Radiologic findings of focal nodal hyperplasia in an asymptomatic 47-year-old woman. Panel A: Contrast-enhanced computed tomography (CT) scan shows an area of slight heterogeneity (arrow) in the right lobe of the liver, but a discrete mass is difficult to identify. Panel B: Technetium-99 sulfur colloid scan shows uptake in the mass (arrow) similar to the rest of the liver. This finding is diagnostic of focal nodular hyperplasia. Panel C: T2-weighted magnetic resonance (MR) image shows the mass (arrow) as slightly increased signal intensity. Panel D: Arterial-phase dynamic gadolinium chelate-enhanced T1-weighted gradient-echo MR image shows rapid intense enhancement of the mass (arrow), typical of focal nodular hyperplasia.