White matter hypointensities and hyperintensities have equivalent correlations with age and CSF β‐amyloid in the nondemented elderly

Abstract

Abstract Introduction T1‐ and T2‐weighted sequences from MRI often provide useful complementary information about tissue properties. Leukoaraiosis results in signal abnormalities on T1‐weighted images, which are automatically quantified by FreeSurfer, but this marker is poorly characterized and is rarely used. We evaluated associations between white matter hyperintensity (WM‐hyper) volume from FLAIR and white matter hypointensity (WM‐hypo) volume from T1‐weighted images and compared their associations with age and cerebrospinal fluid (CSF) β‐amyloid and tau. Methods A total of 56 nondemented participants (68–94 years) were recruited and gave informed consent. All participants went through MR imaging on a GE 1.5T scanner and of these 47 underwent lumbar puncture for CSF analysis. WM‐hypo was calculated using FreeSurfer analysis of T1 FSPGR 3D, and WM‐hyper was calculated with the Lesion Segmentation Toolbox in the SPM software package using T2‐FLAIR. Results WM‐hyper and WM‐hypo were strongly correlated (r = .81; parameter estimate (p.e.): 1.53 ± 0.15; p < .0001). Age was significantly associated with both WM‐hyper (r = .31, p.e. 0.078 ± 0.030, p = .013) and WM‐hypo (r = .42, p.e. 0.055 ± 0.015, p < .001). CSF β‐amyloid levels were predicted by WM‐hyper (r = .33, p.e. −0.11 ± 0.044, p = .013) and WM‐hypo (r = .42, p.e. −0.24 ± 0.073, p = .002). CSF tau levels were not correlated with either WM‐hyper (p = .9) or WM‐hypo (p = .99). Conclusions Strong correlations between WM‐hyper and WM‐hypo, and similar associations with age, abnormal β‐amyloid, and tau suggest a general equivalence between these two imaging markers. Our work supports the equivalence of white matter hypointensity volumes derived from FreeSurfer for evaluating leukoaraiosis. This may have particular utility when T2‐FLAIR is low in quality or absent, enabling analysis of older imaging data sets.

Keywords

• aging
• Alzheimer's disease
• hyperintensity
• hypointensity
• leukoaraiosis
• white matter lesion