The intravenous coronary angiography technique NIKOS is a new method of obtaining an X-ray image of the coronary arteries that is especially easy on the patient. It was developed by the DESY research center in collaboration with doctors from the University Hospital Hamburg-Eppendorf and the Heart Center Bevensen as well as with physicists from the University of Siegen. "The angiography project has come to a very successful conclusion at DESY, and the medical professions can now move forward with the introduction of the technique in clinical practice," reported the project manager, physicist Dr. Wolf-Rainer Dix, at the annual conference of the Hamburg Synchrotron Radiation Laboratory HASYLAB on January 26 at the DESY research center. "Here at DESY we examined a total of 379 patients from all over Germany and from abroad — with an extremely high level of acceptance," said Dix.

With the successful conclusion of the trial at DESY, preparations can theoretically now be made for routine application of the new angiography technique at a specially-equipped clinic. This would require a compact source of monochromatic X-ray radiation. An initial design for such a source, based on a storage ring, has already been created at DESY. If investors can be found to back the project, the draft could form the basis for the industrial study necessary for the construction of a storage ring for medical applications.

The coronary arteries surround the heart and supply it with blood. If they become constricted, a heart attack can result. In order to determine the presence of these life-threatening constrictions (stenoses), doctors normally insert a long catheter into the coronary vessels via the groin and the aorta. They then inject a contrast medium containing iodine through the catheter and make an X-ray. The NIKOS technique, however, eliminates the need for this surgical procedure. Instead, the iodine is injected intravenously into the arm via a small syringe. As the contrast medium is greatly diluted on its journey through the circulatory system, its concentration is relatively low by the time it reaches the coronary arteries. In fact, the concentration is so low that conventional X-ray tubes cannot produce a clear image of the coronary vessels. The HASYLAB scientists, however, utilize the intensive and monochromatic X-ray light from the DORIS ring accelerator at DESY as well as a special "two-color" method to reveal the coronary arteries.

A total of 379 patients were examined at DESY using the NIKOS technique. A diagnosis on the basis of a conventional X-ray exposure made just after their examination was available for 60 of them. The diagnoses based on the different techniques displayed good agreement — even independent, fully untrained cardiologists achieved up to 79 percent agreement in the assessment of the degree of severity of a stenosis, with the figure rising to 82 percent for bypasses.

In addition to NIKOS, there are other non-invasive or minimally-invasive procedures for imaging the coronary vessels, such as magnetic resonance imaging (MRI) and electron beam computed tomography (EBCT). However, compared to these methods, the NIKOS technique currently provides the best image quality. Its resolution is also better and, unlike MRI, metallic implants do not degrade image quality. Nevertheless, none of these methods will be capable of replacing conventional coronary angiography in the long term. This is because the conventional method also allows for interventions during the examination, such as angioplasty or the implantation of a stent. Specific areas exist in which the three techniques can be very effectively applied without risk to the patient. In the case of the NIKOS method, this encompasses the imaging of bypasses and stents for checkups and postoperative examinations. A comprehensive evaluation of the patient studies has shown that image quality and thus the accuracy of the diagnoses could be further increased by means of additional improvements to the NIKOS system, and in particularly in the way the examination is conducted.