Image fusion technique and abdominal applications

Image fusion involving ultrasound is a method, where a previously recorded data set from CT, MRI or PET/CT is loaded into the ultrasound system and fused with the real time ultrasound images. The software for image fusion is available in most high-end ultrasound systems. By means of a magnetic positioning system the transducer can be located spatially and the two or three 3D data sets aligned. The alignment can be made manually by means of common points or planes seen in all data sets, or automatically by the system by recognition of pixel intensities in the images. The latter does not apply for all modalities and all systems. Image fusion involving ultrasound has been applied to several anatomical areas, but most studies have been performed in the liver. The technique is more time consuming than conventional B-mode ultrasound but time spent decreases with increasing user experience. Depending on the body size of the patient and the organ of interest patient positioning should be identical to when the previously recorded data set was recorded, but this is not mandatory. However, for liver applications accuracy of the co-registration may improve if this is taken into account. Also identical in- or expiration may improve the accuracy.