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.
(© 2019 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.)