Clinical Scorecard: Guidelines for Imaging Peritoneal Metastases in Ovarian and Colorectal Cancer: Collaborative Recommendations from ESGAR, ESUR, PSOGI, and EANM

At a Glance

Key Highlights

• CT is widely available and used for initial assessment, treatment monitoring, and recurrence detection but underestimates small or isodense peritoneal metastases.
• MRI is the most accurate imaging modality for assessing the extent of peritoneal metastases and selecting patients for cytoreductive surgery.
• FDG PET/CT is limited for pre-operative staging due to missing small or hypometabolic lesions but useful for detecting extraperitoneal metastases.

Guideline-Based Recommendations

Diagnosis

• Use CT for initial assessment, treatment response monitoring, and suspicion of recurrence in colorectal and ovarian cancer patients.
• Employ MRI with specific sequences (axial T2, STIR-DWI, post-contrast T1) for accurate extent assessment and surgical planning.
• Perform FDG PET/CT according to EANM tumour imaging guidelines combined with diagnostic quality CT to detect extraperitoneal metastases.
• No difference in imaging protocols between colorectal and ovarian cancer for CT, MRI, and FDG PET/CT.

Management

• Use imaging findings, including Peritoneal Cancer Index (PCI) scoring, to guide selection for cytoreductive surgery ± HIPEC.
• Discuss all patients with peritoneal metastases in a multidisciplinary tumour board including experienced radiologists.
• Standardize imaging reports using tools like PROMISE and PAUSE to describe extent and involvement of surgically critical sites.

Monitoring & Follow-up

• Use CT for treatment response monitoring and follow-up due to accessibility.
• Consider whole-body MRI or FDG PET/CT as problem-solving tools for suspected recurrence or extraperitoneal disease.

Risks

• CT underestimates small or isodense lesions, potentially leading to suboptimal surgical selection.
• Diagnostic laparoscopies for staging carry small risks and may be incomplete due to adhesions or confluent tumors.
• Imaging may underestimate total disease extent, especially in mesenteric and serosal bowel involvement.

Patient & Prescribing Data

Colorectal and ovarian cancer patients with peritoneal metastases

Accurate imaging assessment of peritoneal metastases extent using PCI or quantitative scoring guides treatment decisions including surgery and chemotherapy, improving survival outcomes in selected patients.

Clinical Best Practices

• Perform abdominal CT with 1–1.5 mm sections and 3 mm reconstructions in portal venous phase; oral contrast recommended but optional.
• Conduct 3-T MRI with axial T2 (≤4 mm), STIR-DWI (b50 and b1000), and post-contrast T1 sequences; use negative oral contrast (pineapple juice) and intravenous antiperistaltic agents when possible.
• Include PCI scoring and qualitative descriptions of surgically critical sites in imaging reports.
• Use multidisciplinary tumour boards for treatment planning involving radiologists experienced in peritoneal metastases imaging.

References

• ESGAR, ESUR, PSOGI, and EANM Collaborative Guidelines