The DICOM image formatting standard: its role in echocardiography and angiography

Both echocardiography and angiography have traditionally used analog media for long-term storage, but increasingly there is the desire to develop digital storage and exchange methodology. Before digital storage can become a reality, though, standards must be agreed to by the vendor and user community to ensure global intra operability of medical instrumentation. To this end, the National Electrical Manufacturers' Association and various professional organizations from around the world have collaborated to develop the DICOM (Digital Imaging and Communications in Medicine) image formatting standard. This standard specifies the exact way in which digital images are exchanged between instruments, either using a network or storage medium, and distinct standards have been developed for angiography and echocardiography. In angiography, only gray scale images are considered, whereas in echocardiography several different types of image formats are allowed to account for color Doppler echocardiography. Distinct standards have also evolved for disk-based storage. For angiography, only storage on the writable CD-ROM is allowed, whereas echocardiograms may be stored on re-writable magneto-optical disks, floppy disks, and CD-ROMs. Only lossless compression is allowed in the angiographic standard, whereas echocardiography allows the use of the JPEG (Joint Photographic Expert Group) lossy compression algorithm. Currently, all major angiographic and echocardiographic vendors have agreed to support the DICOM standard, and products are beginning to appear, first with disk-based storage but increasingly with network-based exchange of image data.