Preoperative diagnosis of the axillary arch with multidetector row computed tomography and the axillary arch in association with anatomical problems of sentinel lymph node biopsy.

BACKGROUND: The purpose of this study was to describe the preoperative diagnosis of the axillary arch with multidetector row computed tomography (MDCT) in patients who underwent sentinel lymph node (SLN) biopsy. In addition, we investigated anatomical problems of SLN biopsy in the cases that diagnosed this anomaly.
METHODS: From 2003 to 2008, combined procedures with blue dye SLN biopsy and MDCT-assisted axillary node sampling were performed in 550 clinically axilla-negative patients with primary operable breast cancer. We use MDCT for not only the diagnosis of the axillary arch, but also the planning and navigation of SLN biopsy.
RESULTS: The axillary arches were preoperatively diagnosed with MDCT in 59 patients (10.8%) as follows: a single ordinary axillary arch (n = 44), another anomalous muscle besides the ordinary axillary arch (n = 13), and other rare axillary arches (n = 2). The SLN identification failure rate was 1.8% (9/491) for patients without the axillary arch and 5.1% (3/59) for patients with the axillary arch (chi-square test, P = 0.11). Three patients with an axillary arch in whom a SLN could not be identified were observed in 13 patients who had another anomalous muscle besides the ordinary axillary arch (3/13, 23.1%). In the examination of 56 patients with an axillary arch in whom a SLN was identified, variations of the SLN location and/or anomalous muscles covering a SLN were observed in 16 patients (28.5%).
CONCLUSIONS: MDCT is useful for a diagnosis of the axillary arch. The axillary arch should be kept in mind during SLN biopsy because this anomaly would be related to anatomical variations that affect SLN biopsy.