cT classification	Pathological definition	Conventional reference signs a	Auxiliary reference signs b
cT1	Invasion of the mucosa or submucosa	Continuous and complete low‐enhanced bands between the highly enhanced inner layer of the cancer and the slightly high‐enhanced outer stomach muscle	The high‐enhanced of the cancer does not exceed 50% of the total thickness of the gastric wall
cT2	Invasion of the muscularis propria	Interruption or absence of the low enhancement band in the middle layer of the stomach and the slightly high enhanced muscle layer partially remains	The high‐enhanced of the cancer exceeding 50% of the total thickness of the gastric wall
cT3	Invasion of the subserosal connective tissue without invading the visceral peritoneum	High enhancement cancer invades the whole layer of the gastric wall, and the outer surface of the serosa is smooth or with tiny spiculation	Tiny spiculation or blurring of the serosal layer comprising <1/3 of the total lesion area
cT4a	Invasion of the serosa (visceral peritoneum) but not adjacent structures/organs	Irregular or nodular appearance of the outer surface of serosal, intensive spiculation or strand‐like infiltration of the surrounding fat space	A hyperattenuating serosa sign [286], cross‐sectional location [287], extension from the outer gastric wall reaching beyond the perigastric vascular plane
cT4b	Invasion of adjacent structures/organs	Disappearance of the fat space between cancer and adjacent organs, with definite signs of finger press‐like interface or direct infiltration
cN	Classified as N0‐N3 based on the number of metastatic lymph nodes	Short diameter of round‐like enlarged lymph node >6‐8mm	High or heterogenous enhancement, CT attenuation, short‐to‐long axis ratios >0.7, clustered small lymph nodes
Imaging report contents	1. Involved area: □ Lower thoracic esophagus □ Abdominal esophagus □ Esophagogastric junction □ Gastric fundus □ Gastric body □ Gastric angle □ Gastric antrum □ Pylorus □ Duodenum □ Greater curvature □ Lesser curvature □ Anterior wall □ Posterior wall 2. Central location: □ Esophagogastric junction (Siewert type: □ Type I □ Type II □ Type III) □ Upper stomach □ Middle stomach □ Lower stomach □ Pylorus 3. Borrmann classification: □ Type I □ Type II □ Type III □ Type IV □ Type V < Mixed type > 4. cT stage: □ cT0 stage □ cT1 stage □ cT2 stage □ cT3 stage □ cT4a stage □ cT4b stage 5. Organ involvement: □ None □ Liver □ Colon □ Pancreas □ Spleen □ Diaphragm □ Other____ 6. cN stage: □ cN0 stage □ cN1 stage □ cN2 stage □ cN3a stage □ cN3b stage 7. Lymph node metastasis stations: 8. cM stage: □ cM0 stage □ cM1 stage (Metastasis to organ(s):____) 9. Peritoneal metastasis risk (□ Low □ High) 10. Measurement values (Primary lesion____, Length of esophageal involvement____, Metastatic lymph nodes____, Organ metastasis____, Other____) 11. Other information (Image quality, report quality, diagnostic confidence score, etc.)

Notes

^a Reference for clinical T staging. The accuracy of T staging is 70%‐90%, and N staging is 60%‐70%. For CT staging of EGJ cancer, it is necessary to combine axial, coronal, or curved reconstructed images to measure the distance from the center of the tumor to the EGJ line to determine whether staging should be done according to gastric cancer or esophageal cancer standards. In cases where the lesion borders are not clearly defined on CT, X‐ray barium double‐contrast imaging (dynamic images taken from three angles: anteroposterior, left anterior oblique, and right anterior oblique) can be used to assess upper margin involvement of the esophagus.

^b Atypical, uncommon signs or signs that have not been validated through multicenter large‐sample clinical studies can be used as references for staging in cases with atypical signs.

^c It is recommended to use a structured reporting approach. The report content should contain important clinical treatment‐related information, including but not limited to tumor location, classification, staging, lymph node grouping, risk assessment for peritoneal metastasis, precise lesion measurements, and other relevant findings. Additionally, it should provide details about image quality, report quality and diagnostic confidence to enhance the clarity and utility of the reference report for comprehensive clinical evaluation.