[18F]FDG PET/MRI in rectal cancer

Area of Science:

• Oncology
• Radiology
• Nuclear Medicine

Background:

• Rectal cancer staging and restaging are critical for treatment planning and patient management.
• Accurate assessment of tumor extent (T staging), lymph node involvement (N staging), and distant metastasis (M staging) is essential.
• Limitations exist in current imaging modalities for comprehensive rectal cancer evaluation.

Purpose of the Study:

• To systematically review the utility of 18F-FDG PET/MRI in staging and restaging rectal cancer patients.
• To evaluate the diagnostic performance of 18F-FDG PET/MRI for T, N, and M staging.
• To assess the impact of 18F-FDG PET/MRI on treatment decisions and patient selection.

Main Methods:

• Systematic literature review using PubMed, Scopus, and Web of Science databases.
• Adherence to PRISMA criteria for study selection and data extraction.
• Inclusion of ten relevant reports after screening titles, abstracts, and full texts.

Main Results:

• High accuracy for T staging (sensitivity 94-100%, specificity 73-94%) and local recurrence detection.
• Accurate N staging (sensitivity 90-93%, specificity 92-94%) with superior malignant node detection compared to MRI alone.
• Effective detection of liver metastases, outperforming PET/CT and CT, but less effective for lung metastases.

Conclusions:

• 18F-FDG PET/MRI is valuable for rectal cancer restaging post-chemoradiotherapy and selecting patients for rectum-sparing surgery.
• Its accuracy in T and N staging supports its use in treatment planning.
• For M staging, combining 18F-FDG PET/MRI with chest CT is recommended to rule out lung metastases.