SPECT/CT for SLN dissection in vulvar cancer: Improved SLN detection and dissection by preoperative three-dimensional anatomical localisation

• Exact anatomical and three-dimensional localization of SLN by SPECT/CT.
• Visualization of aberrant lymphatic drainage by SPECT/CT.
• SPECT/CT improves detection rates and facilitates intra-operative SLN detection.

ObjectiveIn this study, we assessed the feasibility and clinical advantages of single photon emission computed tomography with CT (SPECT/CT) for sentinel lymph node (SLN) detection in vulvar cancer.MethodsThis is a unicentric prospective trial. Vulvar cancer patients underwent preoperative SLN marking (10 MBq Technetium (TC)-99 m-nanocolloid) and subsequent planar lymphoscintigraphy (LSG) and SPECT/CT for SLN visualization. Directly before surgery, a patent blue dye was injected. We assessed detection rates of SPECT/CT and those of planar LSG and intraoperative detection. We analyzed the sensitivity, negative predictive value and false negative rate.ResultsAt Hannover Medical School, 40 vulvar cancer patients underwent SLN dissection after preoperative LSG and SPECT/CT. The mean diameter of all tumors in final histology was 2.23 (0.1–10.5) cm with a mean tissue infiltration of 3.93 (0.25–11) mm.In preoperative imaging, SPECT/CT identified significantly more SLNs (mean 8.7 (1–35) LNs per patient) compared to LSG (mean 5.9 (0–22) LNs, p < 0.01). In addition, SPECT/CT led to a high spatial resolution and anatomical localization of SLNs. Thus, SPECT/CT identified aberrant lymphatic drainage in 7/40 (17.5%) patients. There were no significant differences, but significant correlation was found between SPECT/CT and intraoperative SLN identification. Regarding inguino-femoral LNs, for all patients who underwent complete groin dissection, sensitivity was 100%, NPV was 100% and false negative rate was 0%.ConclusionSPECT/CT leads to higher SLN identification compared to LSG in vulvar cancer. Due to its higher spatial resolution and three-dimensional anatomical localisation of SLNs, SPECT/CT provides the surgeon with important additional information, facilitates intraoperative SLN detection and predicts aberrant lymphatic drainage.