OBJECTIVE ASSESSMENT OF NICKEL SULFATE PATCH TEST REACTIONS WITH LASER-DOPPLER PERFUSION IMAGING

The laser Doppler perfusion scanning technique was used to assess the superficial blood flow of nickel sulfate hexahydrate patch test reacti ons. There was good agreement between laser Doppler and visual assessm ents when the highest assessment values of reactions were studied. Ear lier detection of reactions was possible with the laser technique. The re was great inter-individual variance in perfusion between identicall y tested patients. 4 patients were visually negative when a TRUE Test( TM) patch test dose of 0.20 mg/cm(2) was applied for 48 h and the test area read 4x up to 168 h. These 4 showed a dose-related increase in p erfusion and visually positive reactions using longer application time s. The instrument allowed a dose reduction not possible for visual ass essments. Reading transparent patches in contact with the skin through transparent semi-occlusive plastic foil or through windows in the tap e strip over the patches, allowed us to detect perfusion at 48 h, wher e a longer application would have been needed using tape and visual as sessments.