Until now the analysis of the trichogram has been a tedious and time consuming process. Attempts to automate the process have been performed several times unsuccessfully. This was mainly because the hair follicles on the scalp grow in groups (follicular units) rather than singly and therefore neighboring hair follicles typically overlap or may be aligned in parallel. Furthermore, any photographic analysis software needs a good contrast between the hair follicles and the scalp skin to be analyzed, and the fact that many hairs lose their natural pigmentation due to aging or pattern alopecia, makes them much more difficult to detect. We have overcome this difficulty by colouring the hairs prior to taking the images, without any negative effect on the collected data.
The TrichoScan® Professional is especially useful for dermatologist is daily hair practice. The used software algorithms are identical to those used in the TrichoScan® Research. However, due to practical reasons, hair thickness and lenght cannot be calculated with the TrichoScan® Professional. Nevertheless, with the calculation of Terminal- and Vellus hair counts, hair thickness is indirectly integrated. The TrichoScan® Professional is distributed by different companies and the analysed areas are for some practical reasons < 1,4 cm², sometimes only 0,6 cm². In addition the resolution is usually lower, compared to the image resolution we use in clinical trials. These are only two reasons why we do not recommend the TrichoScan® Professional for the use in clinical trials. What we offer as services during clinical trials is explained at TrichoScan® Research.
TrichoScan – How to perform
Gray or fair hairs have only limited contrast in comparison to the scalp. Therefore, the clipped hairs within the target area must be dyed for 12-15 minutes with a commercially available solution, which is normally used for the colouring of eyebrows or lashes. The approach to dying hairs for hair growth studies has been described to give the same results as uncoloured hair. For the analysis of hair number and thickness the hairs are coloured immediately after shaving and for the analysis of the hair growth rate and anagen-telogen ratio the hairs are coloured 2-3 days after shaving.
Thereafter, the coloured area is cleaned with an alcoholic solution (Kodan®; Spray, Schülke & Mayr, Vienna, Austria) and digital images are obtained by means of digital ELM systems while the area is still very wet (Fig 1 and 2). Different distributors use different optics and cameras, which means that the analysed area varies slightly. This, however, has no impact on the precision of the technique
ELM is a standard procedure for the analysis of melanocytic nevi, and many dermatologists in Europe already use ELM-systems in daily clinical practice. These devices produce high quality and reproducible digital images, because the images are always taken at the same distance from the lens to the skin surfaces. This digital camera is equipped with a rigid contact lens which ensures that the images are always taken at the same distance from the scalp. Due the fact that the camera must be pressed onto the scalp, the hairs are always flattened. For typical images TrichoScan® images please look at download.
All other techniqual details are shown at TrichoScan® Research. Different distributors can be found at "Distribution". The figure shows a Canon Powershot A640 with the DII-Scope.
Videos: How to perform TrichoScan-Professional
|Marked hairs||Anagen-/Telogen hairs|