18F-FDG PET and 99mTc-ECD SPECT between Ictal and Interictal Phase in a Patient with Status Epilepticus Arising from the Occipital Lobe

A 35-year-old woman suffered from elementary visual symptom that was confirmed as nonconvulsive simple partial status epilepticus arising from the right occipital lobe. 99mTc-ECD SPECT and 18F-FDG PET were done during the ictal and interictal phase, respectively, which were documented by EEG. Subtraction images of SPECT and PET were overlayed on the MRI by SISCOM to compare the area of metabolic change with that of perfusion change. There was no definite mismatch between the hypermetabolic area and the hyperperfusion area during nonconvulsive status epilepticus.

Ictal SPECT-guided Epilepsy Surgery in a Patient with Forme Fruste Tuberous Sclerosis

Tuberous sclerosis is an autosomal dominant disease characterised by hamartomas (tubers) in many organ systems and the four major intracranial manifestations including cortical tubers, white matter abnormalities, subependymal nodules and subependymal giant cell astrocytoma. But there is immense variability in the clinical presentation of tuberous sclerosis and many incomplete forms (formes frustes) exist. Almost all patients with tuberous sclerosis have seizures and mental retardation. The authors experienced a 7-year-old boy with medically intractable epilepsy without any skin lesion or mental retardation. In terms of surgical standpoint for determination of extent of resection, corticectomy on the overriding cortex of right premotor and lesionectomy of periventricular calcified lesion were performed according to ictal single photon emission computed tomography(SPECT), which showed hyperperfusion in the subcortical and calcified area. Histopathologic findings showed a few cytologically abnormal neurons with extensive gliosis, containing many Rosenthal fibers, reactive astrocytes and dense calcification, composing of abundant calcospherites which suggested forme fruste tuberous sclerosis. During the follow-up period of eighteen months, seizure was free after surgery.

Eating Reflex Seizures in a Patient with Congenital Bilateral Perisylvian Syndrome

We report a young man with congenital bilateral perisylvian syndrome (CBPS), who showed eating reflex seizures (ERS). His ERS were related to the taste of foods. The subtracted ictal SPECT co-registered to MRI (SISCOM) revealed the hyperperfusion in the insula as well as the subcortical nuclei and brainstem. The ERS in CBPS may be partially related with the taste function of the insula and SISCOM may be helpful for the localization of the epileptogenic foci in ERS.

Diagnosis of Ictal Hyperperfusion Using Subtraction Image of Ictal and Interictal Brain Perfusion SPECT / 대한핵의학회잡지

A robust algorithm to disclose and display the difference of ictal and interictal perfusion may facilitate the detection of ictal hyperfusion foci. Diagnostic performance of localizing epileptogenic zones with subtracted SPECT images was compared with the visual diagnosis using ictal and interictal SPECT, MR, or PET. Ictal and interictal Tc-99m-HMPAO cerebral perfusion SPECT images of 48 patients(pts) were processed to get parametric subtracted images. Epileptogenic foci of all pts were diagnosed by seizure free state after resection of epileptogenic zones. In subtraction SPECT, we used normalized difference ratio of pixel counts((ictal-interictal)/interictalx100%) after correcting coordinates of ictal and interictal SPECT in semi-automatized 3-dimensional fashion. We found epileptogenic zones in subtraction SPECT and compared the performance with visual diagnosis of ictal and interictal SPECT, MR and PET using post-surgical diagnosis as gold standard. The concordance of subtraction SPECT and ictal-interictal SPECT was moderately good(kappa=0.49). The sensitivity of ictal-interictal SPECT was 73% and that of subtraction SPECT 58%. Positive predictive value of ictal-interictal SPECT was 76% and that of subtraction SPECT was 64%. There was no statistical difference between sensitivity or positive predictive values of subtraction SPECT and ictal-interictal SPECT, MR or PET. Such was also the case when we divided patients into temporal lobe epilepsy and neocortical epilepsy. We conclude that subtraction SPECT we produced had equivalent diagnostic performance compared with ictal-interictal SPECT in localizing epileptogenic zones. Additional value of these subtraction SPECT in clinical interpretation of ictal and interictal SPECT should be further evaluated.