Why can't quantitative values be computed using DSC-MRI?

[phys-student]

I am studying for a comprehensive exam on dynamic contrast enhanced MRI (DCE-MRI) and questions have come up in my practice talks about dynamic susceptibility contrast MRI (DSC-MRI).

In DCE-MRI changes in signal in an artery and the tissue are converted to contrast agent concentration vs time curves, and tracer kinetic models can be applied to those curves to compute quantitative values for K_trans, k_ep, v_p, v_e, etc. On the other hand, when I read about DSC-MRI, which works in a similar way except using T2* weighted signal instead of T1 weighted it usually says that only relative values can be calculated and they never talk about tracer kinetic modelling. Why does it seem like DSC-MRI is incapable of providing quantitative estimates of hemodynamic parameters? Why can't tracer kinetic models be applied to DSC-MRI data?

I don't need a complicated in depth answer since DSC-MRI is not the main topic for my exam, I just need a quick explanation so that I don't sound stupid when the inevitable question comparing the two methods comes up.

 

[Stephen Tashi]

Not that I know anything about your question, but I found this article: "A fully automated method for quantitative cerebral hemodynamic analysis using DSC-MRI"
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2949177/ which mentions kinetic tracer models.

 

[Fervent Freyja]

This paper addresses some of the issues surrounding estimates of those parameters. I think the problem is largely in that DSC-MRI carries a time sensitivity, which this paper introduces a method to correct for, but you will likely understand it more than myself! Hope that helps anyway.
T1- and T2*-dominant extravasation correction in DSC-MRI: Part I—theoretical considerations and implications for assessment of tumor hemodynamic properties