ADVANCED MAGNETIC RESONANCE IMAGING TECHNIQUES DEMONSTRATE OCCULT ABNORMALITIES IN FOCAL EPILEPSY
Abstract number :
2.305
Submission category :
Year :
2004
Submission ID :
794
Source :
www.aesnet.org
Presentation date :
12/2/2004 12:00:00 AM
Published date :
Dec 1, 2004, 06:00 AM
Authors :
1,2Tuuli M. Salmenpera, 1Mark S. Symms, 1Fergus J. Rugg-Gunn, 1Phil A. Boulby, 3Gareth J. Barker, 1Tarek A. Yousry, and 1John S. Duncan
Visual assessment of conventional magnetic resonance imaging (MRI) fails to reveal structural abnormality in 20% of patients with intractable focal epilepsy. Surgical management of these MRI negative patients is often associated with poor outcome. Magnetization transfer imaging (MTR), fast flair T2 (FFT2) and double inversion recovery (DIR) are new imaging techniques that detect developmental and acquired cerebral lesions in epilepsy patients. We investigated whether MTR, FFT2 and DIR can identify abnormalities in patients with focal epilepsy and normal conventional MRI. One hundred and two patients with focal epilepsy and normal conventional MRI were scanned with MTR, FFT2 and DIR using a 1.5T scanner. All patients had scalp ictal video-EEG telemetry recordings to localize the onset of epileptiform activity. Statistical parametric mapping was used to compare the images of each individual patient to a template created from the images of 30 controls. Altogether 40% of the patients had MTR signal abnormalities. T2 and DIR showed signal changes in 58% of the patients. FFT2 and MTR signal abnormalities co-localized in 48%. MTR and DIR findings were concordant in 58%, and DIR and FFT2 in 67% of the patients.
In temporal lobe epilepsy patients FFT2 was abnormal in the temporal lobe (TL) in 36%, DIR in 23% and MTR in 9%, and was confined to the TL ipsilateral to the EEG focus in 19% (FFT2), 13% (DIR) and 2% (MTR).
In frontal lobe epilepsy patients FFT2 was abnormal in the frontal lobe (FL) in 40%, DIR in 43% and MTR in 8%, and was confined to the FL ipsilateral to the EEG focus in 8% (FFT2), 15% (DIR) and 8% (MTR).
Signal changes outside of the presumed lobe of onset were also found in 34% (FFT2), 41% (DIR) and 22% (MTR) of all patients. Advanced MRI with MTR, FFT2 and DIR reveals areas of signal change suggesting underlying structural damage in patients with focal epilepsy and normal conventional MRI. The successful identification of a focus aids the assessment of possible surgical treatment in these patients. (Supported by Academy of Finland, Action Medical Research)