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Logo for the Journal of Rehab R&D
Volume 43 Number 7, November/December 2006
Pages 883 — 890


Abstract - Magnetic resonance imaging technology in transtibial socket research: A pilot study

Arjan W. P. Buis, PhD, CPO;1* Barrie Condon, PhD;2 Dave Brennan, PhD;2 Brendan McHugh, PhD;1
Donald Hadley, PhD, FRCR3

1National Centre for Training and Education in Prosthetics and Orthotics, University of Strathclyde, Glasgow, Scotland; 2Clinical Physics Department and 3Neuroradiology Department, Institute of Neurological Sciences, Southern General Hospital, Glasgow, Scotland
Abstract — Investigations into the shape and volume of transtibial prosthetic sockets are complicated because of the difficulty in establishing an accurate reference grid. Magnetic resonance imaging (MRI) presents a possible solution to this problem. However, the reliability of MRI in defining the residual-limb/cast interface depends on the scanned image not being distorted by the materials present. We investigated the potential of MRI technology to establish the desired reference grid. Distortion from the so-called "chemical shift" may influence the MRI when certain materials are used during the casting process. These materials include plaster of paris (POP) and silicone (in the form of an interface liner). POP is commonly used to capture the shape of the residual limb. However, if the casting technique requires the use of a silicone liner, the liner is placed over the residual limb first and then the POP is applied over the liner. Experimental results indicate that the materials used do not distort or interfere with the scanned image. The object segmentation process that extracts the bone and skin from an MRI scan and enables the establishment of the required reference grid was explored. Results show that extracting the bone structure and using it as the reference grid to quantify the differences in volume and shape of the soft tissues of the residual limb is feasible.
Key words: chemical shift, magnetic resonance imaging, object segmentation, plaster of paris, reference grid, residual limb, residual-limb/cast interface, silicone, transtibial prostheses, transtibial prosthetic sockets.

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