Static Thermography Research Articles

Classic Versus Scarpa-sparing abdominoplasty: An infrared thermographic comparative analysis

Scarpa fascia preservation during abdominoplasty has been shown to have several clinical advantages. The mechanisms behind its efficiency have been the subject of several studies. Three theories have been proposed, relating to mechanical factors, lymphatic preservation, and improved vascularization. This study aimed to further investigate the possible vascular impact of Scarpa fascia preservation by using a thermographic analysis. A single-center prospective study was conducted, involving 12 female patients randomly and equally assigned to one of two surgical procedures: classic (Group A) and Scarpa-sparing abdominoplasty (Group B). Dynamic thermography was applied before and after surgery (one and six months), and two regions of interest (ROIs) were considered. The latter had the same location on every sample, and corresponded to areas where different surgical planes had been used. Static thermography was applied intraoperatively, and four ROIs were considered, located over Scarpa and over the deep fascia. The respective thermal data were analyzed. The general characteristics of both groups were identical. Preoperative thermography demonstrated no differences between groups. Intraoperative higher thermal gradients between lateral and medial ROIs were observed in Group B (P=0.037, right side). Dynamic thermography at one month demonstrated a trend for better thermal recovery and better thermal symmetry (P=0.035, 1-min mark) in Group B. No other differences were found. Dynamic thermography presented a better response when Scarpa fascia was preserved: stronger, faster, and more symmetric. Based on these results, improved vascularization may have a role in explaining the clinical efficiency of a Scarpa-sparing abdominoplasty.

Problems of Active Dynamic Thermography Measurement Standardization in Medicine

Reliability of thermographic diagnostics in medicine is an important practical problem. In the field of static thermography, a great deal of effort has been made to define the conditions for thermographic measurements, which is now the golden standard for such research. In recent years, there are more and more reports on dynamic tests with external stimulation, such as Active Dynamic Thermography, Thermographic Signal Reconstruction or Thermal Tomography. The subject of this report is a discussion of the problems of standardization of dynamic tests, the choice of the method of thermal stimulation and the conditions determining the credibility of such tests in medical diagnostics. Typical methods of thermal stimulation are discussed, problems concerning accuracy and control of resulting distributions of temperature are commented. The best practices to get reliable conditions of measurements are summarized.

Effectiveness of active dynamic and passive thermography in the detection of maxillary sinusitis

ABSTRACT This paper presents a novel approach for sinusitis detection by means of thermography. So far, the role of passive static thermography (PST) for diagnosing the sinusitis has been remarked by many studies. But, it has not been proved as an effective approach for sinusitis detection. With this aim, the automatic and active dynamic thermography (ADT) based approach has been proposed. The study has four steps: (a) data acquisition, PST and ADT of 19 control subjects and 16 sinusitis patients; (b) automatic extraction of maxillary regions; (c) thermal data processing; and (d) thermal data analysis. The effectiveness of ADT and PST approach has been evaluated by comparing their outcomes with physical examinations. Consequently, PST shows failure in the detection of maxillary sinusitis, whereas the outcomes of ADT highly correlate with physical examinations. The frequency analysis of ADT data shows 90% accuracy for sinusitis detection with sensitivity and specificity of 77.27% and 95.83%, respectively. In ADT, it has been observed that the thermal profiles of sinusitis patients are significantly different from those of control group during self-warming phase. Hence, the study shows the encouraging results towards the application of ADT in the diagnosis of sinusitis.

Numerical modelling of skin tumour tissue with temperature-dependent properties for dynamic thermography

Dynamic thermography has been clinically proven to be a valuable diagnostic technique for skin tumour detection as well as for other medical applications, and shows many advantages over static thermography. Numerical modelling of heat transfer phenomena in biological tissue during dynamic thermography can aid the technique by improving process parameters or by estimating unknown tissue parameters based on measurement data. This paper presents a new non-linear numerical model of multilayer skin tissue containing a skin tumour together with thermoregulation response of the tissue during the cooling-rewarming process of dynamic thermography. The thermoregulation response is modelled by temperature-dependent blood perfusion rate and metabolic heat generation. The aim is to describe bioheat transfer more realistically. The model is based on the Pennes bioheat equation and solved numerically using a subdomain BEM approach treating the problem as axisymmetrical. The paper includes computational tests for Clark II and Clark IV tumours, comparing the models using constant and temperature-dependent properties which showed noticeable differences and highlighted the importance of using a local thermoregulation model. Results also show the advantage of using dynamic thermography for skin tumour screening and detection at an early stage. One of the contributions of this paper is a complete sensitivity analysis of 56 model parameters based on the gradient of the surface temperature difference between tumour and healthy skin. The analysis shows that size of the tumour, blood perfusion rate, thermoregulation coefficient of the tumour, body core temperature and density and specific heat of the skin layers in which the tumour is embedded are important for modelling the problem, and so have to be determined more accurately to reflect realistic skin response of the investigated tissue, while metabolic heat generation and its thermoregulation are not.

Thermal contrast of active dynamic thermography versus static thermography

Thermal contrast of active dynamic thermography versus static thermography

Active dynamic thermography method for TRAM flap blood perfusion mapping in breast reconstruction

This paper presents the new method of the transverse rectus abdominis musculocutaneous flap blood perfusion mapping based on the active dynamic thermography. The method is aimed at aiding a surgeon during breast reconstruction procedure. A pair of dTnorm and t90_10 parameters were used as parametric image descriptors of the flap blood perfusion. The method was tested on 38 patients that were subjected to breast reconstruction procedure. This showed that, comparing to the static thermography, this is potentially an objective and effective method of skin flap perfusion assessment that can be performed in the operating room.

A new diagnostic IR-thermal imaging method for evaluation of cardiosurgery procedures

Two methods for monitoring the state of the myocardium during cardiosurgical interventions based on thermal IR imaging are presented below. These methods, called static thermography and active dynamic thermography (ADT), use information about the distribution of temperature on the surface, and an external excitation source to induce thermal transient processes in a tested object. Recording the time series of thermograms allows calculating parametric images – the distribution of the thermal time constant on the visible surface of the myocardium – correlated with the physiological state of the tested tissues. The temperature allows monitoring of vascularization in each phase of cardiosurgical interventions. This is a perfect method for the evaluation of the quality of the inserted graft, as well as the efficiency of cardioplegia, and the quality of many surgical procedures in clinical practice. Such monitoring is prompt, easy and objective, especially if dynamic processes are investigated. During LAD occlusion, the ADT procedure was applied using a cooling external excitation source. In summary, the calculated time constant images provide data of the tested structure and functional information of myocardium infarct. This allows tracking changes in the blood flow in the myocardium and enables the inspection of the quality of the intervention during cardiosurgical procedures.

Active dynamic infrared thermal imaging in burn depth evaluation.

The aim of this study was to find the relationship between active dynamic thermography (ADT) with cold excitation and burn depth. This new modality of evaluation of burns seems to be an attractive proposal for quantitative classification, allowing proper choice of burn wound treatment: conservative or surgical, especially compared with static thermography. The work was an in vivo experiment on domestic pigs, and a small number of patients were also diagnosed as part of the study. Statistical analysis showed a high correlation between the ADT synthetic parameter--thermal time constant, τ--and the classification of burn wounds that were predicted to heal within 3 weeks and so were treated conservatively and those that were predicted to not heal within 3 weeks and so were surgically treated. The results of the study show an accuracy of 60.7% for clinical evaluation, 69.6% for static thermography, 83.0% for ADT, and 84.0% for histopathologic assessment. The authors have concluded that the ADT method with cold excitation is suitable for the qualitative and quantitative assessment of burn depth.

Distal limb cast sores in horses: Risk factors and early detection using thermography

There is a lack of evidence-based data on the prevalence, outcome and risk factors of distal limb cast sores, and no objective tool has been described for the early detection of cast sores. To investigate the prevalence, location, outcome and risk factors of cast sores after application of a distal limb cast and to determine whether static thermography of the cast is a valuable tool for the assessment of sores. A prospective study was conducted on horses treated with a distal limb cast. At each cast removal, cast sores were graded as superficial sores (SS), deep dermal sores (DS) or full thickness skin ulcerations (FS). In several cases, a thermographic evaluation of the cast was performed immediately prior to removal and differences in temperature (AT) between the coolest point of the cast and 2 cast regions predisposed for sore development (dorsoproximal mc/mtIII and palmar/plantar fetlock) were calculated. Mean +/- s.d. total casting time of 70 horses was 31 +/- 18 days. Overall, 57 legs (81%) developed at least SS. Twenty-four legs (34%) ultimately developed DS and one horse had an FS. Multivariable analysis showed that the severity of sores was positively associated with increasing age (OR: 1.111, P = 0.028), a normal (vs. swollen) limb (OR: 3387, P = 0.023) and an increase in total casting time (OR per week: 1.363, P = 0.002). The thermographic evaluation (35 casts) revealed that the severity of sores was positively associated with increasing deltaT (OR: 2.100, P = 0.0005). The optimal cut-off values for the presence of SS and DS were set at, respectively, deltaT = 23 and 43 degrees C. Distal limb cast is a safe coaptation technique with increasing risk of developing sores with time. Thermography is a valuable and rapid clinical tool to monitor the development of cast sores.

Burn depths evaluation based on active dynamic IR thermal imaging—A preliminary study

Proper diagnostic assessment of burn wound depth is of the highest importance in selecting the mode of burn wound treatment. Several diagnostic methods – clinical and histopathological evaluation, as well as methods employing IR imaging – static thermography and active dynamic thermography (ADT) – are compared on the basis of in vivo experiments conducted on three domestic pigs (23 burn wounds). ADT is presented here as a new, reliable and quantitative method of assessing burn wound depth on the basis of discrimination of the thermal properties of burnt tissue. In the case of ADT registration of thermal images was performed following thermal pulse excitation. A series of captured infrared images was used as the basis for calculating the thermal time constant τ for each pixel. The parameter values were compared with histopathological and clinical assessments of burn depth. The mean value of τ was found for burns, which heal within 3 weeks ( τ = 12.08 ± 1.94 s) and for burns, which did not heal during this period ( τ = 9.07 ± 0.68 s), p < 0.05. The accuracy, sensitivity and specificity of all the methods tested were compared, the best results coming from ADT. The ADT method is fast, non-invasive and relatively inexpensive, although it still requires further animal experimentation as well as clinical study to confirm the results.

Static thermography revisited—An adjunct method for determining the depth of the burn injury

The aim of the study was to investigate the relationship between the static thermography figure of merit Δ T (the difference in mean values of skin area temperature for the burn wound area and the unaffected reference skin area) and a means of burn classification which would be most suitable for the choice of treatment. The work was an in vivo animal experiment. Statistical analysis showed a high correlation between the Δ T parameter and histopathological assessment. With regard to the choice of treatment, the most useful correlation was found to be that between Δ T and the classification of burn wounds into those healed in 3 weeks and those unhealed. The results of this study have revealed a quantitative criterion Δ T for burn classification. The study suggests that particular burn centres using static thermography use a Δ T parameter based on their own values for burn classification so as to group burn wounds into those that healed in 3 weeks and those that did not heal. This criterion should be independent of and replace other classification systems. A criterion for the proper choice of burn treatment would then be made more readily available.