Repeatability of a reference region model for analysis of murine DCE-MRI data at 7T

Purpose: To test the repeatability of a reference region (RR.) model for the analysis of dynamic contrast-enhanced MRI (DCE-MRI) in a mouse model of cancer at high field. Materials and Methods: Seven mice were injected with 106 4T1 mammary carcinoma cells and imaged eight to 10 days later on a Varian 7.0T scanner. Two DCE-MRI studies were performed for each mouse (separated by 2.5 hours). The RR model was,used to, analyze the data, and, returned estimates on the perfusion-permeability index (K-trans) for the RR and the tissue of interest (TOI), as well as the extravascular extracellular volume fraction (v(e)) for the TOI. Results: Whent he first injection,Was compared with the second injectiori, all baxameters. tested were highly correlated (r(2) = 0.90, 0.62, 0.82 for the RR K-trans, TOT K-trans, and`TOI v(e), respectively, with P < 0.001 for all). To observe a statistically significant change (at the 5%-level) in a treatment study with 1 seven animals in each group log(10) chapges,of 0.084 and 0.077 in the tumor K-trans and v(e), respectively, are required Conclusion: If a reliable arterial input function (AIF) is unavailable, the RR model is a reasonable alternative to measuring MRI contrast-agent (CA) kinetics in mouse models of cancer at high field.