Transabdominal ultrasonography in preoperative staging of gastric cancer

Abstract

Aim: To investigate the value of transabdominal ultrasonography (US) in the preoperative staging of gastric cancer.

Methods: A total of 198 patients with gastric cancer underwent preoperatively transabdominal US, depth of tumor infiltration was assessed in 125 patients, and lymph node metastasis was assessed in 106 patients.

Results: The staging accuracy of transabdominal US was 55.6%, 75.0%, 87.3% and 71.1% in T1, T2, T3 and T4 carcinomas, respectively. The overall accuracy was 77.6%. The detection rate for pancreatic invasion and liver invasion was 77.4%, 71.4%, respectively. The sensitivity, specificity, accuracy of transabdominal US in assessment of lymph node metastasis were 77.6%, 64.1%, 72.6%, respectively. Various shapes such as round, ovoid, spindle were encountered in benign and malignant lymph nodes. Majority of both benign and malignant lymph nodes were hyperechoic and had a distinct border. Benign lymph nodes were smaller than malignant lymph nodes in length and width (P = 0.000, 0.005). Irregular shape, fusional shape, infiltrative signs, inhomogenous echo were seen mainly in malignant lymph nodes (P = 0.045, 0.006, 0.027, 0.006).

Conclusion: Transabdominal US is useful for preoperative staging in gastric cancer, although it is difficult to differentiate benign from malignant lymph nodes.

Figure 1

Sonograms of T1-T4 carcinoma. A: Submucosal carcinoma (T1) in gastric antrum. Arrow indicates segmental thickening of layers 1-3 of the posterior wall, triangle indicates normal layers 4-5. B: T2 carcinoma. The posterior wall of Gastric body is thickening. Arrow indicates the third hyperechoic layer is obliterated and the fourth hypoechoic layer is thickening, triangle indicates normal layer 5. C: T3 carcinoma. Tumor located in the greater curvature of stomach (STO) is hypoechoic with disap-pearance of wall all layer (arrow). D: T4 carcinoma. Sonogram shows tumor located in antrum (AN) infiltrating duodenum. Arrow indicates the segmental wall thickening of duodenal bulb.

Figure 2

Mucosal carcinoma (T1) was overstaged as a T3 car-cinoma with transabdominal US. Sonogram of gastric body shows hypoechoic wall thickening with ulcer (arrow), loss of wall five-layer structure (triangle).

Figure 3

Metastatic lymph node. A: Sonogram shows a irregular lymph node (arrow) adjacent to the portal vein (PV) with a distinct border and 2.1 × 1.7 cm in size. B: Sonogram shows fusional-shaped lymph node (arrow) (4 × 3 cm) adjacent to the stomach (STO), invading adjacent tissues and having an indistinct border.

Figure 4

Differentiation between benign and metastatic lymph nodes. A: Benign lymph nodes. Sonogram shows multiple small lymph nodes (arrow) adjacent to the lesser curvature of stomach (STO). These hypoechoic lymph nodes are 5-8 mm, and misdiagnosed as metastatic with transabdominal US; Pathologic examination confirms that all theses lymph nodes are reactive and noncancerous. B: Metastatic lymph nodes. Sonogram is similar to figure A. Multiple hypoechoic small lymph nodes (arrow) adjacent to the lesser curvature of stomach (STO) are 5-9 mm, and confirmed metastatic by pathologic examination.

Figure 5

Differentiation between benign and metastatic lymph nodes. A: Benign lymph nodes. Sonogram shows multiple hypoechoic lymph nodes (arrow) adjacent to the greater curvature of stomach (STO). Of them, the largest is 1.8 cm with a distinct border. These lymph nodes are misdiagnosed as metastatic with transabdominal US. Pathologically, all theses lymph nodes are reactive and noncancerous. B: Metastatic lymph node. Sonogram shows hypoechoic lymph node (arrow) adjacent to the lesser curvature of stomach (STO) with 1.6 cm in size and a distinct border. Pathologic examination confirms this lymph node is metastatic.