An image warping method for temporal subtraction images employing smoothing of shift vectors on MDCT images

Abstract

Detection of subtle lesions on computed tomography (CT) images is a difficult task for radiologists, because subtle lesions such as small lung nodules tend to be low contrast, and a large number of CT images must be interpreted in a limited time. A temporal subtraction image, which is obtained by subtraction of a previous image from a current one, can be used for enhancing interval changes (such as shapes of new lesions and the interval changes in existing abnormalities) on medical images by removing most of the normal structures. For detection of lesions in chest radiographs, the temporal subtraction technique has been applied successfully to clinical cases. In this paper, we propose a new method for removing the artifacts in temporal subtraction images obtained from chest multiple detectors CT (MDCT) images by using a smoothing of shift vectors. With our method, more accurate correspondence of normal structures between current and previous images is determined. The new method was applied for 6 clinical cases of MDCT images. Preliminary results indicated that interval changes on the subtraction images were enhanced considerably with reduction of misregistration artifacts. © 2008 Springer-Verlag Berlin Heidelberg.