Jonathan Horsnell

Raman spectroscopy – A potential new method for the intra-operative assessment of axillary lymph nodes

Sentinel Lymph Node Biopsy has become the standard surgical procedure for the sampling of axillary lymph nodes in breast cancer. Intra-operative node assessment of these nodes would allow definitive axillary surgery to take place immediately with associated benefits for patient management. Our experimental study aims to demonstrate that a Raman spectroscopy probe system could overcome many of the disadvantages of current intra-operative methods. 59 axillary lymph nodes, 43 negative and 16 positive from 58 patients undergoing breast surgery at our district general hospital were mapped using Raman micro-spectroscopy. These maps were then used to model the effect of using a Raman spectroscopic probe by selecting 5 and 10 probe points across the mapped images and evaluating the impact on disease detection. Results demonstrated sensitivities of up to 81% and specificities of up to 97% when differentiating between positive and negative lymph nodes, dependent on the number of probe points included. The results would have concurred with histopathology assessment in 89% and 91% of cases in the 5 and 10 point models respectively. Using Raman spectroscopy in this way could allow lymph node assessment within a time-frame suitable for intra-operative use.

Towards the intra-operative use of Raman spectroscopy in breast cancer-overcoming the effects of theatre lighting.

The ability to use Raman spectroscopy to assess tissue in the operative theatre setting could be advantageous for both patients and clinicians. In this study, a method of overcoming the deleterious effects of theatre lighting on the Raman spectra is demonstrated. The effectiveness of this technique is highlighted both within the theatre setting and using human lymph node tissue. The portable MiniRam II Raman spectroscopy device that incorporated a 785-nm laser was used in all experiments. This is an important step towards the use of Raman spectroscopy as a means of analysing sentinel lymph nodes in patients who have been newly diagnosed with breast cancer.