Preoperative imaging of sentinel lymph nodes in gastric cancer using CT lymphography

Abstract

Purpose: Preoperative identification of the sentinel lymph node (SLN) in gastric cancer (GC) patients may have great advantages for the minimally invasive treatment. This study was performed to evaluate the possibility of preoperative SLN detection using CT lymphography.

Materials and methods: Fourteen patients with early GC were enrolled. CT images were obtained before and at 1, 3, and 5 minutes after endoscopic submucosal peritumoral injection of 2 mL iopamidol. For patients with clearly identified SLNs, to make comparisons with the CT lymphography results, intraoperative SLN detection was performed using subserosally injected Indocyanine green (ICG) lymphography and ex vivo ICG and iopamidol lymphography using mammography was also performed.

Results: CT lymphography clearly visualized draining lymphatics and SLNs in 4 (28.6%) out of 14 patients. All clearly visualized SLNs (one to three SLNs per patient) under preoperative imaging were detected in the same location by intraoperative ICG lymphography and ex vivo ICG and iopamidol lymphography using mammography. All preoperative SLN detections were observed with the primary tumors in the lower third of the stomach.

Conclusion: Although our study demonstrated a SLN detection rate of less than 30%, CT lymphography with radio-contrast showed potential as a method of preoperative SLN detection for GC.

Fig. 1

CT lymphography. (A) Upper endoscopy for peritumoral injection of iopamidol at the CT scanning table. (B) Successful preitumoral submucosal injection of iopamidol showing swelling of the lesion. (C) Axial CT image after iopamidol injection (long arrow: SLN, Short arrow: draining lymphatic). SLN, Sentinel lymph node.

Fig. 2

Intraoperative and ex vivo SLN detection. (A) Three-dimensional volume rendering image of CT lymphography. Contrast enhanced SLN (long arrow) and draining lymphatics (short arrow) well-visualized at station #6. Dense iopamidol uptake at the peritumoral area is seen (arrow head) with a related beam hardening artifact. (B) Intraoperative SLN navigation with surserosal injection of ICG. A green colored SLN (long arrow) and a draining lymphatic (short arrow) are well identified with subserosal site injection (arrow head). (C) Ex vivo sentinel lymph node navigation using subserosal injection of ICG. SLN with ICG uptake (long arrow) and peritumoral area (arrow head) are stained green. (D) X-ray mammography. Magnified view shows the draining lymphatic vessel (short arrow) by peritumoral iopamidol injection (arrowhead). SLN, Short arrow: draining lymphatic). SLN, Sentinel lymph node; ICG, Indoc yanine green.

Fig. 3

Results of CT lymphography with iopamidol according to the location of the primary lesion. Success refers to the primary lesion that SLNs were seen on CT lymphography. Failure refers to the primary lesion that SLNs were not seen on CT lymphography. ^*indicates primary lesions with ulcers. SLN, Sentinel lymph node.