STATISTICS OF DEFORMATIONS IN HISTOLOGY AND APPLICATION TO IMPROVED ALIGNMENT WITH MRI

An exact registration of magnetic resonance images (MRI) with histolog ical sections is impeded by local deformations resulting from histolog ical preparation procedures, Therefore, it is desirable to know the pr obability density function of spatial deformations in order to estimat e optimal global least-square transformation parameters from suitable landmarks, For this reason, the statistics of deformations is investig ated, It is shown analytically that the frequency of occurence of the absolute geometrical differences (deformations) are Rayleigh-Bessel di stributed for anisotropic histological preparation procedures and Rayl eigh distributed in the case of isotropic procedures, The probabilisti c analysis is given in conjunction with an iterative optimization tech nique in order to ensure that the probability density function is with in a threshold required for the application to experimental data, The application of the analytical model is investigated with real data, It is shown with this data that the extent of deformations varies with t he size of the histological section, An individual threshold can be se lected on the basis of a Rayleigh-function restricting local correctio ns to small parts of the image, Thus, global misalignment in each sect ion can be avoided, resulting in an improved 3-D reconstruction of the volume, i.e., the transitions from one section to the next are more c ontinuous.