The imaging probe improves Sentinel Node biopsy in breast cancer

Aim. To assess if intra-operative High Resolution (HR) images improve the radio-guided biopsy of sentinel node (SN) for breast cancer study. Methods. The imaging probe (IP) used by us is an hand held, 1inch2 FOV, providing 2mm spatial resolution, built with a position sensitive photomultiplier, a 30 mm long square-hole collimator with integrated crystals- US and UE patented-, home made electronics and software. A notebook serves as monitor, image processor and image archive. We performed SN biopsy after intra-dermal injection of 99mTc nanocollTM and Anger Camera lymphoscintigraphy (ACL) on two groups of 50pts each with T1 breast cancer, identified as group A and B. A and B groups were age, body mass index and cancer size matched. During operation SN was detected with only a common gamma probe (GP) providing acoustic signals in group A, with HR imaging guiding GP in group B. Results. Specificity: Group A: ACL images and GP guided surgeons to withdraw 4 hot spots not containing SN but only fat and enlarged lymph vessels. Group B: No False SN: IP clearly showed HR images of nodes and lymph vessels. Sensitivity. In group A, GP detected double nodes on 12 pts, In group B, IP detected multiple node in 30 patients, three of whom showing 3 nodes and one 4 nodes. Group A showed 13 invaded nodes ( 20,9 %), 2 of which with micro-metastases. Eleven metastases were on the hottest nodes, 2 on less radioactive second nodes. Group B: 21out of the 85 SN (25%) showed invasion, with 6 micro-metastases. Sixteen invasions were observed on hot, 4 on second, 1 on third node. SN Withdrawal time: 11.25 ± 4.7 min in group A and 7.4 ± 2.8 min in group B (P< 0.025). Surgeons considered IP very useful in 19 /50 cases, useful in 21/ 50 cases, of no substantial help in 10 cases.