title: Histometric analysis of skin-radiofrequency interaction using a fractionated microneedle delivery system.
abstract: BACKGROUND
  Fractionated microneedle radiofrequency (RF) devices have been reported to be effective in treatment of various dermatologic disorders.
  
  
  OBJECTIVE
  To analyze histometric changes in skin-RF interactions using a fractionated microneedle delivery system.
  
  
  METHODS
  RF energies were delivered using a fractionated microneedle device to an in vivo minipig model with penetration depths of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.5 mm; RF conduction times of 20, 50, 100, and 1,000 ms; and energy levels of 5.0, 10.0, 20.0, 25.0, 37.5, and 50.0 V.
  
  
  RESULTS
  Immediately after treatment, skin samples showed that the RF-induced coagulated columns in the dermis formed a cocoon-shaped zone of sublative thermal injury. Four days after the treatment, skin specimens demonstrated reepithelialization, and the dermal RF-induced coagulated columns showed mixed cellular infiltration, neovascularization, and granulation tissue formation. Microneedle depth and RF conduction times, but not energy level, significantly affected histometric values of RF-induced dermal coagulation. Microneedle RF treatment affected adnexal structures by coagulating follicular epithelium and perifollicular structures.
  
  
  CONCLUSIONS
  Our data may be of use as an essential reference for choosing RF parameters in treatment of various skin conditions.
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea; Department of Dermatology, Yanbian University Hospital, Yanji, China.
authors.forename: Zhenlong
authors.initials: Z
authors.lastname: Zheng
authors.forename: Boncheol
authors.initials: B
authors.lastname: Goo
authors.forename: Do-Young
authors.initials: DY
authors.lastname: Kim
authors.forename: Jin-Soo
authors.initials: JS
authors.lastname: Kang
authors.forename: Sung Bin
authors.initials: SB
authors.lastname: Cho
mesh_terms: D000818:Animals; D003357:Cosmetic Techniques / Q000295:instrumentation*; D062109:Dermatologic Surgical Procedures / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D009339:Needles; D000078702:Radiofrequency Therapy; D012867:Skin / Q000528:radiation effects*; D013552:Swine; D013556:Swine, Miniature; D014945:Wound Healing