Table 2.
Overview of typical and atypical FNH features
| Typical features | Atypical features | |
|---|---|---|
| Lesion | Lesion enhancement is homogeneous during all phases. | Marked lesion heterogeneity |
| T1 | Moderately hypo- or iso-intense | Strongly hypo- or hyper-intense |
| T2 | Moderately hyper- or iso-intense | Strongly hyper- or hypo-intense |
| Arterial | Intense arterial enhancement | Minimal or no enhancement |
| Portal-venous | Hyperintense (rapid loss of signal intensity compared to arterial phase) or iso-intense | Hypo-intense |
| Equilibrium | Iso-intense or moderately hyperintense | Hypo-intense or strongly hyper-intense |
| Scar | Obligatory for typical FNH if lesion is >3 cm, and may be present if lesion is <3 cm | Absence of scar in lesions >3 cm |
| Presents as a linear or stellate area in the centre of the lesion. | ||
| T1 | Hypo-intense, relative to the surrounding lesion | Hyper-intense |
| T2 | Hyper-intense, relative to the surrounding lesion | Hypo-intense |
| Arterial | Non-enhancing | |
| Portal-venous | Hypo-intense, relative to the surrounding lesion | |
| Equilibrium | Moderately hyperintense or iso-intense | Hypo-intense |