Nanoscale iodized oil emulsion: a useful tracer for pretreatment sentinel node detection using CT lymphography in a normal canine gastric model

Abstract

BACKGROUND: Pretreatment identification of the sentinel lymph nodes (SLNs) in gastric cancer patients may have great advantages for minimally invasive treatment. No reliable method for the detection of SLNs during the pretreatment period in gastric cancer has been established. The aim of this study was to determine whether computed tomographic (CT) lymphography using nanoscale iodized oil emulsion via endoscopic submucosal injection can visualize LNs.

METHODS: Five dogs underwent CT lymphography after endoscopic submucosal injection of 2 ml of a nanoscale iodized oil emulsion. CT images were taken before and 30, 90, and 210 min after contrast injection. Intraoperative SLN detection was performed using endoscopically injected indocyanine green lymphography for comparison.

RESULTS: Computed tomographic lymphography with nanoscale iodized oil emulsion enabled the visualization of 19 enhanced LNs (mean = 3.8/dog, range = 3-6) with a 100% SLN detection rate. The locations of the SLNs were the lesser curvature (n = 7), greater curvature (n = 1), infrapyloric (n = 3), and left gastric (n = 8) areas. Contrast enhancement of SLNs continuously increased and peaked after 210 min at 142.4 ± 42.3 HU. No green LNs were visualized in the three locations that were detected by CT lymphography. However, no additional LNs were visualized using the dye method. The concordance rate based on the LNs between the SLNs on CT lymphography and the green LNs using the ICG method was 84% (16/19), whereas the concordance rate of the stations identified by CT lymphography and the dye method was 78.6% (11/14).

CONCLUSIONS: Computed tomographic lymphography using nanoscale iodized oil emulsion is a promising tool for preoperative SLN detection for early gastric cancer if the biological safety of the nanoscale iodized oil emulsion can be established.