Table 2. Diagnosis of Hepatocellular Carcinoma.

1. Imaging diagnosis: In at risk patients (chronic hepatitis B, chronic hepatitis C, and liver cirrhosis) having lesion ≥ 1 cm on surveillance tests

(1) Non-invasive diagnosis of “definite” HCC is based on typical imaging hallmarks of HCC on multiphase CT or multiphase MRI with extracellular contrast agents or hepatobiliary contrast agents. If first-line imaging is inconclusive, second line examination can be applied. Imaging modalities for second line examinations include multiphase CT, multiphase MRI with extracellular contrast agents or hepatobiliary contrast agents, and contrast-enhanced US with blood pool contrast agents.

(2) Major imaging features for “definite” diagnosis of HCC are defined as arterial phase hyperenhancement with washout in portal venous, delayed or hepatobiliary phases. These criteria should be applied only to lesion which does not show either marked T2 hyperintensity or targetoid appearance on diffusion-weighted images or contrast-enhanced sequence.

(3) Typical hallmark for “definite” HCC diagnosis at contrast-enhanced US is defined as arterial phase hyperenhancement followed by late (> 60 seconds) washout of mild degree.

(4) In nodule(s) with some but not all aforementioned major imaging features of HCC, category of “probable” HCC can be assigned by applying ancillary imaging features.* This category should be applied only to lesion(s) which does not show either marked T2 hyperintensity or targetoid appearance on diffusion-weighted images or contrast-enhanced sequence.

2. Pathologic diagnosis

When imaging-based diagnosis inconclusive or lesion(s) shows atypical imaging features, biopsy is indicated.

^*Ancillary imaging features are summarized in Table 3. CT = computed tomography, HCC = hepatocellular carcinoma, MRI = magnetic resonance imaging, US = ultrasound