Automated Determination of Arterial Input Function for DCE-MRI of the Prostate

Prostate cancer is one of the commonest cancers in the world. Dynamic contrast enhanced MRI (DCE-MRI) provides an opportunity for non-invasive diagnosis, staging, and treatment monitoring. Quantitative analysis of DCE-MRI relies on determination of an accurate arterial input function (AIF). Although several methods for automated AIF detection have been proposed in literature, none are optimized for use in prostate DCEMRI, which is particularly challenging due to large spatial signal inhomogeneity. In this paper, we propose a fully automatic method for determining the AIF from prostate DCEMRI. Our method is based on modeling pixel uptake curves as gamma variate functions (GVF). First, we analytically compute bounds on GVF parameters for more robust fitting. Next, we approximate a GVF for each pixel based on local time domain information, and eliminate the pixels with false estimated AIFs using the deduced upper and lower bounds. This makes the algorithm robust to signal inhomogeneity. After that, according to spatial information such as similarity and distance between pixels, we formulate the global AIF selection as an energy minimization problem and solve it using a message passing algorithm to further rule out the weak pixels and optimize the detected AIF. Our method is fully automatic without training or a priori setting of parameters. Experimental results on clinical data have shown that our method obtained 100% detection accuracy (all detected pixels inside major arteries), and a very good match with expert traced manual AIF. The computation time for each dataset was less than 15 seconds.