Reliability of two techniques for assessing cerebral iron deposits with structural magnetic resonance imaging

Authors

  • Maria C. Valdés Hernández PhD,

    Corresponding author
    1. SINAPSE Collaboration, SFC Brain Imaging Research Centre, Department of Clinical Neurosciences, University of Edinburgh, Edinburgh, UK
    2. Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
    • SFC Brain Imaging Research Centre, Image Analysis Lab, Division of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
    Search for more papers by this author
  • Tina H. Jeong XX,

    1. School of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK
    Search for more papers by this author
  • Catherine Murray MA (Hons),

    1. Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
    2. Department of Psychology, University of Edinburgh, Edinburgh, UK
    Search for more papers by this author
  • Mark E. Bastin DPhil,

    1. SINAPSE Collaboration, SFC Brain Imaging Research Centre, Department of Clinical Neurosciences, University of Edinburgh, Edinburgh, UK
    2. Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
    3. Medical and Radiological Sciences (Medical Physics), University of Edinburgh, Edinburgh, UK
    Search for more papers by this author
  • Francesca M. Chappell PhD,

    1. SINAPSE Collaboration, SFC Brain Imaging Research Centre, Department of Clinical Neurosciences, University of Edinburgh, Edinburgh, UK
    Search for more papers by this author
  • Ian J. Deary MB, ChB, PhD (Edin),

    1. Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
    2. Department of Psychology, University of Edinburgh, Edinburgh, UK
    Search for more papers by this author
  • Joanna M. Wardlaw MB ChB, MD

    1. SINAPSE Collaboration, SFC Brain Imaging Research Centre, Department of Clinical Neurosciences, University of Edinburgh, Edinburgh, UK
    2. Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
    Search for more papers by this author

Abstract

Purpose

To test the reliability of two computational methods for segmenting cerebral iron deposits (IDs) in the aging brain, given that its measurement in magnetic resonance imaging (MRI) is challenging due to the similar effect produced by other minerals, especially calcium, on T2*-weighted sequences.

Materials and Methods

T1-, T2*-weighted, and fluid-attenuated inversion recovery (FLAIR) MR brain images obtained at 1.5T from 70 subjects in their early 70s who displayed a wide range of brain IDs were analyzed. The first segmentation method used a multispectral approach based on the fusion of two or more structural sequences registered and mapped in the red/green color space followed by Minimum Variance Quantization. The second method employed a combined thresholding, size and shape analysis using T2*-weighted images augmented with visual information from T1-weighted data.

Results

Both segmentation techniques had high intra- and interobserver agreement (95% confidence interval [CI] = ± 57 voxels in a range from 0 to 1800), which decreased in subjects with significant microbleeds and/or IDs. However, the thresholding method was more observer dependent in identifying microbleeds and IDs boundaries than the multispectral approach.

Conclusion

Both techniques proved to be in agreement and have good intra- and interobserver reliability. However, they have limitations, specifically with regard to automation and observer independence, so further work is required to develop fully user-independent methods of identifying cerebral IDs. J. Magn. Reson. Imaging 2011;33:54–61. © 2010 Wiley-Liss, Inc.

Ancillary