Dynamic Contrast-enhanced CT of Head and Neck Tumors: Comparison of First-pass and Permeability Perfusion Measurements Using Two Different Commercially Available Tracer Kinetics Models

Rationale and Objectives. To evaluate the interchangeability of perfusion parameters between two software packages for the postprocessing of dynamic contrast-enhanced (DCE) computed tomographic images of head and neck tumors. Materials and Methods. DCE computed tomographic images of 75 patients with head and neck tumors were postprocessed using a software package based on the maximum-slope approach and Patlak analysis, as well as a software package with deconvolution-based analysis incorporating an adiabatic approximation of tissue homogeneity (ATH) model. The evaluated perfusion parameters included blood flow (F), blood volume (v), and permeability-surface area product (PS). Region-of-interest (ROI) analysis of the tumors and the metastatic lymph nodes was performed. The perfusion parameters were compared using the Wilcoxon matched-pairs test and Bland-Altman plots. Results. One hundred fifty-two ROIs of tumors and nodes were outlined and analyzed. Moderate to good correlations were demonstrated between the various perfusion values (r = 0.56-0.72, P <.0001). The Wilcoxon test revealed a significant differencc between the two methods (P <.001), with the F, v, and PS values obtained using the maximum-slope approach and Patlak analysis higher than those obtained using deconvolution-based analysis with the assumptions of the ATH model. The Bland-Altman plots for F and v values revealed a proportionality trend with outliers, which were strongly associated with the magnitudes of the parameters. Analysis of the PS values did not show any systematic bias. Conclusion. There were significant differences in the perfusion parameters obtained using the two software packages, and thus, these parameters are not directly interchangeable.