3D-CT Lymphography for Mapping Metastatic Breast Sentinel Node and Axillary Nodes

Background: The detailed relations between lymph nodes and lymph flow in the breast and the axilla can be clarified using 3D-CT lymphography (LG). We have developed this 3D image-processing system to depict more precise anatomical structure of mammary lymphovascular system. It enables us to perform systematic collection of axillary lymph nodes including sentinel nodes (SNs), and will decrease unnecessary lymph node dissection, even if the SNs have metastasized, and can decrease complications. We reviewed a validity of 3D-CT LG, and a metastatic pattern of axillary nodes and SNs of 40 metastasis-positive cases among 186 SN biopsies. Methods: 3D-CT LG was performed on the day before the surgery to mark SN on the skin. Above the tumor and near the areola, 2 ml of Iopamiron 300 was injected subcutaneously. Images from a 16-channel multidetector-row helical scan were taken at 1 min after injection for SN detection, and at 3 and 5 min for observing advancement of lymph flow into venous angle. They were reconstructed to produce a 3D image of lymph ducts and lymph nodes by shaded volume-rendering method. The axillary lymph node groups from SNs to subclavicular nodes were exposed by partially removing fat tissue and muscle in the 3D image. SN biopsy was performed by dye-staining method using endoscopy. The SNs were found by following the dye in the lymph ducts on video monitor. SNs and the second and the third nodes were sampled by the same way. Results: We performed SN biopsy with 3D-CT LG in 146 patients. 3D-CT LG showed the precise lymphatic flow from the tumor to SNs. The position of SNs was identified by their surrounding pectoral muscles and vascular systems, such as axillary vein, lateral thoracic artery, and thoracodorsal artery. We classified the relationship between the lymph ducts and the drained SNs into four patterns: single duct to single node (n = 88); multiple ducts to single node (n = 29); single duct to multiple nodes (n = 2); and multiple ducts to multiple nodes (n = 27). 3D-CT LG can show sentinel lymph node at only 1 min after injection. But following up to 3 and 5 min after injection, we can follow the lymph ducts after the SLN into the second and third nodes toward the venous angle with the complex plexus in 3D-CT LG. The figure shows five bead-like-grouped lymph nodes beyond the SLN and lymph duct plexuses between them. Detection rate was 100% for SN; 80.1% for the third group; and 30.1% for the fifth group. Multiple nodes were observed in SN (19.9%), in the second group (10.1%), and in the third group (4.3%). SN metastasis was positive in 40 patients, and only SN metastasis was found in 21 patients (52.5%) among them; SN and second group metastases were in 19 patients; SN and second and third group metastases were in 16 patients; and beyond the third group metastasis was in 11 patients. But any skip metastasis beyond second and third nodes was not observed. Conclusions: By 3D-CT LG, we can recognize the accurate and more precise lymph flow and their positional relations to surrounding anatomical architecture. It helps us easily to pursuit lymph flow and to remove sentinel, second, and third nodes by endoscopic technique. 52.5% of SN metastasis-positive patients had no metastasis in other nodes. They can be candidates for preserving their axillary node. 3D-CT LG-guided SN biopsy for the second and third groups will predict their existence and help us to avoid dissecting needless nodes.