Author :Monica Barbu-McInnis, Jose G. Tamez-Pena, Sara Totterman Source : IEEE International Symposium on Biomedical Imaging April 2004 Page(s): Vol. 1 Speaker : Ren-Li Shen Advisor : Ku-Yaw Chang 2007/6/071

Outline Introduction Materials and methods Results Conclusion 2007/6/072

Introduction MRI Noninvasive imaging modality Quantitative evaluation Measure OA(OsteoArthritic) progression Measure overall cartilage volume Not easily reflect focal or local changes Quantitatively measuring changes is to compute cartilage thickness map 2007/6/073

Introduction Segment Compute the tibia medial cartilage thickness map Construct an inter-subject atlas Describe the shape and natural thickness variation Analyse 2007/6/074

Outline Introduction Materials and methods Results Conclusion 2007/6/075

Materials and methods Ten subjects Five male and five female 44.8 years on average 5 with no history of OA, 5 with mild OA Scanned 5 times Using Phillips Gyroscan Intra 1.5T MR imaging system Images acquired in sagittal plane Region growing algorithm Segmentation 2007/6/076

Materials and methods - Computing the thickness map; Inter-subject registration Deal of variability Cartilage thickness Surface area Wide range of cartilage shapes 2007/6/077

Materials and methods - Computing the thickness map; Inter-subject registration All maps rotated to a unique coordinate system Principal moments of inertia Principal axis method Ten rotated maps were scaled to a common space 2007/6/078

Materials and methods - Correlating the thickness maps; Intra-subject registration Calculate origin and orientation of the thickness map In intra-subject registration Assumes the differences in coordinates of thickness points likely due to global changes Good origin approximation of the common coordinate system Derived from the centroid to the two thickness maps 2007/6/079

Materials and methods - Correlating the thickness maps; Intra-subject registration Translation vector Origin Rotation matrix Orientation Thickness maps have been correlated Point by point mean and standard deviation can be calculated 2007/6/0710

Outline Introduction Materials and methods Results Conclusion 2007/6/0711

Results 2007/6/0712

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Results 2007/6/0715

Outline Introduction Materials and methods Results Conclusions 2007/6/0716

Conclusion The developed methodology can determine shape and thickness variations Within the tibia medial cartilage among a set population Future work Planning on applying these methods on a much larger population set 2007/6/0717