[Insight-users] Laplacian level set filter

Thu, 29 Jan 2004 07:50:47 -0800

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Hi Luis,
I was trying to use the Laplacian level set (with anisotropic diffiusion as
a preprocessing step) to improve an already available initial mask. These
are 3D brain T2-weighted images.

I set the # of iterations for diffusion as 10
Time step for diffusion = 0.125
Conductance parameter for diffusion = 2.0

Curvature scaling = 1.0
Propagation Scaling for Laplacian =  1.0
# iterations for Laplacian = 10
Isosurface value = 127.5
Maximum rms error for laplacian = 0.002

The initial mask was quite approximate but the solution was a good starting
point. However, after running with above settings, I found very marginal
improvement.
I was playing with some of the parameters but did not see significant
improvement. 

So my question was, for a 3D MRI T2-weighted image,

1)       what are the recommended values for the above parameters
2)       What is the range of reasonable values to "play with" for each of
these parameters?
3)       What are the parameters for the Laplacian scaling that make the
growing surface move faster? It seems to me that the advancement at each
iteration is very less.

Thanks
Radhika

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<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Hi Luis,<o:p></o:p></span></font></p>

I was trying to use the Laplacian
level set (with anisotropic diffiusion as a
preprocessing step) to improve an already available initial mask. These =
are 3D
brain T2-weighted images.<o:p></o:p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I set the # of iterations for diffusion as =
10<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Time step for diffusion =3D =
0.125<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Conductance parameter for diffusion =3D =
2.0<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Curvature scaling =3D =
1.0<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Propagation Scaling for <span =
class=3DSpellE>Laplacian</span> <span
class=3DGramE>=3D <span =
style=3D'mso-spacerun:yes'>&nbsp;</span>1.0</span><o:p></o:p></span></fo=
nt></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'># <span class=3DGramE>iterations</span> for <span
class=3DSpellE>Laplacian</span> =3D 10<o:p></o:p></span></font></p>

<p class=3DMsoNormal><span class=3DSpellE><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'>Isosurface</span></font></s=
pan><font
size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'> value =3D
127.5<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Maximum <span class=3DSpellE>rms</span> error for =
<span
class=3DSpellE>laplacian</span> =3D 0.002<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

The initial mask was quite approximate but the =
solution was
a good starting point. However, after running with above settings, I =
found very
marginal improvement.<o:p></o:p>

I was playing with some of the parameters but did =
not see significant
improvement. <o:p></o:p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>So my question was, for a 3D MRI T2-weighted =
image,<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1;
tab-stops:list .5in'><![if !supportLists]><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;mso-fareast-font-family:Aria=
l'><span
style=3D'mso-list:Ignore'>1)<font size=3D1 face=3D"Times New =
Roman"><span
style=3D'font:7.0pt "Times New =
Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
</span></font></span></span></font><![endif]><font
size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>what are the
recommended values for the above =
parameters<o:p></o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo1;
tab-stops:list .5in'><![if !supportLists]><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;mso-fareast-font-family:Aria=
l'><span
style=3D'mso-list:Ignore'>2)<font size=3D1 face=3D"Times New =
Roman"><span
style=3D'font:7.0pt "Times New =
Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
</span></font></span></span></font><![endif]><font
size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;font-family:Arial'>What is the
range of reasonable values to "play with" for each of these
parameters?<o:p></o:p></span></font></p>

<![if !supportLists]>3)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
<![endif]>What are the
parameters for the Laplacian scaling that =
make the growing
surface move faster? It seems to me that the advancement at
each iteration is very less.<o:p></o:p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Thanks<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Radhika<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

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