Dear Haim and Ben,
with with 3/4 of the original artery present you should definitely get the
"true" centerline.
By true centerline I mean one that does not deviate inside the aneurysm. In
general,
the reason why it deviates is that lager inscribed spheres can fit the lumen
just below the aneurysm. If you
look at the aneurysm with the centerline of the parent vessel "exiting" your
screen (i.e. the screen being the
plane where the parent vessel cross-section lies), if the radius of curvature
of the portion of the wall opposite
to the neck is larger than the original vessel, then it's likely that the
centerline will deviate, because that
opposite wall will be able to accommodate a larger inscribed sphere. In the
end, it's very much a question
of how deviated is the shape of the vessel at the sides of the neck (just to
clarify, I mean left and right "sides"
in the cross section, I'm not talking about the upstream/downstream portions of
the neck).
In fact I've also seen the opposite case, with aneurysms with less than 1/2 of
the original lumen preserved,
just because that deviation was negligible.
Coming back to the 3/4 rule, with 3/4 of the wall preserved, it means that
there will be a well-defined path
of maximal inscribed spheres that stays completely inside the original lumen.
When you have 1/2 of the lumen preserved, the boundary between the lumen and
the aneurysm is "blurred",
and everything is determined by the shape of the wall on the sides of the neck
down to the opposite side. If
it's similar to the original, the centerline won't likely deviate, if it's
enlarged, the centerline will deviate.
We're talking of rules of thumb, of course.
I hope this is not a confusing explanation...
Luca
On May 21, 2012, at 8:12 AM, Haim Ezer wrote:
> Hello, Ben,
>
> Yes this is what I mean.
>
> I used to use, distance transform based centerline
> (http://www.mathworks.com/matlabcentral/fileexchange/24531-accurate-fast-marching),
>
> in which case, any remaining remnants, from the original artery would suffice.
>
> This is because the distance transform finds for every point, the shortest
> distance to the arterial edge (which is the arterial remnant)
>
> However, VMTK is much more accurate, and offers other advantages.
>
> I think that in VMTK, even less than 3/4 of the original artery's
> circumference will suffice, but this is for Luca to say.
>
> Thanks for your reply
>
> Best regards
>
> Haim
>
> From: "Berkowitz, Benjamin M" <benjamin-berkow...@uiowa.edu>
> To: Haim Ezer <haime...@yahoo.com>; "vmtk-users@lists.sourceforge.net"
> <vmtk-users@lists.sourceforge.net>
> Sent: Sunday, May 20, 2012 9:43 PM
> Subject: RE: [vmtk-users] Avoiding aneurysm removal for parent artery
> reconstruction
>
> Haim,
>
> Do you mean that the angular fraction of the artery still present (not
> enveloped by the aneurysm neck), if >3/4, the centerlines would be correct
> without the aneurysm removal? It makes sense that that would be true. That's
> an interesting thought.
>
> Ben
>
>
>
> From: Haim Ezer [haime...@yahoo.com]
> Sent: Sunday, May 20, 2012 12:45 AM
> To: vmtk-users@lists.sourceforge.net
> Subject: [vmtk-users] Avoiding aneurysm removal for parent artery
> reconstruction
>
> Dear, Luca
>
> I have a question regarding the use of vmtkcenterlines in the presence of an
> aneurysm.
>
> Is it true that if more than 3/4 of the original artery is present,
> vmtkcenterlines will give a correct centerline, without aneurysm removal?
>
> Just by selecting the source point in the arterial source and a target point
> in the arterial end, while ignoring the aneurysm.
>
> This I thought is the result of the maximum inscribed sphere being confined
> to the original artery's diameter.
>
> is this true?
>
> I am not sure I am clear, but what I am trying to get is the true centerline
> (prior to aneurysm development) without aneurysm removal. (This is since you
> wrote:
> "Nevertheless, while the parent artery reconstructions are plausible, it
> remains
> to be proven that they are faithful representations of the pre-aneurysmal
> artery."
> in:
> Ford et al, An objective approach to digital removal of saccular aneurysm:
> techniques and applications. BJR, 2009, ss55-61)
>
>
>
> If I am not clear, please tell me and I will create an image, to show what I
> mean.
>
> Thanks
>
> Haim
>
>
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