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(F)luid (R)egistration and (A)tlas (T)oolkit


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FRAT provides c++ libraries and command line applications for performing fluid registration based operations on 2D and 3D images. The registration method used throughout is based on the large displacement diffeomorphic metric mapping (LDDMM) technique. We use variants of LDDMM to address the problems of time series analysis, cross-sectional atlas building, longitudinal atlas building, and geometric metamorphosis.

Command Line Tools

  • LDDMM: Fluid registration between two images.
  • TimeSeries: Time series analysis of longitudinal data for a single subject.
  • AtlasBuilder: Cross-sectional atlas building for a population of images.
  • LongitudinalAtlasBuilder: Longitudinal atlas building for a population of subjects, each with a longitudinal data set.
  • GeometricMetamorphosis: Perform registration on image pairs undergoing geometric change.
  • FRATUtils: A colleciton of utilitiy functions for working with volumes and time seried files.

Driving Applications

Technical Focus

  • Large Displacement Diffeomorphic Metric Mapping (LDDMM) is the core problem of computing a time-dependent and spatially-varying velocity field which accounts for deformation between a pair of images.
  • Cross sectional atlas construction computes a geometric average of a set of images.
  • Time series registration computes a growth trajectory for a series of longitudinally related images (typically more than two).
  • Longitudinal atlas construction computes the geometric average of a set of time series models. This is used when producing an atlas to represent growth in a population.
  • Geometric metamorphosis registers between images where the underlying structures change and thus a perfect structural match is impossible.