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.

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).

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.

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 .

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.