injected. SNs were identified when the maximum CT attenuation value of the lymph nodes on postcontrast CT images increased by 30 Hounsfield units or more compared with the precontrast images. Patients underwent lobectomy with standard lymph node dissection.

RESULTS

SNs were identified in 36 (87.8%) of the 41 patients. The average number of SNs was 1.6 (range, 1-4). There was 1 false negative case; therefore, the accuracy of SN identification was 97.2% (35/36). In 5 (13.9%) of 36 patients, SNs were outside the lobe-specific lymph node station range (#11i from right S1, #7 from right S1, #4R from right S8, #12u from right S8, #7 and #12l from left S1 + 2).

CONCLUSIONS

CT lymphography demonstrated the diversity of lymphatic spreading patterns and there were cases in which lymph flows are found outside the lymph node dissection range.

Long-term outcomes of sentinel node identification using indocyanine green in patients with lung cancer

BACKGROUND

Sentinel node (SN) biopsy is used in the management of numerous cancers to avoid unnecessary lymphadenectomy. This was a clinical exploration/feasibility study of a novel identification technique for SN biopsy using indocyanine green (ICG) fluorescence imaging during lung cancer surgery.

METHODS

SN biopsy using ICG was performed on 22 patients who had cT1 or T2N0M0 lung cancer. ICG was injected just around the primary tumor. The fluorescence imaging system enabled visualization of the lymphatic vessels draining from the primary tumor toward the lymph nodes. Fluorescently labeled nodes were dissected, and patients were followed-up for prognosis and recurrence to confirm the pattern of lymph node metastasis after surgery.

RESULTS

SNs were successfully identified in 16 (72.7%) of 22 patients. A total of 13 of 16 patients had pathological N0 and three had SN metastasis. The median follow-up time was 92.7 months. Only one patient had no SN metastasis at the postoperative pathological examination and lymph node metastasis during the follow-up period. The accuracy rate was 93.8% (15/16) and the false-negative rate was 7.7% (1/13).

CONCLUSIONS

SNs were identified by ICG fluorescence imaging, and this technique during lung cancer surgery had good identification and accuracy rates throughout the follow-up period.

KEY POINTS

SIGNIFICANT FINDINGS OF THE STUDY: We attempted to identify sentinel lymph nodes by indocyanine green in lung cancer surgery. The identification rate was 72.7%. The accuracy rate was 100% immediately after surgery, and 93.8% after follow-up.

WHAT THIS STUDY ADDS

Sentinel node biopsy by indocyanine green may be useful for lymph node dissection during lung cancer surgery to avoid unnecessary lymphadenectomy.

New Developments in Imaging for Sentinel Lymph Node Biopsy in Early-Stage Oral Cavity Squamous Cell Carcinoma

Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure that aims to identify the first draining lymph node(s) from the primary tumor, the sentinel lymph nodes (SLN), as their histopathological status reflects the histopathological status of the rest of the nodal basin. The routine SLNB procedure consists of peritumoral injections with a technetium-99m [^99mTc]-labelled radiotracer followed by lymphoscintigraphy and SPECT-CT imaging. Based on these imaging results, the identified SLNs are marked for surgical extirpation and are subjected to histopathological assessment. The routine SLNB procedure has proven to reliably stage the clinically negative neck in early-stage oral squamous cell carcinoma (OSCC). However, an infamous limitation arises in situations where SLNs are located in close vicinity of the tracer injection site. In these cases, the hotspot of the injection site can hide adjacent SLNs and hamper the discrimination between tracer injection site and SLNs (shine-through phenomenon). Therefore, technical developments are needed to bring the diagnostic accuracy of SLNB for early-stage OSCC to a higher level. This review evaluates novel SLNB imaging techniques for early-stage OSCC: MR lymphography, CT lymphography, PET lymphoscintigraphy and contrast-enhanced lymphosonography. Furthermore, their reported diagnostic accuracy is described and their relative merits, disadvantages and potential applications are outlined.

Sentinel lymph node biopsy for lung cancer

Sentinel lymph node biopsy is a technique to identify the first lymph node (or nodes) draining a tumor. The underlying principle is that as the first site of cancer spread, evaluation of the sentinel node will be most predictive for wider nodal involvement. The introduction of sentinel node biopsy revolutionized the surgical management of cutaneous melanoma and breast cancer, becoming a key component in the management of such patients. For over 20 years, thoracic surgeons have similarly worked to apply this technique to lung cancer but have thus far not had the same impact on lung surgery. In this review, we will summarize the ongoing discussions on the role of sentinel node biopsy in lung cancer, the methods for identifying the sentinel node, and the techniques for evaluating the sentinel node specimen. We will also highlight some of the pressing questions investigators should consider when designing a trial for sentinel node mapping. This will clarify the current status of sentinel node biopsy in lung cancer and thus highlight important future directions for research.

Minimally invasive electro-magnetic navigational bronchoscopy-integrated near-infrared-guided sentinel lymph node mapping in the porcine lung

Background

The use of near-infrared (NIR) fluorescence imaging with indocyanine green (ICG) for sentinel lymph node (SN) mapping has been investigated in lung cancer; however, this has not been fully adapted for minimally invasive surgery (MIS). The aim of our study was to develop a minimally invasive SN mapping integrating pre-operative electro-magnetic navigational bronchoscopy (ENB)-guided transbronchial ICG injection and intraoperative NIR thoracoscopic imaging.

Methods

A NIR thoracoscope was used to visualize ICG fluorescence. ICG solutions in a 96-well plate and ex vivo porcine lungs were examined to optimize ICG concentrations and injection volumes. Transbronchial ICG injection (n=4) was assessed in comparison to a traditional transpleural approach (n=3), where after thoracotomy an ICG solution (100μL at 100μg/mL) was injected into the porcine right upper lobe for SN identification. For further translation into clinical use, transbronchial ICG injection prior to thoracotomy followed by NIR thoracoscopic imaging was validated (n=3). ENB was used for accurate targeting in two pigs with a pseudo-tumor.

Results

The ICG fluorescence at 10 μg/mL was the brightest among various concentrations, unchanged by the distance between the thoracoscope and ICG solutions. Injected ICG of no more than 500μL showed a localized fluorescence area. All 7 pigs showed a bright paratracheal lymph node within 15 minutes post-injection, with persistent fluorescence for 60 minutes. The antecedent transbronchial ICG injection succeeded in SN identification in all 3 cases at the first thoracoscopic inspection within 20 minutes post-injection. The ENB system allowed accurate ICG injection surrounding the pseudo-tumors.

Conclusions

ENB-guided ICG injection followed by NIR thoracoscopy was technically feasible for SN mapping in the porcine lung. This promising platform may be translated into human clinical trials and is suited for MIS.

Current innovations in sentinel lymph node mapping for the staging and treatment of resectable lung cancer

Despite surgical resectability, early-stage lung cancer remains a challenge to cure. Survival outcomes are hindered by variable performance of adequate lymphadenectomy and the limitations of current pathologic nodal staging. Sentinel lymph node (SLN) mapping, a mainstay in the management of breast cancer and melanoma, permits targeted nodal sampling for efficient and accurate staging that can influence both intraoperative and adjuvant treatment decisions. Unfortunately, standard SLN identification techniques with blue dye and radiocolloid tracers have not been shown to be reproducible in lung cancer. In more recent years, intraoperative near-infrared image-guided lung SLN mapping has emerged as promising technology for the identification of the tumor-associated lymph nodes most likely to contain metastatic disease. Additionally, the clinical relevance of SLN mapping for lung cancer remains pressing, as the ability to identify micrometastatic disease in SLNs could facilitate trials to assess chemotherapeutic response and the clinical effect of occult nodal disease. This review outlines the status of lung cancer lymphatic mapping and techniques in development that may help close the gap between translational research in this field and routine clinical practice.

Lymphoscintigraphy in early-stage non-small cell lung cancer with technetium-99m nanocolloids and hybrid SPECT/CT: a pilot project

OBJECTIVE

The goal of our study was to determine if lymph node activity could be visualized using a hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) scanner with two commonly used colloidal lymphatic radiotracers--99mTc-antimony sulfide colloid (ASC) and 99mTc-filtered sulfur colloid (FSC) in the setting of low-stage non-small cell lung cancer (NSCLC).

METHODS

Patients undergoing CT-guided percutaneous lung biopsies for clinically suspected early-stage lung cancer were randomized to peri-lesional injection of 37 MBq (0.5 mL) of either ASC or FSC. SPECT/CT of the thorax was performed at either 1, 2, or 3 h post-injection. The images were reviewed to determine if lymph node activity separate from the injection site could be identified.

RESULTS

24 patients were included. Lymph node activity was identified in 50% of patients. A total of 15 lymph nodes with activity were visualized including 5 ipsilateral hilar, 6 ipsilateral mediastinal, and 4 distant locations. No contralateral mediastinal or hilar activity was visualized. There was a tendency to improved visualization with ASC and the longer 3 h wait time. Most patients also demonstrated significant pleural, tracheobronchial, and/or systemic activity.

CONCLUSIONS

SPECT/CT imaging can demonstrate lymph node activity separate from the injection site in at least some low-stage NSCLC patients with a perilesional injection of 99mTc nanocolloid tracers. Further investigation into the role of pre-operative lymphoscintigraphy with SPECT/CT in patients with lung cancer is warranted.

Intraoperative nodal staging: role of sentinel node technology

In cases of superficial malignancies such as melanoma or breast cancer, intraoperative lymph node mapping with a sentinel lymph node (SLN) biopsy is an effective and minimally invasive alternative to inguinal or axillary lymph node dissection for early-stage tumors. For primary lung cancer, although much effort has been made to investigate a variety of tracers, such as dyes, radioisotopes, magnetite, and iopamidol, for discerning SLNs, an appropriate agent that produces high identification and accuracy rates has yet to be developed. Further studies are needed to find an ideal tracer for practical use in patients with non-small cell lung cancer.

Accuracy of sentinel node biopsy in the staging of non-small cell lung carcinomas: systematic review and meta-analysis of the literature

BACKGROUND

Not all patients with non-small cell lung carcinoma (NSCLC) have mediastinal lymph node involvement and development of less invasive methods for evaluating mediastinal lymph nodes is important. Sentinel node biopsy has been used for NSCLC since 1999 to decrease the need for mediastinal lymph node dissection. In this review, we searched the literature in this regard and reported the results in a meta-analysis format.

METHODS

Medline, SCOPUS, and ISI web of knowledge were searched using: "(lung AND sentinel)" with no date or language limit. Any study with more than 5 patients and enough information to calculate detection rate and sensitivity was included.

RESULTS

Overall 47 and 43 studies (including subgroups) had the criteria for detection rate and sensitivity pooling respectively. Pooled detection rate was 80.6% [76.8-84%] and pooled sensitivity was 87% [83-90%]. Using radiotracers or both radiotracers and dyes had higher detection rate and sensitivity compared to dye alone. Among studies using radiotracers, highest detection rate was in intra-operative peri-tumoral injection group and highest sensitivity was in peri-tumoral pre-operative injection group. Emerging methods of sentinel node surgery including magnetic materials, fluorescent dyes, CT contrast agents, and carbon nano-particles had promising results.

CONCLUSIONS

Sentinel node mapping using radiotracers is a feasible technique for mediastinal lymph node staging of N0 NSCLC patients. Alternative methods of sentinel node mapping are promising and warrant further studies.