Landmark precision and reliability and accuracy of linear distances estimated by using 3D computed micro-tomography and the open-source TINA Manual Landmarking Tool software

Introduction The wider availability of non-destructive and high-resolution methods, such as micro-computed tomography (micro-CT), has prompted its use in anatomical and morphometric studies. Yet, because of the actual scanning procedure and the processing of CT data by software that renders 3D surfaces or volumes, systematic errors might be introduced in placing landmarks as well as in estimating linear distances. Here we assess landmark precision and measurement reliability and accuracy of using micro-CT images of toad skulls and the TINA Manual Landmarking Tool software to place 20 landmarks and extract 24 linear distances. Landmark precision and linear distances calculated from 3D images were compared to the same landmarks and distances obtained with a 3D digitizer in the same skulls. We also compared landmarks and linear distances in 3D images of the same individuals scanned with distinct filters, since we detected variation in bone thickness or density among the individuals used.