Imaging in Gastric Cancer: Current Practice and Future Perspectives

Abstract

Gastric cancer represents one of the most common oncological causes of death worldwide. In order to treat patients in the best possible way, the staging of gastric cancer should be accurate. In this regard, endoscopy ultrasound (EUS) has been considered the reference standard for tumor (T) and nodal (N) statuses in recent decades. However, thanks to technological improvements, computed tomography (CT) has gained an important role, not only in the assessment of distant metastases (M status) but also in T and N staging. In addition, magnetic resonance imaging (MRI) can contribute to the detection and staging of primary gastric tumors thanks to its excellent soft tissue contrast and multiple imaging sequences without radiation-related risks. In addition, MRI can help with the detection of liver metastases, especially small lesions. Finally, positron emission tomography (PET) is still considered a useful diagnostic tool for the staging of gastric cancer patients, with a focus on nodal metastases and peritoneal carcinomatosis. In addition, it may play a role in the treatment of gastric cancer in the coming years thanks to the introduction of new labeling peptides. This review aims to summarize the most common advantages and pitfalls of EUS, CT, MRI and PET in the TNM staging of gastric cancer patients.

Keywords: X-ray computed; endoscopic ultrasound; endoscopic ultrasound-guided fine needle aspiration; multiparametric magnetic resonance imaging; positron emission tomography computed tomography; stomach neoplasms; tomography.

Figure 1

T2 gastric cancer in a 67-year-old-female patient. (A) Axial 2D image in the portal venous phase showing enhanced wall thickening in the lesser curvature side of the low body of the stomach (white arrow). T2 gastric cancer in a 66-year-old-male patient. (B) Axial 2D image (C) Coronal 2D image and (D) Sagittal 2D image showing enhanced wall thickening (white arrow) in the lesser curvature side of the middle body of the stomach. In both the patients, the tumor invades the muscularis propria layer.

Figure 2

T3 gastric cancer in a 72-year-old male patient. (A) Axial 2D image in the portal venous phase and (B) Coronal 2D reconstruction showing wall thickening (white arrow) in the lesser curvature of the low body of the stomach and inhomogeneous enhancement. The tumor invades the subserosa layer without invasion of the serosa and adjacent structures.

Figure 3

T3 gastric cancer in a 74-year-old female patient. (A) Coronal 2D reconstruction in the portal venous phase and (B) Axial 2D image showing (thick arrows) enhanced wall thickening in the lesser curvature side of the high body of the stomach. (B) also shows a cluster of pathologic round lymph nodes adjacent to the gastric cancer (thin arrows). The tumor invades the subserosa layer without invasion of the serosa and adjacent structures.

Figure 4

(A) Axial 2D image in the portal venous phase of a T4a gastric cancer in a 66-year-old female patient. The tumor (thick arrow) is the enhanced wall thickening in the lesser curvature side of the middle body of the stomach which penetrates the serosa with some solid deposits (white asterisk) in the perivisceral fat tissue and some pathologic lymph nodes (thin arrow) with necrotic-colliquative components inside. (B) Axial 2D image of a T4a gastric cancer in a 78-year-old female patient. The tumor (thick arrow) is the enhanced wall thickening on the lesser curvature side of the low body of the stomach which penetrates the serosa with some spiculatures in the perivisceral fat tissue and a pathologic lymph node (black asterisk).

Figure 5

T4b gastric cancer in a 74-year-old female patient. (A,B). Axial 2D images in the portal venous phase and (C) Coronal multiplanar reconstruction showing (thick arrows) a bulky tumor of the middle-low body of the stomach and of the gastric antrum with necrotic-colliquative components inside, ulcerative alterations and some solid deposits (black asterisks) in the perivisceral fat tissue. The tumor fistulizes and infiltrates the transverse colon (thin arrows).

Figure 6

T4a gastric cancer in a 53-year-old female patient. (A) Axial 2D image in the portal venous phase with distension of the gastric lumen with air shows a bulky circumferential tumor (white arrows) of the low body of the stomach and of the gastric antrum with ulcerations; (B) Virtual gastroscopy delineates a lesion protruding in the lumen of the stomach; (C) Computed tomography gastrography shows a mucosal irregularity (white arrows) with a reduction of the lumen of the stomach.

Figure 7

T3 gastric cancer in a 68-year-old female patient. Contrast enhanced CT with gastric distension using air. (A) Axial 2D image and (B) Coronal 2D image in the portal venous phase with distension of the gastric lumen with air showing a semicircumferential tumor (white arrows) of the low body of the stomach with ulcerations.

Figure 8

Axial 2D images in the portal venous phase show different pathological node locations (black asterisks): (A) pathological lymph nodes in the lesser curvature of the stomach; (B) pathological lymph nodes of the lesser curvature and the celiac artery; (C) pathological lymph nodes of the pancreatic head and para-aortic region. The lymph nodes in the images present an inhomogeneous contrast enhancement with central hypodensity due to the presence of necrotic components inside.

Figure 9

MRI images of a T3 gastric cancer of the gastric antrum in a 79-year-old male patient. (A) Coronal 2D image and (C) Axial 2D image of the Turbo Spin Echo (TSE) T2 sequence showing a circumferential lesion (arrow) invading the subserosa layer with an intermediate signal intensity; (B) Coronal 2D Balance Fast Field Echo (BFFE) sequence showing a circumferential lesion (arrow) with a low signal intensity; (D) Axial Diffusion Weighted Image (DWI) showing an area of signal restriction (arrow) corresponding to the tumor.