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Phototrichogram
For many years dermatologists have been searching for a simple,
noninvasive method to quantitatively evaluate hair loss and hair
growth like the hair pull test and wash test. Particular qualities
and defects characterize both of these techniques. The traditional
trichogram is a semi-invasive technique of great help to the clinician
in the evaluation of alopecia, but poorly tolerated by the patient.
Today, modern technology offers us the possibility of devising a
technique that will guarantee greater degrees of simplicity, reproducibility
and sensitivity and that might eventually become a feasible examination
for use in the general dermatology clinic - the phototrichogram.
 The
phototrichogram, introduced by Saitoh in 1970, is a noninvasive
technique that allows the in vivo study of the hair growth cycle.
It can be used to understand the rate of hair growth, the size of
hair fibers, the frequency of telogen hair follicles, and the quantification
of shed hair. Since Saitoh's original publication detailing the
phototrichogram several variations of the phototrichogram have become
popular techniques of evaluating hair in the clinic and in clinical
research trials.
At its most basic, an area of the scalp, say a centimeter in diameter,
is shaven and macroscopic pictures are taken. A second set of pictures
of the same shaved areas are taken five days later. By comparing
the first picture to the picture 5 days later the dermatologist
can see which hair fibers have not grown (those hair follicles are
in telogen), which hair fibers have grown (those hair follicles
are in anagen), the rate of hair growth (how much longer the growing
hair fibers are after 5 days), the density of the hair in the area
photographed (the number of hairs in the photograph) , and if the
dermatologist is really good he/she can match up the photographs
exactly and see which hair fibers are missing 5 days later, this
gives an indication of the rate of hair shedding.
In clinical research studies, especially those testing new hair
loss treatments, an additional step is taken. Volunteers in the
study have a dot tattooed on their scalp in the area of hair of
interest. This spot is shaved at the start and examined for hair
growth parameters, but the tattoo allows the dermatologists running
the study to come back to the same spot after several months or
even years to do another phototrichogram evaluation. In this way,
dermatologists can produce a detailed quantitative evaluation of
hair growth in exactly the same spot on the scalp over a long term
study period and build up a good idea of what a treatment can do
for hair growth long term. Tattoos are not generally used in the
general dermatology clinics as people do not like the idea. However,
the tattoos used are usually an orange to red color that is barely
visible, the tattoo is literally a dot, and it wanted the tattoo
can be removed with a laser or by biopsy later on.
Digital
phototrichogram
 Until
quite recently all the phototrichogram analysis was done manually.
The photographs on day 0 and 5 days later would be taken and then
placed side by side for comparison. The dermatologist or technician
would literally take a ruler and measure the length of the hair
fibers and their diameter, write all the measurements down by hand,
and then calculate the average hair growth rates and so on. While
this give a lot of accurate data, to produce it is very time consuming
and therefore expensive. As a result the phototrichogram has not
been commonly available in the general dermatology clinic, but dermatologists
have been aware that some similar system is urgently required. For
many years it has been the holy grail of phototrichology to develop
a computerized, automated phototrichogram system to define hair
growth that can be quickly applied in the general dermatology clinic.
 In
2001 a step forward was taken with the development of a phototrichogram
technique named "Trichoscan". This commercial system is
a fully computerized phototrichogram approach. The principle is
the same as the original phototrichogram A small spot on the scalp
is shaved and photos are taken, but this time with a digital close-up
camera. Another photo is taken of the same spot 3-5 days later.
These two photographs are then examined by a software system that
is able to recognize individual hair fibers in the photographs.
Once the computer can see which bits of the photographs are hair
fibers it can measure their size and shape and by comparing the
two photographs the computer can work out which hairs are growing
and which are not. This may sound simple, but actually the software
to make this possible is very complex and took a long time to develop.
Over the past couple of years the Trichoscan system has been reduced
down to a simple package of a digital camera with a special close
up attachment and software that will run on a personal computer.
Although it has only recently come on to the market, it has become
quite popular with dermatologists in Europe and the whole package
can be bought on the Internet (http://www.trichoscan.com).
So far Trichoscan is the only fully computerized phototrichogram
system commercially available, but competing systems are being developed.
Trichogram
references
- Hoffmann R.
TrichoScan: a novel tool for the analysis of hair growth in vivo.
J Investig Dermatol Symp Proc. 2003 Jun;8(1):109-15.
- D'Amico D,
Vaccaro M, Guarneri F, Borgia F, Cannavo S, Guarneri B. Phototrichogram
using videomicroscopy: a useful technique in the evaluation of
scalp hair. Eur J Dermatol. 2001 Jan-Feb;11(1):17-20.
- Hoffmann R.
TrichoScan: combining epiluminescence microscopy with digital
image analysis for the measurement of hair growth in vivo. Eur
J Dermatol. 2001 Jul-Aug;11(4):362-8.
- Chamberlain AJ, Dawber RP. Methods of evaluating
hair growth. Australas J Dermatol. 2003 Feb;44(1):10-8.
- Van Neste D, Leroy T, Sandraps E. Validation
and clinical relevance of a novel scalp coverage scoring method.
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clinical relevance of hair growth evaluation methods. Clin Exp
Dermatol. 2002 Jul;27(5):358-65.
- Van Neste DJ. Contrast enhanced phototrichogram
(CE-PTG): an improved non-invasive technique for measurement of
scalp hair dynamics in androgenetic alopecia--validation study
with histology after transverse sectioning of scalp biopsies.
Eur J Dermatol. 2001 Jul-Aug;11(4):326-31.
- Barth JH, Rushton DH. Measurement of hair
growth. In: Serud J, Jemec GBE, eds. Non-invasive methods and
the skin, vol. 1. Ann Arbor, CRC Press, 1995: 543-8.
- Van Neste DJ, de Brouwer B, De Coster W.
The phototrichogram: analysis of some technical factors of variation.
Skin Pharmacol. 1994;7(1-2):67-72.
- Rushton DH, de Brouwer B, de Coster W,
van Neste DJ. Comparative evaluation of scalp hair by phototrichogram
and unit area trichogram analysis within the same subjects. Acta
Derm Venereol. 1993 Apr;73(2):150-3.
- Hayashi S, Miyamoto I, Takeda K. Measurement
of human hair growth by optical microscopy and image analysis.
Br J Dermatol. 1991 Aug;125(2):123-9.
- Friedel J, Will F, Grosshans E. [Phototrichogram.
Adaptation, standardization and applications] Ann Dermatol Venereol.
1989;116(9):629-36.
- Bouhanna P. [The tractiophototrichogram,
an objective method for evaluating hair loss] Ann Dermatol Venereol.
1988;115(6-7):759-64.
- Gibbons RD, Fiedler-Weiss VC. Computer-aided
quantification of scalp hair. Dermatol Clin. 1986 Oct;4(4):627-40.
- Guarrera M, Ciulla MP. A quantitative evaluation
of hair loss: the phototrichogramm. J Appl Cosmetol 1986;4:61-6.
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