Evaluation of sonographic detectability of different markers within an in vitro simulation model of the axilla.

PURPOSE: Clip-marking of axillary lymph nodes with initial biopsy-confirmed metastasis is required for targeted axillary dissection (TAD), which includes sentinel lymph node dissection (SLND) and selective localization and removal of the clipped targeted lymph node. There have been several studies which examined the feasibility of TAD in routine clinical use. In this context, the optimal clip visualisation was noted as one of the crucial limiting factors. We, therefore, evaluated the sonographic detectability of 10 different commercially available markers within an in vitro model simulating the anatomical composition of the axilla. METHODS: In this standardised model consisting of porcine fat with 30 mm thickness, the visibility of a total of ten markers was analysed in all 3 planes (parallel, diagonal, orthograde) with wire guidance and then classified into either "visibility good", "visibility moderate" or "visibility poor" with regard to the alignment of the transducer. Additionally, "real-life conditions" were simulated, in which the markers were searched without any wires guidance. RESULTS: It was observed that, while not all markers are detectable in fatty tissue, markers with spherical shape (non-embedded Inconel or Nitinol) or rectangular-shaped Titanium markers with embedded material have a clear advantage. 3D-shaped markers can always be detected in all three axes, which is of particular importance in the axilla with its pyramid shape and fatty tissue. CONCLUSION: The shape and the embedding of the material play a crucial role for visibility and efficacy of the marker, as reliable marking of suspicious and pathological axillary lymph nodes is essential for TAD.

Axillary ultrasound for prediction of response to neoadjuvant therapy in the context of surgical strategies to axillary dissection in primary breast cancer: a systematic review of the current literature.

PURPOSE: Data on the optimal treatment strategy for patients undergoing neoadjuvant therapy (NAT) who initially presented with metastatic nodes and convert to node-negative disease (cN+ → ycN0) are limited. Since NAT leads to axillary downstaging in 20-60% of patients, the question arises whether these patients might be offered less-invasive procedures than axillary dissection, such as sentinel node biopsy or targeted removal of lymph nodes marked before therapy. METHODS: We performed a systematic review of clinical studies on the use of axillary ultrasound for prediction of response to NAT and ultrasound-guided marking of metastatic nodes for targeted axillary dissection. RESULTS: The sensitivity of ultrasound for prediction of residual node metastasis was higher than that of clinical examination and MRI/PET in most studies; specificity ranged in large trials from 37 to 92%. The diagnostic performance of ultrasound after NAT seems to be associated with tumor subtype: the positive predictive value was highest in luminal, the negative in triple-negative tumors. Several trials evaluated the usefulness of ultrasound for targeted axillary dissection. Before NAT, nodes were most commonly marked using ultrasound-guided clip placement, followed by ultrasound-guided placement of a radioactive seed. After chemotherapy, the clip was detected on ultrasound in 72-83% of patients; a comparison of sonographic visibility of different clips is lacking. Detection rate after radioactive seed placement was ca. 97%. CONCLUSION: In conclusion, ultrasound improves prediction of axillary response to treatment in comparison to physical examination and serves as a reliable guiding tool for marking of target lymph nodes before the start of treatment. High quality and standardization of the examination is crucial for selection of patients for less-invasive surgery.