[Malignant tumor with false negative 18F-FDG PET image].

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• 18F-FDG PET/CT scans are crucial for cancer diagnosis, but false negatives can occur.
• Understanding factors influencing 18F-FDG uptake is vital for accurate interpretation.

Purpose of the Study:

• To investigate 18F-FDG uptake characteristics in malignant tumors with false-negative PET scans.
• To identify factors affecting 18F-FDG uptake and the diagnostic value of CT in these cases.

Main Methods:

• Retrospective analysis of PET/CT images from 17 cancer patients.
• Visual and semi-quantitative (SUV) analysis of 18F-FDG uptake.
• Comparison of PET/CT findings with CT and histopathological diagnoses.

Main Results:

• False negatives were linked to tumor pathology, differentiation, and size (≤1 cm).
• Some lesions were missed by both PET and CT, while others showed uptake only on enhanced CT.
• Physiological FDG uptake in the digestive tract or urinary system contributed to false negatives.

Conclusions:

• Malignant tumor characteristics (pathology, grade, size) influence 18F-FDG uptake and can lead to false negatives.
• Integrating CT information and refining PET/CT scan protocols can reduce false-negative diagnoses.