title: Combined 7-T MRI and histopathologic study of normal and dysplastic samples from patients with TLE.
abstract: OBJECTIVE
  The purpose of the study was to investigate the abnormalities of cortical lamination observed in temporal lobe specimens obtained during surgery for intractable temporal lobe epilepsy (TLE) with hippocampal sclerosis. Specifically, we aimed to 1) correlate high-field ex vivo MRI with histopathologic analysis and 2) evaluate the effect of tissue fixation on image contrast.
  
  
  METHODS
  A cohort of 13 specimens was considered. T2-weighted imaging and relaxometry were performed during and after fixation using a 7-T experimental scanner. After imaging, the specimens were studied with histopathologic (Black Gold myelin fiber staining) and immunohistochemical (NeuN neuronal staining) methods in order to explore the correspondence between MRI and histopathologic features.
  
  
  RESULTS
  The principal findings of this study are that 1) superior MRI contrast is obtained among the cortical layers using completely fixed specimens as opposed to recently excised tissue, 2) the intensity of the T2-weighted MRI signal is lowest (hypointensity) at the site of highest fiber concentration and cellular density, and highest (hyperintensity) when the density of fibers and cells is lowest, and 3) the MRI signal is altered in presence of abnormal cortical lamination (focal cortical dysplasia type IA).
  
  
  CONCLUSIONS
  High resolution ex vivo MRI enables the study of intracortical organization in normal and pathologic areas. Comparisons between MRI, NeuN, and Black Gold indicate that the differences apparent in T2-weighted images are mainly related to fiber concentration, although neuronal density might also play a role.
authors: Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico C. Besta, via Celoria 11, 20133 Milan, Italy. garbelli.r@istituto-besta.it
authors: R
authors: R
authors: Garbelli
authors: I
authors: I
authors: Zucca
authors: G
authors: G
authors: Milesi
authors: A
authors: A
authors: Mastropietro
authors: L
authors: L
authors: D'Incerti
authors: L
authors: L
authors: Tassi
authors: N
authors: N
authors: Colombo
authors: C
authors: C
authors: Marras
authors: F
authors: F
authors: Villani
authors: L
authors: L
authors: Minati
authors: R
authors: R
authors: Spreafico
mesh_terms: D000328:Adult; D002648:Child; D004833:Epilepsy, Temporal Lobe / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000473:pathology* / Q000503:physiopathology