Comparison of MR imaging with PET and ictal SPECT in 118 patients with intractable epilepsy

BACKGROUND AND PURPOSE: MR imaging, PET, and ictal SPECT have been studied extensively as individual techniques in the localization of epileptogenic f oci, but only a few comparative studies have been done. We evaluated the co ncordance rates of ictal video/EEG, MR imaging, PET, and ictal SPECT to com pare the sensitivities of these imaging methods in the lateralization of ep ileptogenic foci, METHODS: The study included 118 consecutive patients who underwent surgery for medically intractable epilepsy and who were followed up for 12 months o r more. MR imaging was compared retrospectively with ictal video/EEG, FDG-P ET, ictal Tc-99m-HMPAO SPECT, and invasive EEG as to their ability to local ize the epileptogenic focus; the pathologic findings served as the standard of reference. RESULTS: MR imaging was concordant with video/EEG, PET, and ictal SPECT in 58%, 68%, and 58% of patients, respectively. With the pathologic diagnosis as the standard of reference, MR imaging, PET, and ictal SPECT correctly la teralized the lesion in 72%, 85%, and 73% of patients, respectively. Of the patients with good outcomes, MR imaging, PET, and ictal SPECT were correct in 77%, 86%, and 78%, respectively, In the good outcome group, MR imaging was concordant with PET and ictal SPECT in 73% and 62% of patients, respect ively. Of 45 patients who underwent invasive EEG, MR imaging was concordant with the invasive study in 47%; PET in 58%; and ictal SPECT in 56%, Of 26 patients with normal MR findings, PET and ictal SPECT correctly lateralized the lesion in 80% and 55%, respectively. CONCLUSION: Overall concordance among the techniques is approximately two t hirds or less in lateralizing epileptogenic foci, PET is the most sensitive , even though it provides a broad approximate nature of the epileptogenic z one, which is not adequate for precise surgical localization of epilepsy, P ET and/or ictal SPECT may be used as complementary tools in cases of inconc lusive lateralization with ictal video/EEG and MR imaging.