Let the 'filmless' hospital still seem an ideal utopia, within the specific field of catheterisation procedures, medical experts are making a growing use of digital angiography instead of cinefilm. In the Netherlands, an interesting telecardiology project has been set up in which referring hospitals execute catheterisation interventions and in due case present the patient's data to cardiologists and cardiac surgeons of the university hospital in order to decide on further treatment such as for instance coronary artery bypass grafting. Digital image transfer of the catheterisation between the two hospitals involved allows time sparing and more effective service towards the patient.
Clinical physicists W.A. Dijk, K.J. Visscher and their colleagues at the University Hospital of Groningen (AZG) and the Medical Centre at Leeuwarden (MCL) currently are implementing the digital telecardiology system. Both hospitals have their own network, based on twisted pair Ethernet. The images are transmitted by means of an ISDN-on-demand connection. At the MCL-site, the Siemens HICOR digital imaging system is used and the images are stored on CD in two possible formats: the Digital Imaging and Communications in Medicine (DICOM) 3 standard as well as the DYNAVIEW format. The latter is identical to DICOM 3 except for the JPEG compression which causes a certain loss of resolution and possibly might introduce artefacts.
The MCL hospital network connects to the ISDN-link through a multi-protocol router with a dial-up on demand process. The selected and stored frames are sent as an attachment of an E-mail message to the AZG Novell-server which however has no direct link with the Groningen network due to hospital regulations. Another machine, linked to the Groningen network, connects periodically to the Novell-server to check whether images have arrived. If so, the files are transferred with file transfer protocol (FTP) to the image server where they can be viewed and examined on any sufficiently equipped PC. Image storage on CD takes about fifteen minutes. Depending on the format, transmission can take twenty minutes for DYNAVIEW images and one hour for 100 DICOM 3 frames. The unpacking and transportation of the file to the image server is done in one minute.
Patients significantly benefit from this procedure whenever emergency therapeutic treatment is needed. The surgical team at AZG is already able to decide about the strategy to be taken and prepare for the intervention while the patient is still on the way to the hospital. Also in cases of normal consultation, the system enables MCL to receive feedback by telephone on the most effective way to treat the patient. Unnecessary transport can be avoided if consultation shows that only another hospital can offer the right intervention. Finally, the regular patient presentation sessions are shortened because the images were sent on beforehand.
The Engineers Dijk, Visscher and their colleagues consider the general outcome of the telecardiology project as quite positive with regard to its time-saving efficiency, especially where the faster receipt of the DYNAVIEW frames is preferred above the slower transfer of the DICOM-3 images albeit with resolution loss. Yet, they study and work hard on improving the system to try and achieve optimal patient care, completely unhampered by the still existing time delay. Only a drastic decrease of it will enable a more enhanced feedback, compared to telephone.
As a realistic solution, the research team is envisaging the increase of the ISDN-transmission speed by means of more ISDN lines in parallel while images could easily be transferred before storage on a CD. Other compression algorithms based on chaos and wavelet techniques are currently being investigated. Up till now, the telecardiology system has clearly proven its clinical usefulness for 86 patients. In the future, this project will therefore serve as a model for a similar national initiative in the Netherlands.