ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

5. DISCUSSION
Two major limitations can be identified for the present work. First, the predicted
diffusion coefficients had arbitrary units of measurement, because they were calculated
based on the relative T1 signal enhancement and not on the real concentration of the
contrast agent. Although the assumption of a linear relationship between the two values
could be considered acceptable (3), the factor of proportionality is unknown and should
be estimated with phantom-based MRI acquisitions.
The second limitation concerns the fact that the diffusion properties of the contrast
agent inside the intervertebral disc may not adequately represent those of the nutrients
of disc cells (oxygen and glucose). The impact of this assumption may be believed to be
limited due to the small molecular weight of the contrast agent, but it is actually
unknown.
Despite the described critical points, the presented novel computational method proved
to be useful to support the interpretation of data obtained with contrast-enhanced MRI,
and to be able to predict the diffusion properties of the intervertebral disc in a patientspecific
manner, which are difficult to estimate with other non-invasive methods.
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