ABSTRACT
Smartphones are now integral to many telehealth services that provide remote patients with an improved diagnostic standard of care. The ongoing management of burn wounds and scars is one area in which telehealth has been adopted, using video and photography to assess the repair process over time. However, a current limitation is the inability to evaluate scar stiffness objectively and repeatedly: an essential measurement for classifying the degree of inflammation and fibrosis. Optical elastography detects mechanical contrast on a micrometer- to millimeter-scale, however, typically requires expensive optics and bulky imaging systems, making it prohibitive for wide-spread adoption in telehealth. More recently, a new variant of optical elastography, camera-based optical palpation, has demonstrated the capability to perform elastography at low cost using a standard digital camera. In this paper, we propose smartphone-based optical palpation, adapting camera-based optical palpation by utilizing a commercially available smartphone camera to provide sub-millimeter resolution imaging of mechanical contrast in scar tissue in a form factor that is amenable to telehealth. We first validate this technique on a silicone phantom containing a 5 × 5 × 1 mm3 embedded inclusion, demonstrating comparative image quality between mounted and handheld implementations. We then demonstrate preliminary in vivo smartphone-based optical palpation by imaging a region of healthy skin and two scars on a burns patient, showing clear mechanical contrast between regions of scar tissue and healthy tissue. This study represents the first implementation of elastography on a smartphone device, extending the potential application of elastography to telehealth.
ABSTRACT
BACKGROUND: Ultrasound elastography is an imaging technology which can objectively and non-invasively assess tissue stiffness. It is emerging as a useful marker for disease diagnosis, progression and treatment efficacy. OBJECTIVE: To examine current, published research evaluating the use of ultrasound elastography for the measurement of cutaneous or subcutaneous stiffness and to determine the level of validity and reliability, recommended methodologies and limitations. METHODS: MEDLINE, Web of science and Scopus were systematically searched in August 2016 to identify original articles evaluating the use of ultrasound elastography to assess cutaneous stiffness. Relevant studies were then quality evaluated using the Quality Assessment of Diagnostic Accuracy Studies v 2 (QUADAS-2) tool and the Quality Appraisal of Reliability Studies (QAREL). RESULTS: From a total of 688 articles, 14 met the inclusion criteria for full review. Within the 14 studies, elastography was used to evaluate tumors, systemic sclerosis, lymphedema, abscess, and post-radiation neck fibrosis. Only three robust studies demonstrated good interrater reliability, whereas all validity studies had low sample sizes and demonstrated risks of bias. CONCLUSION: Robust evidence supporting the use of ultrasound elastography as a diagnostic tool in cutaneous conditions is low, however, initial indicators support further research to establish the utility of ultrasound elastography in dermatology.
ABSTRACT
INTRODUCTION: Scarring is a significant consequence for patients following a burn. Understanding how patients perceive the physiological scar and define scar severity may provide valuable information regarding how the scar influences quality of life after burn. The Patient and Observer Scar Assessment Scale was the first scar assessment tool validated to include the patients' evaluation of the scars physical qualities, following a burn. Validation studies of this tool have previously been conducted for a discrete scar-site after burn. The aim of this study was to assess the structural validity of the POSAS to capture the patients' evaluation of the total area of burn scar(s). METHOD: Statistical analysis was based on 508 completed POSAS forms from 358 patients. Exploratory factor analysis (EFA) was used initially to identify the number of factors within the tool, then confirmatory factor analysis (CFA) using structural equation modelling explored areas of misfit within each factor and whether the model provided a predicable structure to capture patient perception of scar severity. RESULTS/DISCUSSION: The CFA analysis confirmed that a two dimensional model was superior to a unidimensional model when assessing the patient opinion of their total burn scar. The two dimensions were the physical scar (color, stiffness, thickness and irregularity) and the sensory scar (pain and itch). Further strain analysis of the two factor model identified additional domains. Independent factors influenced the perception of color forming a separate subdomain within the physical domain. Color is a visual characteristic, whereas the other three are predominantly tactile characteristics. A significant relationship between thickness and irregularity suggested they may form another subdomain, however further research is required to confirm this. Both pain and itch were recognized as independent, multidimensional latent variables, which require assessment tools with multidimensional structures. CONCLUSIONS: When assessing the entire burn scar, three independent dimensions influence patient perception: (1) the physical scar, (2) pain and (3) itch. Within the physical domain, color formed a visual subdomain separate to a tactile subdomain. Further development of these domains within a high-order multi-dimensional structure is recommended.
