The Role of 18F-FDG PET/MRI in the Assessment of Primary Intrahepatic Neoplasms

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Primary hepatic neoplasms, including intrahepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC), present diagnostic challenges.
• Accurate differentiation and grading of these tumors are crucial for effective treatment planning and patient outcomes.

Purpose of the Study:

• To evaluate the utility of 18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging (18F-FDG PET/MRI) in distinguishing between mass-forming ICC and HCC.
• To assess the correlation of 18F-FDG PET/MRI findings, specifically apparent diffusion coefficient (ADC) and standardized uptake value (SUV), with histopathologic subtypes and tumor grades.

Main Methods:

• A retrospective analysis of 39 patients with histopathologically confirmed primary hepatic neoplasms (15 ICC, 24 HCC) who underwent 18F-FDG PET/MRI.
• Analysis of ADC and SUV values in relation to histopathologic diagnosis and tumor grade, including calculation of sensitivity and specificity for differentiating ICC from HCC.

Main Results:

• The median SUV of ICC was significantly higher than that of HCC (p=0.002), with an SUV cutoff of 4.41 achieving 86.7% sensitivity and 67% specificity for differentiation.
• ADC values did not significantly differ between ICC and HCC (p=0.283).
• Both SUV and ADC values significantly correlated with tumor grade in HCC, and combining them improved differentiation of low-grade from high-grade HCC (AUC=0.929). ADC also showed significant differences between ICC grades.

Conclusions:

• 18F-FDG PET/MRI, particularly SUV, can aid in differentiating between ICC and HCC.
• The combination of SUV and ADC values shows promise in predicting tumor grade for primary hepatic neoplasms, potentially improving diagnostic accuracy and guiding therapeutic strategies.