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Unbalanced 3-D Tree Structure for Region-Based Coding of Volumetric Medical Images

In this paper, we propose an unbalanced three-dimensional (3-D) coefficient tree structure for 3-D region-of-interest (ROI) coding of medical volumetric data. We compare the proposed coding scheme against 3-D SPIHT and a recent technique that employs optimal tree construction shown to improve the performance of the 3-D SPIHT algorithm. For a MR volumetric dataset, at 0.1 bpp, the proposed region-based coding scheme outperforms by about 0.5 dB. The improvement is more significant at higher bitrates, up to 1 dB compared to SPIHT algorithm and optimal tree construction. In addition, the proposed tree structure provides a more general multiregion multiquality coding framework rather than ROI/non-ROI coding