Cheng-Jen Chang

Pilot study examining the combined use of pulsed dye laser and topical Imiquimod versus laser alone for treatment of port wine stain birthmarks

The objective of this study was to improve port wine stain (PWS) therapeutic outcome in response to laser therapy. Our specific aim was to determine whether the combined use of pulsed dye laser (PDL) therapy and topical Imiquimod versus PDL alone can improve PWS therapeutic outcome.

In vitro and in vivo photosensitizing capabilities of 5-ALA versus Photofrin® in vascular endothelial cells

The objective of the present study was to evaluate the feasibility of photodynamic therapy (PDT) for complicated hemangiomas. The photosensitizing activities of 5‐aminolevulinic acid (5‐ALA) and Photofrin® were evaluated in vitro with human dermal microvascular endothelial cells (MEC) and in vivo with the chicken cox comb.

Chimeric autologous costal cartilage graft to prevent warping.

Background: Carved autologous costal cartilage is widely used in different rhinoplasty procedures because of its availability and proven advantages. However, the usefulness of rib grafts is limited by warping postoperatively. The chimeric autologous costal cartilage graft is proposed. “Chimeric” means the combining of two different tissues (bone and cartilage in this case) to make a single dorsal onlay graft. Methods: From October of 2010 to August of 2013, 31 patients underwent rhinoplasty or nasal reconstruction with costal cartilage graft using the chimeric autologous costal graft method. There were 14 men and 17 women, with ages ranging from 20 to 66 years (average, 33 years). Of the 31 patients, there were 12 with congenital nasal deformities, six with previous nasal trauma, eight with aesthetic rhinoplasty (four with primary rhinoplasty and four with secondary rhinoplasty), and five with nasal deformities after tumor extirpation. Patients’ profiles were documented and photographed. The outcomes were assessed by three plastic surgeons. Results: Follow-up for all patients was 4 to 30 months (average, 14 months). No cartilage warping was noted during the follow-up period. Two patients suffered from minor infection 2 weeks postoperatively. The average operative time for carving cartilage was 10 minutes. The overall average time of making a chimeric autologous costal onlay graft added approximately 20 minutes to the original method. Conclusion: From the clinical observation of all patients during the follow-up period, the chimeric autologous costal cartilage graft was shown to be effective for preventing cartilage warping. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Cryogen spray cooling for spatially selective photocoagulation: a feasibility study with potential application for treatment of hemangiomas

The clinical objective in laser treatment of hemangiomas is to photocoagulate the dilated cutaneous blood vessels, while at the same time minimizing nonspecific thermal injury to the overlying epidermis. We present an in-vivo experimental procedure, using a chicken comb animal model, and an infrared feedback system to deliver repetitive cryogen spurts during continuous Nd:YAG laser irradiation. Gross and histologic observations are consistent with calculated thicknesses of protected and damaged tissues, and demonstrate the feasibility of inducing spatially selective photocoagulation when using cryogen spray cooling in conjunction with laser irradiation. Experimental observation of epidermal protection in the chicken comb model suggests selective photocoagulation of subsurface targeted blood vessels for successful treatment of hemangiomas can be achieved by repetitive applications of a cryogen spurt during continuous Nd:YAG laser irradiation.

Effects of thermal energy accumulations of multi-point heat sources in laser cosmetic surgery:

Thermal energy must be properly controlled to avoid the extensive thermal damage of the normal bio tissue during the medical laser therapy. In the process of the laser surgery, laser heat sources may apply as the multiple-points around the specific target that the distance among these multiple-points are very close. The thermal energies may accumulate due to the effects of the interactions among these multiple heat points. The thermal damage of normal bio tissue may be earlier than the traditional estimation using the single damage criterion. Thus, the aim of this paper presents the safety criteria for the distance among the multiple-points of the laser source applied. In this study, laser heat source at the specific point is also considered as Gaussian distributions and simulated as the double ellipsoid function. The bio-heat transfer finite element methodology considering the interactions among multiple laser heat sources is successfully developed herein.

Thermal distribution and response in Q-switched ruby laser treatment for oculodermal melanosis (Nevus of Ota)

1Department of Plastic Surgery, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan 333, Taipei, China. 2Department of Plastic Surgery, Taipei Medical University Hospital, Taipei 110, Taipei, China. 3Department of Applied Mathematics, National Chung Hsing University, Taichung 402, Taipei, China. 4Department of Mechanical Engineering, Lunghwa University of Science and Technology, Taoyuan 333, Taipei, China.