An Interactive Framework for Boundary Delineation for Medical CBIR

CBIR systems designed for medical applications often require that a human in the loop demarcate the pathology bearing regions in the image, since fully automatic extraction of such regions is still not possible. In our CBIR system for the domain of HRCT images of the lung, physicians did not find this interaction too onerous since the boundary surrounding a pathology bearing region did not have to be precise. But in our new domain, the liver image database, that is unfortunately not the case. The boundaries supplied by the physician must correspond precisely to the outline of the liver or to the boundary of a pathology bearing region inside the liver. To meet this demand, we have developed a new user interaction framework for semi-automatic boundary extraction. All that a physician has to do is to click on a couple of pixels on the boundary to be extracted. The system then tries its best to extend the boundary as far as possible, sometimes even extracting the entire contour correctly. When errors occur, all that the physician is called upon to do is to click on where a correction to the boundary needs to take place. In this manner, an entire boundary can be specified with very little input from the human, which is a most important consideration with physicians as he/she can hardly be expected to click on every boundary point.