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Abstract
Image registration is a fundamental task in medical imaging to align two or more images. The
images might be acquired at various times, by different sensors or with distinct perspectives.
Medical image registration has a wide range of potential applications such as combining
information from multiple imaging modalities, comparing images or reconstructing a threedimensional
volume from a series of two-dimensional images.
Image registration of a series of dual-isotopic and histologic two-dimensional image data
displaying slices of the brain improves tumour diagnostics and lead to an advanced understanding
of the brain functionality on a molecular level.
Registration is the iterative search for a transformation (rigid and non-rigid), mapping points
from one image to corresponding points or structures in the second image. The aim of the
registration process is the alignment of the objects contained in the images. An intrinsic registration
is based on the image intensities and therefore optimises a measure of similarity
calculated on the image pixels.
This paper deals with the implementation and analysis of a configurable software aligning
series of dual-isotopic and histologic two-dimensional images. The gradient descent and the
Downhill Simplex optimisation scheme are used in combination with different measures of
similarity and interpolation methods to align both monomodal and multimodal data. Available
measures of similarity are the mean squares measure, normalized correlation, mutual
information implemented by Mattes and normalized mutual information. The software provides
the interpolation methods nearest neighbour and bspline interpolation with varying
order.
The conclusion shows that the implemented registration software can be executed with all
measures of similarity except for normalized mutual information combined with the gradient
descent and with all measures of similarity combined with the Downhill Simplex optimisation
scheme. Both the monomodal and the multimodal registration of the available data show
good results for all applicable combinations.