Weighted Medical Image Registration with Automatic Mask Generation

Hanno Schumacher, Astrid Franz, Bernd Fischer


Registration of images is a crucial part of many medical imaging tasks. The problem is to find a transformation which aligns two given images. The resulting displacement fields may be for example described as a linear combination of pre-selected basis functions (parametric approach), or, as in our case, they may be computed as the solution of an associated partial differential equation (non-parametric approach). Here, the underlying functional consists of a smoothness term ensuring that the transformation is anatomically meaningful and a distance term describing the similarity between the two images. To be successful, the registration scheme has to be tuned for the problem under consideration. One way of incorporating user knowledge is the employment of weighting masks into the distance measure, and thereby enhancing or hiding dedicated image parts. In general, these masks are based on a given segmentation of both images. We present a method which generates a weighting mask for the second image, given the mask for the first image. The scheme is based on active contours and makes use of a gradient vector flow method. As an example application, we consider the registration of abdominal computer tomography (CT) images used for radiation therapy. The reference image is acquired well ahead of time and is used for setting up the radiation plan. The second image is taken just before the treatment and its processing is time-critical. We show that the proposed automatic mask generation scheme yields similar results as compared to the approach based on a pre-segmentation of both images. Hence for time-critical applications, as intra-surgery registration, we are able to significantly speed up the computation by avoiding a pre-segmentation of the second image.
Original languageEnglish
Title of host publicationMedical Imaging 2006: Image Processing
EditorsJ.P.W. Pluim, J.M. Reinhardt
Number of pages8
Publication date10.03.2006
Pages6144 - 6144 - 8
Article number61442B
ISBN (Print)978-081946423-1
Publication statusPublished - 10.03.2006
EventMedical Imaging 2006: Image Processing - San Diego, United States
Duration: 11.02.200616.02.2006
Conference number: 67519


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