Fig. 1

Normal frontotemporal anatomy and examples of frontotemporal hypoplasia. a-c Normal Sylvian fissure and anterior temporal CSF spaces in control patient c2. NB asymmetric thalamus with focal T2-hyperintensity and facilitated diffusion (inset: ADC map). d-i Mild hypoplasia in late-onset patient p1 not extending dorsally beyond the pars opercularis (arrow in d) of the inferior frontal gyrus and remaining unchanged between first MRI at 8.6 years (d-f) and last follow-up MRI at 15.7 years (g-i). NB T2-hyperintensity of pontine white matter and dentate nucleus (H). j-l Moderate hypoplasia involving the subcentral gyrus in late-onset patient p6 (arrow in j). NB subependymal nodules and focal, asymmetric white matter changes (l). m-r Widely open Sylvian fissure and massively widened anterior temporal CSF spaces in late-onset patient p7 unchanged between MRIs at 61 and 73 years. NB large, subependymal, FLAIR-hyperintense nodule in right frontal horn (o, r; also Fig. 3). (T1w: a, g, m, p; T1w + GAD: j; T2w: b, c, e, f, h, i; FLAIR: K, l, n, o, q, r; ADC: inset in c)