Quantitative tumor perfusion assessment with multidetector CT: Are measurements from two commercial software packages interchangeable?

Purpose: To prospectively determine the level of agreement between tumor blood volume and permeability measurements obtained with two commercially available perfusion computed tomographic ( CT) software packages. Materials and Methods: This study was performed with institutional review board approval; informed consent was obtained from all participants. A total of 44 patients ( 24 men, 20 women; mean age, 68 years; range, 28-87 years) with proved colorectal cancer were examined prospectively with multi-detector row CT. A 65-second tumor perfusion study was performed after intravenous bolus injection of contrast material. Tumor blood volume and permeability were determined with two methods: adiabatic approximation of distributed parameter analysis and Patlak analysis. Agreement between the results was determined by using Bland-Altman statistics. Within-patient variation was determined by using analysis of variance. Results: The mean values for permeability and blood volume, respectively, were 13.9 mL . 100 mL(-1) . min(-1) +/- 3.7 ( standard deviation) and 6.1 mL/100 mL +/- 1.5, as calculated with distributed parameter analysis, and 17.4 mL . 100 mL(-1) . min(-1) +/- 7.3 and 10.1 mL/100 mL +/- 4.2, as calculated with Patlak analysis. The mean difference and 95% limits of agreement, respectively, were -3.6 mL . 100 mL(-1) . min(-1) and -18.4 to 11.2 mL/100 mL(-1) . min(-1) for permeability and -3.9 mL/100 mL and -10.9 to 3.0 mL/100 mL for blood volume. The coefficient of variation was 37.4% for permeability and 46.5% for blood volume. Conclusion: There was disagreement between the methods used to estimate tumor vascularity, which indicated the measurement techniques were not directly interchangeable.