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SPATIO-TEMPORAL ANALYSIS OF THE SIGNIFICANT CHANGES IN CARTILAGE MORPHOLOGY: DATA FROM THE OSTEOARTHRITIS INITIATIVE. Jose Tamez-Pena 1 , Patricia Gonzalez 2 , Edward Schreyer 2 , Saara Totterman 2 , - PowerPoint PPT Presentation
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SPATIO-TEMPORAL ANALYSIS OF THE SIGNIFICANT CHANGES IN
CARTILAGE MORPHOLOGY: DATA FROM THE OSTEOARTHRITIS
INITIATIVEJose Tamez-Pena1, Patricia Gonzalez2, Edward Schreyer2, Saara
Totterman2, 1Biomedicine, Tec de Monterrey, Monterrey, Nuevo Leon, Mexico;
2Qmetrics Technologies, Rochester, NY, USA
Objective
• Visualize, Follow and Quantitate the Areas of Cartilage Loss in an OA population
IntroductionProblem:
• Cartilage Thickness Changes are focal, spatially heterogeneous and bi-directional: Thinning and thickening
• Cohort studies look at population averages• The average of this heterogeneous data
has a very small responsivenessSolution:
• For a subject: Localize and isolate the changes
• For a cohort: Count map of the significant changes in cartilage thickness
Material & Methods
• Osteoarthritis Initiative (OAI) 3D DESS data sets: – Releases 0.C.2, 1.C.2 and 3.C.1 from Progression
cohort.• Three time points: Baseline, 12 month and 24 month.• 138 subjects with 3 time points
– Nonexposed Data Release 0.E.1, 1.E.1 and 3.E.1 (n=108)• Three time points: Baseline, 12 month and 24
month.
– OAI Pilot Scan-Rescan Longitudinal Data for the estimation of scan-rescan variability (n=24)
Multi-Atlas-Based Segmentation• Generate Atlas• Register and Segment Each MRI to the
Atlas (ITK registration modules)• Postprocess the segmentation to
match underlying MRI information.• Visually score the quality of the
segmentation.• Use the registration data to map each
segmentation to the atlas space• Subtract each mapped segmentation
to compute change in cartilage thickness
• Compute Significant Changes• Compute Cohort Averages
Quantitation
Standardized Analysis: Changes in Cartilage Thickness
-0.5 +0.5 -0.5 +0.5
Medial Lateral
Change Measurement: Significant Change Maps
Minus
Change Map
Scan-Rescan SDD MapSignificant Change Map
(Activation Map)
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0.0 +0.5
-0.5 +0.5
-0.5 +0.5
Baseline24 Month
-0.75 +0.75-0.5 +0.5
=
The Scan-RescanStandard Deviation of the Differences (SDD) is used to mark changes in thickness values that higher than the scan-rescan paired errors ( Delta < -1.96*SDD )
Population Maps
Average ReferencedThickness
12 Month Change Map
24 Month Change Maps
Average Change Map
Significant ChangesPrevalence Map
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0.0 0.3 0.0 0.3
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+ =
24 Month Results
-0.25
+0.25
0.0
0.3
-0.5
+0.5
Nonexposed No Denuded Low Denuded High Denuded
n=103 n=51 n=43 n=43 20.6%
9.3%8.1% 11.6%
17.3% 14.7%
3.4%
6.8%
Baseline
24 MonthChange
24 MonthHeat Map
-0.5
+0.5
Nonexposed No-Denuded Low Denuded High Denuded
12M-BL 3.6% 5.4% 7.1% 9.1%
24M-BL 3.4% 7.8% 8.6% 11.0%
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%
Rela
tive
Area
Average Area of Femur Affected by Significant Changes
SRM=0.73P<0.001 P=0.007 P=0.054SRM=0.36
SRM=0.36
SRM=0.39
Nonexposed No-Denuded Low Denuded High Denuded
12M-BL 4.3% 5.9% 7.50% 8.20%
24M-BL 4.6% 7.9% 8.80% 9.50%
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%Re
lativ
e Ar
ea
Average Area of Tibia Affected by Significant Changes
P<0.001
SRM=0.31
Nonexposed No Denuded Low Denuded High Denuded
12M-BL 22.3% 43.1% 76.7% 88.8%
24M-BL 19.4% 58.9% 76.7% 93.0%
0.0%10.0%20.0%30.0%40.0%50.0%60.0%70.0%80.0%90.0%
100.0%
Prop
ortio
n of
Sub
ject
s
Proportion of Subjects Whose Significant Changes were Greater Than
5% of the Femur Area
P=0.009 P=0.001
No Exposed No Denuded Low Denuded High Denuded
12M-BL 35.0% 51.0% 72.1% 72.1%
24M-BL 37.9% 56.9% 74.4% 67.4%
0.0%10.0%20.0%30.0%40.0%50.0%60.0%70.0%80.0%90.0%
100.0%Pr
opor
tion
of s
ubje
cts
Proportion of Subjects Whose Significant Changes were Greater Than
5% of the Tibia Area
P=0.038
Fisher’s Exact Test
Limitations
• Small OA population• Multi-atlas based segmentation is biased
towards atlas models– Less accurate at advanced OA cases– Higher noise at advanced OA cases
Conclusion
• The automated analysis methodology enabled the localization and mapping of the significant changes in cartilage Thickness.
• The significant changes are heterogeneous– Non Exposed OAI cohort did not change– OA subjects with no denuded areas had 2.4% of new
areas of cartilage loss every year. SRM=0.73
• The methodology indicated that not all subjects are affected by loss, and that the prevalence of loss is greater at more advanced OA groups.
Acknowledgements
• The OAI for all the imaging and clinical data
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Baseline 24 Month Change Map
Change Measurement: Significant Change Maps
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