title: 7T MRI in focal epilepsy with unrevealing conventional field strength imaging.
abstract: OBJECTIVE
  To assess the diagnostic yield of 7T magnetic resonance imaging (MRI) in detecting and characterizing structural lesions in patients with intractable focal epilepsy and unrevealing conventional (1.5 or 3T) MRI.
  
  
  METHODS
  We conducted an observational clinical imaging study on 21 patients (17 adults and 4 children) with intractable focal epilepsy, exhibiting clinical and electroencephalographic features consistent with a single seizure-onset zone (SOZ) and unrevealing conventional MRI. Patients were enrolled at two tertiary epilepsy surgery centers and imaged at 7T, including whole brain (three-dimensional [3D] T1 -weighted [T1W] fast-spoiled gradient echo (FSPGR), 3D susceptibility-weighted angiography [SWAN], 3D fluid-attenuated inversion recovery [FLAIR]) and targeted imaging (2D T2*-weighted dual-echo gradient-recalled echo [GRE] and 2D gray-white matter tissue border enhancement [TBE] fast spin echo inversion recovery [FSE-IR]). MRI studies at 1.5 or 3T deemed unrevealing at the referral center were reviewed by three experts in epilepsy imaging. Reviewers were provided information regarding the suspected localization of the SOZ. The same team subsequently reviewed 7T images. Agreement in imaging interpretation was reached through consensus-based discussions based on visual identification of structural abnormalities and their likely correlation with clinical and electrographic data.
  
  
  RESULTS
  7T MRI revealed structural lesions in 6 (29%) of 21 patients. The diagnostic gain in detection was obtained using GRE and FLAIR images. Four of the six patients with abnormal 7T underwent epilepsy surgery. Histopathology revealed focal cortical dysplasia (FCD) in all. In the remaining 15 patients (71%), 7T MRI remained unrevealing; 4 of the patients underwent epilepsy surgery and histopathologic evaluation revealed gliosis.
  
  
  CONCLUSIONS
  7T MRI improves detection of epileptogenic FCD that is not visible at conventional field strengths. A dedicated protocol including whole brain FLAIR and GRE images at 7T targeted at the suspected SOZ increases the diagnostic yield.
authors.affiliation: Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.|IRCCS Stella Maris Foundation, Pisa, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: De Ciantis
authors.affiliation: Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Barba
authors.affiliation: "C. Munari" Epilepsy Surgery Center, Niguarda Hospital, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Tassi
authors.affiliation: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.|IMAGO7 Foundation, Pisa, Italy.
authors.forename: Mirco
authors.initials: M
authors.lastname: Cosottini
authors.affiliation: IRCCS Stella Maris Foundation, Pisa, Italy.|IMAGO7 Foundation, Pisa, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Tosetti
authors.affiliation: IRCCS Stella Maris Foundation, Pisa, Italy.|IMAGO7 Foundation, Pisa, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Costagli
authors.affiliation: Department of Pathology, Niguarda Hospital, Milan, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Bramerio
authors.affiliation: Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.|IRCCS Stella Maris Foundation, Pisa, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Bartolini
authors.affiliation: IRCCS Stella Maris Foundation, Pisa, Italy.|IMAGO7 Foundation, Pisa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Biagi
authors.affiliation: "C. Munari" Epilepsy Surgery Center, Niguarda Hospital, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Cossu
authors.affiliation: "C. Munari" Epilepsy Surgery Center, Niguarda Hospital, Milan, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Pelliccia
authors.affiliation: General Electric MR Scientist, Imago7, Pisa, Italy.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Symms
authors.affiliation: Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.|IRCCS Stella Maris Foundation, Pisa, Italy.
authors.forename: Renzo
authors.initials: R
authors.lastname: Guerrini
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004569:Electroencephalography / Q000379:methods / Q000592:standards; D004828:Epilepsies, Partial / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D055815:Young Adult
keywords: 7T MRI; Epilepsy surgery; Focal cortical dysplasia