Grading of small hepatocellular carcinomas (⩽2 cm): correlation between histology, T2 and diffusion-weighted imaging.

Objective: To evaluate the capacity of diffusion-weighted imaging (DWI) to determine the histological grade of small-sized hepatocellular carcinomas (HCCs) in liver cirrhosis in comparison with T₂ weighted imaging. Methods: 51 cirrhotic patients with 63 histologically proven HCCs ⩽2cm underwent abdominal MRI, including DWI (6-values 50, 400 and 800 s mm^-2) and T₂ weighted sequences, HCCs were classified into well-differentiated HCCs (n = 37) and moderately differentiated HCCs (n = 26). Relative contrast ratios (RCRs) between the lesions and the surrounding liver were performed and compared between the two groups for T₂ weighted images, each 6-value and apparent diffusion coefficients (ADCs). A receiver operating characteristic (ROC) analysis was performed to compare RCRs in T₂ and diffusion-weighted images. Results: We found significant differences in RCRs between well-differentiated vs moderately differentiated HCCs for 6 = 50, 400 and 800 smm^-2 and T₂ weighted images (1.35 ±0.36 vs 1.86 ±0.62; 1.35 ± 0.38 vs 1.82 ± 0.60; 1.27 ± 0.30 vs 1.74 ± 0.53; 1.14 ± 0.18 vs 1.43 ± 0.28, respectively; p< 0.001), whereas no significant differences were observed in ADC and ADC RCR (1.05 ± 0.19 vs 0.99 ± 0.15 and 1.1 ± 0.22 vs 1.09 ± 0.23; p = 0.16 and p = 0.82, respectively). No significant difference was found in the areas under the ROC curve for RCRs of T₂ weighted images and every DWI fa-value (p = 0.18). Conclusion: The RCR measurement performed in DWI 50, 400 and 800 fa-values and T₂ demonstrated a significant difference between well-differentiated and moderately differentiated small-sized HCCs. Furthermore, no difference was shown by using either ADC or ADC RCR. Advances in knowledge: DWI with RCR measurement may be a valuable tool for non-invasively predicting the histological grade of small HCCs. [ABSTRACT FROM AUTHOR]