Fig 2.

Infratentorial malformations in ACTA2 mutation. Upper row: axial T2WI (A and B) at the level of the pons. The twin peaks sign is demonstrated; the pons is flattened with reduction of the anteroposterior diameter and an impression of the basilar artery on the anterior surface with consequent presence of 2 symmetric prominences resembling twin mountains. Middle row: axial T2WI at the level of the cerebral peduncles (C and D) shows mild antero-posterior elongation of the midbrain with reduction of the laterolateral diameter and squeezing of the cerebral peduncles. Right column: normal for comparison.