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Published on: April 14, 2014
Anatomical mapping of white matter hyperintensities (WMH): exploring the relationships between periventricular WMH,
Charles DeCarli1, Evan Fletcher, Vincent Ramey
1Department of Neurology, University of California at Davis, Davis, Calif, USA. cdecarli@ucdavis.edu
Background And Purpose:
MRI segmentation and mapping techniques were used to assess evidence in support of categorical distinctions between periventricular white matter hyperintensities (PVWMH) and deep WMH (DWMH). Qualitative MRI studies generally identify 2 categories of WMH on the basis of anatomical localization. Separate pathophysiologies and behavioral consequences are often attributed to these 2 classes of WMH. However, evidence to support these empirical distinctions has not been rigorously sought.
Methods:
MRI analysis of 55 subjects included quantification of WMH volume, mapping onto a common anatomical image, and spatial localization of each WMH voxel. WMH locations were then divided into PVWMH and DWMH on the basis of distance from the lateral ventricles and correlations, with total WMH volume determined. Periventricular distance histograms of WMH voxels were also calculated.
Results:
PVWMH and DWMH were highly correlated with total WMH (R2>0.95) and with each other (R2>0.87). Mapping of all WMH revealed smooth expansion from around central cerebrospinal fluid spaces into more distal cerebral white matter with increasing WMH volume.
Conclusions:
PVWMH, DWMH, and total WMH are highly correlated with each other. Moreover, spatial analysis failed to identify distinct subpopulations for PVWMH and DWMH. These results suggest that categorical distinctions between PVWMH and DWMH may be arbitrary, and conclusions regarding individual relationships between causal factors or behavior for PVWMH and DWMH may more accurately reflect total WMH volume relationships.
Insights
Periventricular white matter hyperintensities (PVWMH) and deep WMH (DWMH) are highly correlated, suggesting their distinction may be arbitrary. Total white matter hyperintensity (WMH) volume better reflects relationships with causal factors or behavior.
Area of Science:
- Neuroimaging
- White Matter Hyperintensities
- Brain Anatomy
Background:
- White matter hyperintensities (WMH) are often categorized as periventricular (PVWMH) or deep (DWMH) based on location.
- These WMH categories are frequently associated with distinct pathophysiologies and behavioral outcomes.
- Empirical evidence supporting these categorical distinctions has been limited.
Purpose of the Study:
- To investigate the validity of categorical distinctions between PVWMH and DWMH using MRI segmentation and mapping.
- To determine if distinct pathophysiologies or behavioral consequences can be empirically supported for PVWMH versus DWMH.
Main Methods:
- MRI analysis of 55 subjects.
- Quantification and spatial mapping of WMH volume.
- Localization of WMH voxels into PVWMH and DWMH categories based on distance from lateral ventricles.
Main Results:
- PVWMH and DWMH showed high correlations with total WMH volume (R2 > 0.95) and with each other (R2 > 0.87).
- Spatial mapping revealed a continuous expansion of WMH from periventricular to deep white matter with increasing volume.
- No distinct subpopulations for PVWMH and DWMH were identified.
Conclusions:
- Categorical distinctions between PVWMH and DWMH may be arbitrary.
- Total WMH volume is a more reliable measure for understanding relationships with causal factors and behavior.
- Future research should consider WMH as a continuous measure rather than distinct categories.
