DHI — Direct Hair Implantation — is a variation of FUE that modifies the implantation phase using a specialised device called a Choi implanter pen. Understanding how DHI differs from standard FUE helps patients make an informed choice between techniques.
The Core Difference: How Grafts Are Implanted
In standard FUE (including Sapphire FUE), the procedure involves two distinct phases for the recipient area:
- Creating the recipient channels (incisions)
- Inserting grafts into those channels
In DHI, these two steps are combined into one using the Choi implanter pen. The pen has a hollow needle at its tip. The graft is loaded into the needle, and when the surgeon presses the pen against the scalp, the needle creates a channel and simultaneously deposits the graft at the correct depth.
What Is the Choi Implanter Pen?
The Choi pen is a spring-loaded device approximately the size of a thick pen. It has a hollow, bevelled needle tip in sizes ranging from 0.6mm to 1.5mm (selected based on graft size). The graft is loaded into the needle tip with fine forceps, and the device is used to implant directly into the scalp without pre-creating an opening.
Multiple Choi pens are loaded simultaneously by an assistant, allowing the surgeon to work continuously without stopping to reload.
Claimed Advantages of DHI
Reduced time outside the body: Because grafts are implanted as they are loaded, they spend less total time outside the scalp. This theoretically reduces the ischemia time and may improve survival rates.
No pre-made channels: In standard FUE, channels are created in advance, then grafts are inserted. With DHI, the two steps are simultaneous, which may reduce the risk of channel collapse or graft misalignment.
More precise depth control: The Choi pen allows precise control over implantation depth, which is critical for natural-looking results.
Less bleeding: Because no open channels are pre-cut, some surgeons report less bleeding during the implantation phase.
Suitable for higher density: DHI is often used when transplanting into areas with existing hair, where the goal is to increase density without shaving the surrounding hair. The pen allows precise placement without the surgeon needing to visualise open channels through existing hair.
Limitations of DHI
Slower implantation: Loading and using Choi pens is more time-consuming than implanting into pre-made channels. This means DHI sessions take longer or involve fewer total grafts per session.
More expensive: The additional equipment, technique complexity, and longer surgical time make DHI more expensive than standard FUE.
Requires highly skilled team: The Choi pen is technically demanding. Results are highly dependent on the skill of the surgical team loading and using the device.
Not always superior: The claimed advantages of DHI over Sapphire FUE are debated in the literature. Both techniques can produce excellent results in skilled hands; the technique itself is less important than the skill of the surgeon.
Which Is Better: DHI or Sapphire FUE?
There is no universally correct answer. The best technique depends on the patient's specific situation:
DHI may be preferred when:
- Transplanting into areas with existing hair (avoiding shaving)
- Maximum density in a small area is the priority
- The patient has particularly fine or fragile grafts
Sapphire FUE may be preferred when:
- Large sessions (3,000+ grafts) are required
- Cost is a significant factor
- The surgeon has greater experience with Sapphire FUE
Both techniques, performed by experienced surgeons, produce comparable results in the majority of cases. At Estetİstanbul, the appropriate technique is selected based on the individual patient's pattern of loss, donor characteristics, and treatment goals.
Not sure which technique is right for you? Our team will assess your case and explain exactly which approach we recommend and why.