Magnetic resonance images of tuberous sclerosis

Summary

The cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR=1800, TE=120) images and inversion recovery (TR=2100, TI=500–600, TE=40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter. Some of the parenchymal calcifications other than periventricular nodules showed identical MR signal intensities to periventricular nodules, and the rest of the parenchymal calcifications had similar intensities to the subcortical lesions. This indicates that parenchymal calcifications can occur in the demyelinating white matter as well as in the heterotopic tubers in the white matter. The severely mentally retarded patients tended to have a higher number of subcortical lesions and no correlation was noted between the severity of mental retardation and either the number of periventricular nocules or ventricular dilatation.