Clinical Role of Subtraction Ictal SPECT Coregistered to MR Imaging and 18F-FDG PET in Pediatric Epilepsy

AIMS:
A precise assessment of the drug-resistant epileptic pediatric population for surgical candidacy is often challenging, and to date there are no evidence-based guidelines for presurgical identification of the epileptogenic zone. To evaluate the usefulness of radionuclide imaging techniques for presurgical evaluation of epileptic pediatric patients, we compared the results of video-electroencephalography (EEG), brain MR imaging, interictal SPECT, ictal SPECT, subtraction ictal SPECT coregistered to MR imaging (SISCOM), and interictal PET with 18F-FDG.

METHODS:
Fifty-four children with drug-resistant epilepsy who had undergone video-EEG monitoring, brain MR imaging, interictal and ictal brain perfusion SPECT, SISCOM, and 18F-FDG PET were included in this study. All abnormal findings revealed by these neuroimaging techniques were compared with the presumed location of the epileptogenic zone (PEZ) as determined by video-EEG and clinical data. The proportion of localizing studies for each technique was statistically compared. In the 18 patients who underwent resective brain surgery, neuroimaging results were compared with histopathology results and surgical outcome.

RESULTS:
SISCOM and 18F-FDG PET concordance with the PEZ was significantly higher than MR imaging (P < 0.05). MR imaging showed localizing results in 21 of 54 cases (39%), SISCOM in 36 of 54 cases (67%), and 18F-FDG PET in 31 of 54 cases (57%). If we consider SISCOM and 18F-FDG PET results together, nuclear medicine imaging techniques showed coinciding video-EEG results in 76% of patients (41/54). In those cases in which MR imaging failed to identify any epileptogenic lesion (61% [33/54]), SISCOM or 18F-FDG PET findings matched PEZ in 67% (22/33) of cases.

CONCLUSION:
SISCOM and 18F-FDG PET provide complementary presurgical information that matched video-EEG results and clinical data in three fourths of our sample. SISCOM was particularly useful in those cases in which MR imaging findings were abnormal but no epileptogenic lesion was identified. Radionuclide imaging techniques are both useful and reliable, extending the possibility of surgical treatment to patients who may have been discouraged without a nuclear medicine approach.

© 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.