Double contrast-enhanced ultrasonography improves diagnostic accuracy of T staging compared with multi-detector computed tomography in gastric cancer patients

Table 1 Double contrast-enhanced ultrasonography criteria for T staging of gastric cancer

T stage	Pathological definition	DCEUS criteria
T1	Invasion of the mucosa or submucosa	T1a: In the arterial phase, focal thickening of the mucosa is visualized. The lesion shows slightly delayed hyper-enhancement, similar to the submucosal layer. In the venous phase, the lesion shows hypo-enhancement compared to the submucosal layer. The submucosal layer consistently shows hyper-enhancement and is continuous and intact. The muscular layer shows linear hypo-enhancement and is continuous and intact; T1b: In the arterial phase, focal thickening of the mucosa and submucosa are visualized. The lesion shows homogenous hyper-enhancement, similar to the normal submucosal layer. In the venous phase, the lesion shows hypo-enhancement. The enhancing submucosal layer is continuous. The muscular layer shows linear hypo-enhancement and is continuous and intact
T2	Invasion of the muscularis propria	In the arterial phase, disruption of the mucosa, submucosa and partly muscularis propria are visualized. The lesion shows homogenous hyper-enhancement, similar to the normal submucosal layer. In the venous phase, the lesion shows homogenous hypo-enhancement. The hyper-enhancement strip of submucosal layer and partly hypo-enhancement strip of the muscularis propria are disruptive
T3	Invasion of the subserosal connective tissue without invading the visceral peritoneum	In the arterial phase, disruption of the mucosa, submucosa and muscularis propria are visualized. The lesion shows homogenous hyper-enhancement, similar to the normal submucosal layer. In the venous phase, the lesion shows homogenous hypo-enhancement. The hyper-enhancement strip of submucosal layer and hypo-enhancement strip of the muscularis propria are disruptive. A smooth outer margin of the serosa or a few small linear stranding within the serosa are observed. The enhancing serosa is continuous
T4	Invasion of the serosa (visceral peritoneum) or adjacent structures/organs	In the arterial phase, disruption of the mucosa, submucosa, muscularis propria and serosa are visualized. The lesion shows homogenous hyper-enhancement, similar to the normal submucosal layer. In the venous phase, the lesion shows homogenous hypo-enhancement. The hyper-enhancement strip of submucosal and serosal layers and hypo-enhancement strip of the muscularis propria are disruptive; T4a: An irregular nodular margin of the serosa and densely burred or banded infiltration of the adjacent fat plane are visualized; T4b: The adjacent fat plane between the tumor and the adjacent organ is obliterated or the tumor directly infiltrates the adjacent organ

GC: Gastric cancer; DCEUS: Double contrast-enhanced ultrasonography.