A Comparative Study Of The CT Features And TNM Staging Of Proximal And Distal Gastric Cancer,and An Analysis Of The Influencing Factors

Part Ⅰ.Study on CT morphological features of Gastric Bare Area(GBA)Purpose:The prognosis of proximal gastric cancer is worse than that of distal gastric cancer.Studies have found that gastric bare area(GBA)is a risk factor for the prognosis of proximal gastric cancer.By using ascites as an indirect indicator,tracking the course of abdominal ligament,understanding the boundary of gastric bare area on CT,and understanding the blood supply of this area,the GBA is a risk factor for the prognosis of proximal gastric cancer.This study lays a foundation for further study on the difference of TNM staging between proximal gastric cancer and distal gastric cancer.Materials and methods:From 2020 to 2022,241 cases of upper peritoneal effusion on CT were retrospectively retrieved from PACS system.Choice 1.No history of surgery;(2)Ascites could surround the mesentery of the abdomen to show its complete course.The above two criteria were used as inclusion criteria.A total of 64 cases with complete imaging data(including enhanced scan and MPR)were obtained.Cases with obvious changes in abdominal physiological and anatomical structure that affected the observation of intra-abdominal space,and cases with poor image quality were excluded.Finally,20 cases were selected as the research objects.By observing the area of the posterior wall of the stomach without ascites,tracing the course of the ligaments around the stomach,the location,composition and contiguity of the bare gastric area on CT were determined,and the blood supply types of the bare gastric area were understood by enhanced scanning and post-processing techniquesResults:I The bare area was found in all 20 case,which was bounded by the splenophrenic ligament on the left,the lesser omentum on the right,and the gastropancreatic ligament on the lower.Among the 20 case,the blood vessels in the bare area of the stomach could be observed were left inferior phrenic artery(17 cases),short gastric artery(10 cases),and left gastric artery(15 cases).According to the length and area of each blood vessel in the bare gastric area,the blood supply types of the bare gastric area can be divided into three categories: type Ⅰ : inferior phrenic artery dominant;Type Ⅱ : short gastric artery dominant;Type Ⅲ : the left gastric artery was dominant,including 15 cases of type I,1case of type Ⅱ,and 4 cases of type Ⅲ.Conclusion:Ascites was used as an indirect indicator to observe the bare gastric area on CT,and tracing the course of the surrounding mesentery and ligaments could understand the boundary of the bare gastric area.This was similar to the results obtained by previous scholars,which verified the existence of the bare gastric area again.The inferior phrenic artery,short gastric artery and left gastric artery can pass through the bare area of the stomach.Observation of the above vessels can be used as a supplementary means to understand the boundary of the bare area of the stomach.Part Ⅱ.Analysis of TNM staging and CT imaging features of Proximal and Distal Gastric CancerPurpose:To understand the differences in CT diagnostic efficacy of T stage and N stage between proximal gastric cancer and distal gastric cancer,and to understand the differences in distant metastasis between proximal gastric cancer and distal gastric cancer through group comparison study.To investigate the imaging features of gastric bare area,and the effect of gastric bare area on TNM staging of proximal gastric cancer.Materials and methods:We collected and retrieved data from the Picture Archiving and Communication System(PACS)and Hospital Information System(HIS)databases of Zhaoqing First People’s Hospital from January 2016 to September 2022,215 inpatients with gastric cancer,including surgical resection,palliative surgery and laparoscopic surgery,were retrospectively collected and searched continuously.A total of 157 cases with pathological results and complete CT imaging data(including MPR and contrast-enhanced scan)were selected.Inclusion criteria:(1)According to ACJJ 8th edition,the center of the lesion originated from 2cm below the gastroesophageal junction to the pylorus,and the lesion was pathologically confirmed as gastric adenocarcinoma;(2)no history of other abdominal tumors;(3)The interval between gastroscopy or pathology and CT examination was less than 1 month.Exclusion criteria:(1)unclear clinical history and data;(2)poor image quality or obvious artifacts.(3)The stomach was obviously in a state of spasm and contraction,which affected the observation.A total of 93 cases met the above criteria were further screened.The stomach was divided into proximal stomach and distal stomach according to the line between the greater curvature of the stomach and the upper1/3 of the lesser curvature of the stomach.The cases with the center of the lesion above the line were classified as the proximal gastric cancer group(41 cases),and the cases with the center of the lesion below the line were classified as the distal gastric cancer group(52cases).The age,gender,pathological type and Bormann type of the two groups were compared.The measurement data were analyzed by independent sample t test,and the count data were analyzed by chi-square test.The diagnostic efficacy of CT for T stage and N stage was compared between the two groups,and the distant metastasis was compared between the two groups.According to the results of the first part of the study,the proximal gastric cancer group was subdivided into a subgroup involving gastric bare area and a subgroup without gastric bare area.The CT findings and pathological results of the two groups were compared.Results:There was no significant difference in age and Bormann type between proximal gastric cancer and distal gastric cancer.The mean age of proximal gastric cancer group was60.1±10.5 years,and the mean age of distal gastric cancer group was 60.3±8.5 years.The mean gastric wall thickness of proximal gastric cancer was 14.2±3.3mm,and that of distal gastric cancer was 12.1±3.8mm.The gastric wall thickness of distal gastric cancer was significantly different from that of proximal gastric cancer.The thickness of gastric wall in proximal gastric cancer is higher than that in distal gastric cancer.The grander ratio of proximal gastric cancer was statistically different from that of distal gastric cancer.There were significant differences in the proportion of pathological types between proximal gastric cancer and distal gastric cancer.There was no significant difference in sensitivity,positive predictive value,negative predictive value and accuracy between T3 stage and T4 stage of proximal gastric cancer and distal gastric cancer,but there was significant difference in specificity.There was no significant difference in the accuracy of N staging between proximal gastric cancer and distal gastric cancer,and the diagnostic efficacy of CT for N staging was average.In the M-stage CT diagnosis,the distant metastasis rate of proximal gastric cancer was 36.60%,and that of distal gastric cancer was 30.80%,with no statistical difference.The retroperitoneal metastasis rate of proximal gastric cancer was19.50%,and that of distal gastric cancer was 3.84%,with statistical difference.In the proximal gastric cancer group,there were 22 cases in the gastric bare area subgroup and19 cases in the non-gastric bare area subgroup.The outer layer of the gastric wall of proximal gastric cancer involving the gastric bare area was more likely to show imaging manifestations such as spicings,nodules and masses.Conclusion:1.The gender ratio,pathological type constituent ratio and gastric wall thickness of proximal gastric cancer and distal gastric cancer are different.2.Compared with distal gastric cancer,retroperitoneal metastasis is more likely to occur in proximal gastric cancer.3.Gastric cancer in the bare area has more severe morphological changes of the outer wall of the stomach,and the bare area of the stomach mainly affects the judgment of T3 and T4 stages of proximal gastric cancer.