18.3. Computed Tomography and Ultrasound Methods for Simultaneous Evaluation of Articular Cartilage and Subchondral Bone

 Public examination of a doctoral dissertation in the field of medical physics

Doctoral candidate: M.Sc. Techn Antti Aula 

Date and venue: 18.03.2011 at 12 noon, L22, Snellmania, Kuopio campus 

 

ABSTRACT 

Current diagnostic techniques are not able to detect the earliest degenerative changes related to osteoarthritis and osteoporosis. Quantitative ultrasound (QUS) and contrast agent enhanced computed tomography (CECT) are potential techniques for the simultaneous assessment of the health of cartilage and bone. 

The ability of gadolinium and iodine-based contrast agents to detect enzymatic cartilage degradation was evaluated in this study. Moreover, the optimal contrast agent concentrations and diffusion times were estimated. The feasibility of using CECT and QUS (5 MHz) methods for the simultaneous measurement of articular cartilage and subchondral bone was tested with osteochondral samples from visually healthy bovine knees. Furthermore, the effect of bone marrow composition on ultrasound propagation was studied numerically at 1 MHz frequency. 

The CECT technique enabled simultaneous analysis of the contrast agent content in cartilage, bone mineral density and thicknesses of cartilage and subchondral plate. The contrast agent intake increased significantly after enzymatic (trypsin) degradation of cartilage. However, there were no major changes in the contrast agent partition profiles. The contrast agent content in the superficial cartilage correlated significantly with the dynamic modulus of cartilage. Both contrast agents required over 8 hours to reach the diffusion equilibrium. QUS was found to be feasible for the simultaneous measurement of the acoustic properties of articular cartilage and subchondral bone. 

The relationships between the ultrasound parameters and the properties of cartilage and bone were statistically significant. Numerical simulations demonstrated a significant effect of bone marrow composition on the QUS parameters, especially for samples with low bone volume fractions.

In conclusion, when further developed, the CECT and QUS methods may become sensitive quantitative in vivo methods to simultaneously assess the status of articular cartilage and subchondral bone.

The doctoral dissertation of Antti Aula entitled “Computed Tomography and Ultrasound Methods for Simultaneous Evaluation of Articular Cartilage and Subchondral Bone” The opponent in the public examination is Professor Harrie Weinans, Erasmus MC, Orthopaedic Research Laboratory and the custos is Professor Jukka Jurvelin of the University of Eastern Finland. will be examined at the Faculty of Science and Forestry.

Photo available for download at http://www.uef.fi/vaitoskuvat

Contact: Antti Aula, antti.aula@uef.fi, tel. +358 40 355 2342

Publishing year: 2011

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