TrichoScan® Research Overview

For the measurement of hair density (n/cm2), hair diameter (µm), hair growth rate (mm/day) and anagen/telogen ratio, software was developed (TrichoScan®) to analyze these parameters. This technique can be used for clinical studies to compare placebo versus active treatment or to compare different capacities of different hair growth promoting substances. This technique can be used for studying AGA or other forms of diffuse hair loss. Moreover, it can be adopted to study the effect of drugs or laser treatment on hypertrichosis or hirsutism.

TrichoScan® Research– Software

The software works step by step through the following algorithms:

  1. Selection of color component;
  2. Artifact rejection (bubbles and reflections);
  3. Determination of threshold;
  4. Thresholding;
  5. Labeling - Definition of hair regions;
  6. Deselecting of small regions (smaller than minimal hair length);
  7. Tattoo elimination (works by using the fact that the tattoo is a large, dark region located in the center of the image);
  8. Analysis of each hair region: a. Search for the longest straight line (fulfilling several predefined conditions) at the edge of the analysed hair region, b. Reduction of hair region of detected hair;
  9. Repetition of steps 8a and 8b until no more hair is found;
  10. Repetition of analysis of all the hair regions;
  11. Calculation of number of hairs, hair density, and mean/median hair thickness/sum of hair thickness. The algorithm excludes all air bubbles, dust, small haemangiomas, nevi, scales etc. from the calculation without interfering with the number of detectable hairs. In doing so, only hairs are counted, and the precision of the method is almost 100%.

TrichoScan® Research– Precision and Sensitivity

Depending on the zoom and the resolution of the digital camera as well es the magnification of the different optics, the hair thickness detection limit of the software varies between 6µm and 12µm. Hairs smaller than 6 or12 µm can therefore not be analysed. In our opinion this is not a disadvantage as these very tiny hairs are not clinically relevant. It must be kept in mind that this is a systematic difference and occurs for every analysis. Therefore, it has no impact on the TrichoScan® capability to measure changes in hair thickness.

In 2001 TrichoScan® was introduced as a fully-automated method for measurement of  biological parameters of hair growth such as hair density or hair diameter. Whereas in the past the dermatologist or technician must literally measure the length of the hair fibers and diameters with a ruler, image analysis programs now allow for easy analysis of the marked hairs. However, the manual identification of the hairs is a tedious process prone to human error, but manual identification of hairs is sometimes defined as the most precise method of measurement. This might be the case when only the number of hairs in a very small scalp area is counted, but in large areas it is difficult for even well-trained technicians to make accurate manual counts of the total, terminal and vellus hairs as well as hair thickness and hair growth rate. This must result in variable results when the same image is counted two or more times.

At present no real independent side-by-side comparison is available and therefore, several validations trials have been performed in house and the most recent using the 3.0 Version can be found at “download”.

In addition one large validation trail was performed externally by under the rules of GCP. The aim of this study was the validation of the TrichoScan® method by comparative assessment of hair growth paramenters using TrichoScan® software versus manual identification of hairs prior to the final assessment of hair parameters. In short, in this validation study showed an excellent correlation of hair growth parameters analyzed using the fully-automated TrichoScan® method and manual marking of hairs prior to analysis. The results can be seen on this web site under "publications".

TrichoScan® Research - Advantages

Firstly, the TrichoScan® is investigator independent. In other studies using the unit area trichogram, a substantial difference between the collected data from different investigators was noted. In these studies a significantly larger mean total hair count was reported from experienced as against inexperienced observers. Our results show that this is not the case for the TrichoScan® technique. In a clinical trial, the wider margin of error and consequent data variability from manually evaluated images would necessitate a larger study sample size to overcome the effect of the variability on the statistical calculations. Therefore, the TrichoScan® technique is particularly suitable for clinical studies with treatment comparisons.

Secondly, many methods are not strictly validated. The hair weight test is a good example where the hair is clipped in a defined target area. However, the sample error for different investigators is unknown. This is mainly due to the methodology, because once the hairs are clipped a second investigator cannot clip the same area again to assess the reproducibility of the method. In contrast the TrichoScan® is highly validated with defined values for intra-class correlation between the same and different investigators. This is of crucial importance for clinical studies. In cases where the expected differences between placebo and verum treated patients is known, the minimum number of patients necessary to prove this difference can be calculated.

Thirdly, some methods are associated with considerable discomfort to the patient such as the repeated plucking of hairs required by the trichogram technique. The TrichoScan® relies on analyzing a small area of the scalp, which is barely visible afterwards. The tiny tattoo is the only cause of discomfort in the patients.
Fourthly, some methods of counting hairs are tedious and time-consuming. In contrast, TrichoScan® can be performed by experienced hands within 8-12 minutes "hands on".

Please also look at "videos" and "download" where and how to perform a TrichoScan and how to tattoo.

Fig. 1: Trichoscan<sup>®</sup> special camera


Feature TrichoScan® Research
automatic Analysis yes
analysed area up to 2 cm2
Hair dye necessary yes
Hair count yes
Hair lenght / Hair growth rate yes
Hair thickness yes
Terminal hair count yes
Vellus hair count yes
Anagen/Telogen ratio yes
Follicular units on request
Hide results yes
Export of results yes
Artefact correction yes
Email support yes
In house training on request
Camera / Optics Canon PowerShot with swiss made optics