Evaluation of reproducibility for perfusion assessment of tumors in MRI

A method is presented for the calculation of perfusion parameters in dynamic contrast enhanced MRI. This method requires identification of uptake curves for both tumor tissue and plasma. Inter-operator variability in the derived rate constant between plasma and extra-cellular extra-vascular space is assessed using semi-automated tumor margin identification with both manual and automated plasma identification. In addition, an assessment is made of the contribution to total variability made by differences in tumor margin identification and differences in plasma identification. Experimental results show a mean coefficient of variability (CV) for parameter measurement with manual plasma identification of 20.1%, with a mean CV for parameter measurement with automated plasma identification of 6.7%. Analysis shows that 67% of the variability in parameter measurement with manual plasma identification is attributable to differences in identified plasma signal, with the remainder attributable to differences in identified tumor margins.