Localization of the Epileptogenic Zone by Ictal and Interictal SPECT with ^99mTc‐Ethyl Cysteinate Dimer in Patients with Medically Refractory Epilepsy

Abstract

Summary:Purpose: To evaluate the accuracy, feasibility and clinical value of both ictal and interictal y9"Tc-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients with medically refractory epilepsy.Methods: The study included 75 consecutive patients, 48 with temporal lobe epilepsy (TLE group), and 27 with extratemporal epilepsy (ExT group). The accuracy of SPECT was analyzed considering the final diagnosis reached by convergence of clinical, electrophysiologic, structural, pathologic and outcome data.Resulw Ictal SPECT correctly identified the epileptogenic zone in 21 (91.3%) of 23 patients, whereas interictal SPECTs could correctly identify the epileptogenic zone in only 41(62.1%) of 66 patients (x' = 5.56, df = 1, p < 0.05). Results were similar when the two study groups were analyzed separately. Moreover, ictal studies had significantly higher specificity (91.3 vs. 60.6%) and positive predictive value (91.3 vs.66.2%) than interictal studies for the whole series of patients. Considering all tools used in the preoperative workup of these patients, ictal SPECT significantly contributed to the final topographic diagnosis in seven of 14 patients from TLE group and in six of nine patients from the ExT group. In these patients, ictal SPECT either obviated the need for invasive EEG or helped to define where to concentrate the efforts of invasive investigation.Conclusions: These data demonstrate that ictal SPECT can be easily achieved by using 9' "' Tc-ECD and can accurately localize the epileptogenic zone in both temporal and extratemporal epilepsies. Ictal ECD SPECT proved to be significantly more sensitive and specific than interictal ECD SPECT, and clinically useful in the definition of the epileptogenic zone. Key Words: Epilepsy-Single photon emission computed tomography-Ethyl cysteinate dimer-Seizures-Epilepsy surgery.Functional neuroimaging techniques, including singlc photon emission computed tomography (SPECT), have an established role in the preoperative workup of patients with refractory epilepsy (1-3). Indeed, ictal SPECT with an already well-known agent, hexamethyl propyleneamine oxime (HMPAO), has proved to be one of the most sensitive techniques for the localization of ictal onset zones (4-8). Conversely, the interictal modality of SPECT, although easier to obtain, has lower sensitivity (ranging from 30 to 80%) and specificity (from 36 to 95%) for the localization of the epileptogenic zone (3, 9-1 5).

Relationship of Nonlinear Analysis, MRI and SPECT in the Lateralization of Temporal Lobe Epilepsy

“…The sensitivity was higher than that reported by other authors [41, 43]. For example, Dietrich et al [41]disclosed that abnormal regions were detected in 21 of 23 patients with complex partial seizures in a SPECT study, while Oliveira et al [44]reported that ictal SPECT could identify epileptogenic zones in 91.3% of patients as compared with 62.1% for interictal SPECT examination. The different results seen between our study and previous ones may be attributed to several causes, such as (1) differences in seizure type and duration of epilepsy, (2) differences in the criteria applied for detecting abnormalities, and (3) differences in attention to EEG findings.…”

Tratamento cirúrgico das epilepsias na criança

“…O SPECT ictal, que se mostra mais sensível que o interictal na localização da zona de início das crises, é de obtenção difícil, devido à baixa estabilidade do HM-PAO in vitro. Entretanto, o uso do dimer etil-cisteinato tem permitido a obtenção de SPECTs ictais com maior facilidade, constituindo-se num armamentário importante na definição da zona epileptogênica 65 .…”

Synthesis, radio‐LC‐MS analysis and biological evaluation of 99mTc‐techmazenil

“…Bearing in mind the availability and relatively low cost of technetium-99m and the high resolution visualization of Tc-tracers by widely available SPECT-cameras, a technetium-99m labelled compound with the biological characteristics of flumazenil would be an interesting alternative for in vivo visualization of the benzodiazepine receptors in an acute setting analogous to the application of 99m Tc-ECD for the visualization of epileptic foci. 14 The aim of this study was the synthesis and the biological evaluation in mice of …”