Image-Guided Platform-Assisted Sentinel Lymph Node Retrieval in Early Gastric Cancer

Participants in this arm will undergo standardized LECS-SNNS with indocyanine green (ICG) fluorescence mapping. Following initial retrieval of fluorescent SLNs, the remaining SLB tissue will be placed on the Image-Guided Platform for radiographic and optical imaging. The acquired images will be analyzed using a deep learning model to identify and localize suspected LNs. Physicians will subsequently retrieve suspected LNs according to the image-guided and model-generated localization results. Supplementary visual inspection and manual palpation will then be performed when appropriate to identify any additional LNs.

The Image-Guided Retrieval Specimen Platform is an ex vivo LN retrieval system integrating radiographic imaging, optical imaging, and deep learning-based image analysis. Resected SLB tissue is placed on the platform for image acquisition. The acquired images are analyzed using a deep learning model to identify and localize regions suspected of containing LNs. Physicians subsequently retrieve suspected LNs according to the image-guided and model-generated localization results. All retrieved specimens are submitted for standardized pathological examination.

Participants in this arm will undergo the same standardized LECS-SNNS and ICG fluorescence mapping procedure. Following initial retrieval of fluorescent SLNs, the remaining SLB tissue will be systematically examined by experienced physicians using standardized dissection, visual inspection, and manual palpation to identify and retrieve suspected LNs without image-guided or deep learning-assisted localization.

The residual SLB tissue will be systematically examined by experienced physicians using standardized dissection, visual inspection, and manual palpation to identify and retrieve suspected LNs. No Image-Guided Platform or deep learning-assisted localization will be used.

The primary outcome is the per-participant total number of SLNs retrieved from the resected SLB specimen and submitted for intraoperative frozen-section pathological examination. The total number is defined as the sum of fluorescent SLNs identified during initial fluorescence-guided retrieval (SBNs) and additional non-fluorescent LNs retrieved from the residual SLB tissue during subsequent LN retrieval (BNs).

The total number of intraoperatively retrieved SLNs will be compared between the Image-Guided Platform group and the Traditional Palpation group.

The number of ICG-fluorescent specimens initially retrieved as fluorescent SLNs but not subsequently confirmed as actual LNs by pathological examination will be recorded for each participant and compared between the two groups.

The number of additional LNs identified during permanent pathological examination of the residual SLB tissue after completion of intraoperative LN retrieval will be recorded for each participant. These LNs correspond to occult lymph nodes (OBNs) that were not identified during intraoperative LN retrieval.

The total LN harvest from the resected SLB specimen will be recorded for each participant. Total LN harvest is defined as the sum of LNs retrieved during intraoperative LN retrieval and additional LNs identified during permanent pathological examination.

The proportion of participants in whom at least one occult LN is identified during permanent pathological examination after completion of intraoperative LN retrieval will be assessed.

For SLNs examined by both methods, the concordance rate will be calculated as the number of SLNs with concordant pathological classifications between intraoperative frozen-section and permanent pathological examination divided by the total number of SLNs examined by both methods, expressed as a percentage.

The time required to complete LN retrieval from the residual SLB tissue will be recorded for each participant and reported in minutes.

The total workflow time will be recorded for each participant. Timing will begin when the residual SLB tissue, following initial retrieval of fluorescent SLNs, is transferred for further LN retrieval and pathological processing and will end when the intraoperative frozen-section pathology report is issued. The outcome will be reported in minutes.

In the Image-Guided Platform group, the number of additional LNs retrieved by supplementary visual inspection and manual palpation after completion of image-guided LN retrieval will be recorded. This outcome reflects LNs that were not initially identified during image-guided retrieval but were subsequently detected by supplementary manual palpation.

In the Image-Guided Platform group, the number of suspected LNs identified using the platform and subsequently retrieved for pathological examination will be recorded.

The pathological confirmation rate will be assessed separately according to the LN retrieval method used for the residual SLB tissue after initial fluorescent SLN retrieval. For each retrieval method, the pathological confirmation rate will be calculated as the number of retrieved specimens pathologically confirmed as actual LNs divided by the total number of specimens retrieved as suspected LNs, expressed as a percentage.

The LN detection rate of the Image-Guided Platform will be calculated as the number of pathologically confirmed actual LNs correctly identified by the Image-Guided Platform divided by the total number of actual LNs ultimately identified from the residual SLB tissue examined by the platform, expressed as a percentage. The denominator will include pathologically confirmed LNs retrieved with the Image-Guided Platform, additional LNs retrieved by supplementary manual palpation, and additional LNs subsequently identified during permanent pathological examination of the residual SLB tissue.