What is DHI (Direct Hair Implantation)?

DHI (Direct Hair Implantation) is a hair transplant technique where extracted follicular units are loaded into a specialised hollow-tipped implanter device — the CHOI pen (named after Dr. Choi of Kyungpook National University, Korea) — and placed directly into the recipient area without the need to create separate recipient channels beforehand.

In standard FUE (including Sapphire FUE), the process has two distinct steps: first, channels are created across the recipient area using blades or needles; then grafts are implanted into those pre-made channels. In DHI, these two steps are combined into one — the CHOI pen both creates the opening and deposits the graft simultaneously. This eliminates the gap between channel creation and implantation, reducing graft time-out-of-body and improving survival rates.

DHI's unique capability to be performed without pre-shaving the recipient area makes it the technique of choice for women and for men who want the procedure to remain discreet during recovery.

No shave
Recipient area not shaved
CHOI pen
Precision implanter device
Higher
Graft survival vs standard FUE

How the CHOI Implanter Pen Works

The CHOI pen is a hollow-tipped, spring-loaded instrument with a very fine needle (0.8–1.0mm outer diameter) at the tip. Here's the implantation process:

  1. An extracted graft is loaded into the hollow tip of the CHOI pen by a skilled technician under magnification — the graft slides in hair-first with the root end seated in the needle.
  2. Dr. Ashwini positions the pen at the precise angle and depth for that specific graft's intended location on the scalp.
  3. The pen tip penetrates the scalp skin to the calibrated depth, simultaneously creating a micro-opening.
  4. The pen's spring-loaded plunger is activated — ejecting the graft directly into the dermis at the perfect depth, angle, and direction in a single motion.
  5. The pen is withdrawn, leaving the graft perfectly seated in its new location.

This process is repeated thousands of times across the session — each graft individually loaded, positioned, and implanted with precision. Multiple CHOI pens of different tip sizes are used to match the diameter of each graft to the appropriate pen.

DHI Advantages Over Standard FUE

  • No pre-made channels required: Eliminates the separate channel-creation step. The pen creates the opening and deposits the graft in one motion — reducing total procedure time and the window during which the recipient area is an open wound.
  • No shaving of the recipient area: Because DHI doesn't require creating channels in advance (which requires a shaved surface for visibility), the recipient area can remain unshaved. Only the donor area requires minimal trimming. This makes DHI ideal for women and men who wish to avoid shaving.
  • Reduced graft out-of-body time: In standard FUE, grafts may be stored for hours between extraction and implantation while channels are created. DHI shortens this window — grafts are loaded into pens almost immediately after extraction and implanted without delay, improving viability.
  • Precise angle and direction control: The CHOI pen allows extremely precise control of the implantation angle (typically 30–45° for scalp, 10–15° for hairline and eyebrows) and direction — arguably superior to forceps placement into pre-made channels.
  • Density addition in existing hair: DHI allows grafts to be placed precisely between existing hair follicles without disturbing them — ideal for adding density within partially hair-bearing areas. With standard FUE channels, surrounding native follicles may be at risk from the channel creation process.

DHI Limitations vs Sapphire FUE

  • Slower procedure: Loading each graft individually into a CHOI pen is more time-consuming than placing grafts into pre-made channels. DHI sessions take longer per graft — typically making mega sessions (4,000+ grafts) more challenging in a single day.
  • Maximum density per area may be lower: Pre-made channels (particularly with sapphire blades) can be placed at very high density in a planned, systematic way. DHI placement, while precise, may achieve slightly lower maximum density in small areas due to the simultaneous creation-and-implantation approach.
  • Higher technique dependency: Optimal DHI results depend heavily on graft loading quality (a skilled technician is essential) and the surgeon's consistency in maintaining angle and direction through thousands of placements.
💡 Combined Approach at Sapphire Roots

Dr. Ashwini often uses a combined Sapphire FUE + DHI approach: Sapphire FUE for the main bald coverage area (where large-scale, systematic channel creation and density packing is most efficient), and DHI with CHOI pen for the hairline zone (where maximum precision and naturalness of the frontal edge is paramount). This combination leverages the strengths of both techniques.

Who DHI is Best For

  • Women with female pattern hair loss: No shaving of the recipient area — existing hair conceals the procedure throughout recovery. DHI is the gold standard technique for female hair transplant at Sapphire Roots.
  • Men who cannot shave their head: Professionals or those in environments where a shaved head would be inappropriate. DHI allows the procedure to be performed with existing hair length largely intact.
  • Density addition to partially hair-bearing areas: Norwood II–IV men who still have significant existing hair in the thinning zone — DHI adds grafts between existing hairs without disrupting them.
  • Hairline zone precision: The finest, most precise hairline edges — where individual 1-hair graft placement at acute angles is critical — are often best achieved with the CHOI pen.
  • Eyebrow and beard transplant: The ultra-precise angle control of DHI is particularly valuable for facial hair transplant where exact implantation direction is critical to natural results.

Frequently Asked Questions

How is DHI different from FUE?
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In both DHI and FUE, follicular units are extracted one-by-one from the donor zone using a micro-punch — this extraction step is identical. The difference is in the implantation step. FUE creates recipient channels first (with blades or needles), then implants grafts into those channels. DHI uses the CHOI pen to create the channel and deposit the graft simultaneously — eliminating the pre-channel step and enabling no-shave procedures.
Can I choose DHI even if I am male?
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Absolutely. Many male patients prefer DHI to avoid having to shave their head, or specifically for the density-addition advantages in partially hair-bearing areas. Dr. Ashwini will recommend the technique (or combination of techniques) best suited to your specific coverage needs and goals — DHI is always an option for male patients at Sapphire Roots.
Is DHI more expensive than FUE?
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DHI typically carries a modest premium over standard FUE — reflecting the additional time, specialised CHOI pen instruments, and technical complexity. However, the price difference at Sapphire Roots is transparent and clearly communicated during consultation. For many patients — particularly women — the no-shave benefit alone makes DHI the clear preferred choice regardless of the modest cost difference.