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Comparison of SPECT, EEG, CT, MRI, and pathology in partial epilepsy
C Adams1, P A Hwang, D L Gilday
1Division of Neurology, Hospital for Sick Children, Toronto, Canada.
Insights
Single photon emission computed tomography (SPECT) using technetium-99m hexamethylpropyleneamineoxime (99mTc-HmPAO) aids in identifying epilepsy surgery targets. This imaging technique, especially when combined with electroencephalography (EEG), improves localization of seizure foci.
Area of Science:
- Neuroimaging
- Epilepsy Surgery Evaluation
- Nuclear Medicine
Background:
- Partial epilepsy in children often requires surgical intervention.
- Accurate localization of the epileptiform focus is crucial for successful epilepsy surgery.
- Preoperative diagnostic tools include electroencephalography (EEG), computed tomography (CT), and magnetic resonance imaging (MRI).
Purpose of the Study:
- To evaluate the utility of technetium-99m hexamethylpropyleneamineoxime (99mTc-HmPAO) single photon emission computed tomography (SPECT) in localizing seizure foci in pediatric epilepsy surgery candidates.
- To compare the diagnostic accuracy of SPECT with EEG, CT, and MRI in correlating with pathological findings.
Main Methods:
- Twenty children with partial epilepsy underwent preoperative EEG, CT, and SPECT (interictal and postictal).
- Fourteen patients also had MRI.
- SPECT measured regional cerebral blood flow (rCBF) abnormalities, which were correlated with EEG, CT, MRI, and surgical pathology findings.
Main Results:
- SPECT, particularly when combining interictal and postictal scans, correlated with EEG foci in 16 of 20 patients.
- SPECT findings correlated with pathology in 17 patients, showing comparable or superior accuracy to CT (15 patients) and MRI (13 of 14 patients) in some cases.
- SPECT identified abnormalities in patients with normal CT or MRI scans, highlighting its value in improving localization.
Conclusions:
- Technetium-99m hexamethylpropyleneamineoxime SPECT is a valuable adjunctive diagnostic tool for epilepsy surgery evaluation in children.
- SPECT enhances the localization of epileptiform foci, especially when CT or MRI findings are inconclusive.
- The combination of interictal and postictal SPECT provides significant information for surgical planning in pediatric epilepsy.
Abstract:
Twenty children with partial epilepsy who had surgery between the ages of 4 1/2 months and 18 years were studied preoperatively with electroencephalography (EEG), computed tomography (CT), and technetium-99m hexamethylpropyleneamineoxime 99mTc-HmPAO single photon emission computed tomography (SPECT; 20 interictal, 4 postictal). Fourteen had magnetic resonance imaging (MRI). All had an epileptiform focus (12 unilateral, 8 predominantly unilateral) on EEG. The combination of interictal and postictal regional cerebral blood flow (rCBF) abnormalities alone correlated with EEG foci in 16 of 20 patients. Interictal rCBF abnormalities correlated with EEG foci in 14 of 20. CT findings correlated with EEG foci in 14 of 20. MRI findings correlated with EEG foci in 13 of 14. Pathology demonstrated tumor in 6, cortical dysplasia in 4, mesial temporal sclerosis in 3, Sturge-Weber in 2, cavernous hemangioma in 1, Rasmussen encephalitis in 1, porencephalic cyst and gliosis in 1, and cysts found at surgery (but normal histology) in 2. Interictal and postictal SPECT, EEG foci, and CT findings each correlated with the pathology site in 17, 19, and 15 patients, respectively. MRI correlated with pathology site in 13 of 14 patients. Postictal and interictal abnormalities of rCBF correlated with EEG and pathology as frequently as CT. In 5 patients with normal CT scans and in 1 with a normal MRI, postictal and interictal rCBF correlated with EEG and pathology results; however, these 6 patients all had abnormalities on CT or MRI. SPECT, therefore, may be considered a valuable additional diagnostic procedure in the evaluation of epilepsy surgery candidates in that it adds to the evidence of abnormality at the involved site.(ABSTRACT TRUNCATED AT 250 WORDS)