A perspective on medical infrared imaging

Experimental Study of Spectrally Selective MEMS/Metasurface Infrared Detectors

This article reports a comprehensive statistical analysis of uncooled infrared (IR) detectors based on radio frequency (RF) aluminum nitride (AlN) contour mode resonators (CMRs) integrated with spectrally selective IR metasurfaces. Moreover, it reports the lowest noise equivalent power (NEP) recorded from these types of devices ∼ 11 p W / H z . The metasurfaces are printed on top of the AlN resonator body to decouple mechanical, RF, and IR responses. Optical lithography is used to pattern the meta-surfaces, allowing the fabrication of hundreds of spectrally selective IR detectors with different sensing performances within the same chip. An automated characterization system is employed to quickly record parameters such as quality factor, noise, and responsivity. This approach allows to experimentally determine the geometrical dimensions of quasi-optimal IR detectors that exhibit NEP in the p W / H z range and responsivities in the Hz/nW range. Additionally, the detector performance versus IR light is explored using different interrogation mechanisms, namely monitoring the CMR resonance frequency as well as the amplitude and phase of an RF signal that excites the device at resonance. The statistical analysis of hundreds of IR sensors reveals trends between parameters such quality factor and noise floor, and NEP and responsivity. These trends provide useful guidelines for the development of quasi-optimal spectrally selective IR sensors operating at room temperature.

Evaluation of the thermographic response of the lumbar region in dogs with bilateral hip osteoarthritis

Infrared thermography is suggested as a method of medical assistance for evaluating anatomical regions where there may be some inflammatory or painful condition that requires immediate medical attention. For this reason, this study aimed to characterize digital thermography of the lumbar region in police working dogs with hip osteoarthritis, 47 dogs with bilateral hip osteoarthritis were evaluated. A thermographic dorsoventral view of the dogs' backs were obtained, and mean and maximum temperatures were determined. In addition, results from the Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs (LOAD), the Canine Orthopedic Index, and weight-bearing distribution evaluation were collected. Results were compared with an Independent Samples T-Test or ANOVA, followed by an LSD post hoc. Multiple regression was run to predict temperatures from age, sex, breed, body weight, and Orthopedic Foundation for Animals hip score and to predict clinical metrology scores and weight-bearing distribution results from temperature results. The sample included 28 males and 19 females, with a mean age of 6.3 ± 2.5 years and bodyweight of 26.9 ± 5.1 kg, with osteoarthritis hip scores of mild (70.2%), moderate (21.3%), and severe (8.5%). Significant differences were observed in mean temperatures between German Shepherd Dogs (GSD) and Labrador Retrievers (LR) (p < 0.01), and LR and Belgian Malinois (BM) (p=0.02). Mean temperature contributed to the prediction of LOAD and stiffness. LR showed significantly higher temperature values than GSD and BM. No differences were observed between osteoarthritis hip scores and mean temperature values contributed to LOAD scores' prediction. This relation needs to be addressed in further studies, involving a larger number of animals, and to determine changes in response to treatment.

Bioinspired Near-Full Transmittance MgF2 Window for Infrared Detection in Extremely Complex Environments

Due to the extreme complexity of the anti-reflective subwavelength structure (ASS) parameters and the drastic limitation of Gaussian beam manufacturing accuracy, it remains a great challenge to manufacture ASS with ultrahigh transmittance on the surface of infrared window materials (such as magnesium fluoride (MgF₂)) directly by femtosecond laser. Here, a design, manufacturing, and characterization method that can produce an ultrahigh-performance infrared window by femtosecond laser Bessel beam is proposed. Inspired by the excellent anti-reflective and hydrophobic properties of the special structure of dragonfly wings, a similar structural pattern with grid-distributed truncated cones is designed and optimized for its corresponding parameters to achieve near-full transmittance. The desired submicron structures are successfully fabricated by a Bessel beam after effectively shaping the beam. As a practical application, the bioinspired ASS is manufactured on the surface of MgF₂, achieving an ultrahigh transmittance of 99.896% in the broadband of 3-5 μm, ultrawide angle of incidence (over 70% at 75° incidence), and good hydrophobicity with a water contact angle of 99.805°. Results from infrared thermal imaging experiments show that the ultrahigh-transmittance MgF₂ window has superior image acquisition and anti-interference performance (3.9-8.6% image contrast enhancement and more accurate image edge recognition) in an environment with multiple interfering factors, which may play a significant role in facilitating applications of infrared thermal imaging technologies in extremely complex environments.

Imbalance of Peripheral Temperature, Sympathovagal, and Cytokine Profile in Long COVID

A persistent state of inflammation has been reported during the COVID-19 pandemic. This study aimed to assess short-term heart rate variability (HRV), peripheral body temperature, and serum cytokine levels in patients with long COVID. We evaluated 202 patients with long COVID symptoms categorized them according to the duration of their COVID symptoms (≤120 days, n = 81; >120 days, n = 121), in addition to 95 healthy individuals selected as controls. All HRV variables differed significantly between the control group and patients with long COVID in the ≤120 days group (p < 0.05), and participants in the long COVID ≤120 days group had higher temperatures than those in the long COVID >120 days group in all regions analysed (p < 0.05). Cytokine analysis showed higher levels of interleukin 17 (IL-17) and interleukin 2 (IL-2), and lower levels of interleukin 4 (IL-4) (p < 0.05). Our results suggest a reduction in parasympathetic activation during long COVID and an increase in body temperature due to possible endothelial damage caused by the maintenance of elevated levels of inflammatory mediators. Furthermore, high serum levels of IL-17 and IL-2 and low levels of IL-4 appear to constitute a long-term profile of COVID-19 cytokines, and these markers are potential targets for long COVID-treatment and prevention strategies.

Multiscale Deblurred Feature Extraction Network for Automatic Four-Rod Target Detection in MRTD Measuring Process of Thermal Imagers

The minimum resolvable temperature difference (MRTD) at which a four-rod target can be resolved is a critical parameter used to assess the comprehensive performance of thermal imaging systems, which is important for technological innovation in military and other fields. Recently, there have been some attempts to use an automatic objective approach based on deep learning to take the place of the classical manual subjective MRTD measurement approach, which is strongly affected by the psychological subjective factors of the experimenter and is limited in accuracy and speed. However, the scale variability of four-rod targets and the low pixels of infrared thermal cameras have turned out to be a challenging problem for automatic MRTD measurement. We propose a multiscale deblurred feature extraction network (MDF-Net), a backbone based on a yolov5 neural network, in an attempt to solve the aforementioned problem. We first present a global attention mechanism (GAM) attention module to represent strong images of the four-rod targets. Next, a Rep VGG module is introduced to decrease the blur. Our experiments show that the proposed method achieves the desired effect and state-of-the-art detection results, which innovatively improve the accuracy of four-rod target detection to 82.3% and thus make it possible for the thermal imagers to see further and to respond faster and more accurately.

Effects of low-level laser therapy and therapeutic ultrasound on Freund's complete adjuvant-induced knee arthritis model in rats

OBJECTIVES

The aim of this study was to evaluate and monitor the effect of low-level laser therapy (LLLT) and therapeutic ultrasound (TU) alone, or combined with intra-articular prednisolone (P) in Freund's complete adjuvant (FCA)-induced knee arthritis model in rats.

MATERIALS AND METHODS

A total of 56 adult male Wistar rats were divided into seven groups: control (C), disease control (RA), P, TU, LLLT (L), P + TU (P+TU), P + LLLT (P+L) groups. The skin temperature, radiography, joint volume, serum rheumatoid factor (RF), interleukin (IL)-1β, serum tumor necrosis factor-alpha (TNF-α), and histopathological evaluation of joint were performed.

RESULTS

Thermal imaging and radiographic examination provided results consistent with the severity of the disease. The mean joint temperature (°C) was the highest in the RA (36.2±1.6) group on Day 28. The P+TU and P+L groups significantly decreased radiological scores at the end of the study. The rat serum TNF-α, IL-1β, and RF levels in all groups were significantly higher compared to the C group (p<0.05). Compared to the RA group, serum TNF-α, IL-1β, and RF levels were significantly lower in the treatment groups (p<0.05). The P+TU and P+L group was showed minimal chondrocyte degeneration and cartilage erosion and mild cartilage fibrillation and mononuclear cell infiltration of synovial membrane compared to the P, TU, and L group.

CONCLUSION

The LLLT and TU effectively reduced inflammation. In addition, a more effective result was obtained from the use of LLLT and TU combined with intra-articular P. This result may be due to insufficient dose of LLLT and TU, thus further studies should be focus on at higher dose ranges on FCA arthritis model in rats.

The Immediate Effect of Exercising in a Virtual Reality Treadmill (C-Mill) on Skin Temperature of a Man with Lower Limb Amputation

Background

In amputees, exercising can impact the distribution of body temperature. The aim of this case report is to verify the acute effect of exercising in C-Mill on the temperature distribution in the lower limbs of a man with unilateral transfemoral amputation.

Materials and Methods

The thigh and legs of a man with left distal transfemoral amputation were evaluated by thermography (infrared sensor FLIR T650sc) before and after a single 30-minute exercise session performed in a virtual reality treadmill device (C-Mill).

Results

The thermographic evaluation showed a difference in temperature between the thighs both before and after the intervention. However, there was a decrease in asymmetry, which went from 4.0°C to 3.1°C in the anterior view and from 5.3°C to 2.9°C in the posterior view, after the intervention.

Conclusion

Thermography allowed us to assess the difference in temperature in the lower limbs. Even though the temperature discrepancy has decreased after the single exercise session using the C-Mill, this difference persisted.

An update on thermal imaging in rheumatoid arthritis

This review aims to summarise the recent literature concerning the usage of thermal imaging in the study of rheumatoid arthritis (RA). Most RA studies have applied thermal imaging as a static process alone although thermal imaging has been conducted with an additional dynamic/functional component. Algorithms to automate the analysis of thermal imaging in RA have also been described. Several RA thermal imaging studies have demonstrated differences in thermographic findings between RA patients and healthy controls and/or compared thermographic parameters with other clinical/functional/imaging parameters; while fewer studies have assessed the role of thermal imaging in discriminating disease severity in RA. Thermal imaging is a relatively low cost, non-invasive imaging technique offering an objective measurement of joint surface temperature in RA joint inflammation assessment. Although there has been an increasing literature build up on the use of thermography in RA, more validation work is still necessary to delineate the potential role(s) of its use among patients with RA. This timely review focusses on the recent literature concerning thermal imaging, and provides clinicians with an update on its recent development in RA.

Influence of Upper Footwear Material Properties on Foot Skin Temperature, Humidity and Perceived Comfort of Older Individuals

Studying the in-shoe microclimate of older individuals is important for enhancing their foot comfort and preventing foot diseases. However, there is a lack of scientific work that explores the thermo-physiological wear comfort of older individuals with different footwear. This study aims to examine the effects of upper footwear materials on changes and distributions in the foot skin temperature and relative humidity for older individuals. Forty older individuals are recruited to perform sitting and walking activities under four experimental conditions in a conditioning chamber. The findings indicate that footwear upper constructed of highly permeable mesh fabric with large air holes shows fewer changes in foot skin temperature (ranging from 1.3 to 3.3 °C) and relative humidity (ranging from -13.3 to 5.7%) throughout the entire foot during dynamic walking, as well as higher subjective ratings on perceived thermal comfort when compared to footwear made of synthetic leather and composite layers. The findings serve to enhance current understanding of designing footwear with optimum comfort for older adults.

Temperature Asymmetry Analysis between Left and Right Wrist with Sensory and Infrared Thermography

This article reports a thermal analysis of the wrists to analyze the behavior and recovery of skin temperature after 20 min when performing a highly repetitive movement, and two thermography methods (sensory and infrared) and research groups were compared. The tests were carried out with 44 participants who performed a repetitive task for 10 min and integrated into two groups, of which 22 were trained workers from a maquiladora company and were analyzed with sensory thermography, and the other 22 were in the laboratory with infrared thermography with undergraduate students. The study area is the left and right hand, specifically the wrists. The proposed hypothesis is that people with some musculoskeletal problems have a decrease in temperature when starting repetitive tasks and thermal asymmetries, which measurements were recorded at 0, 10, 15, and 20 min after the task was finished. Findings indicate that the temperatures in both wrists behave similarly. The workers reached higher temperatures, and the centigrade degrees of asymmetry difference were also higher. The variable with influence on the temperature was fractured in the arm. After thermally analyzing the temperature behavior between the wrists of both hands, it is concluded that there is an increase in temperature after finishing a repetitive task, and it does not stabilize after 20 min. Both thermography methods observed that the asymmetries are greater than 0.5 °C, detecting the possible pathology of carpal tunnel syndrome.

Assessment of inflammation in patients with rheumatoid arthritis using thermography and machine learning: a fast and automated technique

Objectives

Sensitive detection of joint inflammation in rheumatoid arthritis (RA) is crucial to the success of the treat-to-target strategy. In this study, we characterise a novel machine learning-based computational method to automatically assess joint inflammation in RA using thermography of the hands, a fast and non-invasive imaging technique.

Methods

We recruited 595 patients with arthritis and osteoarthritis, as well as healthy subjects at two hospitals over 4 years. Machine learning was used to assess joint inflammation from the thermal images of the hands using ultrasound as the reference standard, obtaining a Thermographic Joint Inflammation Score (ThermoJIS). The machine learning model was trained and tuned using data from 449 participants with different types of arthritis, osteoarthritis or without rheumatic disease (development set). The performance of the method was evaluated based on 146 patients with RA (validation set) using Spearman’s rank correlation coefficient, area under the receiver-operating curve (AUROC), average precision, sensitivity, specificity, positive and negative predictive value and F1-score.

Results

ThermoJIS correlated moderately with ultrasound scores (grey-scale synovial hypertrophy=0.49, p<0.001; and power Doppler=0.51, p<0.001). The AUROC for ThermoJIS for detecting active synovitis was 0.78 (95% CI, 0.71 to 0.86; p<0.001). In patients with RA in clinical remission, ThermoJIS values were significantly higher when active synovitis was detected by ultrasound.

Conclusions

ThermoJIS was able to detect joint inflammation in patients with RA, even in those in clinical remission. These results open an opportunity to develop new tools for routine detection of joint inflammation.

Diabetic foot thermal image segmentation using Double Encoder-ResUnet (DE-ResUnet)

The use of thermography in the early diagnosis of Diabetic Foot (DF) has proven its effectiveness in identifying areas of the plantar foot that are susceptible to ulcer development. Segmentation of the foot sole is one of the most pertinent technical issues that must be performed with great precision. However, because of the inherent difficulties of foot thermal images, such as unclarity and the existence of ambiguities, segmentation approaches have not demonstrated sufficiently accurate and reliable results for clinical use. In this study, we aim to develop a fully automated, robust and accurate segmentation of the diabetic foot. To this end, we propose a deep neural network architecture adopting the encoder-decoder concept called Double Encoder-ResUnet (DE-ResUnet). This network combines the strengths of residual network and U-Net architecture. Moreover, it takes advantage of RGB (Red, Green, Blue) colour images and fuses thermal and colour information to improve segmentation accuracy. Our database consists of 398 pairs of thermal and RGB images. The population includes two groups. The first group of 54 healthy subjects. And a second group of 145 diabetic patients from the National Hospital Dos de Mayo in Peru. The dataset is splitted into 50% for training, 25% for validation and the last 25% is used for testing. This proposed model provided robust and accurate automatic segmentations of the DF and outperformed other state of the art methods with an average intersection over union (IoU) of 97%. In addition, it is able to accurately delineate the part of toes and heels which are high risk regions for ulceration.

Skin Cancer Detection Using Infrared Thermography: Measurement Setup, Procedure and Equipment

Infrared thermography technology has improved dramatically in recent years and is gaining renewed interest in the medical community for applications in skin tissue identification applications. However, there is still a need for an optimized measurement setup and protocol to obtain the most appropriate images for decision making and further processing. Nowadays, various cooling methods, measurement setups and cameras are used, but a general optimized cooling and measurement protocol has not been defined yet. In this literature review, an overview of different measurement setups, thermal excitation techniques and infrared camera equipment is given. It is possible to improve thermal images of skin lesions by choosing an appropriate cooling method, infrared camera and optimized measurement setup.

The Value of Thermal Imaging for Knee Arthritis: A Single-Center Observational Study

PURPOSE

To compare (non-contact) thermal imaging with power Doppler (PD) for the evaluation of knee arthritis with joint effusion.

MATERIALS AND METHODS

We enrolled patients with knee arthritis who were scheduled to undergo an arthrocentesis of the knee from April to December 2020 at a single tertiary hospital. A thermography camera, FLIR ONE Pro, was used to obtain both thermographic and digital images on subjects. For each subject, thermography, ultrasonography, arthrocentesis, and blood tests were conducted at the same study visit. Thermal imaging findings and clinical characteristics were compared by dividing the subjects into PD-positive and PD-negative groups on ultrasound. The receiver operating characteristic (ROC) curve analysis was used to determine the accuracy of PD positivity.

RESULTS

A total of 30 knee arthritis patients were enrolled in this study. Knee temperature was significantly higher in PD-positive group compared to PD-negative group [maximum temperature (T max): 33.2℃ vs. 30.5℃, p=0.025; minimum temperature (T min): 30.7℃ vs. 27.0℃, p=0.015; average temperature (T ave): 32.1℃ vs. 29.1℃, p=0.016]. Also, the joint fluid white blood cell count was considerably higher in PD-positive group than in PD-negative group (24556 cells/mm³ vs. 7840 cells/mm³, p=0.010). The area under the ROC curve of the point measurement of T max, T min, and T ave ranged between 0.764 and 0.790.

CONCLUSION

In this study, we found that high thermographic temperatures of the knee suggest a positive PD signal. Thus, thermography might be used as an adjuvant tool of PD for non-invasive evaluation of knee arthritis.

Evaluation of skin using infrared thermal imaging for dermatology and aesthetic applications

INTRODUCTION

The use of thermography in the medical field has been experiencing a renaissance due to advances in the infrared thermographic imaging technology, which improves thermographic equipment and promises cost saving and increased safety. Dermatology is one of the most promising fields of application among the medical areas with potential for the use of thermography.

OBJECTIVE

To review the findings on this subject and to describe the use of such technique for dermatology and aesthetic applications.

METHODS

A bibliographic survey was carried out, selecting relevant publications and guidelines, focused on monitoring medical diagnostic applications and benefits of thermography for dermatology, inflammatory skin diseases, and aesthetic applications.

RESULTS

Inflammatory skin diseases lead to changes of the IRT image. A quantification of treatment effects and monitoring changes on skin can be possible by repeated measurements over time.

CONCLUSION

Infrared imaging is a noninvasive, powerful tool in the diagnosis and clinical management of skin conditions and monitoring of aesthetic procedures.

Thermography evaluation of low back pain in pregnant women: Cross-sectional study

BACKGROUND

Low back pain during pregnancy is very common and thermography seems to be a promising method of evaluation for pregnant women, because it is painless and safe. The aim of the present study was to evaluate low back pain, during pregnancy, using thermography together with artificial intelligence.

METHODS

A cross-sectional study was carried out with pregnant women recruited from a university hospital. The following data were collected: (a) clinical data; (b) physical assessment with mobility and low back pain provocation tests; and (c) thermograms acquisitions, in a controlled environment. Artificial intelligence and the statistical tests were used to compare the groups' mean: with low back pain (LBP) and without low back pain (WLBP).

RESULTS

Thirty pregnant women took part, with fifteen in each group. The mean ± Standard Deviation temperature of the lumbar region in both groups were 32.7 ± 1.05 °C and 32.6 ± 1.01 °C for LBP and WLBP, respectively. There was not any difference in temperature between the groups; however, the artificial intelligence software found thermogram differences between groups; furthermore, the correlation between pain intensity and functionality was found.

CONCLUSION

Thermography associated with artificial intelligence analyses demonstrated to be a promising method as an adjunct to clinical evaluation.

Ultrafast Silicon Nanomembrane Microbolometer for Long-Wavelength Infrared Light Detection

The microbolometer is the cornerstone device for imaging in the long-wavelength infrared range (LWIR) at room temperature. The state-of-the-art commercial microbolometers usually have a large thermal time constant (TTC) of over 10 ms, limited by their substantial device heat capacity. Moreover, the minimal pixel size of state-of-the-art bolometer is around 10 μm by 10 μm to ensure sufficient power absorption per pixel. Here, we demonstrate an ultrafast silicon nanomembrane microbolometer with a small heat capacity of around 1.9 × 10^-11J/K, which allows for its operation at a speed of over 10 kHz, corresponding to a TTC of less than 16 μs. Moreover, a compact diabolo antenna is leveraged for efficient LWIR light absorption, enabling the downscaling of the active area size to 6.2 μm by 6.2 μm. Because of the complementary metal oxide semiconductor (CMOS)-compatible fabrication processes, our demonstration here may lead to a future high-resolution and high-speed LWIR imaging solution.

Assessment of neuropathic pain in leprosy patients with relapse or treatment failure by infrared thermography: A cross-sectional study

BACKGROUND

Neuropathic pain (NP) is one of the main complications of leprosy, and its management is challenging. Infrared thermography (IRT) has been shown to be effective in the evaluation of peripheral autonomic function resulting from microcirculation flow changes in painful syndromes. This study used IRT to map the skin temperature on the hands and feet of leprosy patients with NP.

METHODOLOGY/PRINCIPAL FINDINGS

This cross-sectional study included 20 controls and 55 leprosy patients, distributed into 29 with NP (PWP) and 26 without NP (PNP). Thermal images of the hands and feet were captured with infrared camera and clinical evaluations were performed. Electroneuromyography (ENMG) was used as a complementary neurological exam. Instruments used for the NP diagnosis were visual analog pain scale (VAS), Douleur Neuropathic en 4 questions (DN4), and simplified neurological assessment protocol. The prevalence of NP was 52.7%. Pain intensity showed that 93.1% of patients with NP had moderate/severe pain. The most frequent DN4 items in individuals with NP were numbness (86.2%), tingling (86.2%) and electric shocks (82.7%). Reactional episodes type 1 were statistically significant in the PWP group. Approximately 81.3% of patients showed a predominance of multiple mononeuropathy in ENMG, 79.6% had sensory loss, and 81.4% showed some degree of disability. The average temperature in the patients' hands and feet was slightly lower than in the controls, but without a significant difference. Compared to controls, all patients showed significant temperature asymmetry in almost all points assessed on the hands, except for two palmar points and one dorsal point. In the feet, there was significant asymmetry in all points, indicating a greater involvement of the lower limbs.

CONCLUSION

IRT confirmed the asymmetric pattern of leprosy neuropathy, indicating a change in the function of the autonomic nervous system, and proving to be a useful method in the approach of pain.

Modeling of pre-transplantation liver viability with spatial-temporal smooth variable selection

BACKGROUND AND OBJECTIVE

Liver viability assessment plays a critical role in liver transplantation, and the accuracy of the assessment directly determines the success of the transplantation surgery and patient's outcomes. With various factors that affect liver viability, including pre-existing medical conditions of donors, the procurement process, and preservation conditions, liver viability assessment is typically subjective, invasive or inconsistent in results among different surgeons and pathologists. Motivated by these challenges, we aimed to create a non-invasive statistical model utilizing spatial-temporal infrared image (IR) data to predict the binary liver viability (acceptable/unacceptable) during the preservation.

METHODS

The spatial-temporal features of liver surface temperature, monitored by IR thermography, are significantly correlated with the liver viability. A spatial-temporal smooth variable selection (STSVS) method is proposed to define the smoothness of model parameters corresponding to different liver surface regions at different times.

RESULTS

A case study, using porcine livers, has been performed to validate the efficacy of the STSVS method. The comparison results show that STSVS has the better overall prediction performance compared to the past state-of-the-art predictive models, including generalized linear model (GLM), support vector machine (SVM), LASSO, and Fused LASSO. Moreover, the significant predictors identified by the STSVS method indicate the importance of edges of lobes in predicting liver viability during the pre-transplantation preservation.

CONCLUSIONS

The proposed method has the best performance in predicting liver viability. This 'real-time' prediction method may increase the utilization of donors' livers without damaging tissues and time-consuming, yet imprecise feature assessment.

Should We Scan Hidradenitis Suppurativa Patients? A Systematic Review of Radiologic Findings

OBJECTIVE

To bring awareness and close gaps between dermatologists and radiologists about the contribution of imaging techniques for diagnosis, treatment, and follow-up of hidradenitis suppurativa (HS).

DATA SOURCES

Investigators searched the PubMed database for articles on HS and radiology techniques.

STUDY SELECTION

Databases were searched up to December 2018. The query retrieved 257 publications, of which 103 were unique; of these, 7 were inaccessible. From the remaining 96, 33 were irrelevant (did not discuss HS lesion features). After applying the inclusion criteria, 63 studies were relevant to this study.

DATA EXTRACTION

A standardized form was constructed to extract data from eligible studies by two independent authors.

DATA SYNTHESIS

Imaging techniques are significant and useful tools in HS management. Imaging should be carried out to evaluate disease severity, subclinical features, treatment success, and intraoperative patient assessment. Providers should consider nonconventional radiology techniques, which are underused in clinical management of HS. Further, dermatology and radiology require a shared terminology of disease features to better understand patient status.

CONCLUSIONS

Publications on HS lesion imaging have increased over the years. Imaging techniques have proven useful for determining HS severity and treatment effectiveness, as well as intraoperative patient assessment. These authors strongly recommend the use of these techniques in routine clinical practice for patients with HS.

Thermal Simulations of Cancerous Breast Tumors and Cysts on a Realistic Female Torso

Medical thermography has been around for several decades however due to its low specificity it has not become a popular medical diagnostic technique. The development of computational models of heat transfer in biological tissue can provide a deeper knowledge of healthy and nonhealthy thermal patterns which could increase the specificity of this technique increasing its usefulness in clinical diagnosis. In this work, the thermal pattern of cancerous tumors and cysts are calculated through finite element computer simulations using a real human female torso. The simulation results show a thermal pattern that agrees with infrared thermal images taken from female subjects, the simulated thermal patterns show real thermal features that do not appear in simulations performed using other approximate geometries of the breast. Results show that the temperature on the region of the skin closest to the tumor decreases for cysts while it increases for malignant tumors. The temperature patterns show a 20% deviation from thermal simulations using a hemispherical model of the breast, these results reinforce the notion that the geometry used for thermal simulation plays an important role in the accuracy of the simulations. These results are a first step in understanding benign and malignant thermal processes of the breast which might help increase the usefulness of infrared imaging in breast clinical diagnosis.

Body temperature and esthesia in individuals with stroke

Patients with sequelae of stroke commonly report somatosensory losses. It is believed that body temperature may be associated with tactile sensibility and sensorimotor recovery of these patients. Demonstrate the associations among tactile sensibility, cutaneous temperature, subjective temperature perception, and sensorimotor recovery of patients with stroke sequelae. 86 patients with stroke sequelae were included. Patients had standardized regions of interest (ROIs) assessed with infrared thermography (FLIR T650SC) and monofilaments esthesiometry, and global motor recovery was evaluated with Fugl-Meyer Assessment (FMA). The presence of self-reported perception of temperature difference was used to divide the participants into two groups of 43 patients, and correlation tests were applied to establish correlations among variables. There is no clinically relevant association between tactile sensibility and cutaneous temperature of the foot, regardless of the subjective sensation of temperature changes. Sensorimotor recovery evaluated by FMA is associated with the difference of sensibility between both sides of the body (p < 0.001), as well as with the difference of tactile sensibility (p < 0.001). A clinically significant association between the difference of cutaneous temperature and tactile sensibility was not found, regardless of the presence or absence of subjective perception of such temperature difference. However, sensorimotor recovery is correlated with cutaneous temperature differences and tactile sensibility.

Evaluation of digital thermography imaging to assess and monitor treatment of police working dogs with naturally occurring hip osteoarthritis

BACKGROUND

In dogs, thermal imaging has been documented only recently, but a growing interest in this modality has led to studies using thermography to assess pathologies in the canine hip, stifle, elbow, intervertebral disc, and bone neoplasia. This study aimed to evaluate the use of digital thermography in assessing and evaluating treatment response in dogs with hip osteoarthritis (OA) and comparing its results with an objective measure and two clinical metrology instruments. In an experimental, randomized, double-blinded study, one hundred hip joints of fifty police working dogs with bilateral hip OA were evaluated. A dorsoventral and lateral thermographic image were obtained on days 0, 8, 15, 30, 90, and 180. Mean and maximal temperatures were determined. Additionally, the animal's weight-bearing distribution and radiographic examination of the hip joint (extended legs ventrodorsal view) were performed. Copies of the Canine Brief Pain Inventory (CBPI) and Canine Orthopaedic Index (COI) were obtained. Results were analyzed by ANOVA, followed by an LSD post-hoc test, and correlations were assessed with Spearman correlation coefficient, with p < 0.05.

RESULTS

Values recorded on the lateral view were higher than those on the dorsoventral view. No differences or correlations were found between Orthopedic Foundation for Animals hip grades and temperature. Digital thermographic images showed a weak significant correlation with weight-bearing evaluations (r = 0.13, p < 0.01) and different clinical metrology instruments scores (r = - 0.25, p < 0.01 for pain severity score, and r = - 0.21, p = 0.04 for gait). It also correlated with radiographic findings, specifically the circumferential femoral head osteophyte and caudolateral curvilinear osteophyte.

CONCLUSION

To our knowledge, this is the first study presenting the digital thermography assessment of Police working dogs submitted to treatment for hip OA. Digital thermography, mainly based on a lateral view evaluation, showed a weak significant correlation with stance analysis and clinical metrology instruments scores.

Cutaneous temperature and pressure pain threshold in individuals with knee osteoarthritis

Introduction

Osteoarthritis is a common disease in which skin temperature may be included among the pathophysiological factors. Thermography allows the mapping of cutaneous temperature and may be employed in the investigation of osteoarthritis.

Objectives

To evaluate cutaneous temperature of the lower limbs, as well as to verify its association with pressure pain thresholds in individuals with knee osteoarthritis.

Material and methods

This case series study was conducted with individuals of both genders aged 48–77 years with unilateral knee osteoarthritis. Volunteers underwent thermographic evaluation by an infrared sensor (FLIR T650SC). The anterior region of the thigh and leg and the knee area were evaluated. Pressure pain thresholds (PPT) were evaluated by algometry (Pain Diagnostics, Great Neck, USA) at the vastus medialis, vastus lateralis, rectus femoris, and patellar tendon. Data analysis was conducted with the statistical package SPSS v.24 for Windows. Comparisons between affected and unaffected sides were made by paired Student’s t-test or the Mann-Whitney U test, and associations between variables were assessed by Pearson or Spearman’s correlation coefficient. In all cases, the significance level was set at p ≤ 0.05.

Results

Eleven volunteers (63.1 ±9.5 years) participated in this study. When comparing cutaneous temperature, only the region of the knee showed a significant difference between sides (p = 0.02). There were no differences between affected and unaffected knees regarding pain tolerance (PPT) at all sites evaluated. There were also no significant associations between the study variables.

Conclusions

Individuals with knee osteoarthritis presented a higher temperature of the affected knee, but this was not associated with pressure pain thresholds.

A novel use of combined thermal and ultrasound imaging in detecting joint inflammation in rheumatoid arthritis

PURPOSE

To evaluate the use of combined thermal and ultrasound imaging to assess joint inflammation in rheumatoid arthritis (RA).

METHOD

22-joint (bilateral hands) thermography and ultrasonography were performed. For each patient, the MAX, MIN and AVG represent the sum of the temperature differences with a control temperature, for the respective maximum (Tmax), minimum (Tmin) and average (Tavg) temperatures at the joints. MAX (PD), MIN (PD) and AVG (PD) represent the results of combined thermal imaging with a patient's total ultrasound power Doppler (PD) joint inflammation score (Total PD) (when Total PD > median score, MAX, MIN and AVG was multiplied by a factor of 2, otherwise MAX (PD), MIN (PD) and AVG (PD) remained the same as the MAX, MIN and AVG). Pearson correlation and linear regression were used to assess correlation and characterize relationships of imaging parameters with the 28-joint disease activity score (DAS28).

RESULTS

In this cross-sectional study, 814 joints were examined in 37 adult RA patients (75.7 % female, 75.7 % Chinese; mean DAS28, 4.43). Among the imaging parameters, only MAX (PD) and AVG (PD) correlated significantly with DAS28 (correlation coefficient (95 % CI): MAX (PD), 0.393 (0.079, 0.636), P = 0.016; AVG (PD): 0.376 (0.060, 0.624), P = 0.022). Similarly, only MAX (PD) and AVG (PD) demonstrated a statistically significant relationship with DAS28 (regression coefficient (95 % CI): MAX (PD), 0.009 (0.002, 0.015), P = 0.016; AVG (PD), 0.011 (0.002, 0.020), P = 0.022).

CONCLUSIONS

Novel use of combined thermal and ultrasound imaging in RA shows superiority to either imaging alone in terms of correlation with DAS28.

Thermographic imaging of police working dogs with bilateral naturally occurring hip osteoarthritis

Background

Digital thermal imaging is a physiologic, non-invasive, contactless, and non-radiating diagnostic tool that can assess a wide range of musculoskeletal conditions, including hip osteoarthritis (HOA). Fifty police working dogs were evaluated to compare the dorsoventral (DV) and lateral (LT) thermographic images in dogs with naturally occurring bilateral HOA. A DV, and left and right lateral LT images were obtained for each animal in six different moments. They were positioned standing in a symmetrical upright position for the DV view. Each image included the area from the last lumbar to the first coccygeal vertebrae. Each LT view was set with the greater trochanter in the centre of the image. Images were taken with a thermographic camera from a distance of 60 cm. Mean and maximal temperatures were recorded, analyzed with ANOVA, dependent samples t-test, and Spearman correlation, with P < 0.05.

Results

Nine hundred images were considered, collected from 30 males and 20 females, with a mean age of 6.5 ± 2.2 years and bodyweight of 26.7 ± 5.3 kg. The overall value recorded on the DV view was 25.3º ± 9.1 and 28.4º ± 2.8 on the lateral view. These were significantly different (P < 0.01) and with a low correlation (r = 0.10, P = 0.03). German Shepard dogs showed significantly lower values on all views than other breeds (P < 0.01), and heavier dogs had higher values on the lateral view.

Conclusions

This is the first study that describes digital thermography's diagnostic use to evaluate working dogs with naturally occurring HOA, comparing two different views. Future studies should address each one's value in the diagnosis and response to treatment of this disease.

Clinical and diagnostic imaging findings in police working dogs referred for hip osteoarthritis

Background

Osteoarthritis (OA) is the most commonly diagnosed joint disease in veterinary medicine, with at least 80% of the cases of lameness and joint diseases in companion animals being classified as OA. Sporting and working animals are more predisposed to develop OA since they are exposed to chronic fatigue injuries, leading to bone and muscular tissue damage and failure, resulting in clinical signs. To characterize the clinical signs and diagnostic findings of Police working dogs presenting with bilateral hip OA at the time of diagnosis. Fifty animals were evaluated with a bodyweight ≥ 15 kg, be older than two years, and without any medication or nutritional supplements for ≥ 6 weeks.

Results

Weight distribution, joint range of motion at flexion and extension, thigh girth, digital thermography, and radiographic signs were collected. Data from different Clinical Metrology Instruments (CMI) were collected: Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs, Canine Orthopedic Index, and the Hudson Visual Analogue Scale. Results were compared by breed, age, sex, and Orthopaedic Foundation for Animals hip grades with the Independent Samples T-Test, ANOVA followed by a Bonferroni post hoc test, and Pearson correlation coefficient, with p < 0.05. The sample included 30 males and 20 females, with a mean age of 6.5 ± 2.4 years and a bodyweight of 26.7 ± 5.2 kg. Animals with weight distribution below normal levels had significant variations of joint extension and function scores. This evaluation was the only not correlated with at least one breed. Animals with caudolateral curvilinear osteophyte showed a poorer clinical presentation and worse scores in all considered CMIs. Radiographic changes correlated with age and corresponded to worse CMIs scores and weight distribution. Dutch Shepherd Dogs showed better CMI scores than the other considered breeds.

Conclusions

Police working dogs presented with complaints related to hip OA at an early stage of the disease. Hip scores influenced clinical presentation, with moderate cases showing lower thigh girth and worse pain interference and severity, and function scores than mild cases. Patients with severe OA had lower thermographic evaluations than patients with moderate OA. Age was the primary variable influencing considered CMI scores.

Musculoskeletal applications of infrared thermography on back and neck syndromes: a systematic review

INTRODUCTION

Thermography is a noninvasive method to detect temperature changes on or near the surface of the body. Despite its utility has not yet been fully verified, it may be used as a complementary method to screening and/or monitoring treatment effectiveness. This systematic review evaluates the role of infrared thermography as a helpful outcome measure tool in subjects with back and neck syndromes.

EVIDENCE ACQUISITION

A literature search was conducted across the National Library of Medicine (MEDLINE), Web of Science and Scopus databases for studies that evaluated the role of infrared thermography as a helpful outcome measure tool in subjects with back and neck syndromes. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA).

EVIDENCE SYNTHESIS

The search strategy and selection criteria yielded 812 articles. From these, 268 duplicates were removed, and only 16 were in line with the aim of this review. Ultimately, only seven precisely fulfilled the inclusion and exclusion criteria and were included in the review. According to the articles reviewed, thermography seems to give an objective notion of change in inflammatory activity, which can corroborate the usefulness of treatment or the improvement/worsening of the patient's symptoms. The overall quality of research was uneven in the study design, endpoint measures, and sample characteristics.

CONCLUSIONS

The number of high-quality studies of the role of infrared thermography in patients with back and neck syndromes remains limited. More than a diagnostic tool, thermography can be an objective tool for monitoring the effectiveness of treatment by identifying deviations from a healthy state.

Thermography in rheumatoid arthritis: a comparison with ultrasonography and clinical joint assessment

AIM

To compare thermography with ultrasonography and clinical joint assessment in patients with rheumatoid arthritis (RA).

MATERIALS AND METHODS

Thermography and ultrasonography (power Doppler (PD) and grey-scale (GS) joint inflammation scored semi-quantitatively 0-3) were performed sequentially on both hands of 37 RA patients. Using generalised estimating equations analysis, (a) thermographic parameters (TP) were compared between joints based on their PD and GS joint inflammation positivity/negativity status, while (b) TP and ultrasound-detected joint inflammation were compared between joints categorised by their clinical swelling/tenderness status.

RESULTS

Comparing PD positive versus negative joints, the differences in mean values (95% CI) for TP including maximum (T_max), minimum (T_min), average (T_avg), and T_max minus T_min (T_max-min) temperatures (in °C) were 1.37 (0.86, 1.87), 0.91 (0.46, 1.36), 1.16 (0.67, 1.64), and 0.46 (0.28, 0.64), respectively. Comparing GS positive versus negative joints, the corresponding results for thermography were 1.09 (0.67, 1.52), 0.66 (0.32, 1.00), 0.86 (0.47, 1.26), and 0.45 (0.28, 0.62), respectively. p-Values were all <0.001. The differences in mean values (95% CI) for ultrasound scores, but not for TP, were statistically significant for (a) swollen tender joints (PD: 0.67 [0.39, 0.96], p<0.001; GS: 0.86 [0.54, 1.18], p<0.001) and (b) swollen non-tender joints (PD: 0.46 [0.07, 0.84], p=0.021; GS: 0.83 [0.37, 1.29], p<0.001) when compared to non-swollen non-tender joints.

CONCLUSION

Joints in RA patients have significantly higher temperature readings when ultrasound-detected joint inflammation is present. Swollen tender/non-tender joints exhibited a greater degree of ultrasound-detected joint inflammation than non-swollen non-tender joints, although their temperature readings were not significantly higher.

Feasibility Study on the Use of Infrared Thermography to Classify Fattening Pigs into Feeding Groups According Their Body Composition

Fattening pig husbandry and associated negative environmental impacts due to nitrogen inputs by ammonia emissions are current issues of social discussion. New resource-efficient feeding systems offer great potential to reduce excess nutrient inputs into the environment. Using ultrasound measurements, fattening pigs can be divided into performance groups based on their backfat/muscle ratio to feed them according to their nutritional needs. Ultrasound measurements are not suitable for practical use, so alternatives have to be found. As a non-invasive, contactless method, infrared thermography offers many advantages. This study investigated whether infrared thermography can be used to differentiate between “fat” and “lean” animals. Two evaluation methods with different measurement spot sizes were compared. During a fattening period, 980 pigs were examined three times with an infrared camera. Both methods showed significant differences. Body surface temperature was influenced by factors like measurement spot size and soiling of the animals. Body surface temperature decreased (−5.5 °C), while backfat thickness increased (+0.7 cm) in the course of the fattening period. Significant correlations (R > |0.5|; p < 0.001) between both parameters were found. Differentiation between “fat” and “lean” animals, based on temperature data, was not possible. Nevertheless, the application of thermography should be investigated further with the aim of resource-efficient feeding. The results of this feasibility study can serve as a basis for this.

Associations Between Skin Surface Temperature and Pressure Pain Tolerance Thresholds of Asymptomatic Individuals Exposed to Cryotherapy and Thermotherapy

Objective

The purpose of this study was to evaluate associations between skin surface temperature and pressure pain tolerance thresholds (PPTs) of asymptomatic individuals exposed to cryotherapy and thermotherapy.

Methods

Twenty-two asymptomatic female university students aged between 18 and 35 years underwent thermography and algometry assessments at 6 points in both knees before, immediately after, and 20 minutes after the application of frozen (cryotherapy) or heated (thermotherapy) gel bags in the right knee for 20 minutes. Data were analyzed by 1-way analysis of variance, Student t test, and Pearson or Spearman correlation tests.

Results

There was a significant change in skin surface temperature after cryotherapy and thermotherapy, which was maintained after 20 minutes of withdrawal (P < .001). After the intervention, no significant differences were observed regarding PPT compared with the baseline measurements, nor between the experimental and control knees.

Conclusion

Cryotherapy and thermotherapy produced significant changes in the temperature of the evaluated points after their application. No differences in pain tolerance were observed in these asymptomatic participants. There was little association between skin surface temperature and PPT in the knees of healthy women after application of the resources.

Influence of artificial turf temperature on physical performance and muscle contractile properties in football players after a repeated-sprint ability test

This study aimed to analyse the effect of playing surface temperature on muscular and thermal response to a repeated-sprint ability (RSA) test in football players. Thirty-two male football players (23 ± 5 years; 1.77 ± 0.06 m; 71.2 ± 6.7 kg) from two squads of a third-division football club participated in the study. An RSA test was carried out at a high surface temperature (45.34 ± 2.53 °C) and low surface temperature (27.21 ± 2.17 °C). Before and after this test, the muscular response of the players was assessed through tensiomyography and thermograms. The results revealed that performance in the RSA test particularly increased at a higher surface temperature, especially in the first 5 m of the 30 m sprint test. While a reduction in maximal radial displacement (Dm) in the biceps femoris post-RSA was observed at lower surface temperatures, a higher temperature on the thigh, hamstring and calf was found in the higher surface temperature group. In conclusion, higher surface temperatures had an influence on players’ thermal and tensiomyographic profile and improved performance in their repeated-sprint ability. These results suggest a need for coaches and players to be aware of these parameters to ensure adequate functionality and safety of the playing surface.

Pain Tolerance: The Influence of Cold or Heat Therapy

Objectives

Resources of heat or cold therapies have been widely used for their low cost, analgesic action and for assisting the rehabilitation of acute or chronic injuries. The objective of this study was to search for associations between skin surface temperature and pressure pain tolerance thresholds (PPTs) of healthy individuals undergoing cryotherapy and thermotherapy.

Methods

This is an experimental clinical trial with 22 healthy university students aged between 18 and 35 years. Volunteers underwent thermography and algometry assessments at 6 points in both knees before, immediately after, and 20 minutes after the application of frozen (cryotherapy) or heated (thermotherapy) gel bags in the right knee for 20 minutes. Data were analyzed by 1-way analysis of variance, Student's t test, and Pearson or Spearman correlation tests.

Results

There was a significant change in skin surface temperature after cryotherapy and thermotherapy, which was maintained after 20 minutes of withdrawal (P < .001). After the intervention, no significant differences were observed regarding the PPT compared to the baseline measurements, nor between the experimental and control knees.

Conclusion

Cryotherapy and thermotherapy produced significant changes in the temperature of the evaluated points after their application. Despite this, no differences in pain tolerance were observed, and there was little association between skin surface temperature and PPT in the knees of healthy women after application of the resources.

Detection of inflammation from finger temperature profile in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory tissue disease that leads to cartilage, bone, and periarticular tissue damage. This study aimed to investigate whether the use of infrared thermography and measurement of temperature profiles along the hand fingers could detect the inflammation and improve the diagnostic accuracy of the cold provocation test (0 °C for 5 s) and rewarming test (23 °C for180 s) in RA patients. Thirty RA patients (mean age = 49.5 years, standard deviation = 13.0 years) and 22 controls (mean age = 49.8 years, standard deviation = 7.5 years) were studied. Outcomes were the minimal and maximal: baseline temperature (T1), the temperature post-cooling (T2), the temperature post-rewarming (T3), and the Tmax-Tmin along the axis of each finger. The statistical significance was observed for the thumb, index finger, middle finger, and ring finger post-cooling and post-rewarming. Receiver operating characteristics (ROC) analysis to distinguish between the two groups revealed that for the thumb, index finger, middle finger, and ring finger, the area under the ROC curve was statistically significantly (p < 0.05) post-cooling. The cold provocation test used in this study discriminates between RA patients and controls and detects an inflammation in RA patients by the measurement of temperature profiles along the fingers using an infrared camera. Graphical abstract.

Infrared thermography to assess dermatomal levels of labor epidural analgesia with 1 mg/mL ropivacaine plus 0.5 µg/mL sufentanil: a prospective cohort study

BACKGROUND

Assessment of the effectiveness of obstetric epidural analgesia may be difficult and techniques for objective assessment of epidural spread of local anesthetic would be useful. In this prospective cohort study we assessed whether obstetric epidural analgesia from a low concentration of ropivacaine led to significant change in cutaneous temperature, related to sympathetic block detected by infrared thermography, at dermatomes C4, T4, T10, L2 and L5.

METHODS

Women in spontaneous labor who requested epidural analgesia were consecutively recruited. Epidural analgesia was induced with a bolus of 10-15 mL of ropivacaine 1 mg/mL and sufentanil 0.5 µg/mL, followed by continuous epidural infusion. Skin temperature was measured using thermography before and 20 min after the epidural bolus. The verbal pain score using a numeric rating scale was recorded before and 60 min after the epidural bolus. The upper sensory block to cold sensation was tested 30 and 60 min after the bolus by a physician blinded to the skin temperature. Failed epidural analgesia was defined as verbal pain score >3 at 60 min.

RESULTS

Fifty-three parturients were included and analyzed. We found a significant increase in skin temperatures measured at T4, T10, L2 and L5 dermatomes, but not at C4, and a significant difference in the change in skin temperature at T10 between failed (n=3) and successful (n=50) epidural analgesia.

CONCLUSIONS

These results suggest that infrared thermography might be useful for the early diagnosis of successful obstetric epidural analgesia.

Does CABG with Saphenous Vein Grafting and Standard Cardiac Rehabilitation Affect Lower Limb Function? A Clinical Study

BACKGROUND

The aim of the study was to assess lower limb function in response to two cardiac rehabilitation (CR) protocols after coronary artery bypass surgery with saphenous vein grafting.

METHODS

Clinically-stable male patients aged 50-70 years were recruited 4 weeks post-surgery in which to group. Group I (n = 47) receive standard CR in a hospital setting for 3 weeks and Group II (n = 14) receive CR with a resistance training component in an outpatient setting for 8 weeks. Measures included body mass and composition, lower limb temperature distribution, lower limb hemodynamics, and dorsal and plantar flexor muscle strength.

RESULTS

Average temperature of the operated limb decreased only in Group II after cardiac rehabilitation. Venous blood flow improved in both groups as evidenced by increased blood refilling time. Isokinetic strength was greater in Group I.

CONCLUSIONS

The results suggest a 3-week intensive CR protocol to be most effective in restoring lower limb function in CABG patients after saphenectomy.

Analysis of Breast Thermograms Using Asymmetry in Infra-Mammary Curves

The objective of this research is to propose a methodology to analyse breast thermograms in order to detect breast abnormalities, including cancer. This research work mainly target to segmented ROI that show significant increase in temperature as compared to the neighbouring areas and contralateral sides in breast thermograms. The captured frontal thermograms from each patient is initially smoothed using a Gaussian filter with a standard deviation σ = 1.4 to reduce noise. Region of interest is segmented using bifurcation points obtained by identifying curve that passes through infra-mammary fold. Infra-mammary curve is detected using Horizontal projection profile. Once the segmentation for analysis is determined, exact location of an abnormality or a lesion is determined. Heat patterns are analysed for symmetry. Asymmetry analysis usually helps to detect abnormalities. Significance and challenges of thermal images are discussed. Once the segmentation for analysis is determined, exact location of an abnormality or a lesion is determined. Heat patterns are analysed for symmetry. Asymmetry analysis usually helps to detect abnormalities. Further, classifiers based on support vector machine and principal component analysis were tested on the dataset used for evaluation. Experimental results and statistical analysis support the proposed methodology is able to detect breast anomalies with higher accuracy. An average accuracy of 95%, sensitivity of 97.05% and specificity of 92.3% was obtained for a set of sixty images with 35 normal and 25 abnormal thermograms using SVM-RBF classifier.

Changes in local skin temperature after the application of a pulsed Nd:YAG laser to healthy subjects: a prospective crossover controlled trial

Pulsed Nd:YAG laser (1064 nm) is a recent modality that is used for the rehabilitation of musculoskeletal disorders, but there is no evidence about its thermal effects. The aim of the study was to investigate the changes in local skin temperature (LST) after the application of a pulsed Nd:YAG laser to healthy subjects. The study participants were 30 male subjects with an average age of 21.96 (± 0.92) years. A rectangular area (15 × 10 cm²) was marked at the front of the dominant thigh and scanned with a laser beam at 3000 J with 20 J/cm² for 15 min. The other thigh was considered as a control side. The minimum, average, and maximum LSTs were measured using a thermographic camera. The measurements were performed before laser application, immediately after, and then every minute until the LST returned to the pre-treatment value. An independent t test and repeated measures ANOVA were used to analyze the changes in LST. The level of significance was set at p < 0.05. The pulsed Nd:YAG laser significantly increased the minimum, average, and maximum LSTs in comparison with the control. The increase was significant for up to 5 min after the application, and it took 10 min to reach the baseline values. The level of increase was 1.23-4.03 °C, and the average increase was 2.6 °C. The pulsed Nd:YAG laser significantly increased the minimum, average, and maximum LSTs of the thigh area in normal subjects, and the thermal effect lasted for 5 min after application.

Infrared Thermography and Soft Computing for Diabetic Foot Assessment

Recent advancements in digital image processing and soft computing techniques have widened the scope of computer aided diagnosis of medical conditions. Many imaging modalities like MRI, CT, PET, Ultrasound combined with soft computing techniques is already contributing to this trend. With the recent inclusion of infrared thermal imaging, the capability of computer aided diagnosis has increased and has become more safe and convenient. Research in this noncontact and noninvasive imaging technology has steadily increased over the last 50 years. Disease diagnosis based on the correlation of surface temperature distribution of skin is being studied at large and has shown promising results. This chapter will give the reader a solid understanding of the theory behind infrared thermography and the use of soft computing techniques applied to medical image analysis, particularly for diabetic foot complication assessment. The issues and challenges to be addressed in using infrared thermography for diagnostic purposes are also discussed. The reader will get a complete overview of building an intelligent diagnostic system using the two sensational topics of research in machine learning and medical imaging—infrared thermography and soft computing.

Investigating the subjective cooling effect of eyelid cleansing gel on eyelid and ocular surface temperature

PURPOSE

To investigate if the application of Blephagel, an eyelid cleansing gel, causes subjective and/or objective cooling effects by measuring ocular symptomology and temperature.

METHODS

Twenty-five healthy subjects underwent baseline non-invasive temperature measurements on the closed upper eyelid (centrally, nasally, and temporally) and ocular surface temperature (OST) on both eyes using an infrared camera. A standard application of Blephagel was then applied to the closed upper eyelid and eyelashes with a sterile cotton-wool to one eye selected at random. Temperature measures were then repeated on both eyes after 30-60, 120-150, and 180-210 s. At each interval, subjects rated the comfort and any cooling sensation of each eye on a 0-10 scale.

RESULTS

After application of the gel, there was a significant difference in temperature at all locations on the eyelid between the test and control eyes over time (F = 9.322, p < 0.001). Post hoc analysis revealed this was significant from 30 to 60 s interval (36.3 ± 1.1 °C versus 37.2 ± 0.7 °C; p < 0.001) and the 120-150 s interval (36.8 ± 0.8 °C versus 37.2 ± 0.6 °C; p < 0.001). There was no significant variation between the OST locations over time (F = 3.350, p = 0.07). With respect to symptoms, there was a significant increase in cooling sensation in the test eye compared to the control eye over time (F = 10.438, p < 0.001), that remained throughout the experiment.

CONCLUSIONS

Blephagel produces a reduction in temperature of the eyelids that is accompanied with a subjective cooling sensation.

Non-invasive assessment of liver quality in transplantation based on thermal imaging analysis

BACKGROUND AND OBJECTIVE

Liver quality evaluation is one of the vital steps for predicting the success of liver transplantation. Current evaluation methods, such as biopsy and visual inspection, which are either invasive or lack of consistent standards, provide limited predictive value of long-term transplant viability. Objective analytical models, based on the real-time infrared images of livers during perfusion and preservation, are proposed as novel methods to precisely evaluate donated liver quality.

METHODS

In this study, by using principal component analysis to extract infrared image features as predictors, we construct a multivariate logistic regression model for single liver quality evaluation, and a multi-task learning logistic regression model for cross-liver quality evaluation.

RESULTS

The single liver quality predictions show testing errors of 0%. The leave-one-liver-out predictions show testing errors ranging from 9% to 36%.

CONCLUSIONS

It is found that there is a strong correlation between the viability of livers and the infrared image features in both single liver and cross-liver quality evaluations. These analytical methods also determine that the selected significant infrared image features indicate regional difference in viability and show that more stringent pre-implantation evaluation may be needed to predict transplant outcomes.

Mottling score and skin temperature in septic shock: Relation and impact on prognosis in ICU

Introduction

Mottling score, defined by 5 areas over the knee is developed to evaluate tissue perfusion at bedside. Because of the subjective aspect of the score, we aimed to compare mottling score and skin temperature in septic shock with infrared thermography in ICU and the correlation to survival.

Methods

We conducted a prospective and observational study in a teaching hospital in France during 8 months in ICU. All patients with sepsis requiring vasoactive drugs were included. We recorded epidemiologic data, hemodynamic parameters, mottling score and skin temperature with a thermic camera of the 5 mottling areas around the knee (temperatures recorded with FLIR™ software) at bedside. Measures were performed at ICU admission (H0) and six hours after initial resuscitation (H6).

Results

46 patients were included. Median age was 69 (60–78), SOFA score 11 (8–12) mean SAPS II was 57±20 and 28-day mortality rate was 30%. Patients with mottling (score≥1), had a skin temperature of the knee significantly lower (30.7 vs 33,2°C p = 0.01 at H6) than patients without mottling (score = 0). Skin temperatures of the knee in mottling groups 1 to 5 were similar at H0 and H6. Neither mottling score nor skin temperature of the knee were associated with prognostic regarding day-28 mortality.

Conclusions

Skin temperature measured with infrared thermography technology around the knee is lower when mottling sign is present and sign microcirculation alterations. This method, compared to standard mottling score is objective and allows data collections. However, this method failed to predict mortality in ICU patients.

Noninvasive Techniques for the Determination of Burn Severity in Real Time

Visual diagnosis of second-degree burns has proven inadequate for determining the appropriate treatment regimen. Although multiple noninvasive imaging techniques have shown promise for providing information about burn wound severity, the ideal technology to aid burn wound excision would provide real-time readouts. Herein, the authors examine a high-resolution infrared (IR) camera (thermography) and a multiprobe adapter system (MPAS-6; transepidermal evaporative water loss, colorimetry) to assess their usefulness in predicting burn severity. Contact burn wounds of increasing severity were created in a porcine model. Wounds were assessed for 4 days with an IR camera and MPAS-6. In addition, each day, the burn wounds were biopsied for histological analysis to determine burn depth for correlation with noninvasive measures. Surface temperatures decreased with increasing burn severity, which was associated with increasing transepidermal evaporative water loss. Melanin content correlated with the depth of collagen coagulation and was bimodal, with superficial and full-thickness burns having higher values than deep partial thickness wounds. Erythema content was highest in superficial burns and negatively correlated with necrosis (high-mobility group box protein 1 expression). Importantly, surface temperature taken on every single day after injury was predictive of all histologically determined measurements of burn depth (ie, collagen coagulation, apoptosis, necrosis, vascular occlusion). The results indicate that IR imaging and skin quality probes can be used to support the diagnosis of burn severity. Most importantly, IR measurements gave insight into both the zone of coagulation and the zone of stasis on every postburn day studied.

Internal Mammary Vessels' Impact on Abdominal Skin Perfusion in Free Abdominal Flap Breast Reconstruction

Background

Wound healing problems at the donor site in free abdominal flap breast reconstruction cause significant morbidity to patients. No studies have investigated what impact the use of the internal mammary artery in free abdominal flap breast reconstruction has on abdominal skin perfusion. We hypothesized that harvesting the internal mammary vessels (IMV) has a negative effect on abdominal skin perfusion.

Methods

The abdomen and anterior thoracic wall of 17 patients scheduled for secondary free abdominal flap breast reconstruction using IMV was pre-, intra-, and postoperatively examined with dynamic infrared thermography. Qualitative and quantitative analyses of the rate and pattern of recovery in Huger's vascular zones were made with each patient being its own control. Zone III on the side where IMV were used was numbered zone IV. The contralateral zone III was used as reference.

Results

Postoperative abdominal skin perfusion in zone IV was always significantly reduced compared with zone III (1-tailed t test, P < 0.05). The difference between zones II and III was statistically significant for day 1 and 3, but not for day 6 (2-tailed t test, P < 0.05). Skin perfusion in zones II and IV increased during consecutive postoperative days with an increase of hot spots in these areas.

Conclusions

Using the IMV in free abdominal flap breast reconstruction had a significant effect on abdominal skin perfusion and may contribute to abdominal wound healing problems. The reperfusion of the abdominal skin was a dynamic process showing an increase in perfusion in the affected areas during the postoperative days.

A Survey on Computer Vision for Assistive Medical Diagnosis From Faces

Automatic medical diagnosis is an emerging center of interest in computer vision as it provides unobtrusive objective information on a patient's condition. The face, as a mirror of health status, can reveal symptomatic indications of specific diseases. Thus, the detection of facial abnormalities or atypical features is at upmost importance when it comes to medical diagnostics. This survey aims to give an overview of the recent developments in medical diagnostics from facial images based on computer vision methods. Various approaches have been considered to assess facial symptoms and to eventually provide further help to the practitioners. However, the developed tools are still seldom used in clinical practice, since their reliability is still a concern due to the lack of clinical validation of the methodologies and their inadequate applicability. Nonetheless, efforts are being made to provide robust solutions suitable for healthcare environments, by dealing with practical issues such as real-time assessment or patients positioning. This survey provides an updated collection of the most relevant and innovative solutions in facial images analysis. The findings show that with the help of computer vision methods, over 30 medical conditions can be preliminarily diagnosed from the automatic detection of some of their symptoms. Furthermore, future perspectives, such as the need for interdisciplinary collaboration and collecting publicly available databases, are highlighted.