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- Recent use of medical infrared thermography in skin neoplasmsPublication . Ricardo Vardasca, PhD, ASIS, FRPSBackground: Infrared thermal imaging captures the infrared radiation emitted by the skin surface. The thermograms contain valuable information, since the temperature distribution can be used to characterize physiological anomalies. Thus, the use of infrared thermal imaging (IRT) has been studied as a possible medical tool to aid in the diagnosis of skin oncological lesions. The aim of this review is to assess the current state of the applications of IRT in skin neoplasm identification and characterization. Methods: A literature survey was conducted using the reference bibliographic databases: Scopus, PubMed and ISI Web of Science. Keywords (thermography, infrared imaging, thermal imaging and skin cancer) were combined and its presence was verified at the title and abstract of the article or as a main topic. Only articles published after 2013 were considered during this search. Results: In total, 55 articles were encountered, resulting in 14 publications for revision after applying the exclusion criteria. It was denoted that IRT have been used to characterize and distinguish between malignant and benign neoplasms and different skin cancer types. IRT has also been successfully applied in the treatment evaluation of these types of lesions. Conclusion: Trends and future challenges have been established to improve the application of IRT in this field, disclosing that dynamic thermography is a promising tool for early identification of oncological skin conditions.
- A case study on dynamic thermal imaging evaluation of a thyroid nodulePublication . Ricardo Vardasca, PhD, ASIS, FRPSBACKGROUND:The thyroid gland is a butterfly-shaped organ located in the neck anteriorly to the larynx and trachea, typically extending from the level of C5-T1. It is responsible for the release of hormones that control metabolic rates and thereby modifying obligatory and adaptive thermogenesis. This organ can be affected by nodules and cellular malforma- tions, which can result in malignant neoplasia or benign cysts. Those manifestations may change the normal pattern of skin temperature distribution in the affected area. The aim of this study is to investigate the thermal pattern of a subject presenting a hypervascularized nodule located on the left side of the thyroid. MATERIALS AND METHODS: A male with 40 years old presenting a 11x6 mm nodule in the left side of his thyroid, con- firmed by functional doppler imaging, was examined in a controlled environment using a FLIR E60 thermal camera and two aluminium disks to provide a cooling provocation during one minute on the skin, above the thyroid gland location. Thermal images were taken before and until the fifth minute after cooling at an interval of 1 minute. A 26x26 pixel square region of interest (ROI) was drawn in the analysis software to statistically analyze the temperature values, histogram, mean, median and mode temperature, standard deviation, kurtosis and skewness per ROI and side. RESULTS:The ROI presented at baseline a bilateral difference in mean temperature of 0.4 ºC, after cooling this difference was accentuated, the affected side recovered quickly and showed a hot spot in the area of the nodule identified by Doppler imaging. CONCLUSION:This case study showed evidence of the utility on using dynamic infrared thermal imaging when assess ing thyroid nodules, which was confirmed by Doppler imaging to be highly vascularized. However, for diagnostic pur poses the traditional expensive methods such as biopsy and nuclear medicine are still required. Still the application of IRT imaging should be further researched in possible monitoring and documenting the diagnosis and treatment evaluation applied to thyroid conditions.
- Recent application of infrared thermography in work-related musculoskeletal disordersPublication . Ricardo Vardasca, PhD, ASIS, FRPSThe burden of work-related musculoskeletal disorders is an important problem in the occupational setting. New techniques to quantify the exposure to risk factors are important to understand possible pathophysiological mechanisms that may lead to the development of these disorders. Existing methods have known limitations and new approaches are required. Work-related musculoskeletal disorders have been associated with blood flow impairments. Skin temperature is influenced by blood flow and might be an interesting parameter in their management. Thermography is a simple way to record skin temperature and produces a thermal map of the evaluated body part. A literature review was conducted in order to analyze the recent applications of thermal imaging in the management of work-related musculoskeletal disorders.
- Biomedical musculoskeletal applications of infrared thermal imaging on arm and forearm: A systematic reviewPublication . Ricardo Vardasca, PhD, ASIS, FRPSInfrared thermal imaging (IRT) has been a target of research for biomedical musculoskeletal applications, due to the possible association of the physiological data that it provides, through skin temperature measurement, with pathological states. The aim of this systematic review is to acquaint the outcomes of the biomedical application of IRT in arm and forearm evaluation and its future perspectives of research. During the literature review, 926 articles were identified using the search engines PubMed and Scopus, and 10 articles were retrieved from other sources. After screening the abstracts and applying the eligibility criteria on those which were fully accessible, 33 articles were included in the review. It can be observed that IRT has the potential to provide physiological information on the arm and forearm, showing potential to serve as an aid in various pathologies and health situations. Future studies and challenges are identified and proposed, facilitating the improvement and acceptance of the application of IRT in the assessment of arm and forearm’ health status.
- Bilateral comparison of forearm skin temperature during handgrip force exercisePublication . Ricardo Vardasca, PhD, ASIS, FRPSHandgrip force (HGF) test has been used to provide important occupational health information about subject’s nutritional and physiological condition. Handgrip force (average and maximum) and exercise accumulated work can be measured using a dynamometer connected to a computer, other physiological energy spent in the HGF test can be obtained with infrared thermal (IRT) imaging at the anterior forearm region. A protocol has been developed combining both measurements, showing correlations between the measured values and the degrees of similarity between bilateral limbs was assessed, varying at maximum of 1.6 ºC in the considered thermal regions of interest of the forearm. The obtained results on 13 subjects at three different endurance HGF tests showed that the procedure is reproducible and can be applied in both limbs for physiological assessments in occupational, rehabilitation or geriatric contexts.
- Bilateral assessment of body core temperature through axillar, tympanic and inner canthi thermometers in a young populationPublication . Ricardo Vardasca, PhD, ASIS, FRPSThere are several sites in which the human body core temperature can be estimated and used to identify febrile states in a threat of pandemic situations at high-populational-traffic places (e.g. airports, ports, universities, schools, public buildings). In these locations, a fast method is required for temperature screening of masses. The most common methods are axillar and tympanic thermometers. However, in addition, measurement of the inner canthi (IC) of the eye with infrared thermal (IRT) imaging has been suggested as a fast mass measurement screening tool. Objective: It is the aim of this research to identify the bilateral difference of the available body temperature screening methods with potential use for large-scale fever screening and to verify if such a difference is acceptable. Approach: A total of 206 young participants (104 females and 102 males) were recruited, having their temperatures taken with the different methods bilaterally under neutral environmental conditions. The obtained results were statistically processed. Main results: Results established absent reference data for site and method in west European populations. The bilateral differences were minor using the IC of the eye monitored with infrared imaging, which was also proved with the Bland–Altmann limits of agreement. Significance: Based on the findings of this research, despite all methods being able to estimate body core temperature, it is suggested to use IRT images of the IC of the eye, due to its fast, reliable and reproducible procedure for mass screening. Further research is required to understand the higher bilateral variability in using the traditional thermometer axilla and tympanic membrane assessments, since these are the methods currently used within a clinical setup. The same procedure must be applied to fever cases to establish a decision threshold per method.
- Comparison of Different Image Enhancing Techniques for Medical Thermal ImagesPublication . Ricardo Vardasca, PhD, ASIS, FRPSMedical infrared (IR) images are, like other medical images, sensitive to noise, which affects directly the temperature measurement of the subject. There are several noise removal techniques that have good performance on digital images, but may produce different temperature readings on thermal images. Hundred and twenty different noisy images were selected from a database and after being processed with several noise removal techniques, the result was statistically analyzed using the standard parameters: maximum, minimum and mean temperature, standard deviation of same region of interest, root mean square error, signal to noise ratio, cross correlation coefficient. In the end, all techniques were compared and graded according with the results. This investigation shows that all techniques produce different results, the recommended method for improving medical thermal images are the Median, Mean and Wiener filters. Results however suggest that noise filtering should only be applied when specifically needed.
- Thermographic differences due to dynamic work tasks on individuals with different obesity levels: a preliminary studyPublication . Ricardo Vardasca, PhD, ASIS, FRPSObesity has been identified as a potential risk factor for Work-Related Musculoskeletal Disorders (WRMSD). However, literature shows that more studies are required about obesity effects on work performance, including during lifting tasks. Infrared Thermography (IRT) has been emerged as an alternative technique to study WRMSD risk factors. Therefore, the current study aims at testing whether skin temperatures (Tskin) changes are sensitive to work conditions during lifting tasks. The second goal of this work is to analyse possible differences in Tskin changes across individuals with different obesity levels. By applying IRT imaging this study considered 29 participants with different obesity levels, for a repetitive lifting task between floor and shoulders height with a periodicity of 7 seconds up to 2 minutes. Thermal images were registered across 16 Regions Of Interest (ROI) (divided into body anterior and posterior views). Data analysis was performed from the temperatures differential, calculated as the algebric difference between Tskin measured before and after the task. This Tskin difference presented statistical evidence (p < 0.05 for all ROI), with a decrease after the task. The average Tskin decrease of the 8 ROI for anterior view was 0.33(±0.08)ºC and for posterior view was 0.51(±0.08)ºC, being an indicator of muscular overload increased. Results show a relation between the obese participants and the presence of higher cooling in the ROI studied, following the lifting task. These outcomes corroborate that obesity is a WRMSD risk factor and also provides evidence that IRT can be a useful tool to assess the participants’ biomechanics performance.
- Comparison of machine learning strategies for infrared thermography of skin cancerPublication . Ricardo Vardasca, PhD, ASIS, FRPSObjective: The aim of this work was to explore the potential of infrared thermal imaging as an aiding tool for the diagnosis of skin cancer lesions, using artificial intelligence methods. Methods: Thermal parameters of skin tumours were retrieved from thermograms and used as input features for two machine learning based strategies: ensemble learning and deep learning. Results: The deep learning strategy outperformed the ensemble learning one, showing good predictive performance for the differentiation of melanoma and nevi (Precision=0.9665, Recall=0.9411, f1-score=0.9536, ROC(AUC)=0.9185) and melanoma and non-melanoma skin cancer (Precision=0.9259, Recall=0.8852, f1-score=0.9051, ROC(AUC)=0.901). Conclusion: IRT imaging combined with deep learning techniques is promising for simplifying and accelerating the diagnosis of skin cancer. Significance: Despite ongoing awareness campaigns for skin cancer’ risk factors, its incidence rate has continuously been growing worldwide, becoming a major public health issue. The standard first detection method – dermoscopy –, is largely experience-dependent and mostly used to assess melanocytic lesions. As infrared thermal imaging is an innocuous imaging technique that maps skin surface temperature, which may be associated to pathological states, e.g., tumorous lesions, it could be a potential aiding tool for all skin cancer conditions. The application of artificial intelligence methods to process the collected temperature data can save time and assist health care professionals with low experience levels in the diagnosis task. To the best of our knowledge, this is the first study where a data set of skin cancer thermograms is expanded and used for skin lesion differentiation with a deep learning approach.
- Relationship between skin temperature and soft tissue hardness in diabetic patients: an exploratory studyPublication . Ricardo Vardasca, PhD, ASIS, FRPSObjective: The role of skin temperature and soft tissue hardness in the development of plantar ulcers is still in debate. However, the relationship between skin temperature and soft tissue hardness has not been explored. This study intends to analyse an eventual association between skin temperature and soft tissue hardness in the foot of diabetic patients Approach: Twenty diabetic patients enrolled for this study. The analysis was done at the foot level, therefore, skin temperature and soft tissue hardness data of the plantar surface of 40 feet were obtained in eight regions of the foot, two in the heel, two in the midfoot, three in the forefoot and one in the hallux. Information regarding glycaemic control (HbA1c levels) was retrieved from the clinical records of the patients. Main results: After averaging skin temperature and soft tissue hardness in the calcaneum (medial and lateral), in the midfoot (medial and lateral) and in the metatarsal head (1st, 2nd–3rd and 4th–5th), a negative, moderate and significant association was found between skin temperature and soft tissue hardness in the metatarsal head (rho = −0.553; p < 0.001), a positive, low and significant association was found in the midfoot (rho = 0.333; p = 0.036), but no association was found in the heel. The multiple linear regression models with skin temperature as dependent variable and soft tissue hardness as predictor were statistically significant in the metatarsal heads and midfoot, and explained 28.8% (R2 = 0.288, F(1,38) = 15.37, p < 0.001) and 11.9% (R2 = 0.119, F(1,38) = 5.151, p = 0.029) of the variance in skin temperature, respectively. Significance: Skin temperature is negatively associated with soft tissue hardness in the metatarsal head region and positively associated with soft tissue hardness in the midfoot. These findings imply that soft tissue hardness should be considered in the assessment of diabetic foot patients and that this variable should be controlled in studies assessing the determinants of foot skin temperature.