Abstract: A method of delineating a region of interest in a medical image and a system for carrying out the method. An initial point, corresponding to a pixel having an initial pixel intensity is selected on a desired region of interest in an image. A preliminary region of interest is delineated that includes the initial pixel and all connected pixels having a signal intensity in an initial range is delineated and displayed on the image. The initial range of signal intensities is adjusted based on user feedback. An adjusted region of interest is displayed. Also disclosed is a method of quantitatively analyzing a desired parameter in a region of interest of a medical image in real time and a system for carrying out this method.