Fig 1. Eye-of-the-tiger sign (arrows). This 10-year-old boy with the PANK2 mutation shows MR features characteristic of PKAN. The T1-weighted images appear normal, but high signal intensity can be seen in the globus pallidus on proton attenuation (PD), T2-weighted fluid-attenuated inversion recovery (FLAIR), and T2-weighted images in both the axial and coronal planes. With increasingly heavier T2 weighting (PD<FLAIR<T2), there is increasingly conspicuous T2 hypointensity at the periphery because of the magnetic susceptibility effects of excess iron.