Reflector-Guided Localisation of Non-Palpable Breast Lesions: A Prospective Evaluation of the SAVI SCOUT® System

Evolution of localization methods for non-palpable breast lesions: a literature review from a translational medicine perspective

Background and Objective

With an increasing number of non-palpable breast lesions detected due to improved screening, accurate localization of these lesions for surgery is crucial. This literature review explores the evolution of localization methods for non-palpable breast lesions, highlighting the translational journey from concept to clinical practice.

Methods

A comprehensive search of PubMed, Embase, and Scopus databases until September 2023 was conducted.

Key Content and Findings

Multiple methods have been developed throughout the past few decades. (I) Wire-guided localization (WGL) introduced in 1966, has become a reliable method for localization. Its simplicity and cost-effectiveness are its key advantages, but challenges include logistical constraints, patient discomfort, and potential wire migration. (II) Intraoperative ultrasound localization (IOUS) has shown promise in ensuring complete lesion removal with higher negative margin rates. However, its utility is limited to lesions visible on ultrasound (US) imaging. (III) Breast biopsy marker localization: the use of markers has improved the precision of localization without the need for wire. However, marker visibility remains a challenge despite improvements in their design. (IV) Radioactive techniques: radio-guided occult lesion localization (ROLL) and radioactive seed localization (RSL) offer flexibility in scheduling and improved patient comfort. However, they require close multidisciplinary collaboration and specific equipment due to radioactive concerns. (V) Other wireless non-radioactive techniques: wireless non-radioactive techniques have been developed in recent three decades to provide flexible and patient-friendly alternatives. It includes magnetic seed localization, radar techniques, and radiofrequency techniques. Their usage has been gaining popularity due to their safety profile and allowance of more flexible scheduling. However, their high cost and need for additional training remain a barrier to a wider adoption.

Conclusions

The evolution of breast lesion localization methods has progressed to more patient-friendly techniques, each with its unique advantages and limitations. Future research on patient-reported outcomes, cosmetic outcomes, breast biopsy markers and integration of augmented reality with breast lesion localization are needed.

Savi Scout Localization for Extrapelvic Endometriosis Resection

BACKGROUND Endometriosis is a common cause of chronic pelvic pain among women globally. Pharmacological therapy for endometriosis includes non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives, while surgical therapy often involves either laparoscopic excision and ablation of endometriosis implants or open surgery. Surgical therapy is one of the mainstays of treatment especially for extrapelvic endometriomas. However, little guidance exists for the treatment of non-palpable or intermittently palpable lesions of this nature. CASE REPORT A 33-year-old woman with a previous cesarean section presented with complaints of intermittent discomfort in the area between her umbilicus and the surgical incision, for the previous 7 years, that worsened during her menstrual cycle. A 3×3-cm area of fullness was only intermittently palpable during various clinic visits, but was visualizable on computed tomography and magnetic resonance imaging. Given the lesion's varying palpability, a Savi Scout radar localization device was placed into the lesion pre-operatively to aid with surgical resection. The mass was excised, pathologic examination revealed endometrial tissue, and the patient had an uncomplicated postoperative course with resolution of her symptoms. CONCLUSIONS Surgical removal of extrapelvic endometrioma lesions can be made difficult by varying levels of palpability or localizability due to a patient's menstrual cycle. The Savi Scout, most commonly used in breast mass localization, is a useful tool in guiding surgical excision of non-palpable or intermittently palpable extrapelvic endometrioma lesions.

Evaluating Radar Reflector Localisation in Targeted Axillary Dissection in Patients Undergoing Neoadjuvant Systemic Therapy for Node-Positive Early Breast Cancer: A Systematic Review and Pooled Analysis

SAVI SCOUT® or radar reflector localisation (RRL) has proven accurate in localising non-palpable breast and axillary lesions, with minimal interference with MRI. Targeted axillary dissection (TAD), combining marked lymph node biopsy (MLNB) and sentinel lymph node biopsy (SLNB), is becoming a standard post-neoadjuvant systemic therapy (NST) for node-positive early breast cancer. Compared to SLNB alone, TAD reduces the false negative rate (FNR) to below 6%, enabling safer axillary surgery de-escalation. This systematic review evaluates RRL's performance during TAD, assessing localisation and retrieval rates, the concordance between MLNB and SLNB, and the pathological complete response (pCR) in clinically node-positive patients post-NST. Four studies (252 TAD procedures) met the inclusion criteria, with a 99.6% (95% confidence [CI]: 98.9-100) successful localisation rate, 100% retrieval rate, and 81% (95% CI: 76-86) concordance rate between SLNB and MLNB. The average duration from RRL deployment to surgery was 52 days (range:1-202). pCR was observed in 42% (95% CI: 36-48) of cases, with no significant migration or complications reported. Omitting MLNB or SLNB would have under-staged the axilla in 9.7% or 3.4% (p = 0.03) of cases, respectively, underscoring the importance of incorporating MLNB in axillary staging post-NST in initially node-positive patients in line with the updated National Comprehensive Cancer Network (NCCN) guidelines. These findings underscore the excellent efficacy of RRL in TAD for NST-treated patients with positive nodes, aiding in accurate axillary pCR identification and the safe omission of axillary dissection in strong responders.

Magnetic Seed vs Guidewire Breast Cancer Localization With Magnetic Lymph Node Detection: A Randomized Clinical Trial

Importance

Guidewires have been the standard for breast lesion localization but pose operative and logistic challenges. Paramagnetic seeds have shown promising results, but to the authors' knowledge, no randomized comparison has been performed.

Objective

To determine whether the combination of a paramagnetic seed and superparamagnetic iron oxide (SPIO) is equivalent to guidewire and SPIO for breast cancer localization and sentinel lymph node detection (SLND).

Design, Setting, and Participants

This was a phase 3, pragmatic, equivalence, 2-arm, open-label, randomized clinical trial conducted at 3 university and/or community hospitals in Sweden from May 2018 to May 2022. Included in the study were patients with early breast cancer planned for breast conservation and SLND. Study data were analyzed July to November 2022.

Interventions

Participants were randomly assigned 1:1 to a paramagnetic seed or a guidewire. All patients underwent SLND with SPIO.

Main Outcomes and Measures

Re-excision rate and resection ratio (defined as actual resection volume / optimal resection volume).

Results

A total of 426 women (median [IQR] age, 65 [56-71] years; median [IQR] tumor size, 11 [8-15] mm) were included in the study. The re-excision rate was 2.90% (95% CI, 1.60%-4.80%), and the median (IQR) resection ratio was 1.96 (1.15-3.44). No differences were found between the guidewire and the seed in re-excisions (6 of 211 [2.84%] vs 6 of 209 [2.87%]; difference, -0.03%; 95% CI, -3.20% to 3.20%; P = .99) or resection ratio (median, 1.93; IQR, 1.18-3.43 vs median, 2.01; IQR, 1.11-3.47; P = .70). Overall SLN detection was 98.6% (95% CI, 97.1%-99.4%) with no differences between arms (203 of 207 [98.1%] vs 204 of 206 [99.0%]; difference, -0.9%; 95% CI, -3.6% to 1.8%; P = .72). More failed localizations occurred with the guidewire (21 of 208 [10.1%] vs 4 of 215 [1.9%]; difference, 8.2%; 95% CI, 3.3%-13.2%; P < .001). Median (IQR) time to specimen excision was shorter for the seed (15 [10-22] minutes vs 18 [12-30] minutes; P = .01), as was the total operative time (69 [56-86] minutes vs 75.5 [59-101] minutes; P = .03). The experience of surgeons, radiologists, and surgical coordinators was better with the seed.

Conclusions and Relevance

The combination of SPIO and a paramagnetic seed performed comparably with SPIO and guidewire for breast cancer conserving surgery and resulted in more successful localizations, shorter operative times, and better experience.

Trial Registration

ISRCTN.org Identifier: ISRCTN11914537.

Surgeon and Radiologist Evaluation of Electromagnetic Chip Localization for Benign and Malignant Breast Lesions

BACKGROUND

SmartClipTM is a food and drug administration-approved, electromagnetic chip (EMC) localization system that provides three-dimensional navigation for the excision of soft tissue lesions. The purpose of this study was to analyze the accuracy and feasibility of EMC radiologic and surgical localization for benign and malignant breast lesions.

PATIENTS AND METHODS

An institutional review board-approved, single institution, prospective study from October 2020 to September 2022 of 38 women undergoing breast conserving surgery with EMC localization of a single lesion > 5 mm on mammogram (MMG) or ultrasound (US) imaging. Surveys from performing breast radiologists and breast surgeons were collected after image-guided localization and surgical excision.

RESULTS

Seventy-six survey responses from nine radiologists and four surgeons were received. The deployment needle and EMC were highly visible in 86.8% and 76.3% of procedures, respectively. There was no difficulty in deployment for 92.1% of procedures. The EMC was in the correct location on postdeployment MMG in 97.4% of cases. Three instances of EMC migration occurred, one 1 cm from target lesion. The targeted mass and EMC were within the surgical specimen in 97.4% of cases. On specimen radiograph, 39.5% of the EMCs were 0-1 mm from the center of the target lesion, 18.4% were within 2-4 mm, and 23.7% were within 5-10 mm. Mean operating room time for all cases was 65 min. One case required US to localize the target due to console malfunction.

CONCLUSION

There was successful EMC deployment by radiologists with accurate visualization and successful surgical excision in most cases. The EnVisioTM SmartClipTM system is a reproducible and accurate localization method for benign and malignant breast lesions.

Comparison of Wire and Non-Wire Localisation Techniques in Breast Cancer Surgery: A Review of the Literature with Pooled Analysis

Background and Objectives: Wide local excision is a common procedure in the treatment of breast cancer. Wire-guided localisation (WGL) has been the gold standard for many years; however, several issues have been identified with this technique, and therefore, wire-free techniques have been developed. This scoping review synthesises the available literature comparing wire-guided localisation with the wire-free techniques used in breast-conserving cancer surgery. Materials and Methods: Multiple databases including Pubmed and MEDLINE were used to search articles between 1 January 2000 and 31 December 2022. Terms included "breast neoplasms", "margins of excision", and "reoperation". In total, 34/256 papers were selected for review. Comparisons were made between positive margins and re-excision rates of WGL with wire-free techniques including SAVI SCOUT, Magseed, ROLL, and RSL. Pooled p-values were calculated using chi-square testing to determine statistical significance. Results: Pooled analysis demonstrated statistically significant reductions in positive margins and re-excision rates when SAVI SCOUT, RSL, and ROLL were compared with WGL. When SAVI SCOUT was compared to WGL, there were fewer re-excisions {(8.6% vs. 18.8%; p = 0.0001) and positive margins (10.6% vs. 15.0%; p = 0.0105)}, respectively. This was also the case in the ROLL and RSL groups. When compared to WGL; lower re-excision rates and positive margins were noted {(12.6% vs. 20.8%; p = 0.0007), (17.0% vs. 22.9%; p = 0.0268)} for ROLL and for RSL, respectively {(6.8% vs. 14.9%),(12.36% vs. 21.4%) (p = 0.0001)}. Magseed localisation demonstrated lower rates of re-excision than WGL (13.44% vs. 15.42%; p = 0.0534), but the results were not statistically significant. Conclusions: SAVI SCOUT, Magseed, ROLL, and RSL techniques were reviewed. Pooled analysis indicates wire-free techniques, specifically SAVI SCOUT, ROLL, and RSL, provide statistically significant reductions in re-excision rates and positive margin rates compared to WGL. However, additional studies and systematic analysis are required to ascertain superiority between techniques.

Comparison of 3 Different Systems for Non-wire Localization of Lesions in Breast Cancer Surgery

PURPOSE

Localizing breast lesions by marking tumors and their detection using probes during surgery is a common part of clinical practice. Various nonwire localization systems were intended to be compared from different perspectives.

METHODS

Various measurement experiments were performed. Localization techniques, including radioactive seed (RSLS), magnetically guided (MGLS), or radar (SLS), were compared in signal propagation in water and tissue environments, signal interference by surgical instruments, and the practical experience of surgeons. Individual experiments were thoroughly prospectively planned.

RESULTS

The RSLS signal was detectable at the largest evaluated distance, ie, 60 mm. The SLS and MGLS signal detection was shorter, up to 25 mm to 45 mm and 30 mm, respectively. The signal intensity and the maximum detection distance in water differed slightly depending on the localization marker orientation to the probe, especially for SLS and MGLS. Signal propagation in the tissue was noted to a depth of 60 mm for RSLS, 50 mm for SLS, and 20 mm for MGLS. Except for the expected signal interferences by approaching surgical instruments from any direction for MGLS, the signal interruption for RSLS and SLS was observed only by inserting instruments directly between the localization marker and probe. Moreover, the SLS signal interference by instrument touch was noted. Based on surgeons' results, individual systems did not differ significantly for most measurement condition settings.

CONCLUSION

Apparent differences noted among localization systems can help experts choose an appropriate system for a specific situation or reveal small nuances that have not yet been observed in clinical practice.

Experimental and Clinical Advances in Counteracting Progression of Solid Cancers

In recent decades, impressing technological developments have significantly advanced our understanding of cancer [...].

Image-Guided Radar Reflector Localization for Small Soft-Tissue Lesions in the Musculoskeletal System

Preoperative localization of nonpalpable breast lesions using a radar reflector surgical guidance system has become commonplace, but the clinical utility of this emerging technology in the musculoskeletal system has not yet been well established. The system components include a console, a handpiece, an implanted radiofrequency reflector that works as a lesion marker, and an infrared light-emitting probe to guide the surgeon. The reflector can be deployed to localize small nonpalpable nodules within the subcutaneous fat as well as lesions within the deeper soft tissues. It can also be used for lymph nodes and foreign bodies. Localization can be performed both before and after treatment. The objective of this article is to describe the potential applications and our technique and initial experience for radar reflector localization within the musculoskeletal system.

Efficacy and Accuracy of Using Magnetic Seed for Preoperative Non-Palpable Breast Lesions Localization: Our Experience with Magseed

In this retrospective study we share our single-center experience using a magnetic seed for the preoperative localization of non-palpable breast lesions. Patients who underwent a preoperative localization with Magseed^® (Endomagnetics, Cambridge, UK) placement between 2020 and 2022 were enrolled. Indications to Magseed placement have been established during multidisciplinary meetings prior to surgery and all patients underwent breast-conserving surgery (BCS). 45 patients were included. Magnetic seeds have been introduced under ultrasound guidance in 40 patients (88.9%) and under stereotactic guidance in 5 patients (11.1%). We registered a highly successful placement rate (97.8%), with only one case of migration (2.2%). After BCS, all the magnetic seeds were recovered (100% retrieval rate). The re-excision rate for positive margins was 0%. Our experience, with a highly successful placement and retrieval rate and a re-excision rate equal to 0%, is consistent with the encouraging literature published on Magseed so far, suggesting this technique to be extremely effective. Moreover, our single case of seed migration supports the existing data stating that Magseed migration is rare. In conclusion, despite acknowledging Magseed limitations, we highly value the advantages linked to this technique, and we, therefore, uphold its use.

The Evolving Role of Radiofrequency Guided Localisation in Breast Surgery: A Systematic Review

Wire-guided localisation (WGL) has been the gold-standard for localising non-palpable breast lesions before excision. Due to its drawbacks, various wireless alternatives have been developed, including LOCalizer™, which is based on radio-frequency identification (RFID) technology. In this systematic review, we consulted EMBASE, Medline and PubMed databases using appropriate search terms regarding the use of RFID technology in the localisation of occult breast lesions. Retrospective and prospective studies were included if they quoted the number of patients, rate of successful placement, retrieval rate, margin positivity rate and the re-excision rate. In addition, studies comparing RFID to WGL were also included and analysed separately. Seven studies were included in this systematic review spanning 1151 patients and 1344 tags. The pooled deployment rate was 99.1% and retrieval rate was 100%. Re-excision rate was 13.9%. One complication was identified. Two studies compared RFID with WGL (128 vs. 282 patients respectively). For both techniques the re-excision rate was 15.6% (20/128 vs. 44/282 respectively, p value is 0.995). Based on our review, LOCalizer™ is safe and non-inferior to WGL in terms of successful localisation and re-excision rates. However, further research is required to assess the cost effectiveness of this approach and its impact on the aesthetic outcome compared with WGL and other wire free technologies to better inform decision making in service planning and provision.