Compression of Volumetric Medical Image Data Using JPEG2000-Part 2

Aware JPEG2000-3D is an implementation of JPEG2000 Part 2 extensions that enable compression of volumetric medical image data, such as that created by CT and MR scanners. JPEG2000-3D enables a series of two-dimensional images to be further compressed in the third dimension by exploiting correlation between the adjacent images in the series. The result is that better compression ratios can be achieved than if each image in the series were compressed independently.

For lossless compression, Aware JPEG2000-3D achieves a compression ratio 15%-18% greater than if each image in a series is compressed independently. For lossy compression, the results are more dramatic: at a specific compression ratio, JPEG2000-3D increased the average pSNR (quality) of the image sequence by 5-18 dB than by compressing each image independently. This translates to an increase in compression of a factor of two to three times for a given average pSNR value.

The graph below illustrates the performance of JPEG2000-3D compression as compared to JPEG2000 when used to compress a series of medical images (429 images in this example). Compression of all the images independently using JPEG2000 at a ratio of 10:1 yields average quality, or pSNR of 77 dB.

Using JPEG2000-3D to compress the series takes advantage of inter-image correlations. The result is that at a compression ratio of 25:1, JPEG2000-3D yields images of the same average quality, or pSNR, as JPEG2000 at a compression ratio of 10:1. If this series were 1000 MB in size, JPEG2000 would compress it to 100 MB, while JPEG2000-3D could compress it to 40 MB, while achieving the same image quality.

Similarly, while JPEG2000 compression at a ratio of 15:1 yields an average pSNR of 73 dB, JPEG2000-3D can be used to compress at a ratio of 50:1 while maintaining the same level of quality. At this quality level, a 1000 MB image series could be compressed to 67 MB using JPEG2000, and 20 MB using JPEG2000-3D.

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