Abstract: Objective:To summarize the CT imaging features of peritoneal metastasis of gastric cancer (GC).
Methods:The retrospective cross-sectional study was conducted. The clinicopathological data of 78 GC patients with peritoneal metastasis who were admitted to the First Affiliated Hospital of Nanjing Medical University from January 2013 to September 2016 were collected. All the patients underwent plain and enhanced scans of CT, and imaging data were converted to the multiplanar reformation (MPR) and maximum intensity projection (MIP). Observation indicators: (1) CT imaging features of primary lesion of GC; (2) CT diagnostic accurary and imaging features of GC with peritoneal metastasis; (3) CT imaging features of lymph nodes and other abdominal organ metastasis; (4) treatment and follow-up. Patients selected treatment plan according to results of laboratory and imaging examinations and patient′s will. Follow-up using outpatient examination, telephone interview and correspondence was performed to detect the treatment method and patients′ prognosis up to December 2016. The survival time was from post-treatment to death or end of follow-up. Measurement data with skewed distribution were described as M (range).
Results:(1) CT imaging features of primary lesion of GC: primary tumor location of 78 patients: tumor located in the antrum, leather bottle stomach, gastric cardia, lesser curvature, gastric antrum and body and greater curvature were detected in 40, 11, 9, 9, 5 and 4 patients, respectively. All the 78 patients were in T4 stage, including 43 with T4a stage and 35 with T4b stage. (2) CT diagnostic accurary and imaging features of GC with peritoneal metastasis: of 78 patients, 57 were found with peritoneal metastasis by CT examinations before chemotherapy, 15 with peritoneal metastasis by exploratory laparotomy or open surgery and 6 with peritoneal metastasis by follow-up CT re-examinations after gastrectomy. Seventy-two patients were diagnosed as GC with peritoneal metastasis by CT scans, and final diagnosis, missed diagnosis and overdiagnosis were detected in 78, 9 and 3 patients, respectively. The precision, sensitivity, specificity, positive and negative predictive values of CT diagnosis were respectively 98.7%, 88.5%, 99.6%, 95.8% and 98.9%. Location and manifestation of 78 GC with peritoneal metastasis patients: ① Peritoneal effusions: 71 patients were accompanied with peritoneal effusions, including 21 with the slight peritoneal effusions and 50 with moderate and massive peritoneal effusions. ② Greater omentum thickening: greater omentum of 59 patients showed sheet, flocculent and nodular thickening, with a mass and cake-like change. ③ Peritoneal thickening: 54 patients had peritoneal thickening, with the main of nodule-like and thick lines-like thickening; thickening occurred mainly in around the liver, peritoneal cavity and pelvic floor; 11 patients were found with obvious left anterior renal fascia thickening. ④ Mesenteric thickening: 46 patients were found with mesenteric thickening and edema, showing increased fat density with multi-node shadow. ⑤ Lesser omentum and hepatogastric ligament: 18 patients were found with increased fat density of lesser omental bursa, showing striped and nodular shadow. ⑥ Transverse mesocolon: increased local fat density with striped- and nodular-like changes were seen in 15 patients after coronal and sagittal planes reconstruction, including 5 with local wall thickening of transverse colon. ⑦ Ovary: 8 patients had ovarian metastases, including 6 with bilateral metastases and 2 with unilateral metastasis; diameter of metastatic tumor was 3-12 cm. ⑧ Intestinal canal: 6 patients had local intestinal wall thickening, including 3 in small intestine and 3 in transverse colon, thickening tissues were mainly located in the mesentery, showing obvious intestinal wall enhancement. ⑨ Liver capsule node: 2 patients showed multi-node abnormal enhanced lesions under liver capsule. (3) CT imaging features of lymph nodes and other abdominal organ metastasis: 78 patients were accompanied with lymph nodes enlargement, including 41 in N2 stage and 37 in N3 stage; liver metastases were detected in 13 patients; 5 had adrenal metastases, including 3 with bilateral metastases and 2 with unilateral metastasis; 4 had lower GC invading the pancreatic head and body; 2 had upper GC invading the liver and spleen; 1 had leather bottle stomach invading the pancreatic head and neck, and inducing to obstruction of biliary tract. (4) Treatment and follow-up: of 78 patients, 62 underwent systemic chemotherapy, 6 underwent systemic chemotherapy and intraperitoneal hyperthermic perfusion chemotherapy, 5 underwent systemic chemotherapy and local radiotherapy and 5 underwent palliative operations due to gastrointestinal tract obstruction or bleeding. Of 78 patients, 69 were followed up for 15 months (range, 3-21 months), and 9 lost to follow-up. The median survival time of 69 follow-up patients was 12 months (range, 3-19 months).
Conclusions:CT imaging features of peritoneal metastasis of GC show specific sites of metastasis and performance. Combining with CT axial images and images of coronal and sagittal planes reconstruction, adjusting appropriate window width and level would be benefit to observe primary lesions of GC and peritoneal metastasis.