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Improved diagnosis of rheumatism

Especially interesting for
  • rheumatologists
  • hospitals
  • manufacturers of medical equipment

The European Patent Office has granted a patent for a novel diagnostic procedure which was developed at PTB, together with partners from the Charité Hospital in Berlin and industry. This diagnostic procedure could prove to be helpful in diagnosis and therapy control of rheumatoid arthritis.

Fluorescent image of the hands of a 51-year-old patient suffering from rheumatism, recorded with PTB‘s certified device two minutes after the injection of the contrast agent. False-colour representation where the colours red to white stand for the highest intensity. An inflammation is visible on the right hand, not on the left. (Fig.: Helios-Klinikum Berlin-Buch, Prof. Michael N. Berliner)

Approximately 1 % of the population suffers from rheumatism. The earlier this disease is detected and treated, the more probable the chance of maintaining a good quality of life. The highly sensitive diagnostic procedure developed at PTB allows early stages of the disease to be detected. The patent describes the use of indocarbocyanine as a contrast agent in fluorescent imaging for the early detection of inflammatory diseases, in particular rheumatoid arthritis.

Fluorescent imaging is based on nearinfrared light of the spectral range from 700 nm to 900 nm. The body‘s own dyes absorb less of near-infrared light, and it is less scattered by the tissue than visible light; similar to thermal radiation, it penetrates a few centimetres deep into the tissue. This makes the procedure interesting, in particular for the optical examination of finger joints. The near-infrared light excites the fluorescence of the contrast agent indocyanine green (ICG), which has previously been injected intravenously; this contrast agent is approved for invasive diagnostics. As increased vascularization occurs in inflamed joints, these fluoresce much stronger than healthy joints. The emitted fluorescence is detected by means of an extremely sensitive EMCCD (electron- multiplying charge-coupled device) camera in such a way that even small concentrations of the contrast agent can be made visible. For the assessment of the intensity distribution over the palm of the hand, PTB has developed software which, besides the visual assessment, also allows an objective quantitative comparison, similar to the assessment of an X-ray image. The measurement procedure was successfully tested within the scope of an exploratory study carried out on 60 patients and 30 test subjects.

Within the scope of technology transfer, PTB has been working in close collaboration with the mivenion company as a partner for the exploitation of the procedure for some time. At an early stage, the company purchased the licence for the utilization of the now patented trade mark rights and commercialized a device (Xiralite®) based on this principle; several hospitals and practising physicians are already using this device for the early detection of rheumatoid arthritis. The trade mark rights which have now been granted are a significant milestone for the further exploitation of the new diagnostic procedure – and, thus, its establishment. PTB‘s European patent (Optical imaging of rheumatoid arthritis, EP No. 1 931 391 B1), which was granted on 21 December 2011, has now been transposed into the national phase of the European countries.

Scientific publication

Dziekan, T.; Weissbach, C.; Voigt, J; Ebert, B.; Macdonald, R.; Bahner, M.L.; Mahler, M.; Schirner, M.; Berliner, M.; Berliner, B.; Osel, J.; Osel, I.: Detection of rheumatoid arthritis by evaluation of normalized variances of fluorescence time correlation functions. J. Biomed. Opt. 16 (2011) 076015