[Insight-users] Estimation of abdominal volume

[Frederic Perez]

Dear Insight-users,

being stalled at the moment, I thought I better ask you for hints or 
advice. Any help will be greatly appreciated. Our problem follows:

[Input]
We have a set of 3D CT images, obtained using the same scanner, from
a set of patients ($i = 1..N$). For each patient $i$ two images $I$ 
are derived, taken at different days, to assess the response to 
therapy: $I(i, t_0)$ and $I(i, t_1)$.

[Target]
The objective is to measure the difference, per patient, of the 
abdominal volume ($V_a(I(i, t_1)) - V_a(I(i, t_0))$).

[How-to?]
I guess that the segmentation of the true abdominal cavity is a very
difficult problem (small narrowness of the peritoneum, i.e. of the 
membrane lining the abdominal cavity, the hole due to the esophagus,
etc.). Hopefully, however, an approximation will suffice.
So far, for each image we have segmented most of the trunk by means 
of a  pipeline of filters (ExtractImageFilter, MaskImageFilter, etc.):
$T(I(i, t_0))$ and $T(I(i, t_1))$.
We can compute volumes with a ImageMomentsCalculator object, but only
when provided with consistent input we will obtain meaningful results.
This means that we must crop each pair $T(I(i, t_0))$ and
$T(I(i, t_1))$ in such a way that the limiting planes are tightly 
related. The question is, how do we define those limiting planes?
We thought about using anatomical landmarks, automatically defined,
but do not how to do this (maybe with landmarks on the bones?---which
ones?). Is this the right direction to pursue?

May thanks in advance,

Frederic Perez



		
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