title: Not all age-related white matter hyperintensities are the same: a magnetization transfer imaging study.
abstract: OBJECTIVE
  Our aim was to assess whether presumed histologic heterogeneity of age-related white matter hyperintensities (WMH) is reflected in quantitative magnetization transfer imaging measures.
  
  
  METHODS
  From a group of patients participating in a double-blind placebo-controlled multicenter study on the effect of pravastatin (PROSPER), we selected 56 subjects with WMH. WMH were classified as periventricular WMH (PVWMH) and deep WMH (DWMH). PVWMH were subclassified as irregular or smooth, depending on the aspect of their border. Signal intensity of WMH on T1-weighted images was scored as iso- or hypointense. The mean magnetization transfer ratio (MTR) value of different types of WMH was assessed and compared. As a control group, we selected 19 subjects with no or limited WMH.
  
  
  RESULTS
  Mean (SE) MTR of PVWMH (frontal, 31.2% [0.2%]; occipital, 32.2% [0.2%]) was lower than that of DWMH (33.7% [0.5%]). The mean MTR of frontal PVWMH (31.2% [0.2%]) was lower than that of occipital PVWMH (32.2% [0.2%]). Compared with occipital PVWMH, frontal PVWMH more often had a smooth lining (72% frontal versus 8% occipital) and an area with low signal intensity on T1-weighted images (76% frontal versus 35% occipital). MTR did not differ between smooth (31.1% [0.3%]) and irregular (31.6% [0.5%]) PVWMH.
  
  
  CONCLUSIONS
  Age-related WMH are heterogeneous, despite their similar appearance on T2-weighted images. By taking into account heterogeneity of age-related WMH, both in terms of etiology and in terms of severity of tissue destruction, one may obtain better understanding on the causes and consequences of these lesions.
authors.affiliation: Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands. a.spilt@lumc.nl
authors.forename: A
authors.initials: A
authors.lastname: Spilt
authors.forename: R
authors.initials: R
authors.lastname: Goekoop
authors.forename: R G J
authors.initials: RG
authors.lastname: Westendorp
authors.forename: G J
authors.initials: GJ
authors.lastname: Blauw
authors.forename: A J M
authors.initials: AJ
authors.lastname: de Craen
authors.forename: M A
authors.initials: MA
authors.lastname: van Buchem
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000924:Anticholesteremic Agents / Q000627:therapeutic use; D002540:Cerebral Cortex / Q000473:pathology*; D002552:Cerebral Ventricles / Q000473:pathology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000188:drug therapy; D015140:Dementia, Vascular / Q000175:diagnosis* / Q000188:drug therapy; D004292:Dominance, Cerebral / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000473:pathology; D017035:Pravastatin / Q000627:therapeutic use; D011446:Prospective Studies; D012016:Reference Values; D013223:Statistics as Topic
chemical_list: D000924:Anticholesteremic Agents; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D017035:Pravastatin