A dialyzer-based flow system for validating dynamic contrast enhanced MR image acquisition

Purpose: Dynamic contrast enhanced magnetic resonance imaging (MRI) has proven to be quite sensitive for the characterization of masses and early response to therapy. However, it is fraught with a number of procedural challenges as well as a lack of standardization. In this article, we describe the use of a simple dialyzer-based flow system to evaluate reproducibility of dynamic contrast enhanced MRI under active flow conditions.

Methods: The MR signal during a bolus injection of Gd-DTPA was analyzed to test the precision and variability of contrast agent kinetics during a typical dynamic contrast enhanced MRI sequence. A simple model allows an estimation of the washout rate constant of Gd-DTPA through the polysulfone tubules of the dialyzer.

Results: The simple flow phantom described here provided reproducible measurements of the washout rate constants. The washout rate increased from 0.20 ± 0.005 min(-1) to 0.25 ± 0.008 min(-1) over 32 weeks. Measurements were also made at week 24 using dynamic computed tomography and found to be 0.27 ± 0.006 min(-1) . Overall, the computed tomography derived rate constants results were found be ∼12% higher than the corresponding MRI values.

Conclusion: In this study, we show that a simple dialyzer-based flow phantom can be used for testing dynamic contrast enhanced MRI pulse sequences and also allows for short-term reproducibility testing of rate constants.