Improved repeatability of dynamic contrast-enhanced MRI using the complex MRI signal to derive arterial input functions: a test-retest study in prostate cancer patients

Purpose: The arterial input function (AIF) is a major source of uncertainty in tracer kinetic (TK) analysis of dynamic contrast-enhanced (DCE)-MRI data. The aim of this study was to investigate the repeatability of AIFs extracted from the complex signal and of the resulting TK parameters in prostate cancer patients. Methods: Twenty-two patients with biopsy-proven prostate cancer underwent a 3T MRI exam twice. DCE-MRI data were acquired with a 3D spoiled gradient echo sequence. AIFs were extracted from the magnitude of the signal (AIF(MAGN)), phase (AIF(PHASE)), and complex signal (AIF(COMPLEX)). The Tofts model was applied to extract K-trans, k(ep) and v(e). Repeatability of AIF curve characteristics and TK parameters was assessed with the within-subject coefficient of variation (wCV). Results: The wCV for peak height and full width at half maximum for AIF(COMPLEX) (7% and 8%) indicated an improved repeatability compared to AIF(MAGN) (12% and 12%) and AIF(PHASE) (12% and 7%). This translated in lower wCV values for K-trans (11%) with AIF(COMPLEX) in comparison to AIF(MAGN) (24%) and AIF(PHASE) (15%). For k(ep), the wCV was 16% with AIF(MAGN), 13% with AIF(PHASE), and 13% with AIF(COMPLEX). Conclusion: Repeatability of AIF(PHASE), and AIF(COMPLEX )is higher than for AIF(MAGN), resulting in a better repeatability of TK parameters. Thus, use of either AIF(PHASE) or AIF(COMPLEX) improves the robustness of quantitative analysis of DCE-MRI in prostate cancer.