The Diagnostic Role of Optical Coherence Tomography (OCT) in Measuring the Depth of Burn and Traumatic Scars for More Accurate Laser Dosimetry: Pilot Study
November 2016 | Volume 15 | Issue 11 | Original Article | 1375 | Copyright © November 2016
Jill S.Waibel MD,a Ashley C. Rudnick,a Adam J.Wulkan MD,b and Jon D. Holmesc
aMiami Dermatology and Laser Institute, Miami, FL bUniversity of Miami, Department of Dermatology & Cutaneous Surgery, Miami, FL cMichelson Diagnostics Ltd., Maidstone, United Kingdom
Abstract
BACKGROUND: In recent decades, a number of optimal diagnostic technologies have emerged to assist in tissue visualization. Real-time monitoring of skin during laser therapies will help optimize laser parameters for more ef cient therapies. One of these technologies, optimal coherence tomography (OCT), may be used to help visualize burn and traumatic scars. When lasing severe scars, lasers have tunable pulse energies, which are made proportional to the scar thickness as estimated by palpation and the physician eye. This has historically been estimated by the clinician with no objective data. OCT is an emerging non-invasive imaging technique that provides a cross-sectional image of tissue micro-architecture from a depth of 0.7 – 1.5 mm. The signal intensity is related to the tissue optical scattering properties, which in turn is related to tissue constituents such as collagen density. Thus, OCT may provide an objective non-invasive measurement of scar depth.
STUDY: Thirty burn and traumatic scars were imaged with quality, traceable, and veri able OCT data from burn and trauma patients both pre- and post- laser therapy. OCT was rapid and ef cient (approximately 2 minutes) to scan skin to visualize real-time scar tissue in different areas of heterogenous scars. The OCT image of the scar was compared to that of normal tissue in order to identify scar tissue and estimate its depth. Laser parameters were then dialed to treat full thickness of the scar.
RESULTS: Clinical and OCT correlation between atrophic versus hypertrophic scars was found. However, in most cases the clinicians underestimated the depth of the scar in the dermis.
CONCLUSION: The treatment of burn and traumatic scars for both civilian and wounded warriors can be challenging. As these scars are often very deep, OCT allows for non-invasive examination of the thickness of the scar allowing the physician better accuracy for laser settings in the treatment for the full thickness of the scar tissue.
J Drugs Dermatol. 2016;15(11):1375-1380.
INTRODUCTION
Imaging and visualization of skin structure and function is of fundamental importance in the field of dermatology. Optimal coherence tomography (OCT) is a noninvasive diagnostic tool offering real time in vivo visualization of superficial layers of the skin up to 0.7-1.5mm in depth. Recent improvement in image resolution has caused a rapid expansion in the clinical utility of the OCT.1 OCT utilizes interference of coherent laser light to produce images similar to ultrasound. In contrast to ultrasound, OCT uses light as opposed to acoustic waves, resulting in higher resolution images, but with lower penetration.2 Within dermatology, OCT has been used in several inflammatory, vascular, and neoplastic conditions, primarily for its diagnostic capabilities. However, within laser dermatology, OCT has multiple potential applications in which OCT images might be usefully used to help both optimize laser settings, and to monitor the effects of the laser treatments for improved outcomes. OCT has been used to assess scars. Polarization-sensitive OCT has been used to detect changes of birefringence of collagen in skin, however no commercial PS-OCT scanners have been developed to exploit this.3 More recently, standard OCT has been used to assess burn scars by measuring the rate at which the OCT signal is attenuated with depth.4 It has been empirically observed that collagen is probably the dominant constituent of skin scattering the probing laser beam, producing increased response in the detected OCT signal, so that collagen-rich areas appear brighter in the OCT image than collagen-poor areas.5-6 This is also our experience in this study.Given increased survival rates following acute traumas, the incidence of severe cutaneous scars has grown rapidly over the past several years. When injury reaches a depth of 0.56 +/- 0.03, scarring can result. In addition to the cosmetic defect, many of these scars result in hypertrophy/keloid formation,
