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Accurate automatic estimation of total intracranial volume: a nuisance variable with less nuisance.

Malone IB, Leung KK, Clegg S, Barnes J, Whitwell JL, Ashburner J, Fox NC, Ridgway GR - Neuroimage (2014)

Bottom Line: We evaluated Statistical Parametric Mapping 12 (SPM12) automated segmentation for TIV measurement in place of manual segmentation and also compared it with SPM8 and FreeSurfer 5.3.0.These results suggest that SPM12 TIV estimates are an acceptable substitute for labour-intensive manual estimates even in the challenging context of multiple centres and the presence of neurodegenerative pathology.We also briefly discuss some aspects of the statistical modelling approaches to adjust for TIV.

View Article: PubMed Central - PubMed

Affiliation: Dementia Research Centre (DRC), Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. Electronic address: i.malone@ucl.ac.uk.

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Illustration of SPM12 tissue segmentation results and manually edited intracranial mask: (a) Original T1-weighted MRI [miriad_188],5 (b) grey matter, (c) white matter, (d) cerebrospinal fluid; overlaid on each image in red is a contour showing the outline of the intracranial mask after inverse spatial normalisation (i.e. warping from MNI to native space). It can be seen in (d) that the mask excludes some voxels incorrectly segmented as the CSF, and in (c) that the mask achieves a consistent anatomically-defined inferior cut-off, independent of the acquired field-of-view.
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f0010: Illustration of SPM12 tissue segmentation results and manually edited intracranial mask: (a) Original T1-weighted MRI [miriad_188],5 (b) grey matter, (c) white matter, (d) cerebrospinal fluid; overlaid on each image in red is a contour showing the outline of the intracranial mask after inverse spatial normalisation (i.e. warping from MNI to native space). It can be seen in (d) that the mask excludes some voxels incorrectly segmented as the CSF, and in (c) that the mask achieves a consistent anatomically-defined inferior cut-off, independent of the acquired field-of-view.

Mentions: It is important to note that the tissue prior probability templates used in SPM are based on averaging multiple automatically segmented images in standard space (for example, SPM12's priors come from segmentations (using New Segment) of images from the IXI data-set, http://www.brain-development.org/ (Heckemann et al., 2003)), so there is no guarantee that the sum of grey matter, white matter and CSF classes will be exactly consistent with accepted definitions of TIV, particularly with regard to the inferior cut-off and the inclusion of blood-filled sinuses. For this reason, we used the SPM12 tissue prior maps (and corresponding average T1-weighted, T2-weighted and proton-density weighted images from the same IXI data) to create a manually-corrected TIV mask consistent with the protocol described above (though segmented at each slice). Fig. 1 shows the TIV mask applied to tissue classes. Supplementary Fig. 1 shows a typical illustration of the non-brain classes, which are almost entirely located outside the ICV.


Accurate automatic estimation of total intracranial volume: a nuisance variable with less nuisance.

Malone IB, Leung KK, Clegg S, Barnes J, Whitwell JL, Ashburner J, Fox NC, Ridgway GR - Neuroimage (2014)

Illustration of SPM12 tissue segmentation results and manually edited intracranial mask: (a) Original T1-weighted MRI [miriad_188],5 (b) grey matter, (c) white matter, (d) cerebrospinal fluid; overlaid on each image in red is a contour showing the outline of the intracranial mask after inverse spatial normalisation (i.e. warping from MNI to native space). It can be seen in (d) that the mask excludes some voxels incorrectly segmented as the CSF, and in (c) that the mask achieves a consistent anatomically-defined inferior cut-off, independent of the acquired field-of-view.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4265726&req=5

f0010: Illustration of SPM12 tissue segmentation results and manually edited intracranial mask: (a) Original T1-weighted MRI [miriad_188],5 (b) grey matter, (c) white matter, (d) cerebrospinal fluid; overlaid on each image in red is a contour showing the outline of the intracranial mask after inverse spatial normalisation (i.e. warping from MNI to native space). It can be seen in (d) that the mask excludes some voxels incorrectly segmented as the CSF, and in (c) that the mask achieves a consistent anatomically-defined inferior cut-off, independent of the acquired field-of-view.
Mentions: It is important to note that the tissue prior probability templates used in SPM are based on averaging multiple automatically segmented images in standard space (for example, SPM12's priors come from segmentations (using New Segment) of images from the IXI data-set, http://www.brain-development.org/ (Heckemann et al., 2003)), so there is no guarantee that the sum of grey matter, white matter and CSF classes will be exactly consistent with accepted definitions of TIV, particularly with regard to the inferior cut-off and the inclusion of blood-filled sinuses. For this reason, we used the SPM12 tissue prior maps (and corresponding average T1-weighted, T2-weighted and proton-density weighted images from the same IXI data) to create a manually-corrected TIV mask consistent with the protocol described above (though segmented at each slice). Fig. 1 shows the TIV mask applied to tissue classes. Supplementary Fig. 1 shows a typical illustration of the non-brain classes, which are almost entirely located outside the ICV.

Bottom Line: We evaluated Statistical Parametric Mapping 12 (SPM12) automated segmentation for TIV measurement in place of manual segmentation and also compared it with SPM8 and FreeSurfer 5.3.0.These results suggest that SPM12 TIV estimates are an acceptable substitute for labour-intensive manual estimates even in the challenging context of multiple centres and the presence of neurodegenerative pathology.We also briefly discuss some aspects of the statistical modelling approaches to adjust for TIV.

View Article: PubMed Central - PubMed

Affiliation: Dementia Research Centre (DRC), Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. Electronic address: i.malone@ucl.ac.uk.

Show MeSH
Related in: MedlinePlus