This is a prospective observational study which will recruit 90 participants over a three-year period to investigate whether adding magnetic resonance imaging and enterography to routine computed tomography study can better predict the extend of peritoneal carcinomatosis over computed tomography alone.

Hyperthermic Intraperitoneal Chemotherapy (HIPEC) is a new option for patients with peritoneal carcinomatosis and the effectiveness of HIPEC depends on the extend of disease. Currently, pre-operative imaging peritoneal cancer index (PCI) is used to predict the intraoperative tumor extend and completeness of cytoreduction. However, the investigators' previous study and literature review show that imaging PCI usually underestimated intraoperative PCI, resulting in subsequent Open-Close operation. The investigators hypothesize that magnetic resonance imaging (MRI) is a better predictor of the intra-operative PCI than computed tomography (CT), and MR Enterography can better represent tumor deposits in the small intestine. This study aims to test whether the addition of MRI and MR Enterography to CT study improves the prediction performance of the intraoperative PCI and completeness of optimal cytoreduction over CT alone.

Inclusion Criteria:

• Patients with peritoneal carcinomatosis diagnosed by computed tomography
• Schedule for operation at our institute

Exclusion Criteria:

• Age < 20 years old
• Renal function impairment or acute renal failure
• Contraindications for magnetic resonance imaging
• Primary tumor not origins from colorectal cancer, gastric cancer or ovarian cancer

Individual participant data will not be available to other researchers.