Statistical Study on Human Temperature Measurement by Infrared Thermography.

Increased temperature in humans is the symptom of many infectious diseases and it is thus an important diagnostic tool. Infrared temperature measurement methods have been developed and applied over long periods due to their advantage of non-contact and fast measurements. This study deals with a statistical evaluation of the possibilities and limitations of infrared/thermographic human temperature measurement. A short review of the use of infrared temperature measurement in medical applications is provided. Experiments and statistics-based evaluation to confirm the expected accuracy and limits of thermography-based human temperature measurement are introduced. The results presented in this study show that the standard deviation of the thermographic measurement of the eyes maximum temperature was 0.4-0.9 °C and the mean values differences from the armpit measurement were up to 0.5 °C, based on the used IR camera, even though near ideal measurement conditions and permanent blackbody correction were used. It was also shown that a certain number of outliers must be assumed in such measurements. Extended analyses including simulations of true negative/false positive, sensitivity/specificity and receiver operating characteristics (ROC) curves are presented. The statistical evaluation as well as the extended analyses show that maximum eyes temperature is more relevant than a forehead temperature examination.

Anatomical 3D Modeling Using IR Sensors and Radiometric Processing Based on Structure from Motion: Towards a Tool for the Diabetic Foot Diagnosis.

Medical infrared thermography has proven to be a complementary procedure to physiological disorders, such as the diabetic foot. However, the technique remains essentially based on 2D images that display partial anatomy. In this context, a 3D thermal model provides improved visualization and faster inspection. This paper presents a 3D reconstruction method associated with temperature information. The proposed solution is based on a Structure from Motion and Multi-view Stereo approach, exploiting a set of multimodal merged images. The infrared images were obtained by automatically processing the radiometric data to remove thermal interferences, segment the RoI, enhance false-color contrast, and for multimodal co-registration under a controlled environment and a ∆T < 2.6% between the RoI and thermal interferences. The geometric verification accuracy was 77% ± 2%. Moreover, a normalized error was adjusted per sample based on a linear model to compensate for the curvature emissivity (error ≈ 10% near to 90°). The 3D models were displayed with temperature information and interaction controls to observe any point of view. The temperature sidebar values were assigned with information retrieved only from the RoI. The results have proven the feasibility of the 3D multimodal construction to be used as a promising tool in the diagnosis of diabetic foot.

Evaluation of dynamic infrared thermography as an alternative to CT angiography for perforator mapping in breast reconstruction: a clinical study.

BACKGROUND: The current gold standard for preoperative perforator mapping in breast reconstruction with a DIEP flap is CT angiography (CTA). Dynamic infrared thermography (DIRT) is an imaging method that does not require ionizing radiation or contrast injection. We evaluated if DIRT could be an alternative to CTA in perforator mapping. METHODS: Twenty-five patients scheduled for secondary breast reconstruction with a DIEP flap were included. Preoperatively, the lower abdomen was examined with hand-held Doppler, DIRT and CTA. Arterial Doppler sound locations were marked on the skin. DIRT examination involved rewarming of the abdominal skin after a mild cold challenge. The locations of hot spots on DIRT were compared with the arterial Doppler sound locations. The rate and pattern of rewarming of the hot spots were analyzed. Multiplanar CT reconstructions were used to see if hot spots were related to perforators on CTA. All flaps were based on the perforator selected with DIRT and the surgical outcome was analyzed. RESULTS: First appearing hot spots were always associated with arterial Doppler sounds and clearly visible perforators on CTA. The hot spots on DIRT images were always slightly laterally located in relation to the exit points of the associated perforators through the rectus abdominis fascia on CTA. Some periumbilical perforators were not associated with hot spots and showed communication with the superficial inferior epigastric vein on CTA. The selected perforators adequately perfused all flaps. CONCLUSION: This study confirms that perforators selected with DIRT have arterial Doppler sound, are clearly visible on CTA and provide adequate perfusion for DIEP breast reconstruction. TRIAL REGISTRATION: Retrospectively registered at ClinicalTrials.gov with identifier NCT02806518 .

Motion tracking in infrared imaging for quantitative medical diagnostic applications.

In medical applications, infrared (IR) thermography is used to detect and examine the thermal signature of skin abnormalities by quantitatively analyzing skin temperature in steady state conditions or its evolution over time, captured in an image sequence. However, during the image acquisition period, the involuntary movements of the patient are unavoidable, and such movements will undermine the accuracy of temperature measurement for any particular location on the skin. In this study, a tracking approach using a template-based algorithm is proposed, to follow the involuntary motion of the subject in the IR image sequence. The motion tacking will allow to associate a temperature evolution to each spatial location on the body while the body moves relative to the image frame. The affine transformation model is adopted to estimate the motion parameters of the template image. The Lucas-Kanade algorithm is applied to search for the optimized parameters of the affine transformation. A weighting mask is incorporated into the algorithm to ensure its tracking robustness. To evaluate the feasibility of the tracking approach, two sets of IR image sequences with random in-plane motion were tested in our experiments. A steady-state (no heating or cooling) IR image sequence in which the skin temperature is in equilibrium with the environment was considered first. The thermal recovery IR image sequence, acquired when the skin is recovering from 60-s cooling, was the second case analyzed. By proper selection of the template image along with template update, satisfactory tracking results were obtained for both IR image sequences. The achieved tracking accuracies are promising in terms of satisfying the demands imposed by clinical applications of IR thermography.

Dataset of breast thermography images for the detection of benign and malignant masses.

Thermographic image analysis is a subfield of diagnostic image processing aimed at detecting breast abnormalities in women at an early stage. It is a developing field of research and its effectiveness and scope require scientific assessment to be determined. An open-access dataset has been created for the scientific community to test and develop techniques for computational detection of normal and abnormal breast conditions from thermograms. This dataset is a valuable resource for researchers due to the scarcity of publicly available datasets of breast thermographic images. It includes thermographic images of the female chest area in three capture positions: anterior, left oblique and right oblique. The data set comes from 119 women ranging from 18 to 81 years of age. A table is attached to the dataset with the diagnosis of breast pathology, showing that 84 patients had benign pathology and 35 patients had malignant pathology. The diagnoses of women with healthy breast pathology are not included.

Infrared Macrothermoscopy Patterns-A New Category of Dermoscopy.

(1) Background: The authors developed a new non-invasive dermatological infrared macroimaging analysis technique (MacroIR) that evaluates microvascular, inflammatory, and metabolic changes that may be dermoscopy complimentary, by analyzing different skin and mucosal lesions in a combined way-naked eye, polarized light dermatoscopy (PLD), and MacroIR-and comparing results; (2) Methods: ten cases were evaluated using a smartphone coupled with a dermatoscope and a macro lens integrated far-infrared transducer into specific software to capture and organize high-resolution images in different electromagnetic spectra, and then analyzed by a dermatologist; (3) Results: It was possible to identify and compare structures found in two dermoscopic forms. Visual anatomical changes were correlated with MacroIR and aided skin surface dermatological analysis, presenting studied area microvascular, inflammatory, and metabolic data. All MacroIR images correlated with PLD, naked eye examination, and histopathological findings; (4) Conclusion: MacroIR and clinic dermatologist concordance rates were comparable for all dermatological conditions in this study. MacroIR imaging is a promising method that can improve dermatological diseases diagnosis. The observations are preliminary and require further evaluation in larger studies.

Medical applications of infrared thermography: A review.

Abnormal body temperature is a natural indicator of illness. Infrared thermography (IRT) is a fast, passive, non-contact and non-invasive alternative to conventional clinical thermometers for monitoring body temperature. Besides, IRT can also map body surface temperature remotely. Last five decades witnessed a steady increase in the utility of thermal imaging cameras to obtain correlations between the thermal physiology and skin temperature. IRT has been successfully used in diagnosis of breast cancer, diabetes neuropathy and peripheral vascular disorders. It has also been used to detect problems associated with gynecology, kidney transplantation, dermatology, heart, neonatal physiology, fever screening and brain imaging. With the advent of modern infrared cameras, data acquisition and processing techniques, it is now possible to have real time high resolution thermographic images, which is likely to surge further research in this field. The present efforts are focused on automatic analysis of temperature distribution of regions of interest and their statistical analysis for detection of abnormalities. This critical review focuses on advances in the area of medical IRT. The basics of IRT, essential theoretical background, the procedures adopted for various measurements and applications of IRT in various medical fields are discussed in this review. Besides background information is provided for beginners for better understanding of the subject.

Evaluation of Tibia Bone Healing by Infrared Thermography: A Case Study.

BACKGROUND: Thermal imaging has been used as a clinical follow-up technique in several medical specialties. PURPOSE: The aim of this study was to investigate the feasibility of using medical thermography in the diagnosis and follow-up assessment of a severe orthopedic trauma that requires the use of an external circular fixator. PATIENTS AND METHODS: Twenty clinical follow-ups of thermal imaging correlated with X-ray images were performed in a male volunteer, diagnosed with bone nonunion, during 11 months of treatment, in the hospital trauma and reconstruction department. Data were acquired in the regions of interest of the proximal tibia, diaphysis and distal, with a Flir T530 medical grade infrared camera from Flir Systems®, and the data processed by the Matlab® 2019 custom made software. RESULTS: Statistical analysis was performed by Wilcoxon signed-rank test. The results showed a median temperature of 22.2°C, and thus some periods of interruption in the healing process between the third and twentieth clinical follow-up, and a significant increase of the temperature to 34.6°C synchronous with a diagnosis of bone infection by the eleventh clinical follow-up. The thermal images acquired during the 20 clinical follow-ups allow a correlation with the data from the X-ray exams and also with the contralateral limb of the evaluated patient, showing thermal alterations greater than 0.3°C, which are significant of physiological abnormality. CONCLUSION: The thermography exam can be a useful tool for applying on the follow-up of patients after trauma or bone fracture. The results showed important physiological data related to the vascularization necessary for bone repairing, being therefore a good indicator of the healing process. In addition, as infrared thermography does not use ionizing radiation, it can be used countlessly, in complement to the traditional X-ray exams that focus on anatomical data analysis.

Dynamic Infrared Thermography (DIRT) in DIEP flap breast reconstruction: A clinical study with a standardized measurement setup.

OBJECTIVE: Breast reconstructions with perforator flaps from the lower abdomen, commonly known as Deep Inferior Epigastric artery Perforator flap (DIEP-flap), have become the golden standard for autologous breast reconstruction after breast amputation. During this surgical procedure multiple challenging steps are encountered such as the selection of a suitable perforator that provides sufficient blood supply for the flap, surgical dissection of the chosen perforator, determination of perfusion area of the chosen perforator, microsurgical anastomosis, flap inset and shaping the flap into a breast. The current gold standard for perforator mapping is Computed Tomography Angiography (CTA). However, this is a relatively expensive imaging modality that requires intravenous contrast injection and exposes patients to ionizing radiation. More recently, Dynamic Infrared Thermography (DIRT) has been proposed as an alternative imaging modality for perforator identification. DIRT appears to be an ideal alternative technique not only for the identification of the dominant perforators, but also for the mapping of the individual influence of each perforator on the flap perfusion, to monitor integrity of the perforator after dissection and to monitor the patency of the pedicle of the free flap after the anastomosis, during flap inset and flap shaping. STUDY DESIGN: In this clinical study we present the results of the use of DIRT in 33 DIEP-flaps in 21 patients after mastectomy. The same standardized measurement set-up was used for all the flaps in the pre-, intra- and postoperative period. RESULTS: In the pre-operative period DIRT confirmed the location of the 69 perforators shown on the CTA. In the intra-operative period the rate and pattern of rewarming was successfully observed. One perforator was severely damaged during dissection and the DIEP flap was converted to a Muscle Sparing free Transverse Rectus Abdominis Muscle (TRAM) flap, after viability check of the flap by DIRT. DIRT diagnosed one kinking of the pedicle after microsurgical anastomosis. Two flaps were monitored successfully post-operatively. All 33 breast reconstructions were with good outcome. CONCLUSION: The use of DIRT with our standardized measurement setup is a useful, non-invasive tool during breast reconstructions with free DIEP-flaps in all the phases of the reconstruction (pre-, intra- and post-operative). This study confirms that DIRT with the standardized measurement setup provides information on perforator location, blood supply and patency of the anastomosis without interference with the operating surgeon.

Multiday maintenance of extracorporeal lungs using cross-circulation with conscious swine.

OBJECTIVES: Lung remains the least-utilized solid organ for transplantation. Efforts to recover donor lungs with reversible injuries using ex vivo perfusion systems are limited to <24 hours of support. Here, we demonstrate the feasibility of extending normothermic extracorporeal lung support to 4 days using cross-circulation with conscious swine. METHODS: A swine behavioral training program and custom enclosure were developed to enable multiday cross-circulation between extracorporeal lungs and recipient swine. Lungs were ventilated and perfused in a normothermic chamber for 4 days. Longitudinal analyses of extracorporeal lungs (ie, functional assessments, multiscale imaging, cytokine quantification, and cellular assays) and recipient swine (eg, vital signs and blood and tissue analyses) were performed. RESULTS: Throughout 4 days of normothermic support, extracorporeal lung function was maintained (arterial oxygen tension/inspired oxygen fraction >400 mm Hg; compliance >20 mL/cm H2O), and recipient swine were hemodynamically stable (lactate <3 mmol/L; pH, 7.42 ± 0.05). Radiography revealed well-aerated lower lobes and consolidation in upper lobes of extracorporeal lungs, and bronchoscopy showed healthy airways without edema or secretions. In bronchoalveolar lavage fluid, granulocyte-macrophage colony-stimulating factor, interleukin (IL) 4, IL-6, and IL-10 levels increased less than 6-fold, whereas interferon gamma, IL-1α, IL-1ß, IL-1ra, IL-2, IL-8, IL-12, IL-18, and tumor necrosis factor alpha levels decreased from baseline to day 4. Histologic evaluations confirmed an intact blood-gas barrier and outstanding preservation of airway and alveolar architecture. Cellular viability and metabolism in extracorporeal lungs were confirmed after 4 days. CONCLUSIONS: We demonstrate feasibility of normothermic maintenance of extracorporeal lungs for 4 days by cross-circulation with conscious swine. Cross-circulation approaches could support the recovery of damaged lungs and enable organ bioengineering to improve transplant outcomes.

Dynamic infrared thermography (DIRT) in Deep Inferior Epigastric Perforator (DIEP) flap breast reconstruction: standardization of the measurement set-up.

Breast reconstruction with an autologous free Deep Inferior Epigastric Perforator (DIEP) flap is one of the preferred options following mastectomy. A challenging step in this procedure is the selection of a suitable perforator that provides sufficient blood supply for the flap. The current golden standard for perforator mapping is computed tomography angiography (CTA). However, this is a relatively expensive imaging modality that requires intravenous contrast injection and exposes patients to ionizing radiation. More recently, dynamic infrared thermography (DIRT) has been proposed as an alternative imaging modality for perforator identification. DIRT appears to be an ideal alternative technique not only for the identification of the dominant perforators, but also for the mapping of the individual influence of each perforator on the flap perfusion. Multiple studies have been performed with the use of DIRT, unfortunately without standardisation of the measurement set-up. In this technical note we propose a standardised and reproducible measurement set-up for the use of DIRT during breast reconstructions with a free DIEP flap. This set-up can be used pre-, intra- and postoperatively. A standardised measurement set-up will improve the quality of measured data and ensure reproducibility.

Dynamic InfraRed Thermography (DIRT) in DIEP-flap breast reconstruction: A review of the literature.

In the industrialised world still 34% of the breast cancer patients are surgically treated by a mastectomy. Breast cancer patients in general have a good prognosis and a long-term survival. Therefore, it is important that the treatment doesn't focus only on survival but also on the quality of life. Breast reconstruction improves the quality of life. A breast reconstruction with an autologous free DIEP (Deep Inferior Epigastric artery Perforator) flap is one of the preferred options after mastectomy. A challenging step in this procedure is the selection of a suitable perforator that provides sufficient blood supply for the flap. Current techniques to locate the perforator vessels include handheld Doppler, colour Doppler ultrasound (CDU), Magnetic resonance angiography (MRA), computer tomographic angiography (CTA) and dynamic infrared thermography (DIRT). At present CTA is the golden standard and DIRT a new option. The objective of this article is to document whether DIRT can accurately map the position of the perforators and measure their influence on the perfusion of the flap in order to select the best perforators to improve the outcome of breast reconstructions with free DIEP flaps. A systematic review of the literature published between January 1998 and November 23th 2018 was conducted regarding the possible benefit of dynamic infrared thermography (DIRT) in DIEP-flap breast reconstructions. The databases PubMed and Web of Science were used to search for qualified articles. Inclusion criteria were women who underwent a breast reconstruction by means of a DIEP flap where DIRT was used to analyse the blood supply of the flap. The search yielded a total of fourteen suitable articles: six articles being descriptive clinical studies, three case reports, three expert opinions/Overview articles and two systematic reviews. There are only a limited number of studies looking at the use of DIRT in breast reconstruction with DIEP-flaps. Adequate identification of the dominate vessel(s) in DIEP reconstruction is essential for a successful outcome. DIRT appears to be an ideal alternative technique for the identification of the dominant perforators of the flap. With the use of DIRT it is possible to identify the dominant vessel(s) preoperatively. The use of DIRT during the operation allows the tailoring of the surgery and postoperative use may identify vascularisation problems in an early stage. Additional high-quality studies are needed, but DIRT seems to be a valuable investigation for the pre-, per- and postoperative phase of DIEP-flap reconstructions.

The Application of Medical Thermography to Discriminate Neuroischemic Toe Ulceration in the Diabetic Foot.

This study aimed to determine whether thermal imaging can detect temperature differences between healthy feet, nonulcerated neuroischemic feet, and neuroischemic feet with toe ulcers in patients with type 2 diabetes mellitus (T2DM). Participants were prospectively divided into 3 groups: T2DM without foot problems; a healthy, nonulcerated neuroischemic group, and an ulcerated neuroischemic group. Thermal images of the feet were obtained with automated segmentation of regions of interest. Thermographic images from 43 neuroischemic feet, 21 healthy feet, and 12 neuroischemic feet with active ulcer in one of the toes were analyzed. There was a significant difference in toe temperatures between the 3 groups ( P = .001), that is, nonulcerated neuroischemic (n = 181; mean temperature = 27.7°C [±2.16 SD]) versus neuroischemic ulcerated (n = 12; mean temperature = 28.7°C [±3.23 SD]), and healthy T2DM group (n = 104; mean temperature = 24.9°C [±5.04 SD]). A post hoc analysis showed a significant difference in toe temperatures between neuroischemic nonulcerated and healthy T2DM groups ( P = .001), neuroischemic ulcerated and healthy groups ( P = .001). However, no significant differences in toe temperatures were identified between the ulcerated neuroischemic and nonulcerated neuroischemic groups ( P = .626). There were no significant differences between the ulcerated toes (n = 12) and the nonulcerated toes (n = 57) of the same foot in the ulcerated neuroischemic group ( P = .331). Toe temperatures were significantly higher in neuroischemic feet with or without ulceration compared with healthy feet in patients with T2DM. There were no significant differences in temperatures of ulcerated toes and the nonulcerated toes of the same foot, implying that all the toes of the same foot could potentially be at risk of developing complications, which can be potentially detected by infrared thermography.

The identification of higher forefoot temperatures associated with peripheral arterial disease in type 2 diabetes mellitus as detected by thermography.

AIMS: The purpose of this study was to investigate whether heat emitted from the feet of patients with type 2 diabetes (DM) and peripheral arterial disease (PAD) differed from those with type 2 diabetes without complications (DM). METHODS: A non-experimental, comparative prospective study design was employed in a tertiary referral hospital. Out of 223 randomly selected participants (430 limbs) who were initially tested, 62 limbs were categorized as DM+PAD and 22 limbs as DM without PAD. Subjects with evidence of peripheral neuropathy were excluded. Participants underwent thermographic imaging. Automatic segmentation of regions of interest extracted the temperature data. RESULTS: A significant difference in temperature in all the toes between the two groups was found (p=0.005, p=0.033, p=0.015, p=0.038 and p=0.02 for toes 1-5 respectively). The mean forefoot temperature in DM+PAD was significantly higher than that in DM (p=.019), with DM+PAD having a higher mean temperature (28.3°C) compared to DM (26.2°C). Similarly, the toes of subjects with DM+PAD were significantly warmer than those of subjects with DM only. CONCLUSIONS: Contrary to expectations the mean toe and forefoot temperatures in DM patients with PAD is higher than in those with DM only. This unexpected result could be attributed to disruption of noradrenergic vasoconstrictor thermoregulatory mechanisms with resulting increased flow through cutaneous vessels and subsequent increased heat emissivity. These results demonstrate that thermography may have potential in detecting PAD and associated temperature differences.

Medical thermography (digital infrared thermal imaging - DITI) in paediatric forearm fractures - A pilot study.

Trauma is the most common cause of hospitalisation in children, and forearm fractures comprise 35% of all paediatric fractures. One-third of forearm fractures are distal forearm fractures, which are the most common fractures in the paediatric population. This type of fracture represents an everyday problem for the paediatric surgeon. The three phases of fracture healing in paediatric trauma are associated with skin temperature changes that can be measured and then compared with standard plain radiographs of visible callus formation, and eventually these methods can be used in everyday practice. Thermographic assessment of temperature distribution within the examined tissues enables a quick, non-contact, non-invasive measurement of their temperature. Medical thermography is used as a screening method in other parts of medicine, but the use of this method in traumatology has still not been researched.

Role of medical thermography in treatment of Frey's syndrome with botulinum toxin A.

Frey syndrome classically causes gustatory sweating and facial flushing. We describe 2 cases in which medical thermography was used to investigate the symptoms. Images were taken after patients chewed a sialagogue and 2 weeks later they were given injections of botulinum toxin A. Images taken 4 weeks after treatment showed a considerable reduction in sweating and facial flushing, which was supported by the results of quality of life questionnaires completed before and after treatment. Medical thermography is much cleaner than the Minor's starch iodine test. It identifies areas of gustatory sweating, changes in temperature, and vascular changes, which potentially enable treatment to be targeted accurately.