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Examination of anticipated chemical shift and shape distortion effect on materials commonly used in prosthetic socket fabrication when measured using MRI: A validation study. Mohammad Reza Safari, PhD; Philip Rowe, PhD; Arjan Buis, PhD. Aim
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Examination of anticipated chemical shift and shape distortion effect on materials commonly used in prosthetic socket fabrication when measured using MRI: A validation study Mohammad Reza Safari, PhD; Philip Rowe, PhD; Arjan Buis, PhD
Aim • Determine whether chemical shift artifact or image distortion occurs as direct result of materials commonly used in prosthetic socket fabrication. • Verify spatial accuracy and repeatability of magnetic resonance imaging (MRI). • Relevance • MRI is nonionizing, high-resolution technique that can provide clear distinction between tissues and has been proposed for quantifying soft tissue and bone dimension measurement and volume assessment.
Method • Analyzed 7 common prosthetic casting materials: • Silicone. • Silicone gel. • Polyurethane. • Polypropylene. • Pe-lite. • Laminate. • Plaster of paris (POP). • Specimens scanned 9 times. Containers were shuffled so that all materials were scanned in all 9 locations, giving data across field of view of MRI.
Results • Absolute mean difference of glass marker tube length was 1.39 mm (2.98%). • Minimum = 0.13 mm (0.30%). • Maximum = 5.47 mm (14.03%). • Standard deviation = 0.89 mm. • Absolute shift for all materials was <1.7 mm. • This was less than measurement tolerance of ±2.18 mm based on voxel (3-dimensional pixel) dimensions.
Conclusion • MRI is accurate and repeatable method for dimensional measurement when using matter containing water. • Silicone and POP + 1 g/L CS do not: • Show significant shape distortion. • Interfere with MRI image of residual limb.