A New CAD System for the Evaluation of Kidney Diseases Using DCE-MRI Ayman El-Baz 1 , Rachid Fahmi 1 , Seniha Yuksel 1 , Aly A. Farag 1 , William Miller 1 , Mohamed A. El-Ghar 2 , and Tarek Eldiasty 2 1 Computer Vision and Image Processing Laboratory, University of Louisville, Louisville, KY 40292 {elbaz, rachidf, esen, farag}@cvip.uofl.edu http://www.cvip.louisville.edu. 2 Urology and Nephrology Department, University of Mansoura, Mansoura, Egypt Abstract. Acute rejection is the most common reason of graft failure after kidney transplantation, and early detection is crucial to survive the transplanted kidney function. In this paper, we introduce a new approach for the automatic classification of normal and acute rejection transplants from Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE- MRI). The proposed algorithm consists of three main steps; the first step isolates the kidney from the surrounding anatomical structures by evolv- ing a deformable model based on two density functions; the first function describes the distribution of the gray level inside and outside the kidney region and the second function describes the prior shape of the kidney. In the second step, a new nonrigid registration approach is employed to account for the motion of the kidney due to patient breathing. To validate our registration approach, we use a simulation of deformations based on biomechanical modelling of the kidney tissue using the finite element method (F.E.M.). Finally, the perfusion curves that show the transportation of the contrast agent into the tissue are obtained from the cortex and used in the classification of normal and acute rejection transplants. Applications of the proposed approach yield promising re- sults that would, in the near future, replace the use of current technolo- gies such as nuclear imaging and ultrasonography, which are not specific enough to determine the type of kidney dysfunction. 1 Introduction In the United States, approximately 12000 renal transplants are performed an- nually [1], and considering the limited supply of donor organs, every effort is made to salvage the transplanted kidney [2]. Currently, the diagnosis of rejec- tion is done via biopsy which has the downside effect of subjecting the patients to risks such as bleeding and infections. Moreover, the relatively small needle biopsies may lead to over or underestimation of the extent of inflammation in the entire graft [3]. Therefore, a noninvasive and repeatable technique is not only helpful but also needed in the diagnosis of acute renal rejection. In DCE-MRI, a R. Larsen, M. Nielsen, and J. Sporring (Eds.): MICCAI 2006, LNCS 4191, pp. 446–453, 2006. c  Springer-Verlag Berlin Heidelberg 2006