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Objectives: This was an observational study done on a large cohort of patients with tuberous sclerosis complex (TSC) to determine whether i) the presence of α-[(11)C]-methyl-l-tryptophan (AMT) hotspots is related to the duration of seizure intractability, ii) the presence of AMT hotspots is related to specific TSC gene mutations, and iii) there is concordance between areas with an AMT hotspot and seizure lateralization/localization on scalp EEG., Methods: One hundred ninety-one patients (mean age: 6.7 years; median: 5 years; range: 3 months to 37 years) with TSC and intractable epilepsy were included. All patients underwent AMT-PET scan. AMT uptake in each tuber and normal-appearing cortex was measured and correlated with clinical, scalp EEG, and, if available, electrocorticographic data., Results: The longer the duration of seizure intractability, the greater the number of AMT hotspots (r = 0.2; p = 0.03). AMT hotspots were seen in both TSC1 and TSC2. There was excellent agreement in seizure focus lateralization between ictal scalp EEG and AMT-PET (Cohen κ 0.94) in 68 of 95 patients in whom both ictal video-EEG and AMT-PET showed lateralizing findings; in 28 of 68 patients (41%), AMT was more localizing. Furthermore, AMT-PET was localizing in 10 of 17 patients (58%) with nonlateralized ictal EEG., Conclusion: AMT-PET, when used together with video-EEG, provides additional lateralization/localization data, regardless of TSC mutation. The duration of seizure intractability may predict the multiplicity of areas with AMT hotspots.

Purpose of Review: In this review we discuss recent advances in the neuroimaging of patients with tuberous sclerosis complex (TSC), highlighting its application in improving clinical management, particularly in the case of intractable epilepsy., Recent Findings: Progress in structural and functional imaging has led to further characterization of the brain lesions in TSC. New magnetic resonance imaging techniques that can delineate the extent of structural brain abnormalities in TSC have been developed. Diffusion tensor imaging unveils the microstructural abnormalities of the brain lesions and of the morphologically normal appearing white matter in TSC. It can potentially identify the epileptogenic zone. Positron emission tomography scanning with 2-deoxy-2-[18F]fluoro-D-glucose can assess the full extent of functional brain abnormalities in TSC. The use of alpha [11C] methyl-L-tryptophan positron emission tomography scanning has proven to be a useful tool in the identification of epileptogenic tubers and has improved the outcome of surgery for epilepsy in TSC., Summary: Major advances of neuroimaging in TSC have shown evidence of widespread structural and functional brain abnormalities. In TSC patients with intractable epilepsy, new neuroimaging modalities can now provide an accurate assessment of the epileptogenic zone, thereby permitting improved identification of patients who can have good seizure outcome following surgery for epilepsy.