Metabolic alteration transients during paroxysmal activity in an epileptic patient with fixation-off sensitivity: a case study Federico Giove a,b,c , Girolamo Garreffa a,d , Stefano Peca a,b , Marco Carnı ´ a,b , Maria Antonietta Macrı ´ a,e , Carlo Di Bonaventura f , Anna Elisabetta Vaudano f , Anna Teresa Giallonardo f , Massimiliano Prencipe f , Luigi Bozzao f , Patrizia Pantano f , Claudio Colonnese d , Bruno Maraviglia a,b,c, T a Museo storico della fisica e Centro di studi e ricerche b Enrico Fermi,Q 00184 Rome, Italy b Dipartimento di Fisica, Universita ` di Roma b La Sapienza,Q 00185 Rome, Italy c Instituto di Ricovero e Cura a Carattere Scientifico Fondazione Santa Lucia, 00179 Rome, Italy d Istituto di Ricovero e Cura a Carattere Scientifico b Neuromed,Q 86077 Pozzilli (IS), Italy e Dipartimento di Medicina Sperimentale e Patologia, Universita `, di Roma b La Sapienza,Q 00185 Rome, Italy f Dipartimento di Scienze Neurologiche, Universita ` di Roma b La Sapienza,Q 00185 Rome, Italy Received 21 November 2005; accepted 21 November 2005 Abstract The purpose of this study was to investigate short-time metabolic variations related to continuous epileptic activity elicited by fixation-off sensitivity (FOS). Time-resolved magnetic resonance spectroscopy was performed on a patient on whom previous clinical findings clearly indicated presence of FOS. The epileptic focus was localized with a simultaneous electroencephalographic and functional magnetic resonance imaging study. The results showed a linear increase of the sum of glutamate and glutamine with time of paroxysmal activity in epileptic focus and much greater concentration of choline-containing compounds in focus than in the contralateral side. D 2006 Elsevier Inc. All rights reserved. Keywords: Fixation-off sensitivity; Functional magnetic resonance spectroscopy; Time resolved; Epilepsy; Glutamate 1. Introduction Magnetic resonance spectroscopy (MRS) allows to assess noninvasively brain biochemistry by determining relative concentrations of some of the most important brain metabolites. With the use of a 1.5-T clinical scanner, the most prominent proton resonances are due to N-acetylas- partate (NAA), creatine (Cr) and choline-containing com- pounds (Cho). Software and hardware improvements have also allowed to obtain relative concentrations of, among others, the sum of glutamate (Glu) and glutamine (Gln), referred to as Glx, myo-inositol (mI) and, in some conditions, lactate (Lac) and g-aminobutyric acid (GABA). Although several quantification algorithms of MR spectra have been developed during the recent years, both in frequency and in time domain [1,2], a real improvement was obtained only when a large amount of prior knowledge was included in the quantification [3,4]. For this reason, the attractiveness of black box methods such as LCModel [3] is undoubtable. However, different line widths and noise levels of the spectra [5,6] and the basis set compo- sition [7] can have a certain influence on quantitative results. This issue should be taken into account, in parti- cular when spectra that are likely to differ in noise or line width are compared. Proton MRS has proven a useful tool for studying a variety of brain pathologies [8–14]. In particular, various metabolic alterations in epileptic patients have been reported since the advent of clinical application of MRS. In patients suffering from temporal lobe epilepsy (TLE) with hippocampal sclerosis, a decrease of NAA and an increase of Cho and Cr in the ipsilateral temporal lobe were reported. The variations 0730-725X/$ – see front matter D 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.mri.2005.11.003 4 Corresponding author. Dipartimento di Fisica, Universita ` di Roma bLa Sapienza,Q Piazzale Aldo Moro, Rome 00185, Italy. Tel.: +39 06 4454859; fax: +39 06 49913484. E-mail address: bruno.maraviglia@roma1.infn.it (B. Maraviglia). Magnetic Resonance Imaging 24 (2006) 373 – 379