Small hepatocellular carcinoma: using MRI to predict histological grade and Ki-67 expression

To investigate the predictive indicators of small aggressive hepatocellular carcinomas by examining the association between preoperative magnetic resonance imaging (MRI) parameters and Ki-67 expression and histological grade.

Sixty patients with small hepatocellular carcinomas (tumour diameter: ≤3 cm, tumour numbers: ≤2) who underwent curative resection or biopsy after contrast-enhanced and diffusion-weighted MRI were evaluated retrospectively. Signal intensity (SI) of the whole lesion and erector spinae muscle was measured quantitatively. Tumour-to-muscle SI ratio was calculated. The association between these MRI parameters and histological grade and Ki-67 level was then investigated.

There was a significant correlation between tumour-to-muscle SI ratio and histological grade in tissues captured during the non-enhanced T1-weighted (p=0.001), arterial phase (p=0.001), and portal venous phase (p=0.036) of dynamic contrast-enhanced MRI and apparent diffusion coefficient (p=0.027). Arterial inhomogeneous enhancement was also correlated with high-Ki-67 expression (p=0.032).

Preoperative MRI may serve as a non-invasive tool for prediction of small, aggressive hepatocellular carcinomas, which may otherwise be treated conservatively.