Digital image data transmission over long distances using image compression and broadband ISDN

For telecardiological applications, transfer techniques with very large bandwidths are required. Because of the high costs, these techniques are not applicable for the broad community. For data transmission between two hospitals that are over 80 km apart, we have managed to bundle 30 common ISDN base channels into one logical line. The image data are compressed by a factor of 6 using JPEG image compression and are encoded according to the DICOM standard. The system needs 15-20 s to build up a connection with the 30 channels and reaches transmission speeds of up to 1.6 Mbit/s. The transmission of a cardiac study with 1,500 frames takes 5-6 min. After the transmission, the image data are made available in the departmental PACS. This system allows physicians to access the transferred image data from a laboratory or from their offices without delay