Thermographic imaging in cats and dogs : Usability as a clinical method

Thermographic imaging has been studied and used widely in human and equine medicine, but published data from small animal medicine is still lacking. The primary aim of this study was to obtain basic knowledge of the method of thermographic imaging and to map possible areas of its use in companion animals. To determine the requirements for an optimal thermal camera, three cameras with different resolutions (80 x 80 pixels, 180 x 180 pixels and 320 x 240 pixels) were tested. A total of six thermographic images were taken from the hips of 49 dogs of 26 breeds. Two images were shot with each of the three thermal cameras. Two different persons took the thermographic images with the three cameras. Repeatability between thermographers and interpreters was studied. The usability of basic software for interpreting the thermographic images was examined by having three individuals interpret the thermographic images. The camera with the resolution of 320 x 240 pixels was considered the most suitable for thermographic imaging in dogs and, therefore, the rest of the studies were carried out using this camera. The impact of physical exercise on canine superficial temperature was studied with 47 racing greyhounds during two race days. Four superficial temperature points from the right and left hind leg were selected (Tendo calcaneus, Musculus gastrocnemius, Musculus gracilis and Musculus biceps femoris portio caudalis) to compare the changes in superficial temperatures before and after the race. The temperatures differed by 0 4 degrees at each selected point between the right and left legs after the completion of the race. However, no systematic asymmetry was detected between the dogs left and right side. The superficial temperatures were significantly colder when the ambient temperature was lower. Cats are known to be challenging subjects in clinical examinations and, therefore, more feline-friendly study methods are required. Thermographic imaging was used to detect temperature differences between both sides of 103 cats and, further, as an indicator of potentially painful processes. Both long-haired (n = 26) and short-haired (n = 77) cats were included. The cats that tolerated manual manipulation were also physically palpated. Owners filled in a questionnaire about the behaviour of their cat and estimated whether the cat was in any pain. The questionnaire responses, the owner s estimation of pain on a scale and thermographic imaging with palpation suggested that thermographic imaging is a potential tool of choice in clinical practice for detecting and screening cats potentially in pain. Certain drugs used in sedation and anaesthesia affect cardiovascular function. Peripheral temperature changes induced by distinct sedation protocols in dogs (n = 8) were identified by thermographic imaging from the digital and metatarsal foot pads. The obtained foot pad temperatures were compared to the rectal temperature of the same animal. The results indicated that superficial temperature changes caused by certain sedative drugs can be detected and monitored with thermographic imaging. Our studies suggested that thermographic imaging is a practical clinical method with dogs and cats. However, the effects of physical exercise and medications should be taken into consideration when interpreting thermographic images.Lämpökamerakuvantamisessa lämpökameralla havaitaan ja muodostetaan kuva kohteen lämpösäteilystä. Kaikki kohteet, joiden lämpötila ylittää absoluuttisen nollapisteen säteilevät lämpöä. Lämpökamera havaitsee ihmissilmälle näkymättömän lämpösäteilyn, eli infrapunasäteilyn ja muodostaa siitä ihmissilmin nähtävän kuvan. Lämpökameralla otettuja kuvia voi tarkastella kameran näytöltä tai tarkoitukseen soveltuvilla tietokoneohjelmilla. Verrattuna yleisesti käytettyihin kuvantamismenetelmiin, kuten ultraäänitutkimus, röntgenkuvaus tai magneettikuvaus, lämpökamerakuvantaminen voidaan tehdä potilaalle täysin turvallisesta koskematta siihen lainkaan. Lämpökamera ei säteile, vaan havaitsee säteilyä. Lämpökameralla voidaan havaita eläimessä tapahtuvat fysiologiset muutokset jo ennen kuin muutos on aiheuttanut muutoksia anatomisissa rakenteissa, kuten jänteissä tai lihaksissa. Lämpökamerakuvantamista voidaan käyttää eläinten tutkimisessa, jolloin kiinnitetään erityistä huomiota epätasaiseen lämpöjakaumaan tai normaalista poikkeaviin lämpimiin tai kylmiin alueisiin. Lämpökamerakuvantamista on tutkittu ja käytetty laajalti humaanilääketieteessä ja hevoseläinlääketieteessä, mutta tutkimukset ja menetelmän käyttö pieneläimillä on vielä vähäistä. Tämän tutkimuksen tarkoituksena oli saada perustietoa lämpökamerakuvantamisen käytöstä pieneläimillä normaalissa tutkimustilanteessa sekä kartoittaa mahdollisia käyttöalueita kissoilla ja koirilla. Lämpökameroiden resoluutio vaihtelee eri mallien välillä. Optimaalisen eläinlääketieteelliseen käyttöön soveltuvan resoluution selvittämiseksi testasimme kolmea eri resoluution lämpökameraa (80 x 80 pikseliä, 180 x 180 pikselilä ja 320 x 240 pikseliä). Jokaisella kameralla kuvattiin 49:n koiran lonkan aluetta kahden eri kuvaajan toimesta. Lämpökuvat tulkittiin kolmen eri tutkijan toimesta. Toistettavuus kuvaajien ja kuvien tulkitsijoiden välillä oli paras korkeimman resoluution (320 x 240 pikseliä) lämpökameraa käytettäessä. Muissa tutkimuksissa käytettiin tämän tuloksen perusteella 320 x 240 resoluution lämpökameraa. Fyysinen rasitus vaikuttaa elimistön aineenvaihduntaan ja ihon pintaverenkiertoon. Pintalämpötilan muutosta ennen ja jälkeen urheilusuorituksen tutkittiin kuvaamalla 47 greyhound-rotuista koiraa kahden eri kilpailupäivän aikana. Lämpökuvista valittiin tarkasteltavaksi neljä pistettä takajalkojen alueelta. Kuvien perusteella voitiin havaita merkittäviä lämpötilamuutoksia oikean ja vasemman jalan välillä kilpailun jälkeen. Kissat ovat usein vaikeita tutkittavia, sillä ne peittävät kipunsa ja sairautensa tutkijalta. Kissaystävällisiä tutkimustapojen löytäminen on lääketieteellisesti ja hyvinvointisyistä tärkeää. Lämpökamerakuvantamisella tutkittiin 103:n kissan oikean ja vasemman puolen mahdollisia lämpötilaeroja. Lämpötilaeroja tutkittiin myös indikaattorina mahdolliselle kiputilalle. Ne kissat, jotka eivät stressaantuneet käsittelystä, tutkittiin myös tunnustelemalla. Omistajat vastasivat myös kyselyyn kissan liikkumisesta ja käyttäytymisestä sekä arvioivat, onko heidän kissallaan kipuja. Kyselyn tuloksia verrattiin tunnustelun havaintoihin sekä lämpökamerakuvista saatuihin lämpötilaeroihin oikean ja vasemman puolen välillä. Tulosten perusteella lämpökamerakuvantamista voidaan pitää mahdollisena apuvälineenä kissan kivuliaiden tilojen havaitsemiseen. Suurin osa eläinpotilaista rauhoitetaan lääkkeillä tutkimusta tai toimenpidettä varten. Rauhoitteet vaikuttavat verenkiertoelimistön toimintaan ja myös eläimen pinnalliseen verenkiertoon. Rauhoitteiden vaikutusta pintaverenkiertoon tutkittiin kuvaamalla lämpökameralla eri rauhoiteyhdistelmillä rauhoitettujen koirien polkuanturoita. Rauhoitteiden vaikutuksen pintaverenkiertoon voi havaita, ja lämpötilan muutosta rauhoituksen aikana seurata lämpökamerakuvantamisen avulla. Tutkimustemme perusteella lämpökamerakuvantaminen on käytännöllinen menetelmä käytettäväksi osana kissojen ja koirien kliinisestä eläinlääketieteellisestä tutkimusta. Fyysisen rasituksen ja lääkitysten vaikutus on kuitenkin otettava huomioon lämpökamerakuvia tulkittaessa

Depth estimation of inner wall defects by means of infrared thermography

There two common methods dealing with interpreting data from infrared thermography: qualitatively and quantitatively. On a certain condition, the first method would be sufficient, but for an accurate interpretation, one should undergo the second one. This report proposes a method to estimate the defect depth quantitatively at an inner wall of petrochemical furnace wall. Finite element method (FEM) is used to model multilayer walls and to simulate temperature distribution due to the existence of the defect. Five informative parameters are proposed for depth estimation purpose. These parameters are the maximum temperature over the defect area (Tmax-def), the average temperature at the right edge of the defect (Tavg-right), the average temperature at the left edge of the defect (Tavg-left), the average temperature at the top edge of the defect (Tavg-top), and the average temperature over the sound area (Tavg-so). Artificial Neural Network (ANN) was trained with these parameters for estimating the defect depth. Two ANN architectures, Multi Layer Perceptron (MLP) and Radial Basis Function (RBF) network were trained for various defect depths. ANNs were used to estimate the controlled and testing data. The result shows that 100% accuracy of depth estimation was achieved for the controlled data. For the testing data, the accuracy was above 90% for the MLP network and above 80% for the RBF network. The results showed that the proposed informative parameters are useful for the estimation of defect depth and it is also clear that ANN can be used for quantitative interpretation of thermography data

Healing of surgical site after total hip and knee replacements show similar telethermographic patterns

BACKGROUND: Isolated reports indicate the efficacy of infrared thermography for monitoring wound healing and septic complications, but no long-term analysis has ever been performed on this, and there are no data on the telethermographic patterns of surgical site healing after uncomplicated total hip prosthesis and after knee prosthesis. MATERIALS AND METHODS: In this prospective, observational, nonrandomized cohort study, two groups with forty consecutive patients each, who were operated on respectively for total hip and for total knee replacements, underwent telethermographic examination of the operated and contralateral joints prior to and at fixed intervals for up to 1\ua0year after uncomplicated surgery. A digital, portable telethermocamera and dedicated software were used for data acquisition and processing. RESULTS: No thermographic difference was observed preoperatively between the affected side and the contralateral side in both groups. After the intervention, a steep increase in the temperature of the operated joint was recorded after total hip replacement and after knee replacement, with a peak mean differential temperature measured three days postoperatively between the operated and unoperated joint of 3.1\ua0\ub1\ua00.8\ub0C after total hip replacement, and 3.4\ua0\ub1\ua00.7\ub0C after total knee replacement. Thereafter, the mean differential temperature declined slowly to 0.7\ua0\ub1\ua01.1\ub0C and to 0.5\ua0\ub1\ua01.3\ub0C at 60\ua0days, and to 0.0\ua0\ub1\ua01.0\ub0C and -0.1\ua0\ub1\ua01.1\ub0C 90\ua0days post-operatively, respectively. No further changes were observed for up to 1\ua0year after surgery. Results were similar when comparing the average telethermographic values of an elliptical area where the main axis corresponded to the surgical wound. CONCLUSIONS: The surgical sites after uncomplicated total hip or total knee replacement show similar telethermographic patterns for up to 1\ua0year from surgery, and can easily be monitored using a portable, digital, telethermocamera

Comparative study of infrared thermography, ultrasonic C-scan, X-ray computed tomography and terahertz imaging on composite materials

L’évaluation non destructive (NDT) des matériaux composites est compliquée en raison de la vaste gamme de défauts rencontrés (y compris délaminage, microfissuration, fracture de la fibre, retrait des fibres, fissuration matricielle, inclusions, vides et dommages aux chocs). La capacité de caractériser quantitativement le type, la géométrie et l’orientation des défauts est essentielle. La thermographie infrarouge (IRT), en tant que technique de diagnostic d’image, peut satisfaire le besoin industriel croissant de NDT&E. Dans la thèse, la thermographie par excitation optique et mécanique a été utilisée pour étudier différents matériaux composites, dont 1) des préformes sèches en fibres de carbone, 2) des composites de fibres naturelles, 3) des composites hybrides de basalte-fibres de carbone soumis à une charge d’impact (séquence de type sandwich et séquence d’empilement intercalé), 4) des défauts micro-dimensionnés dans un composite polymère renforcé de fibre de carbone (CFRP) en 3D avec une couture de type « joint en T », et 5) des peintures sur toile qui peuvent être considérées comme des matériaux composites. Une nouvelle technique IRT de thermographie de ligne par micro-laser (micro-LLT) a été proposée pour l’évaluation des porosités submillimétriques dans le CFRP. La microscopie de points par micro-laser (micro-LST) et la micro-vibrothermographie (micro-VT) ont également été présentées avec l’utilisation de microlentilles. La thermographie pulsée (PT) et la thermographie modulée « à verrouillage » (LT) ont été comparées à la tomographie par rayons X (TC) pour validation. Le C-scan ultrasonore (UT) et l’imagerie par ondes tera-hertziennes en onde continue (CW THz) ont également été réalisés à des fins comparatives. L’inspection par techniques thermographiques est une question ouverte à discuter pour le public scientifique. En fait, la thermographie par impulsions (PPT) basée sur la transformation de phase a été utilisée pour estimer la profondeur des dommages. Pour traiter les données thermographiques, on a également utilisé la reconstruction de signal thermographique de base (B-TSR), la thermographie des composants principaux (PCT) et la thermographie des moindres carrés partiels (PLST). Enfin, une analyse complète et comparative basée sur le diagnostic d’images thermographiques a été menée en vue d’applications industrielles potentielles.Non-destructive testing (NDT) of composite materials is complicated due to the wide range off laws encountered (including delamination, micro-cracking, fiber fracture, fiber pullout, matrix cracking, inclusions, voids, and impact damage). The ability to quantitatively characterize the type, geometry, and orientation of flaws is essential. Infrared thermography (IRT), as an image diagnostic technique, can satisfy the increasing industrial need for NDT&E. In the thesis, optical and mechanical excitation thermography were used to investigate different composite materials, including 1) carbon fiber dry preforms, 2) natural fiber composites, 3) basalt-carbon fiber hybrid composites subjected to impact loading (sandwich-like and intercalated stacking sequence), 4) micro-sized flaws in a stitched T-joint 3D carbon fiber reinforced polymer composite (CFRP), and 5) paintings on canvas which can be considered as composite materials. Of particular interest, a new IRT technique micro-laser line thermography (micro-LLT) was proposed for the evaluation of submillimeter porosities in CFRP. Micro-laser spot thermography (micro-LST) and micro-vibrothermography (micro-VT) were also presented with the usage of a micro-lens. Pulsed thermography (PT) and lock-in thermography (LT) were compared with x-ray computed tomography (CT) for validation. Ultrasonic C-scan (UT) and continuous wave terahertz imaging (CW THz) were also conducted for the comparative purpose. The inspection by thermographic techniques is an open matter to be discussed for the scientific audience. In fact, pulse phase thermography (PPT) based on phase transform was used to estimate the damage depth. Basic thermographic signal reconstruction (B-TSR), principal component thermography (PCT) and partial least squares thermography (PLST) (another more recent advanced image processing technique) were also used to pro-cess the thermographic data. Finally, a comprehensive and comparative analysis based on thermographic image diagnostics was conducted in view of potential industrial applications

Review of InfraRed Thermography and Ground-Penetrating Radar applications for building assessment

The first appearance of concern for the good condition of a building dates back to ancient times. In recent years, with the emergence of new inspection technologies and the growing concern about climate change and people’s health, the concern about the integrity of building structures has been extended to their analysis as insulating envelopes. In addition, the growing network of historic buildings gives this sector special attention. Therefore, this study presents a comprehensive review of the application of two of the most common and most successful Non-Destructive Techniques (NDTs) when inspecting a building: InfraRed Thermography (IRT) and Ground-Penetrating Radar (GPR). To the best knowledge of the authors, it is the first time that a joint compilation of the state-of-the-art of both IRT and GPR for building evaluation is performed in the same work, with special emphasis on applications that integrate both technologies. The authors briefly explain the performance of each NDT, along with the individual and collective advantages of their uses in the building sector. Subsequently, an in-depth analysis of the most relevant references is described, according to the building materials to be studied and the purpose to be achieved: structural safety, energy efficiency and well-being, and heritage preservation. Then, three different case studies are presented with the aim of illustrating the potential of the combined use of IRT and GPR in the evaluation of buildings for the purposes defined. Last, the final remarks and future lines are described on the application of these two interesting inspection technologies in the preservation and conservation of the building sector.European Union Next GenerationEU/PRTRAgencia Estatal de Investigación | Ref. PDC2021-121239-C32Agencia Estatal de Investigación | Ref. RYC2019-026604-