PET-CT gamma probe-guided lymph node biopsy: a new diagnostic surgical approach

The higher sensitivity of new diagnostic tools makes it easier to detect relapse in asymptomatic stages when classic procedures of lymph node biopsies are difficult to perform. The aim of this article is to describe the combination of gamma probe and 18F-FDG positron emission tomography-computed tomography (PET-CT) images in combination with sentinel lymph node biopsy technique for detection of nonpalpable lymph nodes.

After a dose of 18F-FDG was administered and PET-CT images that showed the location of suspected pathologic lymph nodes were obtained, transcutaneous localization of the lymph nodes with the highest captation of the tracer was done. The gamma probe was programmed to detect the radioactive signal from the F18, instead of the Tc99m that is usual in the sentinel node biopsy technique. Once the hottest point was detected, a short incision was made on this area, and suspicious nodes with the highest uptake registered by the gamma probe were localized and removed. After the surgical removal from the operating field, the surgical pieces stood positive to the gamma probe. Lymph node involvement, and subsequent relapse, was diagnosed before their clinical manifestation.

This methodology confirms new horizons for the surgical approach of lymph node biopsies in patients with previous tumors with 18F-FDG avidity and suspicion of relapse.