Multirate coding of 3D medical data

The last generation medical imaging equipment produce multidimensional (3D or 3D+time) data distributions. On a coding perspective, it is reasonable to expect that the exploitation of the full dimensional correlation among data samples would lead to a sensible improvement in compression performances, especially for isotropic datasets. We propose a fully three-dimensional wavelet-based coding system providing a finely-graded up to lossless data representation in a single bistream. The data are first decorrelated by a 3D discrete wavelet transform, performed by the non-linear lifting scheme mapping integers to integers. This enables the lossless mode and permits the in-place implementation of the transform at a reduced computational complexity. The coding scheme is inspired to the layered-zero coding proposed by Taubman and Zakhor (1994), extended to handle fully 3D subband structures. Performances are characterized with respect to both the 2D version of the same algorithm and the JPEG standard. The rate-saving is strongly influenced by the amount of the data correlation in the z dimension, ranging between 16.5% and 5.5% for the considered datasets.