Semi-and-Automatic Wheal Measurement System for Prick Test Digital Imaging and Analysis

In this work we present a semi-automatic and automatic wheal measurement system, designed, developed and characterized to specifically measure geometry of the wheals in a Prick Test clinical exam. Prick Test is the most diffused front-end analysis for rapid and inexpensive diagnosis of allergies. The skin reaction to specific allergens is observed and measured by visual inspection of the treated area (typically the patient forearm). The skin is exposed to different allergens and the corresponding wheals are analyzed in terms of their geometry: mostly diameters and areas. Visual inspection and diagnosis performed by the Medical Doctor is somehow laborious and subject to variability both intra- and inter-operator, since the doctor subjectivity in detecting and measuring the wheals is significant. Registration of the exam result is rarely available in a digital format, for data transmission, retrieval and comparative analyses. Many of the above criticalities of present Prick Test manual practice are addressed and resolved by the proposed digital image-processing method.