TABLE 3.
Main imaging features of hepatocellular carcinoma (HCC)
| Imaging features | Description |
|---|---|
| Arterial hyperenhancement | Increased enhancement in the arterial phase. Reflects tumor neoangiogenesis. |
| Washout appearance | Hypoenhancement of the lesion compared with background liver tissue. Secondary to HCC extracellular reduced volume, rapid venous drainage and reduced intranodular portal venous supply. |
| Capsule appearance | Observed in approximately 80% of HCCs, detected on delayed phase, secondary to the lack of portal supply to malignant nodules. Corresponds to a pseudocapsule consisting of compressed adjacent liver parenchyma with occasional nonspecific inflammatory cells on histology. |
| Portal vein tumoral thrombosis | HCC invades and grows within the lumen. The vein appears dilated and with the same pattern of enhancement observed in the nodule. |
| T2 hyperintensity | The elevated signal intensity on T2WI can be useful to differentiate HCC from dysplastic nodules. |
| Restricted diffusion | Mildly elevated signal relative to the surrounding liver parenchyma on diffusion weighted imaging (DWI) and low signal intensity on apparent diffusion coefficients (ADC) map. |
| Corona enhancement | Enhancement of the peritumoral parenchyma after enhancement of the tumor itself, because of the passage of contrast through the draining sinusoids and portal venules into the surrounding sinusoids. |
| Intralesional fat | Loss of signal on the opposed-phase T1WI compared with the in-phase images. |
| Lesion iron sparing | Siderotic nodule is likely to be a dysplastic nodule. Development of an iron-free around the nodule suggests HCC foci. |
| Mosaic architecture | Nodular areas interspersed by areas of fibrosis, hemorrhage, arteriovenous shunting and necrosis. Characteristic of progressed HCCs. |
| Nodule-in-nodule architecture | Mildly elevated signal intensity on T2WI within nodule with low signal intensity, representing the focus of HCC within the low density dysplastic nodule, that may also enhance in the arterial phase. |
| Transitional phase hypointensity | Hypointensity compared with background liver following administration of a hepatobiliary contrast agent (2–5 minutes after contrast media administration). |
| Hepatobiliary phase hypointensity | Hypointensity compared with background liver following administration of a hepatobiliary contrast agent (20 minutes after). |
T1W1 = T1 weighted image; T2WI = T2 weighted image