[Three-dimensional techniques in orthopedic ultrasonography]

Three-dimensional ultrasonography is not yet an established method in soft tissue and joint diagnostics as it is in obstetrics. Although a spatial view on the object is fascinating, problems occur in handling. No standard is defined for acquisition or visualisation. For the acquisition of the volume mainly 3D-arrays and image correlation techniques are used. For visualisation planar views of sections out of the volume, but also spatial views in a transparency or surface mode are used. Investigations on feasibility for soft tissue or joints show a higher accuracy, validity and reproducibility for 3D-sonography. Due to the low differences of the acoustic impedance visualisation is confusing in a transparency mode and needs a time consuming postprocessing in a surface mode. Future developments address to the field of faster acquisition ("real time 3D"), higher geometric precision and easier visualisation by automated segmentation. By the three-dimensionality of the data set applications in telematics, navigation and simulation ("sonographic training") are expected.