Compression of Biomedical Images and Signals

Chapter 8

Compression of Dynamic and Volumetric Medical Sequences

8.1. Introduction

Most of the current medical imaging techniques produce three-dimensional (3D) data distributions. Some of them are intrinsically volumetric and represented as a set of two-dimensional (2D) slices, such as magnetic resonance imaging (MRI), computerized tomography (CT), positron emission tomography (PET) and 3D ultrasound, while others (such as angiography and echography) describe the temporal evolution of a dynamic phenomenon as a time sequence of 2D static images (frames), and thus are more correctly labelled as 2D+t. When displayed in rapid succession, these frames are perceived as continuous motion by the human eye.

The most commonly used digital modalities of medical volumetric data generate multiple slices in a single examination. One slice is normally a cross-section of the body part. Its adjacent slices are cross-sections parallel to the slice under consideration. Multiple slices generated this way are normally anatomically or physiologically correlated to each other (Figure 8.1). In other words, there are some image structural similarities between adjacent slices. Although it is possible to compress an image set slice by slice, more efficient compression can be achieved by exploring the correlation between slices.

Medical 2D+t and 3D images have had a great impact on the diagnosis of diseases and surgical planning. The limitations in storage space and transmission bandwidth on the one hand, ...