Skin prick test digital imaging system with manual, semiautomatic, and automatic wheal edge detection and area measurement

A novel biomedical instrument for supporting the physician in Skin Prick Test analysis was designed, developed, characterized, and is now ready for clinical trials. Skin Prick Test is the gold standard front-end analysis for diagnosis of allergies in human subjects. The forearm skin is punctured with different allergens and the resulting reaction wheals are analyzed and compared to standard reaction, with larger areas corresponding to stronger allergy to the specific allergen. The wheals inspection and allergy diagnosis are performed, visually and subjectively, by the Medical Doctor. This procedure is laborious and somehow unreliable, being subject to variability both intra- and inter-operator because the doctor subjectivity in detecting and measuring the wheals is significant. Registration of the exam result is rarely available in a digital format, useful for data saving, transmission, retrieval and comparative analyses. Many of the above criticalities of the actual Prick Test manual practice are addressed and resolved by the proposed biomedical instrumentation that makes use of digital image-processing and data storage. In this work, we present a prototype of wheal measurement system, designed, developed and characterized to specifically measure geometry and areas of the allergic reaction wheals in Prick Test clinical exams. After software developments from previous version of the instrument, the wheal-meter now allows manual, semi-automatic, automatic, and fully-automatic operating conditions always providing digital exams output.