TrichoScan: a novel tool for the analysis of hair growth in vivo

Hair loss or hair thinning is a common complaint in clinical dermatology, and patients seeking advice for hair loss are not necessarily bald. Because the effects of treatment attempts are hard to measure, there is need for a sensitive tool to monitor hair loss and treatment responses. Such a method must be able to analyze the biologic parameters of hair growth, which are: (i) hair density (n per cm2); (ii) hair diameter (microm); (iii) hair growth rate (mm per day); and (iv) anagen/telogen ratio. Herein we present the TrichoScan as a method that combines epiluminescence microscopy with automatic digital image analysis for the measurement of human, and potentially animal hair, in situ. The TrichoScan is able to analyze all four parameters of hair growth with a so-called intraclass correlation of approximately 91% within the same TrichoScan operator and an intraclass correlation of approximately 97% for different TrichoScan operators. The application of the technique is demonstrated by comparing the hair parameters in individuals without apparent hair loss, men with untreated androgenetic alopecia, and men after treatment with finasteride (1 mg per day). We were able to detect a significant increase in hair counts and cumulative hair thickness 3 and 6 mo after treatment. Advantages of the TrichoScan are that it can be used for clinical studies to compare placebo versus treatment, to compare different capacities of hair growth promoting substances, to study androgenetic alopecia and other forms of diffuse hair loss, and to study the effects of drugs and laser treatment on hypertrichosis and hirsutism.