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Biomedical subjects

H T Chugani

Publications and source records attributed to H T Chugani.

At least 37 records · Page 2Linked to original sources
PubMed2000

Statistical parametric mapping: assessment of application in children.

SPM is a powerful technique for the comparison of functional imaging data sets among groups of patients. While this technique has been widely applied in studies of adults, it has rarely been applied to studies of children, due in part to the lack of validation of the spatial normalization procedure in children of different ages. In order to determine if spatial normalization of FDG PET images using SPM96 to an adult template can be successfully applied in children, we applied PET-derived transformation parameters to coregistered MRI images. We then compared contours of spatially normalized MRI images obtained from 13 children with epilepsy (ages 2-14 years, mean 7.6 +/- 3.9 years) with those derived from 17 adult controls (mean age 27.6 +/- 4.5 years). Contours of spatially normalized MRI image volumes derived from the pediatric group were more variable than those obtained from adult controls. The average deviation from the mean adult contour was age-dependent and decreased with age (average deviation (mm) = 2.22 (mm) - 0.021 (mm/year) x years, r = 0.70, P < 0.001). Separate SPM analyses were performed for children less than 6 years (N1 = 6) and for children between 6 and 14 years of age (N2 = 7). SPM analyses performed in both pediatric groups showed significant regions of hypometabolism in locations consistent with their epileptic foci. SPM analyses in the younger group also showed significant artifacts. Therefore, the error associated with spatial normalization of pediatric brains to an adult template in children less than 6 years of age precludes the application of statistical parametric mapping in this age group. Although the error in the spatial normalization procedure for children ages 6 to 14 years is higher than in adults, it appears that this error does not result in artifacts in the SPM analysis. Furthermore, in contrast our previous studies showing large age-related changes in the absolute glucose metabolic rate at puberty, the SPM analysis showed children over 6 years of age appear to display the same pattern of glucose utilization as adults. However, small differences in the pattern of glucose utilization which might occur during late childhood and adolescence may not have been detected due to the sample size.

Adolescent↗
PubMed2000

Evidence for coupling between glucose metabolism and glutamate cycling using FDG PET and 1H magnetic resonance spectroscopy in patients with epilepsy.

The purpose of this study was to examine the relation between glucose metabolism and glutamate concentration in the human brain, in both the normal and diseased state. Regional values of glucose metabolism measured with 2-deoxy-2[F-18]fluoro-D-glucose positron emission tomography (FDG PET) studies and single-voxel proton magnetic resonance spectroscopy (1H MRS) measurements of the glutamate/ glutamine/gamma-aminobutyric acid (Glx) tissue concentration were determined in multiple brain regions in 11 patients (5 girls and 6 boys, mean age 7.5 years) with medically intractable partial epilepsy. FDG PET and 1H MRS studies were performed in the interictal state in seven patients and in the ictal/periictal state in four patients. Regions of interest were identified in epileptic cortex (determined by intracranial and/or scalp electroencephalography) and in contralateral normal brain regions. Lower glucose metabolism and lower Glx concentrations were found in the epileptic focus than in the contralateral normal cortex in all seven patients examined in the interictal state, whereas higher glucose metabolism and higher Glx concentrations were observed in the epileptic focus in the four patients who had ictal/periictal studies. Significant correlations were found between the values of cerebral glucose utilization and Glx concentration in epileptic brain region, in nonepileptic brain regions, and in epileptic and nonepileptic regions combined. These results demonstrate a significant relation between glucose metabolism and glutamate/glutamine concentration in normal and epileptic cerebral cortex. This relation is maintained in both the interictal and ictal states.

Adolescent↗
PubMed2000

Relationship between EEG and positron emission tomography abnormalities in clinical epilepsy.

Positron emission tomography (PET) is a relatively noninvasive neuroimaging method by means of which a large variety of human brain functions can be assessed. Localized neurochemical abnormalities detected by PET were found in patients with partial epilepsy and suggested the use of this modality for localizing epileptogenic regions of the brain. The clinical usefulness of PET is determined by its sensitivity and specificity for identifying epileptogenic areas as defined by ictal surface and intracranial EEG recordings. The findings obtained from comparative EEG and glucose PET data are reviewed with special emphasis on patients undergoing presurgical evaluation because of medically intractable temporal and extratemporal lobe epilepsy. The utility of glucose PET studies for identifying regions of seizure onset is presented, and the limited specificity of glucose metabolic abnormalities for the detection of various EEG patterns in clinical epilepsy is discussed. The authors review the available intracranial EEG and PET comparisons using [11C]flumazenil (FMZ) PET, a tracer for the assessment of tau-amino-butyric acid/benzodiazepine receptor function. They also summarize their experience with [11C]flumazenil PET in identifying cortical regions that show various ictal and interictal cortical EEG abnormalities in patients with extratemporal seizure origin. Finally, the authors demonstrate that further development of new PET tracers, such as alpha-[11C]methyl-L-tryptophan, is feasible and clinically useful and may increase the number of patients in whom PET studies can replace invasive EEG monitoring.

Biomarkers↗
PubMed2000

Is epileptogenic cortex truly hypometabolic on interictal positron emission tomography?

Positron emission tomography (PET) of glucose metabolism is often applied for the localization of epileptogenic brain regions, but hypometabolic areas are often larger than or can miss epileptogenic cortex in nonlesional neocortical epilepsy. The present study is a three-dimensional brain surface analysis designed to demonstrate the functional relation between glucose PET abnormalities and epileptogenic cortical regions. Twelve young patients (mean age, 10.8 years) with intractable epilepsy of neocortical origin underwent chronic intracranial electroencephalographic monitoring. The exact location of the subdural electrodes was determined on high-resolution three-dimensional reconstructed magnetic resonance imaging scan volumes. The electrodes were classified according to their locations over cortical areas, which were defined as hypometabolic, normometabolic, or at the border between hypometabolic and normal cortex (metabolic "border zones") based on interictal glucose PET. Electrodes with seizure onset were located over metabolic border zones significantly more frequently than over hypometabolic or normometabolic regions. Seizure spread electrodes also more frequently overlay metabolic border zones than hypometabolic regions. These findings suggest that cortical areas with hypometabolism should be interpreted as regions mostly not involved in seizure activity, although epileptic activity commonly occurs in the surrounding cortex. This feature of hypometabolic cortex is remarkably similar to that of structural brain lesions surrounded by epileptogenic cortex. Cortical areas bordering hypometabolic regions can be highly epileptogenic and should be carefully assessed in presurgical evaluations.

Brain Diseases, Metabolic↗
PubMed2000

New directions in PET neuroimaging for neocortical epilepsy.

Our results and those of others demonstrate that the development of new PET probes with increasing sensitivity and specificity for epileptogenic brain regions is feasible. Further development of novel tracers guided by knowledge of the biochemical characteristics of epileptogenic cortex from basic studies is the logical next step in the application of neuroimaging to localize epileptogenic cortex. Furthermore, computational advances allowing coregistration of biochemical images with high-resolution MRI anatomic images, as well as electrophysiologic data sets, not only has practical value in guiding surgical resection of epileptogenic neocortex, but this approach contributes to further understanding of the biochemical mechanisms involved in the pathophysiology of neocortical epilepsy.

Epilepsy↗
PubMed1999

Glucose and [11C]flumazenil positron emission tomography abnormalities of thalamic nuclei in temporal lobe epilepsy.

OBJECTIVES: To analyze interictal patterns of thalamic nuclei glucose metabolism and benzodiazepine receptor binding in patients with medically intractable temporal lobe epilepsy (TLE) using high-resolution 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and [11C]flumazenil (FMZ) PET. BACKGROUND: Structural and glucose metabolic abnormalities of the thalamus are considered important in the pathophysiology of TLE. The differential involvement of various thalamic nuclei in humans is not known. METHODS: Twelve patients with TLE underwent volumetric MRI, FDG and FMZ PET, and prolonged video-EEG monitoring. Normalized values and asymmetries of glucose metabolism and FMZ binding were obtained in three thalamic regions (dorsomedial nucleus [DMN], pulvinar, and lateral thalamus [LAT]) defined on MRI and copied to coregistered, partial-volume-corrected FDG and FMZ PET images. Hippocampal and amygdaloid FMZ binding asymmetries and thalamic volumes also were measured. RESULTS: The DMN showed significantly lower glucose metabolism and FMZ binding on the side of the epileptic focus. The LAT showed bilateral hypermetabolism and increased FMZ binding. There was a significant correlation between the FMZ binding asymmetries of the DMN and amygdala. The PET abnormalities were associated with a significant volume loss of the thalamus ipsilateral to the seizure focus. CONCLUSIONS: Decreased [11C]flumazenil (FMZ) binding and glucose metabolism of the dorsomedial nucleus (DMN) are common and have strong lateralization value for the seizure focus in human temporal lobe epilepsy. Decreased benzodiazepine receptor binding can be due to neuronal loss, as suggested by volume loss, but also may indicate impaired gamma-aminobutyric acid (GABA)ergic transmission in the DMN, which has strong reciprocal connections with other parts of the limbic system. Increased glucose metabolism and FMZ binding in the lateral thalamus could represent an upregulation of GABA-mediated inhibitory circuits.

Adolescent↗
PubMed1999

Increased brain serotonin synthesis in migraine.

OBJECTIVE: To measure brain serotonin synthesis with PET using the tracer alpha-[11C]methyl-L-tryptophan in migraine patients. BACKGROUND: Although the cause of migraine remains poorly understood, there is considerable evidence to support a role of the neurotransmitter serotonin in the pathophysiology of migraine. METHODS: We studied 11 women (aged 33+/-7.7 years) with a diagnosis of migraine according to International Headache Society criteria and 8 healthy women (aged 29+/-9.2 years). Five patients were studied before and after chronic treatment with propranolol or nadolol. RESULTS: Serotonin synthesis capacity (K-complex) values in migraine patients were higher than those measured in controls throughout the brain (p = 0.016); mean K-complex for whole brain was 0.0077 + 0.0020 mL/g/min in patients with migraine and 0.0054+/-0.0003 mL/g/min in controls. The regional pattern did not differ between the two groups. However, the K-complex for whole brain in the subgroup of migraine patients with aura (n = 3) did not differ from that of the control group (p = 0.32). In the five patients studied twice (before and after treatment), we found a trend of increased whole-brain K-complex after drug treatment (p = 0.06). CONCLUSIONS: Our findings indicating increased brain serotonin synthesis capacity in migraine patients are consistent with previous reports of systemic alteration of serotonin metabolism in patients without aura. Our results also suggest that the mechanism of action of beta-adrenergic antagonists for migraine prophylaxis may involve regulation of serotonin synthesis.

Adrenergic beta-Antagonists↗
PubMed1999

Cerebellar reorganization following cortical injury in humans: effects of lesion size and age.

OBJECTIVE: The authors investigated chronic cerebellar reorganization following unilateral cortical lesions in children and adults using PET to measure benzodiazepine receptor (BZR) binding with [11C]flumazenil (FMZ) and glucose metabolism with 2-deoxy-2[18F]fluoro-D-glucose (FDG). BACKGROUND: Crossed cerebellar diaschisis (CCD) is defined as decreased metabolism or blood flow in the cerebellum contralateral to a cortical insult measured by functional neuroimaging, and is typically seen in adults with large frontal or parietal lesions. The authors previously reported that CCD of glucose metabolism was not as prominent in children as in adults, and that some children showed a paradoxical pattern of increased glucose utilization in cerebellar cortex contralateral to the cortical lesion. The current study investigated whether CCD is associated with alterations in the gamma-aminobutyric acid (GABA(A))/BZR complex. METHODS: Patients with frontal lesions alone or with parietal lesions were compared with patients with temporal lesions, which are typically not associated with CCD. RESULTS: Children with lesion onset before 1 year of age showed significantly higher glucose utilization in contralateral posterior quadrangular and superior semilunar lobules of cerebellar cortex than did adults. Two patterns of change in cerebellar BZR binding were seen in children: 1) Five of 10 children showed increased BZR binding in the dentate nucleus contralateral to the lesion, and 2) the remaining five children showed no increase in dentate nucleus BZR binding but showed increased binding in the lateral lobules of the cerebellar cortex contralateral to the lesion. Adults showed increased binding only in contralateral dentate nucleus and not in cerebellar cortex. The size and severity of the supratentorial lesion, as well as age at the time of injury, were important factors in these findings. CONCLUSIONS: Reorganization of GABA-mediated mechanisms and glucose metabolism in cerebellum following cortical injury differs with size of lesion and age at the time of injury.

Adolescent↗
PubMed1999

Developmental changes in brain serotonin synthesis capacity in autistic and nonautistic children.

Serotonin content, serotonin uptake sites, and serotonin receptor binding measured in animal studies are all higher in the developing brain, compared with adult values, and decline before puberty. Furthermore, a disruption of synaptic connectivity in sensory cortical regions can result from experimental increase or decrease of brain serotonin before puberty. The purpose of the present study was to determine whether brain serotonin synthesis capacity is higher in children than in adults and whether there are differences in serotonin synthesis capacity between autistic and nonautistic children. Serotonin synthesis capacity was measured in autistic and nonautistic children at different ages, using alpha[11C]methyl-L-tryptophan and positron emission tomography. Global brain values for serotonin synthesis capacity (K complex) were obtained for autistic children (n = 30), their nonautistic siblings (n = 8), and epileptic children without autism (n = 16). K-complex values were plotted according to age and fitted to linear and five-parameter functions, to determine developmental changes and differences in serotonin synthesis between groups. For nonautistic children, serotonin synthesis capacity was more than 200% of adult values until the age of 5 years and then declined toward adult values. Serotonin synthesis capacity values declined at an earlier age in girls than in boys. In autistic children, serotonin synthesis capacity increased gradually between the ages of 2 years and 15 years to values 1.5 times adult normal values and showed no sex difference. Significant differences were detected between the autistic and epileptic groups and between the autistic and sibling groups for the change with age in the serotonin synthesis capacity. These data suggest that humans undergo a period of high brain serotonin synthesis capacity during childhood, and that this developmental process is disrupted in autistic children.

Adolescent↗
PubMed1999

Language organization in patients with early and late left-hemisphere lesion: a PET study.

Functional neuroimaging studies have shown enhanced right-hemisphere language activations in adults with left-hemisphere damage. We hypothesized that this effect would be stronger in patients with lesion occurring early in development. Using [15O]-water PET, we studied eight normal adults and 23 patients with unilateral left lesion during rest, listening to sentences, and sentence repetition. Thirteen patients had lesions with early onset (< 5 years) and ten had lesions with late onset (> 20 years). For listening to sentences, frontotemporal blood flow increases were significantly stronger in the left than in the right hemisphere in normal adults. This normal asymmetry was reduced in patients with late lesion and reversed in those with early lesion. For sentence repetition, analogous group differences were significant for the basal ganglia, but failed to reach significance for the (pre)motor and insular regions. We conclude that left lesion leads to alterations in the asymmetry of language activations (in and beyond the perisylvian areas). In addition, rightward shifts of language activation tend to be stronger as a consequence of early (as compared to late) lesion. Finally, postlesional reorganization appears to reflect a coexistence of 'additive' and 'subtractive' effects, i.e., activation in some regions that are not normally involved in language processing and lack of activation in other (undamaged) regions that are normally activated by language tasks.

Adolescent↗
PubMed1999

A mathematical model for the analysis of cross-sectional brain glucose metabolism data in children.

1. The authors present here a 5-parameter developmental function designed to describe quantitatively the time-course of changes in glucose metabolism with age. This function consists of a plateau phase which is described by the rate of increase with age and the height of the plateau, followed by a decline phase characterized by the rate of decrease to adult levels. These two phases are separated by a distinct point in time, at which the transition between the two phases occurs. 2. The model is designed to fit published data showing that glucose metabolic rate in frontal cortex at birth is about 60% of adult values (mean adult value is 24 mumol/100 g/min) and increases to slightly less than triple adult value by age 3. The metabolic rate remains at this level until the age of approximately 8 years when it starts the decline to adult values. 3. A procedure is presented which allows the approximate computation of the 98% confidence contours in data space for the developmental function. The computation is based on the joint probability function obtained from the model covariance matrix. 4. The newly designed 5-parameter developmental function is well suited to describe maturational changes of glucose metabolism. Due to its excellent model identifiability and the interpretability of individual parameters, this function is better suited for description of maturational changes than the gamma-function. Furthermore, this function may provide a useful framework for interpretation of other data sets during development.

Adolescent↗
PubMed1999

Brain organization for language in children, adolescents, and adults with left hemisphere lesion: a PET study.

1. There is evidence for pronounced brain plasticity during postnatal maturation. The authors hypothesized that left-hemisphere lesion would be associated with greater than normal language participation of the right hemisphere and that atypical asymmetry of perisylvian language activations would be enhanced after lesion occurring in early childhood as compared to lesion occurring later in life. 2. Eleven patients with left-hemisphere lesion (aged 8-33 yrs.) and 9 normal adult comparison subjects were studied, using [15O]-water positron emission tomography. One patient group (N = 6) had early lesion onset (< or = 6 years of age), a second group (N = 5) had lesion onset later in life (> or = 10 years of age). Regional cerebral blood flow (rCBF) changes during listening to sentences (minus rest) and sentence generation (minus repetition) were compared between groups in predefined regions of interest. 3. Variance of regional activations within early and late lesion onset groups was considerable and qualitative inspection revealed only few robust group differences. However, when 4 patient pairs were approximately matched for chronological age, lesion site and VIQ, significantly reduced leftward asymmetry of activations in early lesion patients was found in the prefrontal, inferior frontal, and inferior parietal regions for expressive language, with concordant and marginally significant trends in the inferior frontal and superior temporal regions for receptive language. 4. The results suggest enhanced postlesional plasticity in childhood, while also reflecting strong individual variability probably due to clinical and demographic factors beside lesion onset.

Adolescent↗
PubMed1999

Positron emission tomography in pediatric neurology.

Positron emission tomography (PET) is an accurate and relatively noninvasive way of studying brain activity using systemically administered tracers labeled with positron emitting isotopes. In pediatric neurology, it has great scope not only to elucidate the complexities of the developing brain but also to understand disease processes and characterize biological risk factors. Its greatest clinical utility lies in the field of epilepsy where it is used (in patients with intractable partial epilepsy) to localize epileptogenic foci for surgical resection. In addition, functional brain mapping using PET is increasingly being used to reliably and accurately identify speech and sensory-motor areas to minimize postoperative morbidity. PET is also useful in evaluating neurodegenerative disorders and cognitive abnormalities when magnetic resonance imaging scans are unrevealing. The technology continues to progress rapidly through improvements in imaging and radiopharmacology with potential applications in neurooncology, cerebral vascular disease, and metabolic diseases.

Brain↗
PubMed1999

Brain mapping of language and auditory perception in high-functioning autistic adults: a PET study.

We examined the brain organization for language and auditory functions in five high-functioning autistic and five normal adults, using [15O]-water positron emission tomography (PET). Cerebral blood flow was studied for rest, listening to tones, and listening to, repeating, and generating sentences. The autism group (compared to the control group) showed (a) reversed hemispheric dominance during verbal auditory stimulation; (b) a trend towards reduced activation of auditory cortex during acoustic stimulation; and (c) reduced cerebellar activation during nonverbal auditory perception and possibly expressive language. These results are compatible with findings of cerebellar anomalies and may suggest a tendency towards atypical dominance for language in autism.

Adolescent↗
PubMed1999

Altered in vitro and in vivo flumazenil binding in human epileptogenic neocortex.

In vitro and in vivo parameters of flumazenil (FMZ) binding were measured in spiking and nonspiking neocortex identified by intraoperative electrocorticography in epileptic patients who underwent cortical resection for seizure control. In vitro measures of receptor affinity (K(D)), number (Bmax) and laminar distribution for [3H]-FMZ binding in the epileptic focus (n = 38) were compared to nonspiking cortex from a subgroup of the patients (n = 12) and to tissue obtained from trauma patients (n = 5). The in vitro binding parameters were compared to in vivo [11C]-FMZ binding measured with positron emission tomography (PET) (n = 19). The Bmax was higher in the 38 spiking tissues as compared to the 12 nonspiking tissues (P = .012). Paired comparison of spiking versus nonspiking binding in the 12 patients from whom nonspiking tissue was available showed increases in both K(D) (P = .037) and Bmax (P = .0047) in spiking cortex. A positive correlation was found between K(D) and Bmax values for 38 patients (r = 0.55, P < .0001), the magnitude of the K(D) increase being twice that of the Bmax increase. In addition, there was a significant correlation between the asymmetry indices of the in vivo FMZ binding on PET and in vitro K(D) of spiking cortex (n = 19, r = 0.52, P = .02). The laminar distribution of [3H]-FMZ showed increased FMZ binding in cortical layers V-VI in spiking cortex compared to nonspiking and control cortex. The increased receptor number in spiking cortical layers V-VI may be a compensatory mechanism to decreased GABAergic input. The increased Bmax in spiking cortex was accompanied by a larger decrease in the affinity of FMZ for the receptor suggesting that decreased FMZ binding in the epileptic focus measured with PET is due to a decrease in the affinity of the tracer for the receptor.

Adolescent↗
PubMed1999

Brain activation during intermittent photic stimulation: a [15O]-water PET study on photosensitive epilepsy.

PURPOSE: Intermittent photic stimulation (IPS) is an activation procedure used during electroencephalogram (EEG) recording to elicit paroxysmal discharges in individuals with photosensitivity. Specific responses on EEG recording may be provoked by IPS at different frequencies of flickering in normal individuals and in patients with photosensitive epilepsy. METHODS: Changes in regional cerebral blood flow (rCBF) were studied during IPS in two groups of subjects by using [15O]-water positron emission tomography (PET): a control group consisting of eight healthy adults with photic driving response during IPS on EEG recording (mean age, 25 +/- 10.5 years) without history of neurologic or psychiatric abnormalities and a patient group consisting of four adults (mean age, 33 +/- 7.5 years) with history of photosensitive epilepsy. [15O]-water PET scanning with concomitant EEG monitoring was performed during baseline and IPS at 4-, 14-, and 30-Hz frequencies. RESULTS: The control group showed photic driving response at 14-Hz IPS frequency. The patient group showed photoparoxysmal response at 14 and 30 Hz, but not at 4 Hz. Changes in rCBF were determined by means of statistical parametric mapping. Increases in rCBF in occipital cortex (Brodmann's areas 17, 18, and 19) were observed in both groups. In addition, during photic driving responses, the control group showed rCBF increases in the insula and in the thalamus, on the right side. The patient group showed a significant rCBF increase in the hypothalamic region inferior to the left caudate nucleus during photoparoxysmal response. This activation was not found in the control group. Increased rCBF also was observed in the patient group in the head of the left caudate nucleus, in the left hippocampus, and in left insula during IPS without photoparoxysmal response. No activations in these regions were observed during photoparoxysmal response. CONCLUSIONS: These data may indicate involvement of the hypothalamus in photosensitive epilepsy and may suggest a modulatory function of the caudate nucleus, which might be associated with an inhibition of epileptic discharges during IPS in patients with photosensitive epilepsy.

Adult↗
PubMed1999

[11C]Flumazenil PET in patients with epilepsy with dual pathology.

PURPOSE: Coexistence of hippocampal sclerosis and a potentially epileptogenic cortical lesion is referred to as dual pathology and can be responsible for poor surgical outcome in patients with medically intractable partial epilepsy. [11C]Flumazenil (FMZ) positron emission tomography (PET) is a sensitive method for visualizing epileptogenic foci. In this study of 12 patients with dual pathology, we addressed the sensitivity of FMZ PET to detect hippocampal abnormalities and compared magnetic resonance imaging (MRI) with visual as well as quantitative FMZ PET findings. METHODS: All patients underwent volumetric MRI, prolonged video-EEG monitoring, and glucose metabolism PET before the FMZ PET. MRI-coregistered partial volume-corrected PET images were used to measure FMZ-binding asymmetries by using asymmetry indices (AIs) in the whole hippocampus and in three (anterior, middle, and posterior) hippocampal subregions. Cortical sites of decreased FMZ binding also were evaluated by using AIs for regions with MRI-verified cortical lesions as well as for non-lesional areas with visually detected asymmetry. RESULTS: Abnormally decreased FMZ binding could be detected by quantitative analysis in the atrophic hippocampus of all 12 patients, including three patients with discordant or inconclusive EEG findings. Decreased FMZ binding was restricted to only one subregion of the hippocampus in three patients. Areas of decreased cortical FMZ binding were obvious visually in all patients. Decreased FMZ binding was detected visually in nonlesional cortical areas in four patients. The AIs for these nonlesional regions with visual asymmetry were significantly lower than those for regions showing MRI lesions (paired t test, p = 0.0075). CONCLUSIONS: Visual as well as quantitative analyses of FMZ-binding asymmetry are sensitive methods to detect decreased benzodiazepine-receptor binding in the hippocampus and neocortex of patients with dual pathology. MRI-defined hippocampal atrophy is always associated with decreased FMZ binding, although the latter may be localized to only one sub-region within the hippocampus. FMZ PET abnormalities can occur in areas with normal appearance on MRI, but FMZ-binding asymmetry of these regions is lower when compared with that of lesional areas. FMZ PET can be especially helpful when MRI and EEG findings of patients with intractable epilepsy are discordant.

Adolescent↗