DHI performs the alopecia test prior to the hair transplantation. The test is done through certain software on the PC and with the use of a micro camera. A number of photos from the donor area as well as from the recipient area are taken with the micro camera in order to estimate the local hair density. We also estimate the percentage of the telogen hairs at the donor area as well as the quality and the type of the scalp skin.
In the donor area it is easy to count the exact number of hairs per cm2 thus to calculate the total existing hairs. In the process we can calculate the life time hairs that we can extract from this donor area as follows: total existing hairs of the donor area – 70 hairs X donor area = life time hairs that can be extracted from the donor area. (70hairs per cm2 is the least density that should stay in place in the donor area so that it does no show problematically harvested).
Apart from the total donor area’s density, it is also easy to estimate the presence of multiple hair follicles since we can actually see them. This way we can calculate the possible extraction ratio which is hairs / follicles.
In the process we can estimate the possible hair density that we could achieve after the hair implantation by having always in mind that in one session we can extract up to 30% of the existing hairs of the donor area and that the max safe hair implantation on naked skin, is up to 40grafts per cm2 in one session. These numbers of course appeal to ideal conditions and they differ in case of repeatable sessions or poor donor areas. If the patient desires higher density and there is medically indication for that (according to his age, the grade of alopecia and the possible development of his alopecia based on his family history on androgenetic alopecia), we can increase density in a second session.
Let’s point out that all the estimations-calculations concerning implantation density and extraction ratio based on the alopecia test, even if they are mathematically properly done, yet they may not be the final ones. The actual extraction ratio is finally calculated only once the doctor has started the extraction and within the first 20-30 minutes of the procedure. We should also point out that it is more preferable to have satisfying number of hairs along with a satisfying number of grafts in order to achieve satisfying hair density along with satisfying skin coverage.