NAME
vnodule −
Nodule Segmentation Tool
SYNOPSIS
vnodule
[-H] [if=<inputfile>] [-a] [-n] [-c] [-v] [-]
OVERVIEW
vnodule
is a nodule segmentation utility that performs nodule
segmentation and analysis of a high-resolution CT scan.
Vnodule is invoked from the vrv radiological
viewer by selecting a tight region around the nodule and
pressing the ’n’ key. The program uses vban to
generate a nodule clipping, a resampled image, a thresholded
image, a segmented image, a 3d model, and a colorized
image.
DIRECTORY STRUCTURES
Vnodule is
compatible with two different directory structures. It
defaults to storing all the nodules in one big directory.
The nodules can be grouped by running vgroup, and
growth can be analyzed using vgrowth.
For backwards
compatability, vnodule can handle VPNA-style
directory structures by using the -c flag. In this case,
nodule groups are stored in different directories with the
following convention:
If the case
number is CU0072 and there are four groups of nodules, then
the group directories are:
CU0072
CU0072.2
CU0072.3
CU0072.4
BASIC OPERATION
The vnodule
window is split into two sections. The status text is
displayed on the right, and the review window and buttons
are displayed on the left. On startup, some useful
information about the scan is displayed in the status
text.
First, clicking
on the Nodule button in the top left of the window
brings up a menu. Selecting "New Nodule" (this is
the default) will save the segmentation results as a new
nodule in the directory. Selecting a previous nodule, for
example "Nodule 2", will overwrite the
segmentation results of the second nodule in the directory.
In addition, a thumbnail of the selected nodule will appear
in the review box.
In
VPNA-compatability mode, a Group button is adjacent
to the nodule button. Selecting a group will save the
segmentation results in the appropriate directory. Selecting
the nodule will write to that specific nodule in the group
directory.
Clicking the
Analyze button, begins the segmentation and analysis
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of the nodule. The progress of the segmentation is shown in
the status text. Depending on the size of the nodule, the
segmentation process may take a few minutes. Upon completion
of the segmentation, information about the nodule type
(juxtapleural or not), volume (mm^3), and surface area
(mm^2) is displayed.
The Show
button pops up a new window displaying the montage of the
colorized nodule. Red indicates nodule, while green
indicates high-intensity background (pleural surface or
vessels) and gray indicates background. If no colorized
montage is available, a montage of the normal nodule is
displayed.
Finally, the
nodule can be viewed in more detail by clicking the Run
VPNA button.
ADVANCED OPERATION
If the
segmentation of the nodule is incorrect, then the nodule can
be re-analyzed with modified segmentation parameters.
Change
Threshold will modify the HU threshold used for solid
segmentation. The default is -400.
In addition,
the nodule-sizing parameter and the pleural-segmentation
parameter can be modified by using either the Advanced or
Advanced 2 buttons. Specific values for both parameters can
be selected by using the Advanced button. A pop-up
window will ask for the values of the nodule-sizing and
pleural-segmentation parameters.
The Advanced
2 button provides a much easier way of modifying the
parameters. Clicking the button will bring up a pop-up
window. To change the sizing of the nodule, click on the
appropriate adjustment (even smaller, smaller, no change,
larger, or even larger). This will force the size of the
nodule clipping to be smaller or larger depending on the
selection. To change the pleural-segmentation parameter,
select the appropriate option. Select "more" or
"even more" if the nodule is under-segmented (does
not contain all of the nodule), or select "less"
or "even less" if the nodule is over-segmented
(includes part of the pleural wall).
After the
parameters or threshold have been adjusted, the
"Re-Analyze" button will perform the segmentation
and analysis with the new parameters.
SHORTCUT KEYS
OPTIONS
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if= |
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The input image: the region
selected by the user in vrv. |
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-a |
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does nothing (for vshow compatability) |
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-n |
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does nothing (for vshow compatability) |
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-c |
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Use VPNA-style directories. |
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-v |
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verbose option |
CONSTRAINTS
Must be invoked
from vrv. No guarantees otherwise.
BUGS
--
SEE ALSO
vban(1),
vfindnod(1), vrmwall(1)
AUTHOR
A. B. Chan,
Fall 2001
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