Ten patients with clinical tuberous sclerosis were examined with CT and MR imaging, before and after IV contrast in order to determine the role of Gd-DTPA. Gd-DTPA enhancement occurred in eleven subependymal nodules which did not enhance on CT after IV contrast. As illustrated by previous CT and pathologic observations and related to the histologic similarity of the subependymal nodules and giant-cell astrocytomas, these hyperintense nodules could represent active lesions with the potential to evolve. Four giant-cell astrocytomas were detected both with CT and Gd-DTPA-enhanced MRI; tumor conspicuity and size assessment were improved by postcontrast MRI in two cases. No cortical tuber or heterotopic cluster enhanced; T2-weighted sequences therefore remain necessary for their detection. If pre and post-Gd-DTPA T1- and T2-weighted imaging is negative, CT is clearly the most sensitive modality in the detection of the small calcified subependymal nodules.