title: Evidence of subtle gray-matter pathologic changes in healthy elderly individuals with nonspecific white-matter hyperintensities.
abstract: OBJECTIVE
  To investigate whether additional "occult" tissue changes can be detected in the normal-appearing white matter and gray matter of otherwise normal elderly individuals with nonspecific white-matter hyperintensities on conventional magnetic resonance images of the brain.
  
  
  METHODS
  Conventional and magnetization transfer magnetic resonance images were obtained from 12 otherwise normal elderly subjects with white-matter hyperintensities and 11 age- and sex-matched normal individuals. After automatic tissue segmentation, image coregistration, and masking of T2-visible lesions, we obtained magnetization transfer ratio histograms of the normal-appearing white matter and gray matter. For each histogram, the average magnetization transfer ratio, the peak height, and the peak position were measured. We also calculated the percentages of gray-matter and white-matter volumes normalized over the total volume of the intracranial content and the total normalized brain volumes.
  
  
  RESULTS
  Average magnetization transfer ratio (P =.03) and mean peak position (P =.01) of the gray-matter histograms from elderly individuals with white-matter hyperintensities were significantly lower than the corresponding quantities from those without white-matter hyperintensities. The normalized percentages of gray and white matter and normalized brain volume did not differ between the 2 groups. The average gray-matter magnetization transfer ratio was correlated with the average lesion magnetization transfer ratio (r = 0.68; P<.01).
  
  
  CONCLUSIONS
  This study shows that brain abnormalities in otherwise normal elderly subjects with nonspecific white-matter hyperintensities extend beyond the macroscopic white-matter lesions visualized on conventional magnetic resonance images.
authors.affiliation: Neuroimaging Research Unit, Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
authors.forename: Domenico Maria
authors.initials: DM
authors.lastname: Mezzapesa
authors.forename: Maria Assunta
authors.initials: MA
authors.lastname: Rocca
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Pagani
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.forename: Massimo
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000368:Aged; D000375:Aging; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011859:Radiography