Resting functional MRI with temporal clustering analysis for localization of epileptic activity without EEG

Morgan, Victoria L.; Price, Ronald R.; Arain, Amir; Modur, Pradeep N.; Abou‐Khalil, Bassel

doi:10.1016/j.neuroimage.2003.08.031

Cited by 57 publications

(42 citation statements)

References 35 publications

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“…In a previous study, we developed a technique to localize BOLD interictal epileptiform activity using TCA methods (Morgan et al, 2004). We found significantly greater transient BOLD fluctuations in the epileptogenic than in the contralateral hippocampus in six temporal lobe epilepsy patients.…”

Section: Introductionmentioning

confidence: 90%

Cluster analysis detection of functional MRI activity in temporal lobe epilepsy

2007

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Purpose-The objective of this pilot study was to evaluate the ability of a novel method of cluster analysis, 2dTCA, for identifying and characterizing peak fluctuations in fMRI BOLD signals in the temporal lobes and the default-mode network in temporal lobe epilepsy (TLE) without EEG.Methods-BOLD fMRI images were acquired in seventeen TLE patients and compared to EEG. The timing of significant transient BOLD peaks was estimated by 2dTCA, and activation maps were determined.Results-Sixteen subjects (94%) showed apparent temporal lobe activation. Mesial temporal activation was present in 76.4% (13 patients). Temporal lobe or insula activations were detected ipsilateral to the EEG focus in 64.7% (11 patients), bilaterally with no predominance in 29.4% (5 patients), and exclusively contralateral to the EEG focus in none. Eleven subjects showed activation in the so-called default-mode network including posterior cingulate, bilateral posterior parietal cortex, and sometimes anterior cingulate cortex.Conclusions-These results demonstrate significant positive BOLD fluctuations in the temporal lobes and default-mode regions in a higher percentage of TLE patients than previously reported using other methods. These fluctuations appear physiologically relevant and suggest increased neural activity which may not be detected on scalp EEG, but which may be important in understanding the mechanisms and origins of epileptic discharges.

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Section: Introductionmentioning

confidence: 90%

Cluster analysis detection of functional MRI activity in temporal lobe epilepsy

2007

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“…After preprocessing, the 2dTCA analysis is performed using programs written in IDL software (ITT Visual Information Solutions, Boulder, CO) based on the modifications of the original TCA methods [Gao and Yee, 2003;Liu et al, 2000;Lu et al, 2006;Morgan et al, 2004;Yee and Gao, 2002;Zhao et al, 2004]. Each voxel time course is treated individually as an array, Z(1:N).…”

Section: Tca Vs 2dtca Methodsmentioning

confidence: 99%

“…In this way, each column of the matrix will consist of the histogram of significant signal increases for those voxels whose first time point exceeding the threshold occurred at time point x. This is in contrast to the onedimensional histogram mapping (hist1d(1:N)) of the original TCA method [Liu et al, 2000;Morgan et al, 2004]: and the weighted one-dimensional mapping used by Yee and Gao [Yee and Gao, 2002] and the use of the extremum mapping of Z proposed by Lu et al [Lu et al, 2006]. In these onedimensional methods, the resulting histogram is the reference signal time course used for fMRI analyses.…”

Section: Tca Vs 2dtca Methodsmentioning

confidence: 99%

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Development of 2dTCA for the detection of irregular, transient bold activity

Morgan¹,

Li²,

Abou‐Khalil³

et al. 2007

Human Brain Mapping

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The temporal clustering algorithm (TCA) has been developed in order to detect irregular, transient functional MRI (fMRI) activation signals when the timings of the stimuli are unknown. Unfortunately, such methods are also sensitive to signal changes caused by motion and physiological noise. We have developed a modified TCA technique, 2dTCA, which can detect multiple different timing patterns within a dataset so that signals of interest can be separated from artifacts and those of no interest. The objective of this work was to further develop the 2dTCA methods and evaluate their performance in simulated functional MRI datasets. Comparisons were made with TCA and a freely-distributed independent component analysis algorithm (ICA). We created two different sets of six computer-generated phantoms with one and two different simulated activation time courses present in 10 regions of interest. The phantoms also contained real subject rigid and nonrigid body motion and noise. Sensitivity of detection, defined as the true-positive activation rate at false-positive activation rates varying between 0.0001 and 0.01, was compared between methods. Additionally, specificity of detection of the irregular, transient signal of interest was assessed by comparing the number of signal time courses detected by each algorithm. The results suggest that the increased sensitivity of 2dTCA over TCA in detecting this particular signal of interest is comparable to the detection with ICA, but with fewer other signals detected. A few examples of the successful application of 2dTCA to the localization of interictal activity in preliminary studies of temporal lobe epilepsy are also described.

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“…An important methodological constraint is the dependency on the visualusation of unequivocal interictal epileptic activity during scanning to model the fMRI data [6]: Model-free analysis of fMRI independent of EEG may provide localizing information [7,8,9], however, caution against methodological confounds and careful validation with EEG is necessary [6]. In addition, there should be validation against a gold standard, invasive EEG monitoring, and surgical outcome where possible [3].…”

Section: Introductionmentioning

confidence: 99%

EEG–fMRI mapping of asymmetrical delta activity in a patient with refractory epilepsy is concordant with the epileptogenic region determined by intracranial EEG

Laufs

Hamandi

Walker

et al. 2006

Magnetic Resonance Imaging

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Using continuous EEG-correlated fMRI, we studied a patient with refractory epilepsy. Seizures were characterised by head turning to the left and clonic jerking of the left arm suggesting a right mesial frontal onset. Routine interictal EEG showed symmetrical post-central alpha rhythm and occasional runs of independent, non-lateralized slow activity in the delta band with right frontocentral dominance. Ictal scalp EEG had no lateralizing value. Structural MRI showed no abnormality. There were no clear EEG changes during simultaneous EEG-fMRI. We therefore

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Resting functional MRI with temporal clustering analysis for localization of epileptic activity without EEG

Cited by 57 publications

References 35 publications

Cluster analysis detection of functional MRI activity in temporal lobe epilepsy

Cluster analysis detection of functional MRI activity in temporal lobe epilepsy

Development of 2dTCA for the detection of irregular, transient bold activity

EEG–fMRI mapping of asymmetrical delta activity in a patient with refractory epilepsy is concordant with the epileptogenic region determined by intracranial EEG

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