FUE : Is choi "pen" method is the better option when there is a lack of density to improve ?

Choi is the name of a tool used to aid implantation of follicles. The use of a tool does not necessarily improve the density of a hair transplant. If you give Picasso and an amateur artist each a paintbrush the outcome can be quite different. The same goes for a hair transplant. The fact that one surgeon uses Choi implanters and another uses just forceps is not the only factor in play. What one needs to look for real results as well as the experience of the surgeon and the team. By the way I do use Choi implanters myself as I believe it reduces trauma to follicles and improves outcomes. However, I know of many other clinics who don’t use Choi Implanters and still achieve the same level of results. 

The implantation method does not improve the lack of density. Your surgeon and the team's artistic and technical skill will ultimately determine how many grafts are implanted and your results.

Using a Choi pen does not increase density.  That is only one of the many methods used to place the grafts harvested from the donor area.  The Doctor has complete control over how your density will be based on the spacing of the recipient sites, as well as the carefulness of placing the grafts.  

DHI (choi implanter  used FUE method etc) is just a marketing gimmick.When you look at the web site of  ISHRS (international society of hair restoration surgery ) you will see just 2 tech for HT: FUT and FUE..So , DHI , percutaneus tecnique, golden punch tecnique, ıce graft FUE tecnique etc are all FUE and there is no difference or superiority between each other.What makes difference on result of hair restoration is surgeon's experience level and accuracy of used FUE technique.

The Choi Method I believe is using a hair implanter for placing grafts. There are many types of hair implanters available on the market that are equal to the Choi instruments. Implanters are an excellent way to place grafts into a recipient site