Multimodality imaging for improved detection of epileptogenic foci in tuberous sclerosis complex

Abstract

Cortical tubers with [11C]AMT uptake greater than or equal to normal cortex are significantly related to epileptiform activity in that lobe. Together, interictal [11C]AMT PET and FLAIR MRI improve the detection of potentially epileptogenic tubers in patients with TSC being evaluated for epilepsy surgery.

In Vivo Uptake and Metabolism of α-[11C]Methyl-l-Tryptophan in Human Brain Tumors

“…Subsequent studies in patients with intractable seizures of various etiologies, including malformations of cortical development, found that increased AMT was highly specific for epileptogenic cortical regions and is a useful method for presurgical evaluation of some patients with intractable epilepsy (Asano et al, 2000;Fedi et al, 2001;Juhász et al, 2003). Increased levels of quinolinic acid reported in the cerebrospinal fluid of children with brain tumors (Heyes et al, 1995), and increased IDO activity in malignant gliomas (Uyttenhove et al, 2003) suggested that abnormal tryptophan metabolism via the kynurenine pathway may also occur in brain tumors.…”

α-[ 11 C]-Methyl- l -tryptophan–PET in 191 patients with tuberous sclerosis complex

“…11 We previously reported, in a relatively small number of patients with TSC, that a-[ 11 C]-methyl-Ltryptophan (AMT)-PET scanning may differentiate between epileptogenic tubers (high AMT uptake) and nonepileptogenic tubers (low AMT uptake) and that the location of high AMT uptake corresponds to the seizure focus on EEG. 6,12,13 …”

“…11 We previously reported, in a relatively small number of patients with TSC, that a-[ 11 C]-methyl-Ltryptophan (AMT)-PET scanning may differentiate between epileptogenic tubers (high AMT uptake) and nonepileptogenic tubers (low AMT uptake) and that the location of high AMT uptake corresponds to the seizure focus on EEG. 6,12,13 The present study was performed in 191 patients with TSC and intractable epilepsy who underwent AMT-PET during epilepsy surgery evaluation to address whether i) presence of increased AMT uptake is related to duration of seizure intractability, ii) increased AMT uptake in epileptogenic tubers is related to specific TSC gene mutations, and iii) there is concordance between areas of increased AMT uptake and seizure lateralization/localization on scalp EEG.…”

“…Regions of interest for cortical tubers and dysplastic cortices and contralateral homotopic normal-appearing cortex were delineated using a semiautomated threshold-based software program. 13 Briefly, the AMT-PET images were coregistered to FLAIR, T2-weighted, and FDG images using MPITOOL (Max-Planck Institute, Cologne, Germany) 19 (figure 1), and AMT uptake in each tuber and normal-appearing cortex was measured. Increased AMT uptake in the caudate nucleus and cerebellum was excluded.…”

“…This cutoff is based on previous studies using receiver operating characteristic analysis showing that an AMT uptake ratio of .0.98 resulted in statistically significant detection of epileptogenic tubers with specificity 5 0.91. 13 Because nonepileptogenic tubers show lower AMT uptake than normal cortex, the uptake ratio of such tubers would be much less than 1.0.…”