SPECT/CT sentinel lymph node identification in papillary thyroid cancer: lymphatic staging and surgical management improvement

Continuous innovation in precision radio-guided surgery

Since its origins, nuclear medicine has faced technological changes that led to modifying operating modes and adapting protocols. In the field of radioguided surgery, the incorporation of preoperative scintigraphic imaging and intraoperative detection with the gamma probe provided a definitive boost to sentinel lymph node biopsy to become a standard procedure for melanoma and breast cancer. The various technological innovations and consequent adaptation of protocols come together in the coexistence of the disruptive and the gradual. As obvious examples we have the introduction of SPECT/CT in the preoperative field and Drop-in probes in the intraoperative field. Other innovative aspects with possible application in radio-guided surgery are based on the application of artificial intelligence, navigation and telecare.

Sentinel lymph node mapping: current applications and future perspectives in thyroid carcinoma

Sentinel lymph node (SLN) mapping is a standard, minimally-invasive diagnostic method in the surgical treatment of many solid tumors, as for example melanoma and breast cancer, for detecting the presence of regional nodal metastases. A negative SLN accurately indicates the absence of metastases in the other regional lymph nodes (LN), thus avoiding unnecessary lymph nodal dissection. Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma (TC) with cervical LN metastases at diagnosis in 20-90%, and nodal involvement correlates with local persistence/recurrence. The SLN in PTC is an intraoperative method for staging preoperative N0 patients and for detecting metastatic LNs "in and outside" the cervical LN central compartment; it represents an alternative method to prophylactic central neck node dissection. In this review we summarize different methods and results of the use of SLN in TC. The SLN identification techniques currently used include the selective vital-dye (VD) method, 99mTc-nanocolloid planar lymphoscintigraphy with intraoperative use of a hand-held gamma probe (LS), the combination LS + VD, and the combination LS and preoperative SPECT-CT (LS + SPECT/CT). The application of the SLN procedure in TC has been described in many studies, however, the techniques are heterogeneous, and the role of SLN in TC, with indications, results, advantages and limits, is still debated.

The Diagnostic Accuracy of One-Step Nucleic Acid Amplification for Lymph Node Metastases of Papillary Thyroid Carcinoma： A Systematic Review and Meta-Analysis

BACKGROUND

One-step nucleic acid amplification (OSNA) analysis is a molecular diagnostic technique for lymph node metastases (LNMs) by quantifying cytokeratin 19(CK 19) mRNA. We aim to evaluate the intraoperative diagnostic accuracy of OSNA assay for LNMs of papillary thyroid carcinoma (PTC).

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were searched to retrieve related literature. A meta-analysis was performed using STATA11.0, Meta-Disc 1.4 and RevMan 5.3.

RESULTS

This meta-analysis included six studies involving 987 lymph nodes from 194 patients. The pooled sensitivity, specificity, and area under the summary receiver-operating characteristic curve (AUC) of OSNA for detecting LNM were 0.88, 0.90, and 0.95, respectively.

CONCLUSION

OSNA assay is an accurate molecular diagnosis for intraoperative detection of lymph node metastasis in PTC.

Para-tracheal neck dissection - is dissection of the upper part of level Ⅵ necessary?

Papillary thyroid carcinoma (PTC) has a high propensity for regional metastases, however, the impact of such metastases on the outcome of the patients is minimal. The central compartment of the neck is considered the first and the most common echelon of metastases from thyroid carcinoma. Physical examination along with ultrasonography are the gold standard pre-operative evaluation of patients with PTC. Ultrasonography is highly sensitive in evaluating lateral neck nodes, however, its value in evaluating the central compartment is limited, resulting in a relatively high rate of occult metastases in this compartment. The main potential complications of para-tracheal neck dissection (PTND) are recurrent laryngeal nerve paralysis and hypocalcemia and these may be higher in patients undergoing PTND compared to thyroidectomy alone. New histological data is available showing no evidence of lymph nodes in the central compartment above a level parallel to the inferior border of the cricoid cartilage. These findings support withholding dissection of the upper para-tracheal region routinely as a part of PTND in patients with well-differentiated thyroid cancer. By doing that, the complications may be lower and identical to thyroidectomy alone, thus may abolish arguments against more common use of elective PTND in patients with thyroid carcinoma.

Prophylactic lymph node dissection in clinically N0 differentiated thyroid carcinoma: example of personalized treatment

Considering the 'differentiated thyroid carcinoma (DTC) epidemic', the indolent nature of DTC imposes a treatment paradigm shift toward elimination of recurrence. Lymph node metastases in cervical compartments, encountered in 20-90% of DTC, are the main culprit of recurrent disease, affecting 5-30% of patients. Personalized risk-stratified cervical prophylactic lymph node dissection (PLND) at initial thyroidectomy in DTC with no clinical, sonographic or intraoperative evidence of lymph node metastases (clinically N0) has been advocated, though not unanimously. The present review dissects the controversy over PLND. Weighing the benefit yielded from PLND up against the PLND-related morbidity is so far hampered by the inconsistent profit yielded by PLND and the challenging patient selection. Advances in tailoring PLND are anticipated to empower optimal patient care.

Sentinel lymph node biopsy in medullary thyroid microcarcinomas

The aim of this prospective study was to analyze accuracy of sentinel lymph node biopsy with methylene blue dye for intraoperative detection of lateral metastases in clinically N0M0 medullary microcarcinomas with calcitonin <1,000 pg/mL and selection of true-positive patients for one-time therapeutic lateral dissection. In addition to total thyroidectomy and central neck dissection, all patients had bilateral sentinel biopsy of jugulo-carotid regions after methylene blue injection to decide upon necessity for lateral dissection. If sentinels were benign on frozen section, additional non-sentinels were extirpated, with no further lateral dissection. If sentinels were malignant, one-time lateral dissection was performed. 20 patients were included in this study. Hereditary disease form was observed in 3/20 (15%) of patients with RET proto-oncogene mutation C634F; remaining 17/20 (85%) were negative for germline mutations. There were no allergic reactions to methylene blue and identification rate of sentinels was 100%. In total, 2/20 (10%) cN0 patients had lymphonodal metastases, thus were reclassified as pN1b. Remaining 18/20 (90%) were classified pN0 based on standard pathohistology. Frozen section findings on sentinels were 100% match with standard pathohistology, and there were no skip metastases in lateral compartments. Sensitivity, specificity and accuracy of sentinel biopsy method with methylene dye and frozen section were 100%. Dzodic's sentinel lymph node biopsy method can be used for intraoperative assessment of lateral compartments and optimization of initial surgery of medullary microcarcinomas with calcitonin <1,000 pg/mL. This way, cN0 patients with sentinel metastases can receive one-time lateral dissection, and those without benefit from less extensive surgery.

The sentinel lymph node biopsy technique in papillary thyroid carcinoma: The issue of false-negative findings

BACKGROUND

The management of papillary thyroid carcinoma (PTC) is changed after introduction of sentinel lymph node biopsy (SNB) technique for nodal staging. Some debate still surrounds the accuracy of this procedure in terms of wide heterogeneity of sentinel lymph node detection and false-negative findings.

AIM

to identify the key issues which make it difficult the usefulness of SNB in PTC.

METHODS

A comprehensive computer literature search of meta-analyses published in PubMed/MEDLINE and Cochrane library database until June 30, 2019 was conducted. We used a search algorithm based on this combination of terms: (i) "thyroid neoplasm" or "thyroid cancer" or "thyroid carcinoma" or "thyroid malignancy" or "meta-analysis" or "systematic review") AND (ii) "sentinel lymph node biopsy".

RESULTS

Comparing 4 written meta-analyses published in the literature, the diagnostic performance of SNB technique in PTC has been summarized. Relatively high false-negative rates (FNR) were reported for each SNB methods: vital-dye (VD: 12.7%; 7%; 0-38%), 99mTc-nanocolloid planar lymphoscintigraphy with the use of intraoperative hand-held gamma probes (LS: 11.3%; 16%; 0-40%), combined LS with VD (LS+VD: 0%; 0-17%), LS with the additional contribution of preoperative SPECT/CT (7-8%).

CONCLUSION

Evidence-based data about the diagnostic performance of SNB in PTC are increasing. The nuclear medicine community should reach a consensus on the operational definition of the SLN to better guide the surgeon in identifying the lymph nodes most likely contain metastatic cells. Standardization of SLN identification, removal and analysis are required.

Sentinel Lymph Node Biopsy in Small Papillary Thyroid Cancer: A Meta-analysis

PURPOSE

The aim of this study was to compare reported results on available techniques for sentinel lymph node detection rate (SDR) in papillary thyroid cancer (PTC).

METHODS

The MEDLINE database was searched via a PubMed interface to identify original articles regarding sentinel lymph node biopsy (SNB) in thyroid cancer. Studies were stratified according to the sentinel lymph node (SLN) detection technique: vital-dye (VD), Tc-nanocolloid planar lymphoscintigraphy with the use of intraoperative hand-held gamma probes (LS), both Tc-nanocolloid planar lymphoscintigraphy with intraoperative use of hand-held gamma probe and VD (LS + VD), Tc-nanocolloid planar lymphoscintigraphy with the additional contribution of preoperative SPECT/CT, and intraoperative use of hand-held gamma probe (LS-SPECT/CT). Pooled SDR values were presented with a 95% confidence interval (CI) for each SLN detection techniques. A Z-test was used to compare pooled SDR estimates. False-negative rates were summarized for each method.

RESULTS

Forty-five studies were included. Overall SDRs for the VD, LS, LS + VD, and LS-SPECT/CT techniques were 83% (95% CI, 77%-88%; I = 78%), 96% (95% CI, 90%-98%; I = 68%), 87% (95% CI, 65%-96%; I = 75%), and 93% (95% CI, 86%-97%; I = 0%), respectively. False-negative rates were 0% to 38%, 0% to 40%, 0% to 17%, and 7% to 8%, respectively.

CONCLUSIONS

In patients with PTC, Tc-nanocolloids offer a higher SDR than that of the VD technique. The addition of SPECT/CT improved identification of metastatic SLNs outside the central neck compartment.

Sentinel lymph node biopsy in small papillary thyroid cancer. A review on novel surgical techniques

PURPOSE

Sentinel lymph node biopsy (SNB) in patients with papillary thyroid carcinoma (PTC) and negative for clinically neck lymph node metastatic involvement (N0) has emerged as a promising minimally invasive procedure to detect metastatic nodes.

METHODS

The MEDLINE database was searched via the PubMed interface on 10 January 2018 for the MeSH headings "sentinel lymph node biopsy" and "thyroid carcinoma".

RESULTS

Vital blue dye, radioisotope, and the combination of both techniques are used in PTC patients. These methods and the emerging role of SPECT/CT are discussed in this review. The sentinel lymph node (SLN) identification rates ranged from 0 to 100% for blue dye, 83 to 100% for radioisotopes, and 66 to 100% for the combination of both techniques, respectively.

CONCLUSIONS

SNB based on radioisotope technique with the use of intraoperative gamma-probe is an accurate and safe method that allows the highest SLN detection rate. There is sufficient evidence to propagate the increasing use of SNB procedure that has the potential to avoid prophylactic lymph node surgery in patients clinically N0.

One-step nucleic acid amplification analysis of sentinel lymph nodes in papillary thyroid cancer patients

INTRODUCTION

It is essential to look for methods to define the need for central lymphadenectomy for papillary thyroid cancer patients. The aim is to determine the efficacy of one-step nucleic acid amplification (OSNA) and sentinel lymph node (SLN) biopsy in the intraoperative detection of nodal involvement.

MATERIAL AND METHODS

This prospective, experimental study enrolled 49 patients with clinically negative lymph nodes. Intraoperatively, 1% Patent Blue dye was injected intratumorally. Lymph nodes that stained blue were defined as SLNs. They were directly cut into blocks at 2-mm intervals. Nonadjacent blocks were subjected to either the OSNA assay or histological examination.

RESULTS

Sixty-five SLNs were found in 43 (87.8%) patients. There were 20 (30.8%) histopathologically positive SLNs. According to the OSNA, 22 (33.8%) SLNs were positive. The OSNA results were different from histopathology in 8 (12.3%) SLNs. The OSNA gave a positive result in 5 (7.7%) SLNs, while they were not involved according to the histopathology. However, OSNA upstaged N status from N0 to N1 only in 2 (3.1%) patients. Inverse results (histopathology +, OSNA-) were obtained in 3 (4.6%) SLNs. Positive and negative predictive values (PPV and NPV) for OSNA were 0.77 and 0.93, respectively. The concordance rate between examinations was 85.5%.

CONCLUSIONS

In some patients with clinically negative lymph nodes, OSNA and SLN biopsy may prevent unnecessary central lymphadenectomy. On the other hand, the sentinel lymph node biopsy may reveal the presence of potentially involved sentinel lymph nodes outside the central compartment. These SLNs can also be assessed by means of OSNA.

Selective sentinel lymph node biopsy in papillary thyroid carcinoma in patients with no preoperative evidence of lymph node metastasis

INTRODUCTION

Lymphadenectomy is recommended during surgery for papillary thyroid carcinoma when there is evidence of cervical lymph node metastasis (therapeutic) or in high-risk patients (prophylactic) such as those with T3 and T4 tumors of the TNM classification. Selective sentinel lymph node biopsy may improve preoperative diagnosis of nodal metastases.

OBJECTIVE

To analyze the results of selective sentinel lymph node biopsy in a group of patients with papillary thyroid carcinoma and no evidence of nodal involvement before surgery.

PATIENTS AND METHOD

A retrospective, single-center study in patients with papillary thyroid carcinoma and no clinical evidence of lymph node involvement who underwent surgery between 2011 and 2013. The sentinel node was identified by scintigraphy. When the sentinel node was positive, the affected compartment was removed, and when sentinel node was negative, central lymph node dissection was performed.

RESULTS

Forty-three patients, 34 females, with a mean age of 52.3 (±17) years, were enrolled. Forty-six (27%) of the 170 SNs resected from 24 (55.8%) patients were positive for metastasis. In addition, 94 (15.6%) out of the 612 lymph nodes removed in the lymphadenectomies were positive for metastases. Twelve of the 30 (40%) low risk patients (cT1N0 and cT2N0) changed their stage to pN1, whereas 12 of 13 (92%) high risk patients (cT3N0 and cT4N0) changed to pN1 stage.

CONCLUSIONS

Selective sentinel lymph node biopsy changes the stage of more than 50% of patients from cN0 to pN1. This confirms the need for lymph node resection in T3 and T4 tumors, but reveals the presence of lymph node metastases in 40% of T1-T2 tumors.

Radio-Guided Lymph Node Mapping in Bladder Cancer Using SPECT/CT and Intraoperative γ-Probe Methods

PURPOSE

Lymph outflow from bladder tumor differs between individuals, making the prediction of the metastatic landing sites difficult. A "blind" template of lymphadenectomy has been tested as a solution to this problem. We believe that it is feasible to find methods enabling more precise lymph nodes (LNs) evaluation. The aims of our study were to evaluate the possibility of LNs mapping in case of muscle invasive bladder cancer (MIBC) and to compare the 2 methods of their detection.

PATIENTS AND METHODS

Our study group consisted of 38 cN0 MIBC patients. Lymph nodes mapping was performed by SPECT/CT lymphoscintigraphy using Tc-nanocolloid, followed by intraoperative verification with γ-ray probe. Lymph nodes with increased radiotracer uptake (hot spots) were removed, and then pelvic LNs dissection was conducted. Lymph nodes resected as hot spots and LNs resected with lymphadenectomy were separately examined by a pathologist.

RESULTS

An average of 3 hot spots (range, 1-5) were identified in each case. For 36 of 38 patients, both preoperative SPECT/CT and intraoperative γ-probe evaluation results were obtained. Ninety-five percent of hot spots were found distally and caudally to the uretero-iliac crossing; 5% were found proximal. Lymph nodes outside the pelvic LNs dissection area did not contain metastases. In 2 patients, metastases were found in LNs without increased radiotracer uptake, and the observed hot spots contained no metastases.

CONCLUSIONS

Radio-guided LNs mapping in case of MIBC is feasible. Preoperative detection of hot spots using SPECT/CT and intraoperative γ-ray detection probe gives similar results.

Radioguided sentinel lymph node biopsy in patients with papillary thyroid carcinoma

BACKGROUND

The ATA guidelines do not recommend prophylactic central compartment neck dissection in patients with T1-T2 papillary thyroid carcinoma (PTC) with no clinical evidence of lymph node metastasis, however patients' staging is recommended. Lymph node metastasis may be present also in small PTC, but preoperative ultrasound identifies suspicious cervical lymphadenopathy in 20-30% of patients. The role of sentinel lymph node biopsy (SLNB) remain open to debate. It has been shown that the identification rate of SLN in PTC patients is improved using a radiotracer compared to a dye technique. The aim of this systematic review was to evaluate the role of radioguided SLNB (rSLNB) in the treatment of PTC patients.

METHODS

A systematic search was performed in the PubMed and Embase database to identify all original articles regarding the application of rSLNB in PTC patients. The primary outcome was false negative rate (FNR) of the rSLNB; the secondary outcomes were SLN intraoperative identification rate (IIR), site of lymph node metastasis, and persistent disease during follow up.

RESULTS

Twelve studies were included. Most of PTC patients were T1-T2. The overall SLN IIR, SLN metastatic rate, and FNR were 92.1%, 33.6%, and 25.4%, respectively. Overall, lymph node metastasis were found in the central compartment (23.0%) and in the lateral compartments (10.6%). The persistent disease in patients who underwent SLNB associated to lymph node dissection (LND) in the same compartment of the SLN regardless of the SLN status was 0.6%.

CONCLUSIONS

In all PTC patients, also in T1-T2 stage, due to the high FNR the SLNB performed alone should be abandoned and converted into a technique to guide the lymphadenectomy in a specific neck compartment (i.e., central or lateral) based on the radioactivity, regardless of the SLN status, for better lymph node staging and selection of patients for postoperative radioiodine ablation.

Radioguided surgery and the GOSTT concept: From pre-operative image and intraoperative navigation to image-assisted excision

Radio-guided surgery has been developed for application in those disease scheduled for surgical management, particularly in areas of complex anatomy. This is based on the use of pre-operative scintigraphic planar, tomographic and fused SPECT/CT images, and the possibility of 3D reconstruction for the subsequent intraoperative locating of active lesions using handheld devices (detection probes, gamma cameras, etc.). New tracers and technologies have also been incorporated into these surgical procedures. The combination of visual and acoustic signals during the intraoperative procedure has become possible with new portable imaging modalities. In daily practice, the images offered by these techniques and devices combine perioperative nuclear medicine imaging with the superior resolution of additional optical guidance in the operating room. In many ways they provide real-time images, allowing accurate guidance during surgery, a reduction in the time required for tissue location and an anatomical environment for surgical recognition. All these approaches have been included in the concept known as (radio) Guided intraOperative Scintigraphic Tumour Targeting (GOSTT). This article offers a general view of different nuclear medicine and allied technologies used for several GOSTT procedures, and illustrates the crossing of technological frontiers in radio-guided surgery.

Utility of sentinel lymph node biopsy for thyroid cancer: a comprehensive review

Sentinel lymph node biopsy (SLNB) is a minimally invasive lymphatic mapping technique, used to identify lymph node micrometastases and stage multiple cancer types. Despite the performance of SLNB for thyroid cancer having been under study since 1998, its role has remained controversial. The objective of this review is to summarize current research reporting on SLNB for thyroid cancer, focusing on recent studies of its application to differentiated thyroid cancer. The technique and potential benefits of SLNB are reviewed with regards to its ability to identify lymph node metastases, aid in cancer prognostication, and direct surgical and medical treatment.

Synthesis of the first radiolabeled 188Re N-heterocyclic carbene complex and initial studies on its potential use in radiopharmaceutical applications

A novel approach towards the synthesis of radiolabeled organometallic rhenium complexes is presented. We successfully synthesized and analyzed the first (188)Re-labeled N-heterocyclic biscarbene complex, trans-dioxobis(1,1'-methylene-bis(3,3'-diisopropylimidazolium-2-ylidene))(188)rhenium(V) hexafluorophosphate ((188)Re-4) via transmetalation using an air-stable and moisture-stable silver(I) biscarbene complex. In order to assess the viability of this complex as a potential lead structure for in vivo applications, the stability of the (188)Re-NHC complex was tested in physiologically relevant media. Ultimately, our studies illustrate that the complex we synthesized dissociates rapidly and is therefore unsuitable for use in radiopharmaceuticals. However, it is clear that the transmetalation approach we have developed is a rapid, robust, and mild method for the synthesis of new (188)Re-labeled carbene complexes.