Docteur de l'université Automatic Segmentation and Shape Analysis ...
Docteur de l'université Automatic Segmentation and Shape Analysis ...
Docteur de l'université Automatic Segmentation and Shape Analysis ...
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22 Chapter 2 Literature Review<br />
• the inferior medial bor<strong>de</strong>r;<br />
• <strong>and</strong> the use of arbitrary lines.<br />
One of the most wi<strong>de</strong>ly adopted protocol (15% of the studies reviewed by Geuze<br />
et al., 2004) was <strong>de</strong>veloped by Watson et al. (1992), with high inter-rater reliability<br />
reported (di Sclafani et al., 1998; Du et al., 2001). It <strong>de</strong>fines the hippocampus com-<br />
prising the hippocampus proper, subicular complex, <strong>de</strong>ntate gyrus, <strong>and</strong> including<br />
the white matter structures of alveus <strong>and</strong> fimbria. According to this protocol, the<br />
hippocampus is traced on the coronal plane. The head of hippocampus is sepa-<br />
rated from amygdala by the inferior horn of the lateral ventricle (mainly CSF),<br />
which extends to the <strong>de</strong>ep part of the uncus forming the uncal recess. If the<br />
inferior horn is not visible in the image, the following three alternatives may be<br />
used to outline the hippocampus-amygdala boundary: the alveus, an arbitrary<br />
line from the inferior horn of lateral ventricle to the sulcus at the inferior margin<br />
of the semilunar gyrus, or from straight horizontal line connecting the plane of the<br />
inferior horn of the lateral ventricle with the surface of the uncus. The posterior<br />
bor<strong>de</strong>r is <strong>de</strong>fined by the section with the crus of fornix separating the hippocampus<br />
from the fimbria. The inferior bor<strong>de</strong>r is drawn to inclu<strong>de</strong> the subicular complex<br />
<strong>and</strong> uncal cleft, separating from the parahippocampal gyrus by the angle between<br />
the most medial extent of subiculum <strong>and</strong> parahippocampal gyrus. This protocol<br />
is estimated to inclu<strong>de</strong> 90-95% of the total volume of hippocampal formation.<br />
The protocol set forth by Watson et al. (1992) has been used to validate the au-<br />
tomatic segmentations provi<strong>de</strong>d by Alzheimer’s Disease Neuroimaging Initiative<br />
(ADNI) 2 . The automatic segmentation uses the high-dimensional brain mapping<br />
tool SNT (Surgical Navigation Technologies), which is commercially available from<br />
Medtronic Surgical Navigation Technologies (Louisville, Colorado, USA). The val-<br />
idation was been performed on the normal aging, MCI <strong>and</strong> AD subjects (Hsu et al.,<br />
2002). The hippocampal volumes from ADNI used in the preparation of this thesis<br />
are segmented using the SNT tool, with corrections by qualified reviewers. Com-<br />
pared to the manual segmentation protocol, the automated SNT segmentation<br />
2 Available at www.loni.ucla.edu/ADNI. For a <strong>de</strong>scription of the data provi<strong>de</strong>d by ADNI,<br />
see §3.4.2.1.