title: Fluid-attenuated inversion recovery: correlations of hippocampal cell densities with signal abnormalities.
abstract: BACKGROUND
  Hippocampal sclerosis (HS) is characterized by hippocampal atrophy and increased signal on T2-weighted images and on fluid-attenuated inversion recovery (FLAIR) images.
  
  
  OBJECTIVE
  To quantitate cell loss and compare it with signal abnormalities on FLAIR images.
  
  
  METHODS
  Thirty-one patients with temporal lobe resection, pathologically proven HS, and Engel class I and II outcome were included: 20 with HS only and 11 with HS associated with pathologically proven cortical dysplasia (dual pathology). The signal intensity on FLAIR was rated as present or absent in the hippocampus and correlated with the neuronal losses in the hippocampus.
  
  
  RESULTS
  FLAIR signal increases were present in 77% (24/31) of all patients studied. In patients with isolated HS, 90% (18/20) had ipsilateral signal increases, but in patients with dual pathology, only 55% (6/11; p < 0.02) showed FLAIR signal increase. Hippocampal cell losses were significantly higher in the isolated HS group. The average cell loss in patients with FLAIR signal abnormalities was 64.8 +/- 8.0% as compared with only 32.7 +/- 5.1% in patients with no FLAIR signal abnormalities. There was a significant positive correlation between the presence of signal abnormality and average hippocampal cell loss in both pathologic groups.
  
  
  CONCLUSIONS
  Ipsilateral FLAIR signal abnormalities occur in the majority of patients with isolated HS but are less frequent in those with dual pathology. The presence of increased FLAIR signal is correlated with higher hippocampal cell loss.
authors.affiliation: Department of Neurology, Cleveland Clinic Foundation, OH, USA. diehlb@ccf.org
authors.forename: B
authors.initials: B
authors.lastname: Diehl
authors.forename: I
authors.initials: I
authors.lastname: Najm
authors.forename: A
authors.initials: A
authors.lastname: Mohamed
authors.forename: E
authors.initials: E
authors.lastname: Wyllie
authors.forename: T
authors.initials: T
authors.lastname: Babb
authors.forename: Z
authors.initials: Z
authors.lastname: Ying
authors.forename: A
authors.initials: A
authors.lastname: Hilbig
authors.forename: W
authors.initials: W
authors.lastname: Bingaman
authors.forename: H O
authors.initials: HO
authors.lastname: Lüders
authors.forename: P
authors.initials: P
authors.lastname: Ruggieri
mesh_terms: D000328:Adult; D001284:Atrophy; D002452:Cell Count; D002540:Cerebral Cortex / Q000473:pathology; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005911:Gliosis / Q000175:diagnosis* / Q000473:pathology; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D009410:Nerve Degeneration / Q000175:diagnosis* / Q000473:pathology; D009474:Neurons / Q000473:pathology; D011612:Psychosurgery; D012598:Sclerosis; D013702:Temporal Lobe / Q000473:pathology / Q000601:surgery