Sentinella: Portable gamma camera versus conventional scintigram for intraoperative sentinel lymph node detection in breast cancer.

Abstract

22 Background: Sentinel lymph node biopsy (SLNB) is a standard practice for staging the axilla in breast cancer. Access to nuclear medicine department and sentinel node imaging remain an issue in number of hospitals in the UK and rest of the world. Preoperative scintigrams are performed to confirm uptake of radioactivity and localisation of nodes in centres where facilities are available. Sentinella is a portable imaging camera used intraoperatively to produce real time visual localisation of SLNs. Sentinella was tested in a controlled laboratory environment at our centre followed by the first use of this device in breast cancer patients from UK. Methods: Sensitivity and spatial resolution of Sentinella was compared with conventional gamma camera (CGC).Intraoperative Sentinella Scans were performed in 130 patients and their yield compared with Lymphoscintigrams from CGC. Further Sentinella scans were performed after the axilla was deemed clear by silent activity of hand held gamma probe. Results: Sentinella resolution is comparable with the CGC for objects close to the camera. Sentinella detects high radioactivity (500 kBq) faster than CGC (1 vs 2.5min). In cases of low radioactivity (10kBq) Sentinella was equally accurate and faster than CGC, when placed nearer to skin.Intra-operative Sentinella scans detected an average of 2 sentinel nodes compared to 1.4 nodes by CGC scans. Sentinella demonstrated a serial decay in activity with removal of every hot node and its LED guidance helped in detecting residual nodes. Sentinella picked up extra nodes in 5/130 cases after the axilla was found silent using hand held gamma probe. In 2/130 cases extra nodes found using Sentinella had presence of cancer that led to a complete axillary clearance. Conclusions: This data confirms the excellent sensitivity and specificity of the machine in localisation of radioactive nodes. This new imaging technique increases our pick up of SLNs intraoperatively that are missed due to inadequate visualisation and provide a superior detection compared to static scintigram imaging. This portable gamma camera can replace the use of conventional lymphoscintigrams saving camera time and cost.