Author :Monica Barbu-McInnis, Jose G. Tamez-Pena, Sara TottermanSource :IEEE International Symposium on Biomedical Imaging

April 2004 Page(s): 840 - 843 Vol. 1

Speaker : Ren-Li ShenAdvisor : Ku-Yaw Chang

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OutlineIntroductionMaterials and methodsResultsConclusion

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IntroductionMRI

Noninvasive imaging modalityQuantitative evaluation

Measure OA(OsteoArthritic) progression

Measure overall cartilage volumeNot easily reflect focal or local changes

Quantitatively measuring changes is to compute cartilage thickness map

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IntroductionSegmentCompute the tibia medial cartilage thickness

mapConstruct an inter-subject atlas

Describe the shape and natural thickness variation

Analyse

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OutlineIntroductionMaterials and methodsResultsConclusion

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Materials and methodsTen subjects

Five male and five female44.8 years on average5 with no history of OA, 5 with mild OA

Scanned 5 times Using Phillips Gyroscan Intra 1.5T MR imaging

systemImages acquired in sagittal plane

Region growing algorithmSegmentation

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Materials and methods-Computing the thickness map; Inter-subject registrationDeal of variability

Cartilage thickness Surface area

Wide range of cartilage shapes

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Materials and methods-Computing the thickness map; Inter-subject registrationAll maps rotated to a unique coordinate

systemPrincipal moments of inertia Principal axis method

Ten rotated maps were scaled to a common space

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Materials and methods-Correlating the thickness maps;Intra-subject registrationCalculate origin and orientation of the

thickness mapIn intra-subject registration

Assumes the differences in coordinates of thickness points likely due to global changes

Good origin approximation of the common coordinate systemDerived from the centroid to the two thickness

maps

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Materials and methods-Correlating the thickness maps;Intra-subject registrationTranslation vector

OriginRotation matrix

Orientation

Thickness maps have been correlatedPoint by point mean and standard deviation

can be calculated

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OutlineIntroductionMaterials and methodsResultsConclusion

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Results

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Results

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Results

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Results

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OutlineIntroductionMaterials and methodsResultsConclusions

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ConclusionThe developed methodology can determine

shape and thickness variationsWithin the tibia medial cartilage among a set

populationFuture work

Planning on applying these methods on a much larger population set

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