LATERALIZATION OF HUMAN TEMPORAL-LOBE EPILEPSY BY P-31 NMR SPECTROSCOPIC IMAGING AT 4.1 T

Objective: To compare the phosphorous metabolite ratios in the mesial temporal lobe of healthy volunteers (n = 20) with the corresponding ra tios in patients with temporal lobe epilepsy (n = 30) using P-31 NMR s pectroscopic imaging and to lateralize the seizure focus in temporal l obe epilepsy patients using various phosphorous metabolite ratios-phos phocreatine to inorganic phosphate (PCr/Pi), PCr to adenosine triphosp hate (PCr/gamma-ATP), and (gamma-ATP/Pi)-and to compare with clinical lateralization results, Methods: All P-31 NMR spectroscopic imaging st udies were performed on a high-field, 4.1 T, whole-body NMR spectrosco pic imaging system using a P-31/H-1 double-tuned volume coil. Results: We found an average reduction of 15% in the PCr/Pi and gamma-ATP/Pi r atios compared with the corresponding ratios in healthy volunteers in the entire mesial temporal lobe, and more than a 90% reduction in thes e two ratios in the anterior region of the epileptogenic mesial tempor al lobe. These ratios were also reduced significantly in the ipsilater al lobe when compared with their corresponding values in the contralat eral lobe. In patients we lateralized the seizure focus, based on thes e P-31 NMR data, and compared the results with the clinical lateraliza tion. The lateralization based on either the PCr/Pi or the gamma-ATP/P i ratio yielded a correspondence of 70 to 73% with the final clinical lateralization. In the subgroup of patients (n = 9) that needed intrac ranial EEG for the presurgical lateralization because of inconclusive results from the noninvasive methods, a 78% correspondence was found w ith the P-31 NMR-based lateralization, whereas MRI provided a correspo ndence of only 33%, and scalp EEG provided a correspondence of only 56 %. Conclusions: These results suggest the utility of adding the P-31 N MR method to the group of noninvasive modalities used for presurgical decision making in temporal lobe epilepsy patients.