Tumor Discrimination Using Textures Presented by: Maysam Heydari.
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Transcript of Tumor Discrimination Using Textures Presented by: Maysam Heydari.
Introduction
• Main goal: Discrimination between different tumor grades/types using textural properties
• Tumor pathologies:– Grade 2: astro (7), oligo (22)– Grade 3: aa (2), ao (1), amoa (1)– Grade 4: gbm (17)
Introduction
• Patient data:– 50 unique patient-study pairs:
• 25 expert segmented patients• 25 Maysam segmented patients
– For each patient, the study nearest to the biopsy date (in the range ±52 weeks) was picked.
– The nearest biopsy was chosen to determine the pathology.
Weeks between study and biopsy
Expert segmented
weeks weeks
# of
pat
ient
s
Maysam segmented(low grade tumors)
Texture Features
• Features extracted on the segmented tumors: ENH (T1, T1C) and EDE (T2) on every slice.
• Each pixel in the tumor receives a texture intensity:– Gray Level Co-occurrence Matrices (GLCM)– MR8– BGLAM left-to-right symmetry similarity values
Texture Features
• GLCM stat measures:– Energy: “orderliness” of pixels
– Contrast:
€
Pi, j2
i, j=1
N
∑
€
Pi, j i − j( )2
i, j=1
N
∑
Texture Features
• MR8 filter bank:• For each filter, max
response over 6orientations
• Filters:– 3 scales of edge filters– 3 scales of bar filters– A Gaussian– Laplacian of Gaussian
Texture Features
• BGLAM:– Texture similarity of the segmented tumor
to the symmetric side of the brain.
Method
• For each patient, T1, T1C, and T2 histograms constructed over all the tumor pixels (texture intensities) over all slices.
• Histograms normalized and ranges adjusted over all tumors.
Method
• Each patient’s tumor is represented by a histogram for each modality and texture feature.
• The histograms are used as vector inputs to kmeans (k = 2) clustering.
Test Resultslowgrade/highgrade: mismatch rates
T1 T1C T2Raw 0.3600 0.3600 0.10001st MR8 0.2800 0.3800 0.40002nd MR8 0.2600 0.3800 0.42003rd MR8 0.4000 0.3800 0.28004th MR8 0.3000 0.3800 0.40005th MR8 0.2400 0.3600 0.40006th MR8 0.2800 0.3800 0.36007th MR8 0.3400 0.4000 0.12008th MR8 0.4000 0.4200 0.1400Energy 0.4400 0.3200 0.4600Contrast 0.3800 0.2800 0.4200BGLAM 0.3200 0.2000 0.4200
Test Resultsgbm/rest: mismatch rates
T1 T1C T20.3200 0.3200 0.14000.3600 0.4600 0.44000.3400 0.4600 0.42000.4800 0.4600 0.24000.3800 0.4600 0.48000.3200 0.4400 0.44000.3600 0.4600 0.36000.4200 0.4800 0.20000.4800 0.5000 0.22000.4400 0.3200 0.46000.3800 0.3600 0.38000.3200 0.2000 0.4200
Raw1st MR82nd MR83rd MR84th MR85th MR86th MR87th MR88th MR8EnergyContrastBGLAM