Image objects of different types may be created from a 3D Ultrasound image acquisition, illustrated in Figure A.59-1. It can be seen that there are two different types of data related to 3D image acquisition: 3D volume datasets and several kinds of 2D image derived from the volume dataset.
Figure A.59-1: Types of 3D Ultrasound Source and Derived Images (Informative)
The 3D volume dataset (the diagonally shaded box in Figure A.59-1) contains a Cartesian volume or two or more temporally related Cartesian volumes. 3D volume datasets are exchanged using the Enhanced US Volume SOP Class, and are suitable for subsequent Multi-Planar Reconstruction and rendering operations. Within each Enhanced US Volume instance, each Cartesian volume consists of a set of parallel planes, and each plane consists of one or more frames each of a single data type. All Cartesian volumes have the same spacing between adjacent planes.
Most acquisition devices construct the Cartesian volume by resampling data from a different acquisition geometry. The method of generation of the Cartesian volume, its relationship to spatially-related 2D frames (whether the volume was created from spatially-related frames, or spatially-related frames extracted from the Cartesian volume), and the algorithms used for Multi-Planar Reconstruction and rendering operations are outside the scope of this standard.
The 2D image types represent collections of frames that are derived from the volume dataset, namely 3D rendered views (projections), separate Multi-Planar Reconstructed (MPR) views, or sets of spatially-related source frames, either parallel or oblique (the cross-hatched boxes in Figure A.59-1). The Ultrasound Image and Ultrasound Multiframe Image IOD’s are used to represent these derived images. See Section A.6 for the Ultrasound Image IOD description or section A.7 for the Ultrasound Multi-frame Image IOD description.
Note: See PS3.17 “3D Ultrasound Volumes” for an informative discussion on the use of these objects for the exchange of 3D ultrasound volume data.