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Rheumatism in the finger? Software decides objectively

Analytical procedure developed at PTB supports diagnosis of rheumatism

12.04.2011

Much in medical diagnostics is a matter of experience. It is, therefore, helpful - especially when dealing with new procedures - if a doctor can also include objective analytical methods in the decision process. A method which is to make the diagnosis of rheumatism even more reliable in this respect has now been developed and presented at the Physikalisch-Technische Bundesanstalt (PTB). It is the third part of a success story which began with two different prototypes developed at PTB for the fluorescence imaging of the rheumatic inflammation of finger joints and has now arrived at doctors' surgeries and hospitals after a partner company acquired the licence for it and put the method on the market. By doing so the company correspondingly expanded the method's field of application. The data analysis software just presented is to improve the information content of the imaging method still further. It compares the time-dependent progress of the fluoresce signals from the suspicious finger joints to the progress in the fingertips which are not inflamed. This can help doctors above all in cases of doubt where it is not clear if suspicious diagnostic findings are to do with the individual features of a respective patient (or rather of that patient's skin) or if there really is a centre of rheumatism. The first tests resulted in an accuracy of the new evaluation method of up to 72 % in combination with a camera-supported imaging system and even 92 % was reached with a laser scanner system.

Lage und Ausdehnung der untersuchten Fingergelenk-Regionen. DIP: distales Interphalangealgelenk, PIP: proximales Interphalangealgelenk, MCP: Metacarpalgelenk, FS: Fingerspitze als Referenzregion. Ergebnisse des Daumens sind nicht mit in die Auswertung eingegangen.

Die ROC-Kurven visualisieren die Güte der Trennung zwischen gesunden und erkrankten Gelenken der Studienteilnehmer. Eine Kurve auf der Diagonalen entspräche einer vollständigen Überlappung der Gruppen, je weiter die Werte einer Kurve von dieser Geraden entfernt sind, desto besser die Trennung.

Contact at PTB:
Dr. Thomas Dziekan, Dr. Bernd Ebert
PTB Working Group 8.31 Tissue Optics and Molecular Imaging
Tel. +4930 3481-7384
e-mail: bernd.ebert(at)ptb.de