Reproducibility of quantitative dynamic contrast-enhanced MRI in newly presenting glioma.

We have investigated the reproducibility of dynamic contrast enhanced imaging techniques in nine patients with cerebral glioma. Patients were imaged twice with a 2 day interval between scans. Maps were produced of the time taken to achieve 90% enhancement (T90), the maximal intensity change per time interval ratio (MITR), the volume transfer coefficient between plasma and the extravascular extracellular space (K(trans)) and the extravascular extracellular contrast distribution volume, v(e). Measurements of K(trans) greater than 1.2 min(-1) were used to exclude pixels where first pass perfusion effects dominated the measurement. Measures of the test-retest coefficient of variation (CoV) and intraclass correlation coefficients were used to assess reproducibility for measurements from a volume of interest containing enhancing tissue from the whole tumour. MITR showed poor reproducibility (mean CoV 17.9%, 95% confidence limits for group comparisons 20.2%). T90 showed good reproducibility (mean CoV 7.1%, 95% confidence limits for group comparisons 5.2%). Calculated values of K(trans) and v(e) also showed good reproducibility (mean CoV 7.7% and 6.2% respectively, 95% confidence limits for group comparisons 6.2% and 4.8%, respectively). We conclude that the measurements of K(trans) and v(e) derived from pharmacokinetic analysis are sufficiently reproducible to support their use as a biological markers in therapeutic trials.

Simultaneous mapping of blood volume and endothelial permeability surface area product in gliomas using iterative analysis of first-pass dynamic contrast enhanced MRI data.

We describe a novel method for the calculation of endothelial permeability surface area product from dynamic contrast enhanced MRI. The technique uses iterative estimation to automatically decompose tissue residue function into intravascular and extravascular components, which are subsequently used to generate tumour blood volume, which is equal to relative cerebral blood volume calculated from T(1) weighted images and corrected for contamination by contrast agent leakage (rCBV(T1)(corrected), and endothelial permeability (k(fp)) maps. The technique was assessed in patients with cerebral glioma (n=5) by examining the reproducibility of endothelial permeability and rCBV(T1)(corrected) between two separate examinations conducted with a 2-day interval. The technique produces maps of endothelial permeability that appear to be free of any contribution from intravascular contrast agent. Maps of rCBV(T1)(corrected) show close correlation with maps of blood volume calculated from independently acquired dynamic susceptibility weighted MRI examinations, with no evidence of residual permeability effects. The results were highly reproducible with strong intra-class correlation between the two examinations for mean values and for 97.5 percentiles of endothelial permeability and rCBV(T1)(corrected). The excellent reproducibility of this technique and the ability to calculate endothelial permeability and rCBV(T1)(corrected) values from rapidly acquired data sets offer considerable advantages over conventional approaches and support the use of this methodology for therapeutic monitoring or trials of novel therapeutic agents.