invernizzi_tutorial_..

Tutorial: matplotlib
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Fare clic per modificare stili del testo dello schema
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Dynamic
phase-contrast
(PC) MRI is being used for quantitation of
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pulsatile
motion
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In order to achieve accurate and consistent flow measurements, a
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reliable automated method for segmentation of the lumen region is
needed.
The difference in temporal information from pixels located in the
lumen and in the surrounding tissue is used as a segmentation
Criterion. (Alperin and Lee 2004)
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The
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automated
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procedure
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includes
stili del
four
testo
steps:
dello schema
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1) selecting
a reference
velocity waveform
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2) generating
CC map
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3) computing optimal CC threshold
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4) tracking the edge of the segmented region
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1)
Fare
selecting
clic per
a modificare
reference velocity
stili del testo dello schema
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waveform
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PhaseTerzo
contrast
image with location of the
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reference
waveform
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2) generating CC map
The CC coefficient is used to quantify
similarity between the reference
waveform and waveforms obtained
from other pixels in the image
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3)
• computing
Fare clic optimal
per modificare
CC threshold
stili del testo dello schema
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A histogram
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number of pixels with
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CC value
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the threshold
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threshold
values
is
generated.
The optimal threshold CC value is
selected at the point
of transition from region C to region B
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des
crip
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4) tracking
Fare
clic per
the
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edge of the
stili del testo dello schema
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segmented
region
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Region-growing
algorithm is applied
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to obtain a
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segmentated
similarity threshold value
criterion.
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if C(xy)>threshold OK
Imp
lem
ent
atio
n
Use IPython for interactive processing analysis
Fare
stili
del (loadtxt
testo dellofunction)
schema
Load clic
dataper
filemodificare
into numpy
array
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Visualize temporal data (imshow function) and choose time
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reference image.
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Apply
rectangular selection to select a sub-region of interest.
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(RectangleSelector)
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Choose a pixel inside the lumen area (picker event)
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Plot the waveform of selected pixel and of the surrounding
ones (using subplot)
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Compute CC matrix and plot CC histogram (bar)
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Track the edge of the segmented region and show it (imshow)
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Plot the 3d-surface and animate it through time
(plot_surface and animation)
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