Sentinel node biopsy using a magnetic tracer versus standard technique: the SentiMAG Multicentre Trial

Match detection analysis on SentiMag® system and standard technique in SLNB of breast cancer

INTRODUCTION

In breast cancer surgery, there are techniques for sentinel lymph node biopsy (SLNB) that do not require Nuclear Medicine, such SentiMag®, which uses ferromagnetic particles. The main purpose of this analysis is to study the degree of concordance in SLNB between SentiMag® and the standard method (Tc99 radiotracer). The secondary objective is to identify factors that impact in sentinel node detection rate and matching detection rate between both probes.

METHODS

Observational and retrospective study performed from January to December 2021 focused on patients undergoing breast surgery and SLNB who were injected with both tracers, the ferromagnetic SentiMag® and Tc99 radiotracer. Once the diagnostic accuracy tests were performed, a further evaluation of the detection rate for each probe and the concordance between probes were accomplished. After those results, a deeper analysis of differences in detection rates for each probe and concordance between probes were assessed for various factors: neoadjuvant therapy, BMI, mitotic index, and triple-negative immunohistochemical profile.

RESULTS

The clinical study had a sample size of 70 patients. The overall false-negative rate (FNR) was 4.3%. The detection rate was the same for each technique (85.7%). A total of 106 nodes were biopsied, with a concordance rate of 70.75%. Significant differences were found in concordant nodes according to neoadjuvant therapy (p-value 0.012). For the Ki-67 factor (<20 or ≥20), significant differences were found in detected nodes (p-value 0.031 gamma probe; p-value 0.124 SentiMag®).

CONCLUSIONS

The detection rates of SentiMag® and the gamma probe are equivalent. The application of the dual technique minimizes the FNR. A high mitotic index affects the detection rate of the gamma probe, and neoadjuvant therapy negatively impacts the concordance rate.

Research on Spatial Localization Method of Magnetic Nanoparticle Samples Based on Second Harmonic Waves

Existing magnetic tracer detection systems primarily rely on fundamental wave signal acquisition using non-differential sensor configurations. These sensors are highly susceptible to external interference and lack tomographic localization capabilities, hindering their clinical application. To address these limitations, this paper presents a novel method for achieving the deep spatial localization of tracers. The method exploits second harmonic signal detection at non-zero field points. By considering the combined nonlinear characteristics of the coil's axial spatial magnetic field distribution and the Langevin function, a correlation model linking the signal peak and bias field is established. This model enables the determination of the tracer's precise spatial location. Building on this framework, a handheld device for localizing magnetic nanoparticle tracers was developed. The device harnesses the second harmonic response generated by coupling an AC excitation field with a DC bias field. Our findings demonstrate that under conditions of reduced coil turns and weak excitation fields, the DC bias field exhibits exclusive dependence on the axial distance of the detection point, independent of particle concentration. This implies that the saturated DC bias field corresponding to the second harmonic signal can be used to determine the magnetic nanoparticle sample detection depth. The experimental results validated the method's high accuracy, with axial detection distance and concentration reduction errors of only 4.8% and 4.1%, respectively. This research paves the way for handheld probes capable of tomographic tracer detection, offering a novel approach for advancing magnetically sensitive biomedical detection technologies.

Surface Engineering of Magnetic Iron Oxide Nanoparticles for Breast Cancer Diagnostics and Drug Delivery

Data published in 2020 by the International Agency for Research on Cancer (IARC) of the World Health Organization show that breast cancer (BC) has become the most common cancer globally, affecting more than 2 million women each year. The complex tumor microenvironment, drug resistance, metastasis, and poor prognosis constitute the primary challenges in the current diagnosis and treatment of BC. Magnetic iron oxide nanoparticles (MIONPs) have emerged as a promising nanoplatform for diagnostic tumor imaging as well as therapeutic drug-targeted delivery due to their unique physicochemical properties. The extensive surface engineering has given rise to multifunctionalized MIONPs. In this review, the latest advancements in surface modification strategies of MIONPs over the past five years are summarized and categorized as constrast agents and drug delivery platforms. Additionally, the remaining challenges and future prospects of MIONPs-based targeted delivery are discussed.

The Introduction of Magtrace® Lymphatic Tracer for Axillary Sentinel Node Biopsy for Breast Cancer in a Rural Scottish District General Hospital: Initial Experience, Perspectives, Outcomes and Learning Curves

BACKGROUND

Magtrace is a supraparamagnetic iron lymphatic tracer that has had increasing use in sentinel node biopsy (SNB) for breast cancer and has theoretical logistical benefits in centres where nanocolloid use may be associated with such issues. We describe our initial experience with the introduction of Magtrace into our routine practice by dual localisation with nanocolloid, comparing performance, and concordance.

MATERIALS AND METHODS

This was prospective study of the first patients undergoing axillary SNB using Magtrace in a single centre. These patients had dual localisation with nanocolloid and Magtrace. Subjective global assessments of Magtrace and nanocolloid performance as well as objective signal strength and anatomical concordance were compared across multiple timepoints in the operative journey.

RESULTS

A total of 30 consecutive patients underwent SNB within the timeframe of this study. While there were no failed SNB, 8 issues were reported including 4 issues of perceived imperfect localisation on global assessment. No patient had a failed or abandoned SNB, and only 1 case had a potential challenge in subsequent management after histopathological examination of the retrieved nodes. The majority of these issues occurred in the first half of the study period. There was overall weak to moderate positive correlation between Magtrace and nanocolloid signals of the retrieved sentinel nodes (Spearman's ρ = 0.392, P = .043).

CONCLUSION

This study suggests that introducing Magtrace was feasible and safe in the context of a rural breast cancer service. A possible strategy to ameliorate the learning curve associated with these procedures is the routine dual localisation in the initial phases of performing Magtrace localisation.

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.

Superparamagnetic iron oxide (SPIO) for sentinel lymph node detection in vulvar cancer

OBJECTIVES

Sentinel lymph node (SLN) detection with superparamagnetic iron oxide (SPIO) nanoparticles has been widely studied and standardized for breast and prostate cancer, but there is scarce evidence concerning its use in vulvar cancer. The objective of this study was to compare SLN detection using a SPIO tracer injected at the time of the surgery detected by a magnetometer, with the standard procedure of using a technetium 99 radioisotope (Tc99) detected by a gamma probe, in patients with vulvar cancer.

METHODS

The SPIO vulvar cancer study was a single-center prospective interventional non-inferiority study of SPIO compared to Tc99, conducted between 2016 and 2021 in patients who met the GROINSS-V study inclusion criteria for selective sentinel lymph node dissection in vulvar cancer.

RESULTS

We included 18 patients and a total of 41 SLNs. The level of agreement between tracers was 92.7% (80.6%-97.4%), corresponding to 38 out of 41 SLNs, which confirms the non-inferiority of SPIO compared to Tc99. The SLN detection rate per groin was 96.3 (81.7%-99.3) using Tc99 and 100% (87.5%-100%) using SPIO. Both tracers had a detection rate of 100% for positive lymph nodes.

CONCLUSIONS

The use of SPIO as a tracer for detecting SLNs in patients with vulvar cancer has shown to be non-inferior to that of the standard radiotracer, with the advantages of not requiring nuclear medicine and being able to inject it at the time of surgery after induction of anesthesia.

A new bimodal approach for sentinel lymph node imaging in prostate cancer using a magnetic and fluorescent hybrid tracer

PURPOSE

To obtain initial data on sentinel lymph node (SLN) visualisation by pre-operative magnetic resonance imaging (MRI) and intra-operative bimodal SLN identification using a new magnetic fluorescent hybrid tracer in prostate cancer (PCa) patients.

METHODS

Ten patients at > 5% risk for lymph node (LN) invasion were included. The day before surgery, a magnetic fluorescent hybrid tracer consisting of superparamagnetic iron oxide nanoparticles (SPION) and indocyanine green was transrectally injected into the prostate. Five hours after injection, transversal pelvic MRI scans were recorded and T2*-weighed images were screened for pelvic LNs with SPION uptake. Intra-operatively, magnetically active and/or fluorescent SLNs were detected by a handheld magnetometer and near-infrared fluorescence imaging (FI). Extended pelvic lymph node dissection (PLND) and radical prostatectomy completed the surgery. All resected specimens were checked ex situ for magnetic activity and fluorescence and were histopathologically examined.

RESULTS

Pre-operative MRI identified 145 pelvic LNs with SPION uptake. In total, 75 (median 6, range 3‒13) magnetically active SLNs were resected, including 14 SLNs not seen on MRI. FI identified 89 fluorescent LNs (median 8.5, range 4‒13) of which 15 LNs were not magnetically active. Concordance of the different techniques was 70% for pre-operative MRI vs. magnetometer-guided PLND and 88% for magnetic vs. fluorescent SLN detection.

CONCLUSION

These are the first promising results of bimodal, magnetic fluorescent SLN detection in PCa patients. Our magnetic fluorescent hybrid approach provides the surgeon a pre-operative lymphatic roadmap by using MRI and intra-operative visual guidance through the application of a fluorescent lymphatic agent. The diagnostic accuracy of our new hybrid approach has to be evaluated in further studies.

TRIAL REGISTRATION

DRKS00032808. Registered 04 October 2023, retrospectively registered.

Melanin-Based Nanoparticles for Lymph Node Tattooing: Experimental, Histopathological and Ultrastructural Study

In breast cancer, Targeted Axillary Dissection (TAD) allows for the selective excision of the sentinel lymph node (SLN) during primary tumor surgery. TAD consists of the resection of labelled SLNs prior to neoadjuvant chemotherapy (NACT). Numerous clinical and preclinical studies have explored the use of carbon-based colloids for SLN tattooing prior to NACT. However, carbon vectors show varying degrees of inflammatory reactions and, in about one fifth of cases, carbon particles migrate via the lymphatic pathway to other nodes, causing the SLN to mismatch the tattooed node. To overcome these limitations, in this study, we explored the use of melanin as a staining endogenous pigment. We synthesized and characterized melanin-loaded polymeric nanoparticles (Mel-NPs) and used them to tattoo lymph nodes in pig animal models given the similarity in the size of the human and pig nodes. Mel-NPs tattooed lymph nodes showed high identification rates, reaching 83.3% positive identification 16 weeks after tattooing. We did not observe any reduction in the identification as time increased, implying that the colloid is stable in the lymph node tissue. In addition, we performed histological and ultrastructural studies to characterize the biological behavior of the tag. We observed foreign-body-like granulomatous inflammatory responses associated with Mel-NPs, characterized by the formation of multinucleated giant cells. In addition, electron microscopy studies showed that uptake is mainly performed by macrophages, and that macrophages undergo cellular damage associated with particle uptake.

Skin Staining After Injection of Superparamagnetic Iron Oxide for Sentinel Lymph Node Dissection: A Retrospective Study of Two Protocols for Injection and Long-Term Follow-Up

OBJECTIVE

Sentinel lymph node (SLN) dissection is a highly accurate surgical procedure allowing detection of lymph node invasion in patients with clinically negative axilla in early breast cancer. Superparamagnetic iron oxide (SPIO) is a marker used during SLN procedure, allowing the same detection rate as isotopes (Tc-99). A drawback of SPIO is skin staining that can occur around the injection site. The goal of this retrospective study was to assess the frequency of skin staining after oncological breast surgery with SPIO, and the impact of two different injection protocols on the rate of skin staining.

MATERIALS AND METHODS

Data from breast cancer patients undergoing magnetic tracer SLN detection (SLND) procedure in a single department between 2020 and 2022 was reviewed. Injection protocol P1 consisted of retro-areolar injection of Magtrace 0.8 mL. Injection protocol P2, consisted of retro-tumoral injection with 1 mL. Presence of skin staining was assessed at day 10 after surgery. The evolution and satisfaction of the patients was assessed at six and 12 months.

RESULTS

In total 175 sentinel lymph node biopsy procedures were performed (P1: 141/P2: 34), consisting of breast conservative surgery (BCS) (P1: 70%/P2: 53%) or mastectomy (P1: 30%/P2: 47%) with SLN. SLN detection rate was 97.7%. Skin staining was reported in 23% and occurred more often after BCS (31.6%) compared to mastectomy (6.8%). When BCS was performed, peritumoral injection was associated with a decreased risk of skin staining compared with retro-areolar injection (22.2% vs. 33.3%, respectively). When present skin staining persisted for 12 months, but most of the patients described only a slight discomfort. The low rate of discoloration after mastectomy, as previously reported, can be explained by the removal of skin and glandular tissue in which the tracer accumulates. Less skin staining in P2 may be because of a shorter interval between injection and surgery and the removal of the excess of SPIO during the lumpectomy.

CONCLUSION

SPIO injection is a safe surgical technique. After mastectomy, the rate of discoloration was low. Despite the persistent skin discoloration in 58.6% in our study, patient satisfaction was high. Deeper injection, reduced doses, massage of the injection site and peritumoral injection may reduce skin staining.

Development of a human-size magnetic particle imaging device for sentinel lymph node biopsy of breast cancer

In this study, a novel human-size handheld magnetic particle imaging (MPI) system was developed for the high-precision detection of sentinel lymph nodes for breast cancer. The system consisted of a highly sensitive home-made MPI detection probe, a set of concentric coils pair for spatialization, a solenoid coil for uniform excitation at 8 kHz@1.5 mT, and a full mirrored coil set positioned far away from the scanning area. The mirrored coils formed an extremely effective differential pickup structure which suppressed the system noise as high as 100 dB. The different combination of the inner and outer gradient current made the field free point (FFP) move in the Z direction with a uniform intensity of 0.54T/m, while the scanning in the XY direction was implemented mechanically. The third-harmonic signal of the Superparamagnetic Iron Oxide Nanoparticles (SPIONs) at the FFP was detected and then reconstructed synchronously with the current changes. Experiment results showed that the tomographic detection limit was 30 mm in the Z direction, and the sensitivity was about 10 μg Fe SPIONs at 40 mm distance with a spatial resolution of about 5 mm. In the rat experiment, 54 μg intramuscular injected SPIONs were detected successfully in the sentinel lymph node, in which the tracer content was about 1.2% total injected Fe. Additionally, the effective detection time window was confirmed from 4 to 6 min after injection. Relevant clinical ethics are already in the application process. Large mammalian SLNB MPI experiments and 3D preoperative SLNB imaging will be performed in the future.

Assessing the Sentimag system for guiding sentinel node biopsies in patients with breast cancer

INTRODUCTION

Sentinel lymph node biopsy for breast cancer is a method to localize and excise the first draining lymph node from an invasive cancer of the breast. The histopathologic evaluation of the sentinel lymph node is used for predicting recurrence and survival and thus, guiding oncologists for treatment-decision making to administer adjuvant therapies. The ability to identify the sentinel node depends on methods to map lymphatic drainage from the breast to the sentinel node and accurately discriminate that node from other non-sentinel lymph nodes of the axilla.

AREAS COVERED

This review covers the clinical demand for technologies to assist the surgeon in intraoperative lymphatic mapping to specifically identify the sentinel lymph node in patients with breast cancer. Performance characteristics are reviewed for superparamagnetic iron oxide tracers used in lymphatic mapping compared to other current available technologies for lymphatic mapping.

EXPERT OPINION

The Magtrace (superparamagnetic iron oxide tracer) Sentimag (handheld magnetic probe) system is an FDA-approved technology for intraoperative lymphatic mapping to facilitate sentinel lymph node biopsy in breast cancer with technologic performance characteristics that are equivalent to 99Technetium-sulfur colloid. Barriers to broader utilization primarily center around the need for nonmetallic devices to be used for the conduct of surgery, which would interfere with the paramagnetic method for tracer localization.

Radio-Guided Occult Lesion Localization With 99m Tc for the Localization of Nonpalpable Melanoma and Soft Tissue Sarcoma Lesions: A Feasibility Study

PURPOSE OF THE REPORT

Localization techniques are needed to facilitate resection of nonpalpable lesions. In this study, the feasibility of radio-guided occult lesion localization (ROLL) with 99m Tc is investigated for the localization of nonpalpable, small, suspicious, or proven melanoma or soft tissue sarcoma lesions at various locations throughout the body.

PATIENTS AND METHODS

Patients with nonpalpable, suspicious, or proven melanoma or soft tissue sarcoma lesions were selected for this study. Within 24 hours before surgery, a median dose of 33.92 MBq 99m Tc-labeled human albumin particles ( 99m Tc-NA or 99m Tc-MAA) was injected in the lesion under ultrasound guidance. A hand-held gamma probe was used to detect the radioactive signal and guidance during surgery.

RESULTS

In this study, 20 patients with a total of 25 lesions were included and analyzed. The median size of the lesions was 1.8 cm (interquartile range [IQR], 1.8-4.0 cm), of which 44% were intramuscular located and 36% were subcutaneous, and 20% consisted of suspicious lymph nodes, mostly in the lower extremity. At median 4 hours (IQR, 3-6 hours) postinjection, 99m Tc ROLL showed a 100% intraoperative identification rate with proper signal identification with the gamma probe in all patients. With a median surgery time of 76 minutes (IQR, 45-157 minutes), all targeted lesions could be resected without 99m Tc-related complications, resulting in 88% microscopically margin-negative resection. No reoperations were needed for the same lesion.

CONCLUSIONS

The 99m Tc ROLL procedure is feasible for the localization and excision of small, nonpalpable melanoma and soft tissue sarcoma lesions at various locations in the body.

Comparison of Different Techniques for the Assessment of Sentinel Lymph Node Biopsy in Melanoma: A Systematic Review

Background

The gold standard for sentinel lymph node staging in melanoma is the use of the combined technique of radioisotope plus blue dye. New techniques and alternative methods have been proposed, with the promise of achieving comparable efficacy. We then carried out a literature search.

Methods

We conducted a literature search using the "sentinel lymph node biopsy" and "melanoma" keywords, then selected the case-control studies (the quality of which was assessed using the STROBE criteria).

Results

Twelve studies of 13,017 were selected, concerning the identification rate of indocyanine green fluorescence and indocyanine green-99mtc-nanocolloid techniques. We have found a comparable identification rate between the various techniques, even if given the small population present for some techniques, the results did not reach statistical significance.

Conclusions

The use of new techniques in sentinel lymph node detection promises results comparable to the gold standard techniques, but further studies are needed to validate these methods in the context of melanoma surgery.

A Fluorescent and Magnetic Hybrid Tracer for Improved Sentinel Lymphadenectomy in Prostate Cancer Patients

In prostate cancer, sentinel lymph node dissection (sLND) offers a personalized procedure with staging ability which is at least equivalent to extended LND while inducing lower morbidity. A bimodal fluorescent-radioactive approach was introduced to improve sentinel LN (SLN) detection. We present the first in-human case series on exploring the use of a fluorescent-magnetic hybrid tracer in a radiation-free sLND procedure. Superparamagnetic iron oxide nanoparticles and indocyanine green were administered simultaneously in five prostate cancer patients scheduled for extended LND, sLND and radical prostatectomy. In situ and ex vivo fluorescence and magnetic signals were documented for each LN sample detected via a laparoscopic fluorescence imaging and magnetometer system. Fluorescence and magnetic activity could be detected in all patients. Overall, 19 lymph node spots could be detected in situ, 14 of which were fluorescently active and 18 of which were magnetically active. In two patients, no fluorescent LNs could be detected in situ. The separation of the LN samples resulted in a total number of 30 SLNs resected. Ex vivo measurements confirmed fluorescence in all but two magnetically active SLNs. One LN detected in situ with both modalities was subsequently shown to contain a metastasis. This study provides the first promising results of a bimodal, radiation-free sLND, combining the advantages of both the magnetic and fluorescence approaches.

Top 100 cited classical articles in sentinel lymph nodes biopsy for breast cancer

Background

The sentinel lymph node biopsy (SLNB) takes on a critical significance in breast cancer surgery since it is the gold standard for assessing axillary lymph node (ALN) metastasis and determining whether to perform axillary lymph node dissection (ALND). A bibliometric analysis is beneficial to visualize characteristics and hotspots in the field of sentinel lymph nodes (SLNs), and it is conducive to summarizing the important themes in the field to provide more insights into SLNs and facilitate the management of SLNs.

Materials and methods

Search terms relating to SLNs were aggregated and searched in the Web of Science core collection database to identify the top 100 most cited articles. Bibliometric tools were employed to identify and analyze publications for annual article volume, authors, countries, institutions, keywords, as well as hotspot topics.

Results

The period was from 1998 to 2018. The total number of citations ranged from 160 to 1925. LANCET ONCOLOGY and JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION were the top two journals in which the above articles were published. Giuliano, AE was the author with the highest number of articles in this field with 15. EUROPEAN INST ONCOL is the institution with the highest number of publications, with 35 articles. Hotspots include the following 4 topics, false-negative SLNs after neoadjuvant chemotherapy; prediction of metastatic SLNs; quality of life and postoperative complications; and lymphography of SLNs.

Conclusion

This study applies bibliometric tools to analyze the most influential literature, the top 100 cited articles in the field of SLNB, to provide researchers and physicians with research priorities and hotspots.

New techniques versus standard mapping for sentinel lymph node biopsy in breast cancer: a systematic review and meta-analysis

New tracers for sentinel lymph node biopsy (SLNB), as indocyanine green (ICG), superparamagnetic iron oxide (SPIO) and micro bubbles, have been recently introduced in clinical practice showing promising but variable results. We reviewed the available evidence comparing these new techniques with the standard tracers to evaluate their safety. To identify all available studies, a systematic search was performed in all electronic databases. Data regarding sample size, mean number of SLN harvested for patient, number of metastatic SLN and SLN identification rate of all studies were extracted. No significant differences were found in terms of SLNs identification rates between SPIO, RI and BD but with a higher identification rate with the use of ICG. No significant differences were also found for the number of metastatic lymph nodes identified between SPIO, RI and BD and the mean number of SLNs identified between SPIO and ICG versus conventional tracers. A statistically significant differences in favor of ICG was reported for the comparison between ICG and conventional tracers for the number of metastatic lymph nodes identified. Our meta-analysis demonstrates that the use of both ICG and SPIO for the pre-operative mapping of sentinel lymph nodes in breast cancer treatment is adequately effective.

Sentinel Lymph Node Detection in Breast Cancer: An Innovative Technique

(1) Background: Sentinel lymph node biopsy is important in the search for metastases, especially in patients with malignant breast disease. Our study proposed new techniques to prevent complications such as possible postoperative seroma formation, pain or hypoesthesia of the axillary cord and medial arm surface, as well as motor deficits, to avoid disabling outcomes and presents initial data from our experience with the sentinel lymph node biopsy technique. (2) Methods: We mainly used two radioactive tracer detection techniques and a new technique using a radiotracer called Sentimag-magtrace. The positive lymph node was located and removed to perform histologic analysis. In our study, we evaluate 100 patients who underwent breast cancer surgery. (3) Results: We calculated the identification rates of the different methods of sentinel lymph node detection and found that it was 88.9% using radioactive tracers vs. 89.5% using the magnetic tracer technology (Sentimag). (4) Conclusions: Thus, this technique avoids radiation exposure for both patients and health care providers, and can reduce costs and time.

Axillary sentinel lymph node identification using superparamagnetic iron oxide versus radioisotope in early stage breast cancer: The UK SentiMag trial (SMART study)

BACKGROUND & OBJECTIVES

Sentinel lymph node biopsy (SLNB) is an accurate and reliable method for staging the axilla in early breast cancer. The gold standard technique for localizing the sentinel lymph node (SLN) is the use of radioisotope with or without blue dye. However, this technique has its limitations. Various alternatives have been explored to overcome the disadvantages of the standard SLNB technique and superparamagnetic iron oxide mapping agents have garnered significant attention. The SMART study aims to compare the magnetic technique using the superparamagnetic iron oxide particles (SPIO, Sienna+®) to the radioisotope technique (Tc99) +/- blue dye, for SLN identification in patients with early breast cancer.

METHODS

A prospective, multicenter study was done that recruited 109 clinically node-negative early-stage breast cancer patients from five centres in the United Kingdom (UK). The patients received radioisotope ± blue dye injections, followed by intraoperative injection of magnetic tracer prior to SLNB. The sentinel node identification rate was compared between the magnetic and standard techniques to evaluate detection rate (per patient and per node), non-inferiority and concordance.

RESULTS

Data was analysed for 107 patients. The per patient detection rate was 98.13% (105/107) when using the magnetic tracer and 92.26% (103/107) when using the standard technique. The nodal detection rate was 93.07% (188/202 nodes) when using the magnetic tracer and 96.53% (195/202) when using the standard technique. Of the 31 patients with positive sentinel lymph nodes (SLNs), all 31 (100%) were detected by both techniques.

CONCLUSION

Our study demonstrates that the magnetic technique is a feasible method for SLNB, with an identification rate that is not inferior to the standard technique. The magnetic technique offers a suitable alternative to the standard technique thereby avoiding the need for the complexities of nuclear medicine, the hazards of radiation and the anaphylaxis risk of blue dye.

Use of Superparamagnetic Iron Oxide (SPIO) Versus Conventional Technique in Sentinel Lymph Node Detection for Breast Cancer: A Randomised Controlled Trial

BACKGROUND

The objective of this study is to compare the efficacy of the superparamagnetic iron oxide (SPIO)-guided and standard techniques for sentinel lymph node (SLN) detection in early breast cancer. Multiple inferiority trials have concluded the non-inferiority of SPIO to the conventional radioisotope technique, with or without blue dye, in detecting SLNs.

PATIENTS AND METHODS

From July 2018 to August 2022, patients clinically diagnosed with node-negative invasive breast cancer were randomised into the study group (SPIO) and control group (radioisotope and blue dye). Patient data and disease characteristics were prospectively collected. SLN detection rates were compared between the two groups.

RESULTS

A total of 282 patients undergoing 288 sentinel lymph node biopsy (SLNB) procedures were recruited, and 144 SLNB procedures were randomised into each group. The baseline patient and disease characteristics were comparable. SLN localisation failed in one patient in each group; the success rate of SLNB was 99.3%. The SPIO group demonstrated a higher mean number of SLNs harvested (3.3 versus 2.8, p = 0.039) and longer mean procedure duration (33.1 min versus 22.3 min, p = 0.01) than the control group did. In the study group, the concordance rates per patient and node were 99.3% and 94.6%, respectively. Sixty-seven positive SLNs were detected in 37 patients. The concordance rates per malignant SLNB procedure and positive SLN were 97.3% and 96.8%, respectively.

CONCLUSION

Single-tracer SPIO-guided SLNB was non-inferior to the dual technique (radioisotope and blue dye) and could safely replace the gold standard for SLN mapping in early breast cancer.

Is Sentinel Lymph Node Biopsy Necessary in Patients who Undergo Prophylactic Mastectomy?

BACKGROUND

Over the last decade, rates of risk-reducing prophylactic mastectomy (PM) have risen dramatically. A topic of debate regarding the procedure is whether to use sentinel lymph node biopsy (SLNB) at the time of PM and what factors might predict for such need. In order to assess the rate of identifying presence of occult invasive breast cancer in the PM specimen, we performed a retrospective review of the pathology findings from a single-surgeon case-series of PM.

METHODS

Patients undergoing PM between January 2013 and June 2019 at Orlando Health Cancer Institute were identified for a retrospective chart review. Demographic, clinical, and histopathological data from the surgical procedure were collected and analyzed for the incidence of occult invasive breast cancer in the PM specimen.

RESULTS

A total of 146 consecutive patients with PM were identified; 120 (82.2%) underwent contralateral PM (CPM) and 26 (17.8%) underwent bilateral PM (BPM). Final pathology of the 172 PM specimens identified 4 (3.3%) with lobular carcinoma in situ, 3 (2.5%) with atypical ductal hyperplasia, and 2 (1.7%) with atypical lobular hyperplasia and 2 (1.7%) with intraductal papilloma. No invasive malignancy was detected in any of the 172 PM specimens.

CONCLUSIONS

The absence of occult invasive carcinoma in 172 consecutive PM specimens suggests a limited clinical utility in routinely performing SLNB in this setting. This study also suggests that use of preoperative breast MRI imaging could offer a potential non-invasive tool to detect occult malignancy and select patients who can safely undergo omission of SLNB at the time of PM.

Nanoparticles in Clinical Trials: Analysis of Clinical Trials, FDA Approvals and Use for COVID-19 Vaccines

Nanoparticles are heterologous small composites that are usually between 1 and 100 nanometers in size. They are applied in many areas of medicine with one of them being drug delivery. Nanoparticles have a number of advantages as drug carriers which include reduced toxic effects, increased bioavailability, and their ability to be modified for specific tissues or cells. Due to the exciting development of nanotechnology concomitant with advances in biotechnology and medicine, the number of clinical trials devoted to nanoparticles for drug delivery is growing rapidly. Some nanoparticles, lipid-based types, in particular, played a crucial role in the developing and manufacturing of the two COVID-19 vaccines-Pfizer and Moderna-that are now being widely used. In this analysis, we provide a quantitative survey of clinical trials using nanoparticles during the period from 2002 to 2021 as well as the recent FDA-approved drugs (since 2016). A total of 486 clinical trials were identified using the clinicaltrials.gov database. The prevailing types of nanoparticles were liposomes (44%) and protein-based formulations (26%) during this period. The most commonly investigated content of the nanoparticles were paclitaxel (23%), metals (11%), doxorubicin (9%), bupivacaine and various vaccines (both were 8%). Among the FDA-approved nanoparticle drugs, polymeric (29%), liposomal (22%) and lipid-based (21%) drugs were the most common. In this analysis, we also discuss the differential development of the diverse groups of nanoparticles and their content, as well as the underlying factors behind the trends.

Evaluation of New Tracers in the Identification of Sentinel Lymph Node in Patients with Early Breast Cancer

Purpose

Sentinel node mapping is the standard of care for evaluation of axilla for women with early node negative breast cancer. Validation of a new tracer for sentinel node biopsy requires full axillary lymph node dissection to establish its performance indicators. This exposes about 70% of women to unnecessary axillary dissection with its attendant morbidity.

Aims and Objective

To investigate the predictive value of identification of sentinel lymph nodes by a tracer for knowing its sensitivity and false-negative rates (FNR).

Methods

A linear regression on data from a network meta-analysis was carried out, and the correlation between identification and sensitivity and its predictive value were ascertained.

Results

A strong linear relationship was observed between identification and sensitivity of sentinel node biopsy (correlation coefficient r = 0.97). The sensitivity and false negativity can be predicted by the identification rate. An identification rate of 93% corresponds to sensitivity = 90.51% and a FNR = 9.49%. The current literature on newer tracers has been succinctly reviewed.

Conclusion

The linear regression demonstrated a very high predictive value of identification rate for ascertaining the sensitivity and FNRs of sentinel node biopsy. A new tracer for sentinel node biopsy can be introduced in clinical practice, if it achieves an identification rate of 93% or more.

Evolution and refinement of magnetically guided sentinel lymph node detection in breast cancer: meta-analysis

BACKGROUND

Superparamagnetic iron oxide nanoparticles (SPIO) have been used as a tracer for sentinel lymph node (SLN) localization in breast cancer, demonstrating comparable performance to the combination of radioisotope (RI) and blue dye (BD).

METHODS

A systematic literature search and meta-analysis with subgroup and meta-regression analysis were undertaken to update the available evidence, assess technique evolution, and define knowledge gaps. Recommendations were made using the GRADE approach.

RESULTS

In 20 comparative studies, the detection rate was 97.5 per cent for SPIO and 96.5 per cent for RI ± BD (risk ratio 1.006, 95 per cent c.i. 0.992 to 1.019; P = 0.376, high-certainty evidence). Neoadjuvant therapy, injection site, injection volume or nodal metastasis burden did not affect the detection rate, but injection over 24 h before surgery increased the detection rate on meta-regression. Concordance was 99.0 per cent and reverse concordance 97.1 per cent (rate difference 0.003, 95 per cent c.i. -0.009 to 0.015; P = 0.656, high-certainty evidence). Use of SPIO led to retrieval of slightly more SLNs (pooled mean 1.96 versus 1.89) with a higher nodal detection rate (94.1 versus 83.5 per cent; RR 1.098, 1.058 to 1.140; P < 0.001; low-certainty evidence). In meta-regression, injection over 24 h before surgery increased the SPIO nodal yield over that of RI ± BD. The skin-staining rate was 30.8 per cent (very low-certainty evidence), and possibly prevented with use of smaller doses and peritumoral injection.

CONCLUSION

The performance of SPIO is comparable to that of RI ± BD. Preoperative injection increases the detection rate and nodal yield, without affecting concordance. Whether skin staining and MRI artefacts are reduced by lower dose and peritumoral injection needs to be investigated.

Ultrasound-assisted carbon nanoparticle suspension mapping versus dual tracer-guided sentinel lymph node biopsy in patients with early breast cancer (ultraCars): phase III randomized clinical trial

BACKGROUND

Appropriate tracing methods for sentinel lymph node biopsy (SLNB) play a key role in accurate axillary staging. This prospective, non-inferiority, phase III RCT compared the feasibility and diagnostic performance of ultrasound-assisted carbon nanoparticle suspension (CNS) mapping with dual tracer-guided SLNB in patients with early breast cancer.

METHODS

Eligible patients had primary breast cancer without nodal involvement (cN0), or had clinically positive lymph nodes (cN1) that were downstaged to cN0 after neoadjuvant chemotherapy. Patients were randomly assigned (1 : 1) to undergo either ultrasound-assisted CNS sentinel lymph node (SLN) mapping (UC group) or dual tracer-guided mapping with CNS plus indocyanine green (ICG) (GC group). The primary endpoint was the SLN identification rate.

RESULTS

Between 1 December 2019 and 30 April 2021, 330 patients were assigned randomly to the UC (163 patients) or GC (167 patients) group. The SLN identification rate was 94.5 (95 per cent c.i. 90.9 to 98.0) per cent in the UC group and 95.8 (92.7 to 98.9) per cent in the GC group. The observed difference of -1.3 (-5.9 to 3.3) per cent was lower than the prespecified non-inferiority margin of 6 per cent (Pnon-inferiority = 0.024). No significant difference was observed in metastatic node rate (30.5 versus 24.4 per cent; P = 0.222), median number of SLNs harvested (3 (range 1-7) versus 3 (1-8); P = 0.181), or duration of surgery (mean(s.d.) 7.53(2.77) versus 7.63(3.27) min; P = 0.316) between the groups. Among the subgroup of patients who had undergone neoadjuvant treatment, the SLN identification rate was 91.7 (82.2 to 100) per cent in the UC group and 90.7 (81.7 to 99.7) per cent in the GC group.

CONCLUSION

The diagnostic performance of ultrasound-assisted CNS mapping was non-inferior to that of dual tracer-guided SLN mapping with CNS plus ICG in patients with early breast cancer.

REGISTRATION NUMBER

NCT04951245 (http://www.clinicaltrials.gov).

Sentinel lymph node mapping with superparamagnetic iron oxide for melanoma: a pilot study in healthy participants to establish an optimal MRI workflow protocol

BACKGROUND

Current pre-operative Sentinel Lymph Node (SLN) mapping using dual tracing is associated with drawbacks (radiation exposure, logistic challenges). Superparamagnetic iron oxide (SPIO) is a non-inferior alternative for SLN mapping in breast cancer patients. Limited research has been performed on SPIO use and pre-operative MRI in melanoma patients to identify SLNs.  METHODS: Healthy participants underwent MRI-scanning pre- and post SPIO-injection during 20 min. Workflow protocols varied in dosage, massage duration, route of administration and injection sites. The first lymph node showing a susceptibility artefact caused by SPIO accumulation was considered as SLN.

RESULTS

Artefacts were identified in 5/6 participants. Two participants received a 0.5 ml subcutaneous injection and 30-s massage, of which one showed an artefact after one hour. Four participants received a 1.0 ml intracutaneous injection and two-minute massage, leading to artefacts in all participants. All SLNs were observed within five minutes, except after lower limb injection (30 min).

CONCLUSION

SPIO and pre-operative MRI-scanning seems to be a promising alternative for SLN visualization in melanoma patients. An intracutaneous injection of 1.0 ml SPIO tracer, followed by a two-minute massage seems to be the most effective technique, simplifying the pre-operative pathway. Result will be used in a larger prospective study with melanoma patients.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05054062) - September 9, 2021.

The Application of Magnetic Nanoparticles for Sentinel Lymph Node Detection in Clinically Node-Negative Breast Cancer Patients: A Systemic Review and Meta-Analysis

Superparamagnetic iron oxide (SPIO), an alternative mapping agent, can be used to identify sentinel lymph nodes in patients with clinically node-negative breast cancer. However, its performance in comparison with the standard method, using a radioisotope (technetium-99 m, Tc) alone or in combination with blue dye, remains controversial. Hence, a systematic review and meta-analysis were conducted to evaluate the diagnostic accuracy of SPIO and its clinical impact in the management of breast cancer. The PubMed, Embase, and Cochrane databases were comprehensively searched from inception to 1 May 2022. Cohort studies regarding the comparison of SPIO with standard methods for sentinel lymph node identification were included. A total of 19 prospective cohort studies, which collectively included 2298 clinically node-negative breast cancer patients undergoing sentinel lymph node identification through both the standard method and SPIO, were identified. The detection rate for sentinel lymph nodes (RR, 1.06; 95% CI, 1.05−1.08; p < 0.001) was considerably higher in the SPIO cohorts than in the standard method cohorts, although this difference was not significant in detected patients, patients with positive sentinel lymph nodes, or positive sentinel lymph nodes. Compared with the standard method, the SPIO method could be considered as an alternative standard of care for sentinel lymph node detection in patients with clinically node-negative breast cancer.

Implementation of sodium alginate-Fe3O4 to localize undiagnosed small pulmonary nodules for surgical management in a preclinical rabbit model

Many methods are used to locate preoperative small pulmonary nodules. However, deficiencies of complications and success rates exist. We introduce a novel magnetic gel for small pulmonary nodules localization in rabbit model, and furtherly evaluate its safety and feasibility. Rabbits were used as the experimental objects. A magnetic gel was used as a tracer magnet, mixed as sodium alginate-Fe₃O₄ magnetic fluid and calcium gluconate solution. In short-term localization, a coaxial double-cavity puncture needle was applied to inject the gel into the lung after thoracotomy, and a pursuit magnet made of Nd-Fe-B permanent magnetic materials was used to attract the gel representing location of the nodule. In long-term localization, the gel was injected under X-ray guidance. Imaging changes to the lung were observed under X-ray daily. Thoracotomy was performed to excise tissue containing the gel, and hematoxylin-eosin staining was used to observe the tissue on postoperative days 1, 3, 5, and 7. Observe tissues morphology of heart, liver, spleen, and kidney in the same way. The gel was formed after injection and drew lung tissue to form a protrusion from the lung surface under the applied magnetic field. No complication was observed. The shape and position of the gel had not changed when viewed under X-ray. Pathological analysis showed the gel had a clear boundary without diffusion of magnetic fluid. All tissues retained good histologic morphology and no magnetic fluid was observed. Our study preliminarily suggested that the technique using sodium alginate-Fe₃O₄ magnetic gel to locate small pulmonary nodules with guidance of X-ray, and to search for them under an applied magnetic field during the operation is safe and feasible.

Preclinical evaluation of a mannose-labeled magnetic tracer for enhanced sentinel lymph node retention in the head and neck

Sentinel lymph node biopsy in cancers of the head and neck offers demonstrated clinical and diagnostic value, but adoption is limited by concerns about the detrimental consequence to survival of false negative results in a highly curable setting. The aim of this study was to demonstrate potential to overcome this via application of a novel mannose-labeled magnetic iron oxide tracer. In a large animal model, preoperative imaging and intraoperative magnetometer detection were used to identify magnetic lymph nodes. Iron quantification mapped the distribution of tracer within lymphatic levels. Over a 4-week test period, uptake of magnetic tracer in lymph nodes increased in a linear-like fashion, with a substantial percentage of accumulated iron (83%) being retained in the sentinel node. This result indicates a high affinity of mannose-labeled particles to the sentinel node, while providing a means for the magnetometer probe to indicate node status based on intraoperative signal.

Minimally invasive evaluation of the clinically negative inguinal node in penile cancer: Dynamic sentinel node biopsy

The presence of lymph node metastasis is the most important prognostic factor in penile cancer (PeCa). Due to limited sensitivity of currently available imaging modalities, invasive staging approaches remain indispensable for adequate nodal staging. As an alternative to radical inguinal lymphadenectomy and with the aim to reduce morbidity, staging strategies such as modified lymphadenectomy and dynamic sentinel node biopsy (DSNB) have been introduced. Over the years, DSNB evolved into a safe and reliable staging technique when performed in high volume centers. Recent enhancements of the procedure such as Single-photon emission computed tomography/computed tomography (SPECT/CT) and the introduction of hybrid tracers have improved pre- and intraoperative sentinel node (SN) visualization. Other technologies such as superparamagnetic iron oxide nanoparticles could have a potential future role to further refine DSNB. Future efforts should be aimed at optimizing diagnostic accuracy whilst minimizing perioperative morbidity.

Comparative Analysis of Postoperative Complications of Sentinel Node Identification Using the SentiMag® Method and the Use of a Radiotracer in Patients with Breast Cancer

(1) Background: The purpose of the study was a retrospective, comparative assessment of complications of the surgical sentinel node biopsy (SNB) procedure in breast cancer using the radiotracer method and the SentiMag® method on groups of patients after 3.5 years of use. (2) Methods: The material was a group of 345 patients with primary surgical breast cancer who underwent the SNB procedure with the use of a radiotracer in combination with wide local excision (WLE), simple amputation (SA) with SNB and an independent SNB procedure in the period from May 2018 to January 2021 in the Department of Oncological Surgery. Of the patients who were monitored in the Hospital Outpatient Clinic, 300 were enrolled. The analyzed group was compared in terms of the occurrence of the same complications with the group of 303 patients also operated on in our center in the period from January 2014 to September 2017, in which SN identification was performed using the SentiMag® method. (3) Results: The most common complications found were sensation disorders in the arm, which occurred in 16 (14.1%) patients using the radiotracer method, SentiMag®-11 (9.9%). By comparing the complication rate between the methods with the radiotracer (n = 300) and SentiMag® (n = 303), no significant differences were found. (4) Conclusions: Sentinel node (SN) identification using the radiotracer method and the SentiMag® method are comparable diagnostic methods in breast cancer, with a low risk of complications.

Exploratory Study of Superparamagnetic Iron Oxide Dose Optimization in Breast Cancer Sentinel Lymph Node Identification Using a Handheld Magnetic Probe and Iron Quantitation

Simple Summary

Sentinel lymph node biopsy (SLNB) using super magnetic iron oxide (SPIO) and magnetic probes is expected to be a simple and safe method of detecting cancerous lymph nodes without using radioisotopes (RIs). A multicenter trial of SLNB was conducted using a handheld magnetic probe and SPIO (Rizobist^®) and its non-inferiority with the conventional RI method. The quantity of iron in SLN was measured to examine the necessary dosage and administration method for sufficient SLN detection in the case of this test. Further, a clinical trial was conducted to determine the possibility of SLNB with a half-dose of SPIO (1.0 mL → 0.5 mL), and the resulting iron volume measured at that time was also examined. This study demonstrates that sufficient iron content reaches SLN even at an SPIO dose of 0.5 mL.

Abstract

This exploratory study compared doses of ferucarbotran, a superparamagnetic iron oxide nanoparticle, in sentinel lymph nodes (SLNs) and quantified the SLN iron load by dose and localization. Eighteen females aged ≥20 years scheduled for an SLN biopsy with node-negative breast cancer were divided into two equal groups and administered either 1 mL or 0.5 mL ferucarbotran. Iron content was evaluated with a handheld magnetometer and quantification device. The average iron content was 42.8 µg (range, 1.3–95.0; 0.15% of the injected dose) and 21.9 µg (1.1–71.0; 0.16%) in the 1-mL and 0.5-mL groups, respectively (p = 0.131). The iron content of the closest SLN compared to the second SLN was 53.0 vs. 10.0 µg (19% of the injected dose) and 34.8 vs. 4.1 µg (11.1%) for the 1-mL and 0.5-mL groups, respectively (p = 0.001 for both). The magnetic field was high in both groups (average 7.30 µT and 6.00 µT in the 1-mL and 0.5-mL groups, respectively) but was not statistically significant (p = 0.918). The magnetic field and iron content were correlated (overall SLNs, p = 0.02; 1-mL, p = 0.014; 0.5-mL, p = 0.010). A 0.5-mL dose was sufficient for SLN identification. Primary and secondary SLNs could be differentiated based on iron content. Handheld magnetometers could be used to assess the SLN iron content.

Feasibility of Magnetic Technique for Axillary Staging after Neoadjuvant Therapy in Breast Cancer Patients

PURPOSE

Optimal axillary staging after neoadjuvant chemotherapy (NAC) in node-negative breast cancer is an area of controversy. Sentinel node biopsy with Technetium-sulphur colloid (99m Tc) alone or with blue dye is the recommended technique for evaluating axilla in these patients. However, this technique has drawbacks such as limited access to nuclear departments and timing limitations related to Tc injection exposing patients to unnecessary radiation. Superparamagnetic iron oxide nanoparticles (SPIO) may represent a valid option for SLN biopsy. In this study, we assessed the feasibility of the magnetic technique (Sentimag) with combination of isosulfan blue dye in breast cancer patients who received NAC.

METHODS

The study sample consisted of 54 female breast cancer patients who received NAC. Sentinel node localization was performed using magnetic technique and blue dye. Sentinel node identification rate (IFR) of magnetic technique was calculated and postoperative complications were assessed.

RESULTS

Sentinel lymph node was detected in 52 patients with Sentimag method (identification rate = 96.3%, 95% CI: 87.4-98.9%). Blue dye was successful to find SLN in 38 patients (identification rate = 70%). The most common histologic type was invasive ductal (n = 51; 94.4%). Mean tumor size was 2.1 cm after NAC. Most of patients had T2 (n = 30; 55.5%) and HER2 + positive (n = 49; 90.7%) cancer.

CONCLUSION

Sentimag which is a magnetic technique appears to be safe, easy to perform with minimal adverse effects, may be an alternative and accurate technique in patients with NAC, especially in breast units where nuclear medicine unit is not available.

Supplemental data for this article is available online at https://doi.org/10.1080/08941939.2022.2038737 .

A Propensity Score Matched Analysis of Superparamagnetic Iron Oxide versus Radioisotope Sentinel Node Biopsy in Breast Cancer Patients after Neoadjuvant Chemotherapy

The standard method for nodal staging in breast cancer (BC) patients after neoadjuvant chemotherapy (NAC) is sentinel lymph node biopsy (SLNB) with a radioisotope (RI) injection. However, SLNB after NAC results in high false-negative rates (FNR), and the RI method is restricted by nuclear medicine unit dependency. These limitations resulted in the development of the superparamagnetic iron oxide (SPIO) method, reducing FNR and presenting a comparable detection rate. This bi-institutional cohort comparison study aimed to assess the efficacy of SPIO and radioisotope SNLB in BC patients after NAC using Propensity Score Matching (PSM) analysis. The study group comprised 508 patients who underwent SLNB after NAC for ycT1-4N0M0 BC between 2013 and 2021 in two high volume centers. Data were retrieved from prospectively conducted databases. In the SPIO group, the median of retrieved sentinel lymph nodes (SLNs) was significantly higher than in the RI group (3 vs. 2; p < 0.0001). The SPIO method was associated with a significantly higher chance of retrieving at least three lymph nodes when compared to the RI method (71% vs. 11.3%; p < 0.0001). None of the analyzed demographic and clinical variables had a statistically significant influence on the efficacy of SLNs retrieval in the RI group, while in the SPIO group, patients with ≥three harvested SLNs had lower weight and decreased BMI. Based on this PSM analysis, SPIO-guided SLNB allowed the efficient retrieval and detection of SLNs in BC patients after NAC compared to RI.

A Propensity Score Matched Analysis of Superparamagnetic Iron Oxide versus Radioisotope Sentinel Node Biopsy in Breast Cancer Patients after Neoadjuvant Chemotherapy

Simple Summary

This Propensity Score Matched Analysis aimed to assess the efficacy of superparamagnetic iron oxide (SPIO) and radioisotope sentinel lymph node biopsy (SNLB) in breast cancer (BC) patients after neoadjuvant chemotherapy (NAC). One hundred and twenty-four patients were eligible for final analysis. In the SPIO group, the median of retrieved sentinel lymph nodes (SLNs) was significantly higher than in the RI group. The SPIO method was associated with a significantly higher chance of retrieving at least three SLNs when compared to the RI method. SPIO-guided SLNB allows efficient retrieval and detection of SLNs in BC patients after NAC when compared to RI.

Abstract

The standard method for nodal staging in breast cancer (BC) patients after neoadjuvant chemotherapy (NAC) is sentinel lymph node biopsy (SLNB) with a radioisotope (RI) injection. However, SLNB after NAC results in high false-negative rates (FNR), and the RI method is restricted by nuclear medicine unit dependency. These limitations resulted in the development of the superparamagnetic iron oxide (SPIO) method, reducing FNR and presenting a comparable detection rate. This bi-institutional cohort comparison study aimed to assess the efficacy of SPIO and radioisotope SNLB in BC patients after NAC using Propensity Score Matching (PSM) analysis. The study group comprised 508 patients who underwent SLNB after NAC for ycT1-4N0M0 BC between 2013 and 2021 in two high volume centers. Data were retrieved from prospectively conducted databases. In the SPIO group, the median of retrieved sentinel lymph nodes (SLNs) was significantly higher than in the RI group (3 vs. 2; p < 0.0001). The SPIO method was associated with a significantly higher chance of retrieving at least three lymph nodes when compared to the RI method (71% vs. 11.3%; p < 0.0001). None of the analyzed demographic and clinical variables had a statistically significant influence on the efficacy of SLNs retrieval in the RI group, while in the SPIO group, patients with ≥three harvested SLNs had lower weight and decreased BMI. Based on this PSM analysis, SPIO-guided SLNB allowed the efficient retrieval and detection of SLNs in BC patients after NAC compared to RI.

Breast MRI in patients after breast conserving surgery with sentinel node procedure using a superparamagnetic tracer

BACKGROUND

A procedure for sentinel lymph node biopsy (SLNB) using superparamagnetic iron-oxide (SPIO) nanoparticles and intraoperative sentinel lymph node (SLN) detection was developed to overcome drawbacks associated with the current standard-of-care SLNB. However, residual SPIO nanoparticles can result in void artefacts at follow-up magnetic resonance imaging (MRI) scans. We present a grading protocol to quantitatively assess the severity of these artefacts and offer an option to minimise the impact of SPIO nanoparticles on diagnostic imaging.

METHODS

Follow-up mammography and MRI of two patient groups after a magnetic SLNB were included in the study. They received a 2-mL subareolar dose of SPIO (high-dose, HD) or a 0.1-mL intratumoural dose of SPIO (low-dose, LD). Follow-up mammography and MRI after magnetic SLNB were acquired within 4 years after breast conserving surgery (BCS). Two radiologists with over 10-year experience in breast imaging assessed the images and analysed the void artefacts and their impact on diagnostic follow-up.

RESULTS

A total of 19 patients were included (HD, n = 13; LD, n = 6). In the HD group, 9/13 patients displayed an artefact on T1-weighted images up to 3.6 years after the procedure, while no impact of the SPIO remnants was observed in the LD group.

CONCLUSIONS

SLNB using a 2-mL subareolar dose of magnetic tracer in patients undergoing BCS resulted in residual artefacts in the breast in the majority of patients, which may hamper follow-up MRI. This can be avoided by using a 0.1-mL intratumoural dose.

Application of Magnetic Nanoparticles for Rapid Detection and In Situ Diagnosis in Clinical Oncology

Screening, monitoring, and diagnosis are critical in oncology treatment. However, there are limitations with the current clinical methods, notably the time, cost, and special facilities required for radioisotope-based methods. An alternative approach, which uses magnetic beads, offers faster analyses with safer materials over a wide range of oncological applications. Magnetic beads have been used to detect extracellular vesicles (EVs) in the serum of pancreatic cancer patients with statistically different EV levels in preoperative, postoperative, and negative control samples. By incorporating fluorescence, magnetic beads have been used to quantitatively measure prostate-specific antigen (PSA), a prostate cancer biomarker, which is sensitive enough even at levels found in healthy patients. Immunostaining has also been incorporated with magnetic beads and compared with conventional immunohistochemical methods to detect lesions; the results suggest that immunostained magnetic beads could be used for pathological diagnosis during surgery. Furthermore, magnetic nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs), can detect sentinel lymph nodes in breast cancer in a clinical setting, as well as those in gallbladder cancer in animal models, in a surgery-applicable timeframe. Ultimately, recent research into the applications of magnetic beads in oncology suggests that the screening, monitoring, and diagnosis of cancers could be improved and made more accessible through the adoption of this technology.

Sentinel lymph node biopsy with a handheld cordless magnetic probe following preoperative MR lymphography using superparamagnetic iron oxide for clinically N0 early oral cancer: A feasibility study

PURPOSE

Radioisotope (RI) tracers are generally used for preoperative mapping of sentinel lymph node (SLN) and intraoperative detection with a portable γ probe. However, the use of RI has several limitations. Therefore, a method without RI is required for the widespread application of SLN biopsy. The purpose of this study was to evaluate the feasibility of SLN biopsy with a handheld cordless magnetic probe following magnetic resonance lymphography (MRL) using superparamagnetic iron oxide (SPIO) and for clinically N0 early oral cancer.

MATERIALS AND METHODS

MRL using SPIO and SLNB with the handheld cordless magnetic probe were performed for 27 patients with clinically N0 early oral cancer.

RESULTS

In all 27 patients (100%), SLNs were detected by MRL, and the total and mean number of SLNs were 73 and 2.7, respectively. All SLNs identified by MRL were detectable using the magnetic probe in all patients.

CONCLUSIONS

SLNB with handheld cordless magnetic probe following preoperative SLN mapping by MRL using SPIO is feasible, without RI use, for neck management in cases of clinically N0 early oral cancer.

Modelling of Dynamic Behaviour in Magnetic Nanoparticles

The efficient development and utilisation of magnetic nanoparticles (MNPs) for applications in enhanced biosensing relies on the use of magnetisation dynamics, which are primarily governed by the time-dependent motion of the magnetisation due to externally applied magnetic fields. An accurate description of the physics involved is complex and not yet fully understood, especially in the frequency range where Néel and Brownian relaxation processes compete. However, even though it is well known that non-zero, non-static local fields significantly influence these magnetisation dynamics, the modelling of magnetic dynamics for MNPs often uses zero-field dynamics or a static Langevin approach. In this paper, we developed an approximation to model and evaluate its performance for MNPs exposed to a magnetic field with varying amplitude and frequency. This model was initially developed to predict superparamagnetic nanoparticle behaviour in differential magnetometry applications but it can also be applied to similar techniques such as magnetic particle imaging and frequency mixing. Our model was based upon the Fokker-Planck equations for the two relaxation mechanisms. The equations were solved through numerical approximation and they were then combined, while taking into account the particle size distribution and the respective anisotropy distribution. Our model was evaluated for Synomag®-D70, Synomag®-D50 and SHP-15, which resulted in an overall good agreement between measurement and simulation.

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.

Optimization of SPIO Injection for Sentinel Lymph Node Dissection in a Rat Model

The magnetic technique, consisting of a magnetic tracer and a handheld magnetometer, is a promising alternative technique for sentinel lymph node dissection (SLND) and was shown to be non-inferior to the standard technique in terms of identification rates. In this study, injection characteristics (iron dose, dilution, time course and massaging) were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model. 202 successful SLNDs were performed. Iron uptake in the SLN is proportional (10% utilization rate) to the injection dose between 20 and 200 μg, showing a plateau uptake of 80 μg in the SLN around 1000 μg injection. Linear regression showed that time had a higher impact than dilution, on the SLN iron uptake. Massaging showed no significant change in iron uptake. The amount of residual iron at the injection site was also proportional to the injection dose without any plateau. Time was a significant factor for wash-out of residual iron. From these results, preoperative injection may be advantageous for SLN detection as well as reduction in residual iron at the injection site by potential decrease in required injection dose.

Optimization of SPIO Injection for Sentinel Lymph Node Dissection in a Rat Model

Simple Summary

In this study, the following injection characteristics were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model: (a) iron dose, (b) effect of dilution, (c) effect of injecting at different time courses and (d) effect of massaging the injection site. In conclusion, injection dose and time were primary factors for the SLN iron uptake. The result from this study will provide a background for magnetic procedures.

Abstract

The magnetic technique, consisting of a magnetic tracer and a handheld magnetometer, is a promising alternative technique for sentinel lymph node dissection (SLND) and was shown to be non-inferior to the standard technique in terms of identification rates. In this study, injection characteristics (iron dose, dilution, time course and massaging) were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model. 202 successful SLNDs were performed. Iron uptake in the SLN is proportional (10% utilization rate) to the injection dose between 20 and 200 μg, showing a plateau uptake of 80 μg in the SLN around 1000 μg injection. Linear regression showed that time had a higher impact than dilution, on the SLN iron uptake. Massaging showed no significant change in iron uptake. The amount of residual iron at the injection site was also proportional to the injection dose without any plateau. Time was a significant factor for wash-out of residual iron. From these results, preoperative injection may be advantageous for SLN detection as well as reduction in residual iron at the injection site by potential decrease in required injection dose.

Sentinel Lymph Node Biopsy: Indications and Technique

Sentinel lymph node biopsy is a key tool in the care of many patients with melanoma. The indications for the procedure have gradually become clearer over the 3 decades since the technique was developed. For appropriately selected patients, it carries enormous significance. Although it is a minimally invasive procedure, it does carry some risk. It is also a multidisciplinary procedure, requiring knowledge and experience from several specialties including nuclear medicine, surgery, and pathology.

Techniques for sentinel node biopsy in breast cancer

INTRODUCTION

Sentinel node biopsy (SNB) is the standard of care in women with breast cancer (BC) and clinically non suspicious axillary lymph nodes (LNs), due to its high negative predictive value (NPV) in the assessment of nodal status. SNB has significantly reduced complications related to the axillary lymph node dissection, such as lymphedema and upper limb dysfunction.

EVIDENCE ACQUISITION

The gold standard technique for SNB is the blue dye (BD) and technetium labelled nanocolloid (Tc-99m) double technique. However, nuclear medicine is not available in all Institutions and several new tracers and devices have been proposed, such as indocyanine green (ICG) and superparamagnetic iron oxides (SPIO). All these techniques show an accuracy and detection rate not inferior to that of the standard technique, with different specific pros and cons. The choice of how to perform a SNB primarily depends on the surgeon's confidence with the procedure, the availability of nuclear medicine and the economic resources of the Institutions. In this setting, new tracers, hybrid tracers and imaging techniques are being evaluated in order to improve the detection rate of sentinel lymph nodes (SNs) and minimize the number of unnecessary axillary surgeries through an accurate preoperative assessment of nodal status and to guide new minimally invasive diagnostic procedures of SNs. In particular, the contrast-enhanced ultrasound (CEUS) is an active field of research but cannot be recommended for clinical use at this time.

EVIDENCE SYNTHESIS

The ICG fluorescence technique was superior in terms of DR, as well as having the lowest FNR. The DR descending order was SPIO, Tc, dual modality (Tc/BD), CEUS and BD.

CONCLUSIONS

This paper is a narrative review of the most common SNB techniques in BC with a focus on recent innovations.

Advancing intraoperative magnetic tracing using 3D freehand magnetic particle imaging

Purpose

Sentinel lymph node biopsy is a routine procedure for nodal staging in penile cancer. Most commonly, this procedure is guided by radioactive tracers, providing various forms of preoperative and intraoperative guidance. This is further extended with fluorescence imaging using hybrid radioactive–fluorescence tracers. Alternatively, a magnetic-based approach has become available using superparamagnetic iron-oxide nanoparticles (SPIONs). This study investigates a novel freehand magnetic particle imaging and navigation modality (fhMPI) for intraoperative localization, along with a hybrid approach, combining magnetic and fluorescence guidance.

Materials and methods

The fhMPI set-up was built with a surgical navigation device, optical tracking system and magnetometer probe. A dedicated reconstruction software based on a look-up-table method was used to reconstruct a superficial 3D volume of the SPION distribution in tissue. For fluorescence guidance, indocyanine green (ICG) was added to the SPIONs. The fhMPI modality was characterized in phantoms, ex vivo human skin and in vivo porcine surgery.

Results

Phantom and human skin explants illustrated that the current fhMPI modality had a sensitivity of 2.2 × 10^–2 mg/mL SPIONs, a resolving power of at least 7 mm and a depth penetration up to 1.5 cm. Evaluation during porcine surgery showed that fhMPI allowed for an augmented reality image overlay of the tracer distribution in tissue, as well as 3D virtual navigation. Besides, using the hybrid approach, fluorescence imaging provided a visual confirmation of localized nodes.

Conclusion

fhMPI is feasible in vivo, providing 3D imaging and navigation for magnetic nanoparticles in the operating room, expanding the guidance possibilities during magnetic sentinel lymph node procedures. Furthermore, the integration of ICG provides the ability to visually refine and confirm correct localization. Further clinical evaluation should verify these findings in human patients as well.

A complete magnetic sentinel lymph node biopsy procedure in oral cancer patients: A pilot study

OBJECTIVES

To assess the feasibility and merits of a complete magnetic approach for a sentinel lymph node biopsy (SLNB) procedure in oral cancer patients.

MATERIALS AND METHODS

This study included ten oral cancer patients (stage cT1-T2N0M0) scheduled for elective neck dissection (END). Superparamagnetic iron oxide nanoparticles (SPIO) were administered peritumorally prior to surgery. A preoperative MRI was acquired to identify lymph nodes (LNs) with iron uptake. A magnetic detector was used to identify magnetic hotspots prior, during, and after the SLNB procedure. The resected sentinel LNs (SLNs) were evaluated using step-serial sectioning, and the neck dissection specimen was assessed by routine histopathological examination. A postoperative MRI was acquired to observe any residual iron.

RESULTS

Of ten primary tumors, eight were located in the tongue, one floor-of-mouth (FOM), and one tongue-FOM transition. SPIO injections were experienced as painful by nine patients, two of whom developed a tongue swelling. In eight patients, magnetic SLNs were successfully detected and excised during the magnetic SLNB procedure. During the END procedure, additional magnetic SLNs were identified in three patients. Histopathology confirmed iron deposits in sinuses of excised SLNs. Three SLNs were harboring metastases, of which one was identified only during the END procedure. The END specimens revealed no further metastases.

CONCLUSION

A complete magnetic SLNB procedure was successfully performed in eight of ten patients (80% success rate), therefore the procedure seems feasible. Recommendations for further investigation are made including: use of anesthetics, magnetic tracer volume, planning preoperative MRI, comparison to conventional technique and follow-up.

Introducing SentiMag in a rural setting: A 5-year experience

BACKGROUND

The Sentimag device is a probe that contains a sensitive magnetometer which detects either an implantable magnetic marker (MagSeed) or an infectable superparamagnetic ironoxide nanoparticle tracer (MagTrace). MagSeed is used to localise impalpable breast lesions; MagTrace is used to identify sentinel lymph nodes. In Australasia, Sentinel lymph node (SLN) biopsy, using radioactive colloid injection, is a mainstay of prognostication in breast surgery in patients with a clinically negative axilla. In addition, radioactive seeds or hookwires have been used to detect impalpable breast lesions. Gisborne Hospital has been using the SentiMag device since June 2016 to both identify sentinel lymph nodes (Magtrace) and impalpable tumours (Magseed). This study gives perspective over more than 5 years on how this new technology can benefit patients and clinicians in the rural setting.

METHODS

Patient data had been collected by the operative surgeon prospectively and corroborated with the coding department. Consecutive cases performed by a single surgeon were included in this study. Inclusion criteria were: (1) any patient who needed localisation of an impalpable breast lesion; (2) any patient who needed a sentinel lymph node biopsy; (3) cases were collected from January 2013 with the large majority of cases were collected between January 2015 and Jan 2020. Comparisons were made between patients with different localisation methods. Basic demographics were collected at the time of the surgery and outcomes then recorded. Staging, lymph node status, lymph node detection rates and complications were collected. Mode of tumour and sentinel node location was recorded. Financial data was collected from administrative staff via receipts and invoices of purchases to the hospital.

RESULTS

Of the 125 patients included in this study: 23 underwent magnetic seed insertion; 15 underwent a hookwire insertion; 45 cases used MagTrace injection; 71 cases used radioactive colloid injection. There was a significantly higher detection rate of two or more sentinel nodes in the SentiMag group. (91% vs. 71.8%, p = 0.01). Neither complication rates, nor cancer detection rates were significantly different. Eighty-four (67.2%) cases did not require tumour location.

CONCLUSION

SentiMag is safe to use in a rural setting. Using the SentiMag system can simplify care for patients and surgeons and was shown to be cost effective in our hospital.