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SPECT Imaging of Epilepsy: An Overview and Comparison with F-18 FDG PET  [PDF]
Sunhee Kim,James M. Mountz
International Journal of Molecular Imaging , 2011, DOI: 10.1155/2011/813028
Abstract: Epilepsy surgery is highly effective in treating refractory epilepsy, but requires accurate presurgical localization of the epileptogenic focus. Briefly, localization of the region of seizure onset traditionally dependents on seizure semiology, scalp EEG recordings and correlation with anatomical imaging modalities such as MRI. The introduction of noninvasive functional neuroimaging methods, including single-photon emission computed tomography (SPECT) and positron emission tomography (PET) has dramatically changed the method for presurgical epilepsy evaluation. These imaging modalities have become powerful tools for the investigation of brain function and are an essential part of the evaluation of epileptic patients. Of these methods, SPECT has the practical capacity to image blood flow functional changes that occur during seizures in the routine clinical setting. In this review we present the basic principles of epilepsy SPECT and PET imaging. We discuss the properties of the SPECT tracers to be used for this purpose and imaging acquisition protocols as well as the diagnostic performance of SPECT in addition to SPECT image analysis methods. This is followed by a discussion and comparison to F-18 FDG PET acquisition and imaging analysis methods. 1. Introduction Epilepsy surgery can be highly effective in treating refractory epilepsy if performed in properly selected patients with well-delineated ictal foci [1]. The greatest challenge is accurate localization, but only a small fraction of the patients whose epilepsy becomes refractory ultimately receive surgery. In the past, localization of the region of seizure onset was dependent upon scalp, cortical, and depth electroencephalography (EEG). However, scalp EEG has disadvantages such as dependency on cortical surface effects and low spatial resolution that can lead to mislocalization of epileptogenic foci. Both cortical and depth EEG have a limited spatial sampling area that is confined to regions accessible by electrode placement. Depth EEG can detect signals from deeper structures, but it is more invasive, which can lead to surgical complications [2]. The introduction of noninvasive neuroimaging methods, such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI), has dramatically changed presurgical epilepsy evaluation. These imaging methods have become powerful tools for the investigation of brain function and an essential part of the evaluation of epileptic patients. Of these methods, only SPECT has the practical capacity to
Ictal and interictal SPECT in patients with frontal lobe epilepsy.- This paper was awarded the ADAC Prize at the Brazilian Congress of Nuclear Medicine, Recife, Brazil, December 1998.  [cached]
Wichert-Ana, Lauro.,Kato, Mery .,Terra Bustamante, Vera Cristina.,Rodrigues Velasco, Tonicarlo.
Alasbimn Journal , 1999,
Abstract: The frontal lobe seizures present variable clinical and electroencephalographic features that play some difficulties in the presurgical work-up for epilepsy. The aim of the present study is to determine the role of ictal and interictal SPECT in the localization of the epileptogenic zone in frontal lobe epilepsies. We evaluated 13 patients, 6 men and 7 women, with mean age of 16yr, and with medically intractable frontal lobe seizures. All patients were submitted to ictal SPECT and 11 also to interictal scans. Ictal SPECT studies were contributive in 54% of patients, and nonlateralized and nonlocalized, or contralateralized in the remaining patients. Interictal SPECT showed normal perfusion in 45,5% of patients, hypoperfusion localized in the suspected epileptogenic zone in 45,5%, and diffuse findings in the other 9%. We conclude that the sensitivity of ictal and interictal SPECT studies in frontal lobe epilepsies is lower than that for temporal lobe seizures, thus confirming previous data.
Statistical voxel-wise analysis of ictal SPECT reveals pattern of abnormal perfusion in patients with temporal lobe epilepsy
Amorim, Bárbara Juarez;Etchebehere, Elba Cristina Sá de Camargo;Camargo, Edwaldo Eduardo;Rio, Pablo Augusto;Bonilha, Leonardo;Rorden, Chris;Li, Li Min;Cendes, Fernando;
Arquivos de Neuro-Psiquiatria , 2005, DOI: 10.1590/S0004-282X2005000600014
Abstract: objective: to investigate the pattern of perfusion abnormalities in ictal and interictal brain perfusion spect images (bsi) from patients with temporal lobe epilepsy (tle). method: it was acquired interictal and ictal bsi from 24 patients with refractory tle. bsis were analyzed by visual inspection and statistical parametric mapping (spm2). statistical analysis compared the patients group to a control group of 50 volunteers. the images from patients with left-tle were left-right flipped. results: it was not observed significant perfusional differences in interictal scans with spm. ictal bsi in spm analysis revealed hyperperfusion within ipsilateral temporal lobe (epileptogenic focus) and also contralateral parieto-occipital region, ipsilateral posterior cingulate gyrus, occipital lobes and ipsilateral basal ganglia. ictal bsi also showed areas of hypoperfusion. conclusion: in a group analysis of ictal bsi of patients with tle, voxel-wise analysis detects a network of distant regions of perfusional alteration which may play active role in seizure genesis and propagation.
Avalia??o de foco epileptogênico do lobo temporal: correla??o entre SPECT ictal, ressonancia magnética e ressonancia magnética com espectroscopia de prótons
Diegues, Maria Elena Martins;Pellini, Marcos Pinto;Alves-Leon, Soniza Vieira;Domingues, Romeu C?rtes;
Radiologia Brasileira , 2004, DOI: 10.1590/S0100-39842004000100003
Abstract: the purpose of this study was to determine the degree of concordance between radiological and radioisotopic methods and, if positive, to evaluate the usefulness of ictal spect in the localization of the epileptogenic focus. ictal brain spect, magnetic resonance imaging (mri) and magnetic resonance spectroscopy (mrs) were performed on six patients with refractory temporal lobe epilepsy. ictal spect was performed after withdrawal of the anti-epileptogenic drugs during video-eeg monitoring, using 99mtc-ecd, administered to patients at the time of the ictus. mri was performed in t1, t2 and flair sequences and mrs was obtained using the press technique, with a single voxel positioned in both hippocampi. the statistical analysis included the determination of the values of kappa (k), standard error (se) and significance level (p) for the lateralization of the ictal focus. the analysis of all findings was based on eeg localization of the ictal discharge, seizure duration (109-280 s; 152 s average) and time of radiotracer injection (30-262 s; 96 s average). we obtained correlated data in four patients (67%), and values of k = 0.67, se = 0.38, and p = 0.041. we concluded that there is a concordance between ictal spect, mri and mrs data and the usefulness of the radioisotopic procedure is related to a nondiagnostic eeg and when there is a discordant or misleading diagnosis after a comparative analysis of eeg and mrs.
The hazards of lack of co-registration of ictal brain SPECT with MRI: A case report of sinusitis mimicking a brainstem seizure focus
Tracy Butler, Lawrence J Hirsch, Jan Claassen
BMC Medical Physics , 2004, DOI: 10.1186/1471-2385-4-2
Abstract: A young woman with encephalitis and refractory seizures underwent brain SPECT during a period of frequent seizure-like episodes, and during a seizure-free period. A focal area of increased radiotracer uptake present only when she was experiencing frequent seizure-like episodes was originally localized to the brainstem, but with later computerized co-registration of SPECT to MRI, was found to lie outside the brain, in the region of the sphenoid sinus.Low-resolution SPECT images present difficulties in interpretation, which can be overcome through co-registration to higher-resolution structural images.Radiotracers used for brain single photon emitted computed tomography (SPECT) pass the blood-brain barrier and bind intracellularly on their first pass through the circulation, providing a "snapshot" of cerebral perfusion at a particular timepoint. When injected during a focal epileptic seizure, an area of significantly increased radiotracer uptake typically corresponds to the region of maximal abnormal activity, often the seizure focus. This ictal pattern of cerebral blood flow can be compared to an interictal/baseline pattern obtained when the patient is not having a seizure, to provide unique information about the nature and location of a patient's epileptic focus, which can be used to guide therapy [See [1] for a review of the use of SPECT in epilepsy].A previously-healthy young woman developed behavioral changes followed by seizures and refractory status epilepticus. She was diagnosed with encephalitis and treated with antiviral and multiple antiepileptic agents. She required nasotracheal intubation and mechanical ventilation for respiratory support. She experienced persistent episodes of facial twitching resembling seizures. These episodes were not however associated with an ictal EEG pattern on continuous video/EEG monitoring. To clarify the nature of these episodes, 99mTc-HMPAO was injected during a period of frequent twitching. Brain SPECT showed a prominent foc
Epistaxis during a generalized seizure leading to an atypical ictal SPECT finding at the skull base
Wichert-Ana, Lauro;Ferruzzi, Emerson Henklain;Alexandre Jr, Veriano;Velasco, Tonicarlo Rodrigues;Bianchin, Marino Muxfeldt;Terra-Bustamante, Vera Cristina;Kato, Mery;Santos, Antonio Carlos;Azevedo-Marques, Paulo Mazzoncini de;Oliveira, Lucas Ferrari de;Sakamoto, Américo Ceiki;
Journal of Epilepsy and Clinical Neurophysiology , 2006, DOI: 10.1590/S1676-26492006000700007
Abstract: introduction: generalized tonic-clonic seizures (gtcs) are among the most dramatic types of epileptic seizures and may be accompanied by rising blood pressure and pulse rate, physical injuries from falling, muscular convulsions, tongue biting, or aspiration pneumonia. epistaxis is an uncommon complication of generalized seizures and investigations should exclude local or systemic disorders. objective: we aim to report a 29-year-old male patient with medically intractable right temporal lobe epilepsy whose ictal spect showed a conspicuous high extracerebral accumulation of the tracer at the skull base. methods: the tracer 99mtc-ecd was injected during a gtcs complicated by simultaneous epistaxis during a long term video-electroencephalographic monitoring. results: initially, spect images showed an unexpected hot spot at the skull base suggesting pharyngeal or pituitary tumors. clinical history disclosed chronic sinusitis and rare episodes of epistaxis. white and red cells blood count, platelet count, serum biochemistry, coagulation tests, and rest arterial blood pressure were normal. computed tomography and mri excluded sinusoidal expansive or vascular lesions, head trauma, fractures or acute infections. subtracted spect disclosed a focal high concentration of the radiotracer within the left sphenoid sinus, probably related to the nose bleeding. conclusion: this is a singular case of a brain spect artifact secondary to a nasal bleeding during a generalized seizure that was misinterpreted as neoplastic disease. also, this case raises concerns about the pathophysiological relationship among epileptic seizures, nasal bleedings and chronic sinusitis.
Brain SPECT in mesial temporal lobe epilepsy: comparison between visual analysis and SPM
Amorim, Bárbara Juarez;Ramos, Celso Darío;Santos, Allan Oliveira dos;Lima, Mariana da Cunha Lopes de;Min, Li Li;Camargo, Edwaldo Eduardo;Cendes, Fernando;Etchebehere, Elba Cristina Sá de Camargo;
Arquivos de Neuro-Psiquiatria , 2010, DOI: 10.1590/S0004-282X2010000200001
Abstract: objective: to compare the accuracy of spm and visual analysis of brain spect in patients with mesial temporal lobe epilepsy (mtle). method: interictal and ictal spects of 22 patients with mtle were performed. visual analysis were performed in interictal (visual(inter)) and ictal (visual(ictal/inter)) studies. spm analysis consisted of comparing interictal (spm(inter)) and ictal spects (spm(ictal)) of each patient to control group and by comparing perfusion of temporal lobes in ictal and interictal studies among themselves (spm(ictal/inter)). results: for detection of the epileptogenic focus, the sensitivities were as follows: visual(inter)=68%; visual(ictal/inter)=100%; spm(inter)=45%; spm(ictal)=64% and spm(ictal/inter)=77%. spm was able to detect more areas of hyperperfusion and hypoperfusion. conclusion: spm did not improve the sensitivity to detect epileptogenic focus. however, spm detected different regions of hypoperfusion and hyperperfusion and is therefore a helpful tool for better understand pathophysiology of seizures in mtle.
Interictal SPECT in the presurgical evaluation in epileptic patients with normal MRI or bilateral mesial temporal sclerosis
Marques, Lucia H.N.;Ferraz-Filho, José R.L.;Lins-Filho, Mário L.M.;Maciel, Marina G.;Yoshitake, Rafael;Filetti, Sarah V.;
Arquivos de Neuro-Psiquiatria , 2009, DOI: 10.1590/S0004-282X2009000400012
Abstract: the aim of this study was to evaluate the sensitivity of interictal compared to ictal spect in the lateralization of the epileptogenic focus in refractory temporal lobe epilepsy (tle) patients that present with normal magnetic resonance imaging (mri) or bilateral mesial temporal sclerosis (mts). thirty patients with tle, for whom mri examinations were normal or who presented with bilateral mts, were retrospectively studied. using a confidence interval of 95% and a level of significance for p-value <0.05, an estimated agreement rate of 73% with a minimum agreement rate of 57% was calculated comparing interictal and ictal spects. in conclusion the interictal spect is only useful when associated with the ictal spect and does not substitute it in the localization of epileptogenic areas in patients with normal mri or bilateral mts.
Structural and functional neuroimaging in intractable epilepsy
Chinchure Swati,Kesavadas Chandrasekharan,Thomas Bejoy
Neurology India , 2010,
Abstract: Medical management remains unsatisfactory in about a third of patients with epilepsy and some of them are candidates for resective epilepsy surgery. Structural and functional neuroimaging plays an important role in the identification of the precise cortical region responsible for seizures and is very crucial for a good surgical outcome. Furthermore, identification of eloquent cortical areas near the region to be resected is essential to avoid postoperative neurologic deficit. The magnetic resonance imaging (MRI) protocol for epilepsy can be individually tailored depending on the seizure semiology and possibly electroencephalography. New MRI techniques demonstrate the structure of the brain in fine detail, help in understanding the underlying pathology, and demonstrate functional activity of the brain with high spatial and temporal resolution. Metabolic imaging techniques, such as positron emission tomography (PET) and single photon emission tomography (SPECT) visualize metabolic alterations of the brain in the ictal and interictal states. In MR-negative epilepsy patients, these techniques may have localizing value. The proper use and interpretation of the findings provided by these new technologies is crucial. In this review article, we discuss various conventional and advanced MRI techniques, interpretation of various findings, and the role of functional imaging modalities, such as functional MRI, PET, and SPECT in the localization of epileptogenic substrate as well as for understanding the pathophysiology, propagation, and neurochemical correlates of epilepsy.
Avalia o de foco epileptogênico do lobo temporal: correla o entre SPECT ictal, ressonancia magnética e ressonancia magnética com espectroscopia de prótons  [cached]
Diegues Maria Elena Martins,Pellini Marcos Pinto,Alves-Leon Soniza Vieira,Domingues Romeu C?rtes
Radiologia Brasileira , 2004,
Abstract: O objetivo deste trabalho foi determinar a existência de concordancia entre os métodos radioisotópico e radiológico e, em caso positivo, avaliar a utilidade do SPECT ictal na determina o do foco epileptogênico. Foram realizados SPECT ictal, ressonancia magnética (RM) e ressonancia magnética com espectroscopia de prótons (RME) em seis pacientes com epilepsia de lobo temporal refratária. O SPECT ictal foi realizado após a retirada das drogas antiepilépticas durante monitoramento por vídeo-EEG, utilizando-se o 99mTc-ECD, administrado aos pacientes no início da crise. As imagens de RM foram obtidas em T1, T2 e FLAIR, com cortes de 3 e 5 mm de espessura, e a RME foi realizada com técnica PRESS, com voxel único posicionado no hipocampo, bilateralmente. A análise estatística incluiu os valores de Kappa (k), erro-padr o (ep) e o nível de significancia (p) para a lateraliza o do foco. Os achados foram analisados com base na localiza o por EEG da descarga ictal, no tempo de dura o da crise (109-280 s; média: 152 s) e no tempo de administra o do tra ador (30-262 s; média: 96 s). Obtivemos dados correlatos em quatro pacientes (67%), com valores de k = 0,67, ep = 0,38 e p = 0,041. Concluímos que existe concordancia entre SPECT ictal, RM e RME, e a utilidade do procedimento radioisotópico está relacionada aos casos em que o EEG n o é diagnóstico e quando há discordancia ou indefini o diagnóstica na análise comparativa entre EEG, RM e RME.
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