The feasibility of breast cancer sentinel lymph node mapping at CT lymphography

Objective To evaluate the feasibility of sentinel lymph node(SLN) mapping with CT lymphography (CT-LG). Methods Twenty-five patients with confirmed breast cancer and no palpably axillary lymph node underwent CT-LG examination. The first one or more lymph nodes along the lymph duct draining from the injection sites to axilla were defined as SLNs, and then the LG results were compared with sentinel lymph node biopsy (SLNB). The over- and underestimation of LG were evaluated. The quality of LG imaging was classified Grade Ⅰ and Ⅱ according to lymph duct appearance on volume rendering (VR). The body mass index (BMI) ＞ 25 was considered obesity. Fisher exact test was used for the statistics. Results (1)Of 25 patients, 5 had local mastectomy history. BMI ＜ 25 was found in 20 cases, and ≥25 was in 5 cases. (2) All SLNs were showed by CT-LG, and Grade Ⅰ and Ⅱ imaging quality were achieved in 21 cases ( 84. 0% ) and 4 cases ( 16. 0% ), respectively. The obese patient tended to have a poor imaging quality ( P ＜ 0. 05 ). (3) Fifty-six SLNs and 45 lymph ducts in all 25 patients were identified on CT-LG. Compared with the results of SLNB, 7 cases ( 28. 0% ) and 9 cases ( 36. 0% ) were over- and underestimated respectively by CT-LG due to obesity and local mastectomy ( P ＜ 0. 05 ). (4) Fifty-two negative SLNs in 18 patients and 15 positive SLNs in 7 patients were confirmed by pathology through SLNB, while 56 SLNs were delineated on CT-LG with 43 negative and 13 positive. The shape in 32. 6% of the negative SLNs (14/43) and 76. 9% of the positive SLNs (10/13) was round,the difference was significant (P＜0. 05). The filling defect on the center in 9.3% of negative SLNs (4/43) and 23. 1% of positive SLNs (3/13) was demonstrated, and irregular filling defect on the margin was found only in 30.8% of positive SLNs (4/13). 3 SLNs in 2 patients combined with small satellite lymph nodes on CT-LG were also confirmed to have tumor infiltration. Conclusion CT-LG can clearly demonstrate the breast lymphatic pathway and may potentially be used for breast SLN mapping, while the imaging quality can be influenced by the obesity and local mastectomy. Key words: Breast neoplasms;  Sentinel lymph node biopsy;  Tomography, X-ray computed; Lymphography