Developing a comprehensive presurgical functional MRI protocol for patients with intractable temporal lobe epilepsy: a pilot study

Abstract

Our aim was to put together and test a comprehensive functional MRI (fMRI) protocol which could compete with the intracarotid amytal (IAT) or Wada test for the localisation of language and memory function in patients with intractable temporal lobe epilepsy. The protocol was designed to be performed in under 1 h on a standard 1.5 tesla imager. We used five paradigms to test nine healthy right-handed subjects: complex scene-encoding, picture-naming, reading, word-generation and semantic-decision tasks. The combination of these tasks generated two activation maps related to memory in the mesial temporal lobes, and three language-related maps of activation in a major part of the known language network. The functional maps from the encoding and naming tasks showed typical and symmetrical posterior mesial temporal lobe activation related to memory in all subjects. Only four of nine subjects also showed symmetrical anterior hippocampal activation. Language lateralisation was best with the word generation and reading paradigms and proved possible in all subjects. The reading paradigm enables localisation of language function in the left anterior temporal pole and middle temporal gyrus, areas typically resected during epilepsy surgery. The combined results of this comprehensive f MRI protocol are adequate for a comparative study with the IAT in patients with epilepsy being assessed for surgery.

Language activation distributions revealed by fMRI in post-operative epilepsy patients: Differences between left- and right-sided resections

“…Visual stimuli were projected with a beamer on a transparency screen and synchronised with the MRI system using custom-made software. The paradigm was previously tested in healthy volunteers (Deblaere et al, 2002;Aldenkamp et al, 2003). After the fMRI sessions subjects were asked to repeat as many as possible generated words and to tell the contents of the text.…”

“…For anatomical reference and to determine the resection volume, a 3D T1-weighted fast-field echo pulse sequence was conducted, with parameters TR 11 ms, TE 3.5 ms, flip angle 11 • , matrix 256 × 256 × 150, and voxel size 1 mm × 1 mm × 1 mm. The images of the controls have been acquired in similar way as described elsewhere (Deblaere et al, 2002), but were analysed differently to be consistent with the patient data.…”

“…that are known to be essential for language processing (Ojemann et al, 1989) and that have been previously identified to be activated in controls for the same language tasks (Deblaere et al, 2002). These regions comprise the inferior and middle frontal cortex (Brodmann areas, BA 44-47), the superior frontal cortex (BA 6, 9, and 10), the anterior temporal lobe (BA 38), the posterior and inferior temporal lobe (BA 20 and 21), and the temporo-parietal junction (BA 39 and 40).…”

Language brain dominance in patients with refractory temporal lobe epilepsy: a comparative study between functional magnetic resonance imaging and dichotic listening test

“…The number of activated voxels in each ROI (L and R) was then counted, and a lateralization index (LI) was calculated as follows [9][10][11][12][13][14][15][16] . The number of activated voxels on the right side is subtracted from the number of activated voxels on the left side, and the result is divided by the sum of the two quantities, LI=(L-R)(L+R).…”

Improvement of Clinical Language Localization with an Overt Semantic and Syntactic Language Functional MR Imaging Paradigm

“…21 These regions are likely to be involved in word perception 20 and lexicosemantic 21 and phonological processing. 22 The middle temporal gyrus seems to be particularly relevant in sentence tasks, 23 whereas the superior temporal gyrus is more frequently activated during word tasks. 24 In the posterosuperior temporal gyrus (includ- Temporofrontal Region of Interest: Semantic-versusSyntactic Tasks.…”