Author : Williams, T.G. Taylor, C.J. Waterton, J.C. Holmes, A Source : Macro to Nano, 2004.IEEE International Symposium on Macro to Nano, 2004.IEEE International Symposium on Biomedical Imaging Publication Date: April 2004 On page(s): Vol. 1 Speaker : Ren-Li Shen Advisor : Ku-Yaw Chang 1

Outline Introduction Method Result Conclusion 2

Introduction MR imaging techniques Accurate representation of regional articular cartilage thickness Insensitive to the localised changes Need aggregate across patients Aggregate Minimum Description Length (MDL) method of Davies 3

Outline Introduction Method Result Conclusion 4

Method -Data acquisition Determine normal range in 20 healthy females 15 ‘Statics’ One knee imaged at one of three sites 5 ‘Travellers’ Both knees imaged at all three sites 5

Method -About Correspondences Define anatomically equivalent points MDL automatic model optimisation method Each bone surface mapped onto the unit sphere Defined equally spaced points Mapped back onto each bone surface Using Iterative Closest Point(ICP) algorithm 6

Method -Measuring cartilage thickness Changes in cartilage due to disease Capture cartilage thickness maps Built a thickness map Measuring cartilage thickness Above a dense set of points on underlying bone 7

Method -Aggregating thickness maps Need more accurate estimation Provides a basis for analysing differences between groups The maps were commensurate All sampled at the same set of corresponding points Compute simple summary maps 8

Outline Introduction Method Result Conclusion 9

Result Healthy cartilage Thicker in the load bearing regions Thinner toward the edges 10

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Outline Introduction Method Result Conclusion 14

Conclusion Demonstrated that Building a statistical shape model in the knee joint optimised with a Minimum Description Length provides dense, anatomically equivalent correspondences 3D cartilage thickness measurements taken at corresponding points provide the normal range of cartilage coverage and thickness distribution in healthy female knees 15