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In vivo hippocampal measurement and memory: a comparison of manual tracing and automated segmentation in a large community-based sample.

Cherbuin N, Anstey KJ, Réglade-Meslin C, Sachdev PS - PLoS ONE (2009)

Bottom Line: Few studies have systematically compared the performance of the two techniques.Inspection of 2D and 3D models suggested that this difference was largely due to greater inclusion of boundary voxels by the automated method and variations in subiculum/entorhinal segmentation.This study supports the use of automated measures, based on Freesurfer in this instance, as being sufficiently reliable and valid particularly in the context of larger sample sizes when the research question does not rely on 'true' hippocampal volumes.

View Article: PubMed Central - PubMed

Affiliation: Centre for Mental Health Research, Australian National University, Canberra, Australian Capital Territory, Australia. nicolas.cherbuin@anu.edu.au

ABSTRACT
While manual tracing is the method of choice in measuring hippocampal volume, its time intensive nature and proneness to human error make automated methods attractive, especially when applied to large samples. Few studies have systematically compared the performance of the two techniques. In this study, we measured hippocampal volumes in a large (N = 403) population-based sample of individuals aged 44-48 years using manual tracing by a trained researcher and automated procedure using Freesurfer (http://surfer.nmr.mgh.harvard.edu) imaging suite. Results showed that absolute hippocampal volumes assessed with these methods were significantly different, with automated measures using the Freesurfer software suite being significantly larger, by 23% for the left and 29% for the right hippocampus. The correlation between the two methods varied from 0.61 to 0.80, with lower correlations for hippocampi with visible abnormalities. Inspection of 2D and 3D models suggested that this difference was largely due to greater inclusion of boundary voxels by the automated method and variations in subiculum/entorhinal segmentation. The correlation between left and right hippocampal volumes was very similar by the two methods. The relationship of hippocampal volumes to selected sociodemographic and cognitive variables was not affected by the measurement method, with each measure showing an association with memory performance and suggesting that both were equally valid for this purpose. This study supports the use of automated measures, based on Freesurfer in this instance, as being sufficiently reliable and valid particularly in the context of larger sample sizes when the research question does not rely on 'true' hippocampal volumes.

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Related in: MedlinePlus

Bland-Altman diagrams plotting the difference in hipocampal volumes computed with the manual and automated methods against their average for each hippocampal pairs for the right (top) and left (bottom) hippocampus.The even scatter suggests there is no systematic error between methodologies beside the difference in absolute volume.
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pone-0005265-g003: Bland-Altman diagrams plotting the difference in hipocampal volumes computed with the manual and automated methods against their average for each hippocampal pairs for the right (top) and left (bottom) hippocampus.The even scatter suggests there is no systematic error between methodologies beside the difference in absolute volume.

Mentions: The sample studied was composed of 178 men and 225 women with a mean age of 46.7 years and a mean education level of 14.9 years. Average manually traced volumes were 2992 mm3 (SD 355) for the left and 3068 mm3 (SD 340) for the right hippocampus. Average automatically segmented volumes were 3688 mm3 (SD 372) for the left and 3974 mm3 (SD 381) for the right hippocampus (Figure 2). The difference between traced and automatically segmented volumes was significant for both left (t(402) = 27.12, p<.001) and right (t(402) = 35.66, p<.001) hippocampus. Bland-Altman diagrams (Figure 3) plotting the difference in hippocampal volume between methods against their average for each hippocampal pairs show that apart from the absolute difference in volume between the two measurement methods there is no evidence of other systematic error and while some outliers are present, they are few.


In vivo hippocampal measurement and memory: a comparison of manual tracing and automated segmentation in a large community-based sample.

Cherbuin N, Anstey KJ, Réglade-Meslin C, Sachdev PS - PLoS ONE (2009)

Bland-Altman diagrams plotting the difference in hipocampal volumes computed with the manual and automated methods against their average for each hippocampal pairs for the right (top) and left (bottom) hippocampus.The even scatter suggests there is no systematic error between methodologies beside the difference in absolute volume.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2667216&req=5

pone-0005265-g003: Bland-Altman diagrams plotting the difference in hipocampal volumes computed with the manual and automated methods against their average for each hippocampal pairs for the right (top) and left (bottom) hippocampus.The even scatter suggests there is no systematic error between methodologies beside the difference in absolute volume.
Mentions: The sample studied was composed of 178 men and 225 women with a mean age of 46.7 years and a mean education level of 14.9 years. Average manually traced volumes were 2992 mm3 (SD 355) for the left and 3068 mm3 (SD 340) for the right hippocampus. Average automatically segmented volumes were 3688 mm3 (SD 372) for the left and 3974 mm3 (SD 381) for the right hippocampus (Figure 2). The difference between traced and automatically segmented volumes was significant for both left (t(402) = 27.12, p<.001) and right (t(402) = 35.66, p<.001) hippocampus. Bland-Altman diagrams (Figure 3) plotting the difference in hippocampal volume between methods against their average for each hippocampal pairs show that apart from the absolute difference in volume between the two measurement methods there is no evidence of other systematic error and while some outliers are present, they are few.

Bottom Line: Few studies have systematically compared the performance of the two techniques.Inspection of 2D and 3D models suggested that this difference was largely due to greater inclusion of boundary voxels by the automated method and variations in subiculum/entorhinal segmentation.This study supports the use of automated measures, based on Freesurfer in this instance, as being sufficiently reliable and valid particularly in the context of larger sample sizes when the research question does not rely on 'true' hippocampal volumes.

View Article: PubMed Central - PubMed

Affiliation: Centre for Mental Health Research, Australian National University, Canberra, Australian Capital Territory, Australia. nicolas.cherbuin@anu.edu.au

ABSTRACT
While manual tracing is the method of choice in measuring hippocampal volume, its time intensive nature and proneness to human error make automated methods attractive, especially when applied to large samples. Few studies have systematically compared the performance of the two techniques. In this study, we measured hippocampal volumes in a large (N = 403) population-based sample of individuals aged 44-48 years using manual tracing by a trained researcher and automated procedure using Freesurfer (http://surfer.nmr.mgh.harvard.edu) imaging suite. Results showed that absolute hippocampal volumes assessed with these methods were significantly different, with automated measures using the Freesurfer software suite being significantly larger, by 23% for the left and 29% for the right hippocampus. The correlation between the two methods varied from 0.61 to 0.80, with lower correlations for hippocampi with visible abnormalities. Inspection of 2D and 3D models suggested that this difference was largely due to greater inclusion of boundary voxels by the automated method and variations in subiculum/entorhinal segmentation. The correlation between left and right hippocampal volumes was very similar by the two methods. The relationship of hippocampal volumes to selected sociodemographic and cognitive variables was not affected by the measurement method, with each measure showing an association with memory performance and suggesting that both were equally valid for this purpose. This study supports the use of automated measures, based on Freesurfer in this instance, as being sufficiently reliable and valid particularly in the context of larger sample sizes when the research question does not rely on 'true' hippocampal volumes.

Show MeSH
Related in: MedlinePlus