| J Nucl Med 2001 Aug;42(8):1158-1165 |
The utility of a 3-dimensional, large-field-of-view, sodium iodide
crystal--based PET scanner in the presurgical evaluation of partial epilepsy.
O'Brien TJ, Hicks RJ, Ware R, Binns DS, Murphy M, Cook MJ.
(18)F-FDG PET is an accurate and reliable technique for localizing medically refractory
temporal lobe epilepsy, but widespread use has been hindered by limited reimbursement in
many countries because of the high cost of traditional PET equipment and radioisotopes.
Additionally, the place of FDG PET as a cost-effective tool for presurgical evaluation of
epilepsy has been questioned because of limited data showing that FDG PET provides
localization information incremental to that provided by more established techniques,
particularly MRI and ictal electroencephalography (EEG). Three-dimensional (3D),
large-field-of-view, sodium iodide crystal-based scanners have lower equipment and running
costs and better multiplanar resolution than traditional 2-dimensional bismuth germinate
(BGO) systems but have not yet been validated for evaluation of epilepsy. Our purpose was
to investigate the localization rate, accuracy, and prognostic value of FDG PET images
acquired on a 3D, large-field-of-view, sodium iodide crystal-based PET scanner in the
presurgical evaluation of intractable partial epilepsy. We also wanted to establish the
incremental value of FDG PET over established MRI and ictal EEG techniques. METHODS:
Fifty-five patients who were surgical candidates because of medically refractory partial
epilepsy were examined. For most of these patients, the lesions had not been clearly
localized on conventional assessment. The FDG PET scans were reviewed independently by 2
reviewers who were unaware of the patients' clinical details, ictal EEG findings, and
volumetric MRI results, and the FDG PET results were correlated with those of MRI and EEG
and with postsurgical outcome. RESULTS: Forty-two patients (76%) had localizing FDG PET
images (37 temporal, 5 extratemporal). The ictal EEG recordings were localizing in 66%,
and the MRI findings were localizing in 27% (which increased to 35% after the MRI findings
were reviewed again after PET). Concordance between the site of the PET localizations and
the site of the MRI or EEG localizations was 100%. The PET images were localizing in 63%
and 69% of patients with nonlocalizing ictal EEG and MRI findings, respectively.
Twenty-one of 24 patients who subsequently underwent epilepsy surgery had localizing FDG
PET images; of these 21 patients, 18 (86%) had a class I outcome. Multiple regression
analysis showed the FDG PET results to be predictive of postsurgical outcome independently
of the MRI findings. CONCLUSION: For intractable partial epilepsy, FDG PET using a 3D,
large-field-of-view, sodium iodide crystal-based scanner provided clinically useful
localizing information that was at least as accurate as the results reported for
traditional BGO-based scanners. The PET images provided prognostically significant
localization information incremental to that provided by volumetric MRI and ictal EEG,
particularly if 1 of these studies was nonlocalizing.
