High-resolution (2.6-mm) PET in partial complex epilepsy associated with mesial temporal sclerosis.

Valk, Peter E.; Laxer, Kenneth D.; Barbaro, Nicholas M.; Knezevic, S.; Dillon, William P.; Budinger, Thomas F.

doi:10.1148/radiology.186.1.8416586

Cited by 33 publications

(19 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2B) and the thalamic ROI ( Table 1). The higher concordance with the side of the HA for the mesial temporal ROI (100%) compared with the lateral temporal ROI (77.5%) supports other recent studies that have found the mesial hypometabolism to be more reliable in lateralizing the epileptogenic side in TLE (15, 23,24). However, when the magnitude of the MRI hippocampal volume ratio was compared with the magnitude of the PET AI, no correlation was found for either of the temporal regions (Fig.…”

Section: Discussionsupporting

confidence: 77%

Hippocampal Atrophy Is Not a Major Determinant of Regional Hypometabolism in Temporal Lobe Epilepsy

Newton²,

et al. 1997

View full text Add to dashboard Cite

Summary: Purpose:The pathophysiologic basis for the [ 'sF]fluorodeoxyglucose positron-emission tomography (FDG-PET) temporal lobe hypometabolism in patients with hippocampal sclerosis (HS) is uncertain. We tested the hypothesis that hippocampal atrophy, which is strongly correlated with hippocampal cell loss, is largely responsible for the regional hypometabolism in HS.Methods: Regions of interest (ROIs) on FJlG-PET scanning were determined in the medial, lateral, and posterior temporal lobe, thalamus, and basal ganglia. A righaeft asymmetry index for each ROI was calculated. These results were correlated with hippocampal magnetic resonance imaging (MRI) volume ratios.Results: There was no correlation between the magnitudes of the FDG-PET asymmetry index and the MRI volume ratio for the mesial or lateral temporal regions (r = -0.09, r = -0.04). When the rightneft asymmetry index was compared with the righaeft hippocampal volume ratio, correlations for the mesial temporal ROI (r = 0.79, p < 0.0001) and lateral temporal ROI (r = 0.57, p < 0.0005) were found. These, however, simply indicated that both tests accurately reflect the side of the epileptogenic region. The concordance of the side of relative hypometabolism of the FDG-PET with the side of the hippocampal atrophy was higher for the mesial temporal region (100%) than for the lateral (77.5%).Conclusions: The lack of correlation between the magnitudes of the ratios argues against hippocampal atrophy and cell loss having a central role in the FDG-PET temporal hypometabolism. Key Words: FDG-PET-Hippocampal atrophyHypometabolism-Temporal lobe epilepsy-Volumetric MRI.Hippocampal sclerosis (HS) is found in -60% of patients undergoing surgical treatment for refractory temporal lobe epilepsy (TLE) (1-3).[ lsF]Fluorodeoxyglucose positron-emission tomography (FDG-PET) is increasingly being used in the noninvasive workup of patients for epilepsy surgery and demonstrates interictal temporal hypometabolism in -80% of patients with pathologically proven HS (4). However, the pathophysiologic basis for the hypometabolism is still poorly understood (5). The distribution of the hypometabolism is usually more extensive that the pathologic lesion (6) and the intracranial EEG-defined site of seizure onset (7-9). In addition, despite the pathology and seizure focus being located in the mesial temporal region, prominent lateral temporal hypometabolism also is often found (8,lO-13).It has been suggested that the temporal hypometabolism may be at least in part due to hippocampal cell loss and atrophy, with the extensive hypoperfusion resulting from deafferentation of hippocampal projections (5,6,(14)(15)(16). Regional cerebral insults have been shown to cause hypometabolism at distant sites (17,lS). The magnitude of hippocampal atrophy (HA), as measured by volumetric magnetic resonance imaging (MRI), has been shown to correlate strongly with the severity of hippocampal cell loss in pathologic studies (19,20). In our study, we correlated the magnitude of the volumetric MRI hippocamp...

show abstract

Section: Discussionsupporting

confidence: 77%

Hippocampal Atrophy Is Not a Major Determinant of Regional Hypometabolism in Temporal Lobe Epilepsy

Newton²,

et al. 1997

View full text Add to dashboard Cite

show abstract

“…12 25 Although some underestimation of the degree and overestimation of the extent of hypometabolism of mesial temporal structures is expected due to the increase of the partial volume averaging and decrease of the recovery coefficient,13 the involvement of the lateral neocortex in mesial temporal lobe epilepsy is still poorly understood.…”

Section: Discussionmentioning

confidence: 99%

Interictal regional slow activity in temporal lobe epilepsy correlates with lateral temporal hypometabolism as imaged with 18FDG PET: neurophysiological and metabolic implications

Koutroumanidis

Binnie

Elwes

et al. 1998

Journal of Neurology, Neurosurgery & Psychiatry

View full text Add to dashboard Cite

Objectives-The phenomenon of interictal regional slow activity (IRSA) in temporal lobe epilepsy and its relation with cerebral glucose metabolism, clinical data, MRI, and histopathological findings was studied. Methods-Interictal 18F-fluorodeoxyglucose positron emission tomography (FDG PET) was performed under continuous scalp EEG monitoring in 28 patients with temporal lobe epilepsy not associated with intracranial foreign tissue lesions, all of whom subsequently underwent resective surgery. Regions of interest (ROIs) were drawn according to a standard template. IRSA was considered lateralised when showing a 4:1 or greater ratio of predominance on one side. Results-Sixteen patients (57%) had lateralised IRSA which was always ipsilateral to the resection and of maximal amplitude over the temporal areas. Its presence was significantly related to the presence of hypometabolism in the lateral temporal neocortex (p=0.0009). Logistic regression of the asymmetry indices for all measured cerebral regions confirmed a strong association between IRSA and decreased metabolism of the posterior lateral temporal neocortex only (p=0.009). No significant relation could be shown between slow activity and age at onset, duration of the epilepsy, seizure frequency, and MRI evidence for hippocampal atrophy. Furthermore, IRSA was not specifically related to mesial temporal sclerosis or any other pathology. Conclusions-Interictal regional slowing in patients with temporal lobe epilepsy not associated with a mass lesion is topographically related to the epileptogenic area and therefore has a reliable lateralising, and possibly localising, value. Its presence is irrelevant to the severity or chronicity of the epilepsy as well as to lateral deactivation secondary to neuronal loss in the mesial temporal structures. Although slow EEG activity is generally considered as a non-specific sign of functional disturbance, interictal regional slowing in temporal lobe epilepsy should be conceptualised as a distinct electrographic phenomenon which is directly related to the epileptogenic abnormality. The strong correlation between interictal regional slowing and lateral temporal hypometabolism suggests in turn that the second may delineate a field of reduced neuronal inhibition which can receive interictal and ictal propagation. (J Neurol Neurosurg Psychiatry 1998;65:170-176) Keywords: electroencephalography; slow wave activity; temporal lobe epilepsy; positron emission tomography Regional delta activity, either continuous and polymorphic or intermittent and rhythmic, is the most common EEG abnormality caused by underlying mass lesions, 1 2 is usually associated with white matter and thalamic locations, and is thought to reflect a deaVerentiation of the overlying cortex.3 Interictal regional slow activity (IRSA) is often seen in patients with partial epileptic seizures, and in this context it may be considered a reliable lateralising sign when adequately supported by ipsilateral epileptiform discharges. However, little attention has been ...

show abstract

“…statistics from 3 12 patients reported in the literature who underwent FDG PET show that 205 had temporal lobe localization of reduced metabolism, 32 had extratemporal localization, and 75 were unlocalized (Engel et al, 39826;Theodore et al, 1986Theodore et al, , 1990bAbou-Khalil et al, 1987;Stefan et al, 1987Stefan et al, , 1990; Swartz et al, 1989Swartz et al, , 1992; Chugani et al, 1990;Debets et al, 1990;Sackellares et al, 1990;Henry et al, 1991;Leiderman et al, 1992;Chee et al, 1993;Coubes et al, 1993;Hajek et al, 1993;Radtke et al, 1993;Valk et al, 1993). Temporal lobe deficits in metabolism were highly correlated with temporal lobe EEG abnormalities; discordance with EEG was seen in this group in only 2%.…”

Section: Fig 3 Lnterictal Fluorodeoxyglucose Pet Image Of a 46-yearmentioning

confidence: 99%

“…The overall sensitivity of interictal FDG-PET to temporal lobe epilepsy as judged by EEG criteria was 84%, with a specificity of 86%, and sensitivity for extratemporal epilepsy (documented by EEG) was 33%, with 95% specificity (Tables 3 and 8). Using a standard of pathology, sensitivity and specificity were both lower (Tables 5 and 9) (Chugani et al, 1990;Sackellares et al, 1990;Stefan et al, 1990;Theodore et al, 1990b;Swartz et al, 1992;Radtke et al, 1993;Valk et al, 1993). Despite this relatively lower yield in extratemporal compared with temporal lobe epilepsy for PET imaging of the epileptogenic area, the approach has been particularly fruitful in young children with refractory epilepsy, negative MRI, and poor EEG localization.…”

Section: Fig 3 Lnterictal Fluorodeoxyglucose Pet Image Of a 46-yearmentioning

confidence: 99%

The Relative Contributions of MRI, SPECT, and PET Imaging in Epilepsy

1994

View full text Add to dashboard Cite

Functional and structural neuroimaging techniques are increasingly indispensable in the evaluation of epileptic patients for localization of the epileptic area as well as for understanding pathophysiology, propagation, and neurochemical correlates of chronic epilepsy. Although interictal single photon emission computed tomography (SPECT) imaging of cerebral blood flow is only moderately sensitive, ictal SPECT markedly improves yield. Positron emission tomography (PET) imaging of interictal cerebral metabolism is more sensitive than measurement of blood flow in temporal lobe epilepsy. Furthermore, PET has greater spatial resolution and versatility in that multiple tracers can image various aspects of cerebral function. Interpretation of all types of functional imaging studies is difficult and requires knowledge of time of most recent seizure activity and structural correlates. Only magnetic resonance imaging (MRI) can image the structural changes associated with the underlying epileptic process, and quantitative evidence of hippocampal volume loss has been highly correlated with seizure onset in medial temporal structures. Improved resolution and interpretation have made quantitative MRI more sensitive in temporal lobe epilepsy, as judged by pathology. When judged by electroencephalography (EEG), ictal SPECT and interictal PET have the highest sensitivity and specificity for temporal lobe epilepsy; these neuroimaging techniques have lower sensitivity and higher specificity for extratemporal EEG abnormalities. Regardless of the presence of structural abnormalities, functional imaging by PET or SPECT provides complementary information. Ideally these techniques should be used and interpreted together to improve the localization and understanding of epileptic brain.

show abstract

High-resolution (2.6-mm) PET in partial complex epilepsy associated with mesial temporal sclerosis.

Cited by 33 publications

References 0 publications

Hippocampal Atrophy Is Not a Major Determinant of Regional Hypometabolism in Temporal Lobe Epilepsy

Hippocampal Atrophy Is Not a Major Determinant of Regional Hypometabolism in Temporal Lobe Epilepsy

Interictal regional slow activity in temporal lobe epilepsy correlates with lateral temporal hypometabolism as imaged with 18FDG PET: neurophysiological and metabolic implications

The Relative Contributions of MRI, SPECT, and PET Imaging in Epilepsy

Contact Info

Product

Resources

About