A NEW medical imaging system will give doctors in different hospitals the chance to diagnose illnesses without seeing the patient. The high-speed network, the first of its kind in Southeast Asia, is designed to transmit and process images of patients taken by sophisticated diagnostic machines. Using the network, called Magnet, doctors can share ideas to offer a more precise diagnosis. Under Magnet, 100 medical images, together with data, graphics or even voices, can be transmitted between hospitals in one or two seconds. To safeguard patients, the information can only be reached by registered users of the network, mainly radiologists and surgeons. Magnet is the first result of a $2 million project started by the Information Engineering Department of the Chinese University 18 months ago. The expensive optical-fibre link needed for the network's high quality and high capacity transmission is provided by Hong Kong Telecom. The communication network, inaugurated yesterday, has been in operation for two months. It connects the Prince of Wales and St Teresa's Hospitals with the Chinese University. ''St Teresa's Hospital was chosen for its hi-tech diagnostic machines, such as magnetic resonance imaging which are not yet used in the Prince of Wales,'' said Dr Wong Po-choi, of the Chinese University. The network, which is capable of international connections, will be extended to all hospitals in Hong Kong. Its instalment would cost about $300,000 for each hospital, but the cost would not be passed on to patients, according to St Teresa's radiologist, Dr Hector Ma Tin-ging.