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Sentinel Lymph Node Biopsy in Breast Cancer

The sentinel lymph node biopsy is standard in clinical routine for many solid tumors worldwide. The clinical motivation of this procedure is to find out if a tumor has metastasized to the surrounding lymph nodes. This succeeds by surgically extracting the so-called sentinel lymph node(s), the first lymph node(s) draining the tumor.

Intra-operatively the invasive resection of the sentinel lymph node(s) is guided by a radiation detector [Kuehn2005]. The declipseSPECT imaging system has potential for performing the imaging intra-operatively, providing a 3-D picture including the depth information and correlating this imaging data with the patient anatomy for image guided, minimally invasive resection. Furthermore, an image directly after the resection in the operation room allows the confirmation of a complete resection i.e. that all radioactive lymph node were extracted. declipseSPECT contributes to a safe and minimally invasive resection of the sentinel lymph nodes and a validation of its complete removal [Schnelzer2010].

The search for the sentinel nodes in breast cancer patients is based on your profound 3-D capabilities and the interpretation of gamma probe readings while moving over the operation site. declipseSPECT enables, for the first time worldwide, intra-operative 3-D imaging, 3-D high resolution image viewing, and depth measurements to pinpoint the target region. The generated 3-D images are in direct correlation with the anatomy, enabling the guidance of surgical instruments for a direct approach to the sentinel nodes. After dissection of the sentinel lymph node the system provides quality assurance and a tool for documentation of the complete removal of radioactive structures or if additional nodes are detected - image based feedback while still in the operating room.

A standard workflow using declipseSPECT is provided below:

3-D Breast Imaging in the operation room before intervention:

Full 3-D image acquisition enables precise identification and localization Direct correlation with anatomy provides intuitive orientation and referencing Overview of activity distribution ensures detection of hidden sentinel nodes behind injection site (eliminates shadowing effects) and allows in-situ decision support on what needs to be resected
Figure: In this case the injection site was around the nipple and one axillary sentinel lymph nodes was clearly visible. The generated 3-D images are projected with augmented reality techniques on the real-time video image for intuitive anatomical referencing and guidance.

Navigation to the sentinel nodes during intervention:

Orientation, localization and identification in 3-D ensure safety during procedure Depth measurement provides minimally invasive, fast and intuitive access to the surgical region of interest
Figure: The navigation mode shows the activity distribution in 3-D including depth measurement from the tip of the gamma probe to the sentinel lymph node(s).

Control of complete resection of all sentinel nodes:

Orientation, localization and identification in 3-D ensure safety during procedure and documents complete removal Documentation provides transparent and reliable follow up treatments
Figure: After removal of the sentinel lymph nodes a second image documents the removed activity from the axilla. No further sentinel lymph node(s) marked with Tc-99m is visible.