Magnetic detection of sentinel lymph node in papillary thyroid carcinoma: The MAGIC-PAT study results

The diagnosis and management of small and indeterminate lymph nodes in papillary thyroid cancer: preoperatively and intraoperatively

Although thyroid cancer is an indolent tumor with a favorable prognosis, lymph node metastasis (LNM) serves as a major concern for many patients. Because LNM is strongly correlated with recurrence, distant metastasis, and shortened survival, a precise and timely diagnosis and following appropriate management for LNM are necessary. However, significant challenges still exist in the diagnosis of small LNs (<1 cm in diameter), and their low volume makes it difficult to determine whether they are metastatic or benign. Therefore, the diagnostic technique for these small and indeterminate LNs (siLNs) has been one of the leading research subjects in recent years. The implementation of innovative technologies, such as contrast-enhanced ultrasonography, frozen section, and molecular detection, has brought great progress to the diagnosis of siLNs. Meanwhile, the strategies for managing siLNs in clinical practice have evolved considerably over the past several years, with several appropriate options recommended by guidelines. In this review, we aim to provide a systematic overview of the latest studies and potential evidence about effective approaches for detecting and evaluating siLNs. Furthermore, the following management modalities of siLNs in different situations are well discussed.

Sentinel node mapping in thyroid cancer: an overview

In this paper we describe the current status of sentinel node mapping (SNM) in thyroid tumors and its potential perspectives. SNM in thyroid cancer has been tested since the end of the twentieth century, mainly in papillary thyroid cancer (PTC) and in medullary thyroid cancer (MTC). In PTC, it has been employed to find occult lymph node metastases in the central compartment of the neck as an alternative or indication for prophylactic dissection, by several methods. All of them have proven effective in spotting sentinel nodes, but the results have been somewhat diminished by uncertainty about the clinical significance of occult metastases in differentiated thyroid cancer. SNM in MTC has also been used to find occult lymph node metastases in the lateral compartments of the neck, also with excellent results hindered by a similar doubt about the real clinical significance of MTC micrometastases. Well designed, adequately sized randomized controlled trials are lacking, so SNM in thyroid tumors remains an interesting yet experimental methodology. New technology is emerging that could facilitate such studies, which could add solid information about the clinical significance of occult neck metastases in thyroid cancer.

A Comprehensive Grading System for a Magnetic Sentinel Lymph Node Biopsy Procedure in Head and Neck Cancer Patients

Simple Summary

With 30% of clinically negative early-stage oral cancer patients harboring occult metastasis, an accurate staging of metastatic lymph nodes (LN) is of utmost importance for treatment planning. A magnetic sentinel lymph node biopsy (SLNB) procedure is offered as an alternative to conventional SLNB in oral oncology, however, a grading system is missing. A proper grading system is preferred to connect the different components of the magnetic SLNB: preoperative imaging, intraoperative detection, and histopathological examination of sentinel lymph nodes (SLNs). This study aims to provide a first grading system based on the distribution of a magnetic tracer, by means of preoperative magnetic resonance imaging (MRI), intraoperative estimation of iron content, and histopathological assessment of resected nodes. Pre- and post-operative MRI and harvested SLNs of eight tongue cancer patients with successful magnetic SLNB procedure were used for analyses.

Abstract

A magnetic sentinel lymph node biopsy ((SLN)B) procedure has recently been shown feasible in oral cancer patients. However, a grading system is absent for proper identification and classification, and thus for clinical reporting. Based on data from eight complete magnetic SLNB procedures, we propose a provisional grading system. This grading system includes: (1) a qualitative five-point grading scale for MRI evaluation to describe iron uptake by LNs; (2) an ex vivo count of resected SLN with a magnetic probe to quantify iron amount; and (3) a qualitative five-point grading scale for histopathologic examination of excised magnetic SLNs. Most SLNs with iron uptake were identified and detected in level II. In this level, most variance in grading was seen for MRI and histopathology; MRI and medullar sinus were especially highly graded, and cortical sinus was mainly low graded. On average 82 ± 58 µg iron accumulated in harvested SLNs, and there were no significant differences in injected tracer dose (22.4 mg or 11.2 mg iron). In conclusion, a first step was taken in defining a comprehensive grading system to gain more insight into the lymphatic draining system during a magnetic SLNB procedure.

Magnetometer-Guided Sentinel Lymph Node Dissection in Prostate Cancer: Rate of Lymph Node Involvement Compared with Radioisotope Marking

Simple Summary

Pelvic lymph node dissection is recommended in prostate cancer according to the patients’ individual risk for nodal metastases. Targeted removal of sentinel lymph nodes increases the number of detected lymph node metastases in patients with prostate cancer. We previously established magnetometer-guided sentinel lymph node dissection in patients with prostate cancer to overcome logistical and technical disadvantages associated with the standard radioisotope-guided technique. This retrospective study compared the magnetometer-guided and standard techniques in terms of their ability to detect lymph node metastases. Using the magnetometer-guided technique, more sentinel lymph nodes were detected per patient. The detected rates of lymph node involvement matched the predictions in both techniques equally well. Our findings confirm the reliability of magnetometer-guided sentinel lymph node dissection and highlight the importance of the sentinel technique for detecting lymph node metastases in prostate cancer.

Abstract

Sentinel pelvic lymph node dissection (sPLND) enables the targeted removal of lymph nodes (LNs) bearing the highest metastasis risk. In prostate cancer (PCa), sPLND alone or combined with extended PLND (ePLND) reveals more LN metastases along with detecting sentinel LNs (SLNs) outside the conventional ePLND template. To overcome the disadvantages of radioisotope-guided sPLND in PCa treatment, magnetometer-guided sPLND applying superparamagnetic iron oxide nanoparticles as a tracer was established. This retrospective study compared the nodal staging ability between magnetometer- and radioisotope-guided sPLNDs. We analyzed data of PCa patients undergoing radical prostatectomy and magnetometer- (848 patients, 2015–2021) or radioisotope-guided (2092 patients, 2006–2015) sPLND. To reduce heterogeneity among cohorts, we performed propensity score matching and compared data considering sentinel nomogram-based probabilities for LN involvement (LNI). Magnetometer- and radioisotope-guided sPLNDs had SLN detection rates of 98.12% and 98.09%, respectively; the former detected more SLNs per patient. The LNI rates matched nomogram-based predictions in both techniques equally well. Approximately 7% of LN metastases were detected outside the conventional ePLND template. Thus, we confirmed the reliability of magnetometer-guided sPLND in nodal staging, with results comparable with or better than radioisotope-guided sPLND. Our findings highlight the importance of the sentinel technique for detecting LN metastases in PCa.

Magnetic detection of sentinel nodes in oral squamous cell carcinoma by means of superparamagnetic iron oxide contrast

The aim was to evaluate sentinel node detection capacity by means of a magnetic probe in 11 patients with oral squamous cell carcinoma at stages T1-T2 received submucosal injections of a superparamagnetic iron oxide contrast agent (SPIO). A magnetic probe was used for sentinel node biopsy. The use of SPIO and magnetic probes in the early stages of oral cancer may offer an alternative to conventional radioisotope techniques and/or elective neck dissection.