Challenges to I-125 Seed Localization of Metastatic Axillary Lymph Nodes Following Neoadjuvant Chemotherapy

Abstract

Objective The objective of this retrospective study is to characterize challenges with ultrasound (US)-guided localization of clipped metastatic axillary lymph nodes after neoadjuvant chemotherapy. Methods After institutional review board approval, our radiology database was searched for all radioactive seed localizations (RSLs), which use a low-dose radioactive isotope, Iodine-125, performed for clipped axillary lymph nodes between January 1, 2016, and December 31, 2018. The details of each procedure were reviewed. RSL was defined to be successful if US-guidance was used, and postlocalization imaging showed the seed was no more than 1 cm away from the target. Cause and subsequent management of unsuccessful localizations were documented. Results During the study period, 139 clipped axillary lymph nodes (in 138 women and 1 man) were scheduled for preoperative RSL. The overall success rate of RSL was 106/139 (76%). The number of unsuccessful localizations was 10/37 (27%) in 2016, 7/39 (18%) in 2017, and 16/63 (25%) in 2018, with a total unsuccessful case frequency of 33/139 (24%) over the entire study period. The mean time interval between marker placement and localization was 6.0 months (range 0.4–18.1 months). The coil biopsy marker was the most frequently used marker. Conclusions Preoperative US-guided I-125 seed localization of clipped metastatic axillary lymph nodes is suboptimal or unsuccessful 24% of the time. Other options for non-US imaging-guided localizations, such as tomosynthesis, are available for consideration when US detection is unsuccessful.

Using US Twinkling Artifact to Identify Breast Biopsy Markers: Brief Report

“…While most commercial biopsy markers are made of metal or generally hyperechoic materials, their small US scattering cross-sections may inhibit their visibility in complicated scattering tissue like the breast or the axilla, especially if not encountering the object at a favorable angle for obtaining strong reflectivity. Larger markers, such as the Tumark series that take advantage of the temperature-dependent expansion of nitinol, are not consistently readily visible on B-mode US images ( 1 , 3 , 4 ). The cork, a smaller (1.4 × 1.4 × 3.0 mm) marker, is challenging to detect on B-mode US images, but it exhibits an appreciable twinkling signature.…”

“…There is a clinically unmet need to make breast biopsy markers more sonographically conspicuous for localization purposes ( 1 – 3 ). In the setting of favorable response to neoadjuvant systemic therapy, biopsy markers can be challenging to localize, with studies showing up to 24% of patients exhibiting sonographically occult markers at the time of preoperative localization ( 4 , 5 ). In a recent study, Tumark (Hologic) and Hydromark (Devicor Medical Products) markers, believed to improve US visualization at the time of localization, were successfully visualized and localized in only 50% (25 of 50) of patients ( 3 ).…”