Axillary Sentinel Lymph-Node Biopsy: Gamma Probe Assisted Sonographic Localisation

Abstract

To evaluate axillary sentinel lymph-node (SLN) identification and localisation with gamma probe-assisted sonography. The study comprises 42 patients. Sonographically guided peri-lesional injection of the radiopharmacon was performed on 40 breasts. Two patients with melanoma of the upper extremity underwent intracutaneous injection. After the acquisition of images with the gamma camera, the delineated lymph nodes were marked on the skin. A high-frequency transducer with an adapted gamma probe was then used to identify the SLN. Before surgery, the SLN was localised with a hook-wire. Node activity was controlled intraoperatively. In two out of 42 cases, lymphatic mapping did not reveal SLNs. Multiple SLNs at different sites, all with similar activity, were demonstrated in one patient, while in another patient the sonographically visible lymph nodes were too small for exact correlation. Hook-wire localisation of the SLN was performed in the remaining 38 axillary spaces. Gamma probe-assisted sonography allowed for correct localisation of SLNs in 35/38 patients (92 %). Localisation was not correct in 3 patients (8 %), but in all cases the hook-wire was located next to the SLN. Preoperative identification and correct localisation of the SLN is possible in a high percentage of cases. This method allows rapid intraoperative detection of the SLN and could be used for exact correlation of sonographic appearance and histopathological results.