Fluorescent imaging strengthens surgical oncology care

Specialist veterinary teams are using Near-Infrared Fluorescence (NIRF) imaging to support accurate sentinel lymph node identification and removal in dogs and cats with cancer.

Experts in Soft Tissue Surgery are working with colleagues in the Oncology Service at the Hospital for Small Animals and using the advanced intraoperative imaging capability to strengthen case management of referred animals.

Imaging tool

NIRF technology allows surgeons to visualise lymphatic drainage pathways from tumours, by tracking a fluorescent dye, most commonly indocyanine green (ICG). This is injected at the site of a tumour or tumour scar, and can then be followed to the sentinel node. To the naked eye, the skin surface and other tissues will look normal, but with the NIRF camera system the relevant nodes fluoresce, enabling real-time localisation and targeted dissection for removal.

Clinical need

The tool can aid accurate identification of tumour spread to lymph nodes, as a critical part of staging cancer in dogs and cats. The sentinel lymph node is the first to drain a primary tumour and so is expected to be the first site to harbour metastases. Removing metastatic nodes can contribute to tumour control, and knowing whether the sentinel node is positive or negative for tumour spread can significantly influence prognosis, treatment recommendations and overall case planning.

Surgical challenge

Identifying and removing lymph nodes can be difficult. Although metastatic nodes may be enlarged, they may only be a few millimetres in size and obscured by surrounding fat or deeper tissues. Drainage patterns are not always predictable, and in some patients the tumour may drain to more than one sentinel node, increasing the chance that clinically relevant nodes could be missed without mapping.

Imaging advantages

By supporting real-time sentinel lymph node mapping, NIRF can improve the reliability of lymph node identification, can help reveal when more than one draining node is present, and increase confidence when nodes are small or difficult to locate.

Future potential

While sentinel lymph node mapping is a key current application, ongoing research suggests that in the future NIRF may have additional uses. These may potentially include applications in chylothorax surgery, surgery for biliary tract obstruction, and identifying blood supply to skin for reconstructive surgery.

Referral service

The Soft Tissue Surgery and Oncology teams at the Hospital for Small Animals are among the largest teams of Specialist vets and nurses in the UK. For referrals and case discussion, please contact hfsareception@ed.ac.uk