title: Cerebral metabolism and perfusion in MR-negative individuals with refractory focal epilepsy assessed by simultaneous acquisition of (18)F-FDG PET and arterial spin labeling.
abstract: The major challenge in pre-surgical epileptic patient evaluation is the correct identification of the seizure onset area, especially in MR-negative patients. In this study, we aimed to: (1) assess the concordance between perfusion, from ASL, and metabolism, from (18)F-FDG, acquired simultaneously on PET/MR; (2) verify the utility of a statistical approach as supportive diagnostic tool for clinical readers. Secondarily, we compared (18)F-FDG PET data from the hybrid PET/MR system with those acquired with PET/CT, with the purpose of validate the reliability of (18)F-FDG PET/MR data. Twenty patients with refractory focal epilepsy, negative MR and a defined electro-clinical diagnosis underwent PET/MR, immediately followed by PET/CT. Standardized uptake value ratio (SUVr) and cerebral blood flow (CBF) maps were calculated for PET/CT-PET/MR and ASL, respectively. For all techniques, z-score of the asymmetry index (zAI) was applied for depicting significant Right/Left differences. SUVr and CBF images were firstly visually assessed by two neuroimaging readers, who then re-assessed them considering zAI for reaching a final diagnosis. High agreement between (18)F-FDG PET/MR and ASL was found, showing hypometabolism and hypoperfusion in the same hemisphere in 18/20 patients, while the remaining were normal. They were completely concordant in 14/18, concordant in at least one lobe in the remaining. zAI maps improved readers' confidence in 12/20 and 15/20 patients for (18)F-FDG PET/MR and ASL, respectively. (18)F-FDG PET/CT-PET/MR showed high agreement, especially when zAI was considered. The simultaneous metabolism-perfusion acquisition provides excellent concordance on focus lateralisation and good concordance on localisation, determining useful complementary information.
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK. Electronic address: i.galazzo@ucl.ac.uk.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Boscolo Galazzo
authors.affiliation: Institute of Nuclear Medicine, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Maria Vittoria
authors.initials: MV
authors.lastname: Mattoli
authors.affiliation: Neuroradiology Unit, Department of Diagnostic and Pathology, University Hospital Verona, Verona, Italy.
authors.forename: Francesca Benedetta
authors.initials: FB
authors.lastname: Pizzini
authors.affiliation: Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London, UK; Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, UK.
authors.forename: Enrico
authors.initials: E
authors.lastname: De Vita
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Barnes
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.
authors.forename: John S
authors.initials: JS
authors.lastname: Duncan
authors.affiliation: Department of Radiology, University College London Hospitals, London, UK.
authors.forename: Hans Rolf
authors.initials: HR
authors.lastname: Jäger
authors.affiliation: Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London, UK; Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, UK.
authors.forename: Xavier
authors.initials: X
authors.lastname: Golay
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Jamshed B
authors.initials: JB
authors.lastname: Bomanji
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.
authors.forename: Matthias
authors.initials: M
authors.lastname: Koepp
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Groves
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Fraioli
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology*; D000069279:Drug Resistant Epilepsy / Q000000981:diagnostic imaging; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013113:Spin Labels
chemical_list: D013113:Spin Labels; D019788:Fluorodeoxyglucose F18
keywords: Arterial spin labeling; Cerebral blood flow; Epilepsy; Glucose; Positron emission tomography; Simultaneous PET/MR