Roland Sebastian Talanow MD, PhD, Presenter: Nothing to Disclose

Guiyun Wu MD, Abstract Co-Author: Nothing to Disclose

PET imaging is used in patients with refractory epilepsy for presurgical evaluation. The value of PET scans in patients with frequent spiking activity on EEG and ictal activity shortly after injection of FDG is unknown. The purpose of this study was to evaluate PET imaging findings in this patient population in relation to the surgical outcome.

294 patients (143 female, 153 male; age 1 day to 64 years) with refractory epilepsy were identified and underwent PET imaging for presurgical workup. All patients underwent surgical treatment for seizure focus removal. Surgical outcome was measured as seizure-free, improved and failed. EEG, which covers activity from 30 min before and 30-45 min after injection of FDG, was classified as true interictal (normal), interictal with frequent spikes and ictal (clinical seizure present). The level of metabolism on PET scan was defined as hypermetabolic, normal and hypometabolic.

Of 294 patients, 260 (88%) had true interictal PET imaging, 14 (5%) had ictal imaging, 20 (7%) had interictal but frequent spiking activity based on EEG. In patients with true interictal PET, 95% patient demonstrated hypometabolism in the area of resection, with 85% being seizure-free or improved. 5% of patients demonstrated normal metabolism with 83% being seizure-free. In patients with interictal but frequent spiking activity, 9 (45%) demonstrated hypermetabolism, whereas 9 (45%) showed hypometabolism and 2 (10%) had normal metabolism in the resected regions. In patients with ictal PET, 6 patients (43%) showed hypermetabolism and 8 (57%) had hypometabolism in the resected regions. For patients with frequent interictal spikes or ictal EEG with PET findings of hypermetabolism, the seizure-free rate was 92%. For patients with frequent spikes or ictal EEG with PET findings of hypometabolism, the seizure-free rate was 100%. With a normal EEG, the seizure-free rate was also 100% (2 cases).

Both PET hypermetabolism and hypometabolism in patients with frequent spiking activity and ictal state correlated well with the surgical outcome.

Surgical outcome in refractory epilepsy can be predicted by PET imaging even in patients with frequent seizures or spiking activity.

Talanow, R, Wu, G, Correlation of PET Hypo- and Hypermetabolism with Surgical Outcomes in Refractory Epilepsy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5000907.html