Peritoneal Metastases: Their Associated Imaging Features

Abstract

Peritoneal Metastases (PM) detection remains a challenge even with modern imaging. Knowing imaging features of abnormal findings frequently associated with PM is of interest to improve PM detection. Although ascites is a common imaging finding of PM, the presence of ascites alone, even in patients with known cancer, is not enough to diagnose PM. The peritoneum should be read as an own organ with careful analysis of the ligament (e.g. falciform and hepatoduodenal ligament), the mesos and the omenta. Indirect manifestations of visceral peritoneal involvement is a segment of small bowel fixed to the parietal peritoneum, the appearance of blockage of free circulation of ascites, plurisegmental bowel obstruction and clumped bowel that is a strong predictor of diffuse involvement of the visceral peritoneum by a high grade tumor. Ovarian and umbilical metastases are frequently associated with PM in particular in digestive cancers. Moreover, ovarian metastases has been shown to be less responsive to chemotherapy than other metastases and should not be chosen as a target lesion for RECIST assessment. The presence of cardiophrenic angle lymph nodes also increases the possibility of metastatic spread in peritoneum. Finally, the most common PM mimickers include colonic diverticulum, mesenteric lymph nodes, splenosis implants, fat necrosis and postoperative changes after cytoreductive surgery and HIPEC.