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Imaging the neocortex in epilepsy with double inversion recovery imaging.
Fergus J Rugg-Gunn1, Philip A Boulby, Mark R Symms
1The MRI Unit, National Society for Epilepsy, Chalfont St Peter, Gerrards Cross, Bucks, SL9 0RJ, UK.
Neuroimage
|February 8, 2006
Summary
Double inversion recovery imaging (DIR) detects subtle abnormalities in epilepsy patients, even when conventional MRI appears normal. This quantitative MRI technique aids in identifying occult lesions and characterizing epileptic foci for presurgical evaluation.
Area of Science:
- Neuroimaging
- Epileptology
- Quantitative MRI
Background:
- Partial seizures can stem from acquired lesions or malformations of cortical development (MCD).
- Conventional MRI may not always detect subtle or occult epileptogenic lesions.
- Quantitative MRI techniques are needed for improved characterization of epileptic foci.
Purpose of the Study:
- To quantitatively evaluate double inversion recovery (DIR) imaging in patients with partial seizures.
- To compare DIR findings with conventional MRI and electroclinical data.
- To assess the utility of DIR in identifying subtle structural abnormalities associated with epilepsy.
Main Methods:
- Whole brain DIR imaging and Statistical Parametric Mapping (SPM) were used.
- Quantitative analysis of DIR signal intensity (DSI) was performed voxel-by-voxel.
- Patients included those with acquired lesions, MCD, cryptogenic focal epilepsy, and normal conventional MRI.
Main Results:
- DIR identified abnormal DSI in most patients with acquired lesions and MCD, often revealing abnormalities missed by conventional MRI.
- Abnormal DSI was detected in 15/33 patients with cryptogenic focal epilepsy, correlating with EEG and clinical data in 10.
- Group analysis of MRI-negative patients showed abnormal DSI in specific white matter regions, localizing seizure onset.
Conclusions:
- DIR is a sensitive quantitative MRI technique for patients with MCD and acquired cerebral damage.
- Abnormal DSI in MRI-negative patients suggests occult epileptogenic lesions with subtle structural abnormalities.
- DIR is a valuable tool for characterizing epileptic foci and aiding in presurgical evaluation.