Infrared thermography: a rapid, portable, and accurate technique to detect experimental pneumothorax

Hemopneumothorax detection through the process of artificial evolution - a feasibility study

BACKGROUND

Tension pneumothorax is one of the leading causes of preventable death on the battlefield. Current prehospital diagnosis relies on a subjective clinical impression complemented by a manual thoracic and respiratory examination. These techniques are not fully applicable in field conditions and on the battlefield, where situational and environmental factors may impair clinical capabilities. We aimed to assemble a device able to sample, analyze, and classify the unique acoustic signatures of pneumothorax and hemothorax.

METHODS

Acoustic data was obtained with simultaneous use of two sensitive digital stethoscopes from the chest wall of an ex-vivo porcine model. Twelve second samples of acoustic data were obtained from the in-house assembled digital stethoscope system during mechanical ventilation. The thoracic cavity was injected with increasing volumes of 200, 400, 600, 800, and 1000 ml of air or saline to simulate pneumothorax and hemothorax, respectively. The data was analyzed using a multi-objective genetic algorithm that was used to develop an optimal mathematical detector through the process of artificial evolution, a cutting-edge approach in the artificial intelligence discipline.

RESULTS

The in-house assembled dual digital stethoscope system and developed genetic algorithm achieved an accuracy, sensitivity and specificity ranging from 64 to 100%, 63 to 100%, and 63 to 100%, respectively, in classifying acoustic signal as associated with pneumothorax or hemothorax at fluid injection levels of 400 ml or more, and regardless of background noise.

CONCLUSIONS

We present a novel, objective device for rapid diagnosis of potentially lethal thoracic injuries. With further optimization, such a device could provide real-time detection and monitoring of pneumothorax and hemothorax in battlefield conditions.

Effect of osteopathic treatment on a scar assessed by thermal infrared camera, pilot study

BACKGROUND

Scar formation is influenced by mechanical forces and may generate mechanical tension. Scars induce a temperature difference in the body objectified by thermal imaging camera. The osteopath's task is to ensure the tissue good mobility in the body. The aim of this study was to measure the influence of osteopathic treatment on a scar by thermal camera.

METHOD

12 subjects were analyzed: 4 scars by wounds and 8 by operations. A thermal camera was used to measure the temperature variations of the scars and peri-scar area after cooled stimulation. Measurements were made before and after osteopathic treatment.

RESULTS/FINDINGS

A significant difference was found between the scar and the peri-scar area before osteopathic treatment (p = 0.044) and no significant difference after osteopathic treatment (p = 0.069). Results showed that osteopathic treatment on a scar induces a more homogeneous local warming temperature.

CONCLUSION

The osteopathic treatment allows different warming between scar and peri-scar area; this suggests a modification of the connective tissue function after osteopathic treatment. Further studies are required to better understand the function of connective tissue and the mechanism of healing.

A pilot study of the Leicester ED medical infrared imaging protocol in fever and sepsis

BACKGROUND

Medical Infrared Imaging (MII) is an investigative method that can be potentially used in emergency care to non-invasively detect thermal signatures associated with change in blood flow. We have developed a protocol for the use of MII in the Emergency Department (ED) and shown that it is feasible. To derive initial data for sample size calculations, we performed an exploratory study in patients with fever and sepsis.

METHODS

The Leicester MII protocol was used to image the temperature patterns along the arm among three patient groups (control, fever and sepsis) of a total 56 patients. Anatomical markers were used to divide this gradient into upper arm, forearm, hand and finger regions. Variations in measurements within and between these regions were described.

RESULTS

The thermal gradient down the arm was successfully extracted in all patients. The distribution of values in each region of the arm was described in control, fever and sepsis patients. There was a significant gradient between upper arm and finger in controls (2.75, p < 0.0001), but no gradient in fever (p = 0.944) or sepsis (p = 0.710). This was reflected in the finger/arm difference, which was of -2.74°C (±3.50) in controls, -0.39C (±2.48) in fever, and -1.80°C (±3.09) in sepsis.

CONCLUSIONS

This study found different thermal gradients along the arm in control and febrile groups, and defined the degree of individual variation. It is likely that the difference between upper arm temperature and finger temperature (representing the temperature gradient down the arm) may be more useful than absolute measurements in future studies.

There's an app for that: A handheld smartphone-based infrared imaging device to assess adequacy and level of aortic occlusion during REBOA

BACKGROUND

Advances in thermal imaging devices have made them an appealing noninvasive point-of-care imaging adjunct in the trauma setting. We sought to assess whether a smartphone-based infrared imaging device (SBIR) could determine presence and location of aortic occlusion in a swine model. We hypothesized that various levels of aortic occlusion would transmit significantly different heat signatures at various anatomical points.

METHODS

Six swine (35-50 kg) underwent sequential zone 1 (Z1) aortic cross clamping as well as zone 3 (Z3) aortic balloon occlusion (resuscitative endovascular balloon occlusion of the aorta [REBOA]). SBIR images and readings (FLIR One) were taken at five anatomic points (axilla [A], subcostal [S], umbilical [U], inguinal [I], medial malleolar [M]) and were used to determine significant thermal trends 5 minutes to 10 minutes after Z1 and Z3 occlusion. Significant (p ≤ 0.05) thermal ratio patterns were identified and compared among groups, and images were reviewed for obvious qualitative differences at the various levels of occlusion.

RESULTS

Body temperatures were similar during control (CON), Z1 occlusion, and Z3 occlusion, ranging from 94.0 °F to 100.9 °F (p = 0.126). No significant temperature differences were found among A, S, U, I, M points prior to and after aortic occlusions. Among the anatomical 2-point ratios evaluated, A/M and S/M ratios were the best predictors of aortic occlusion, whether at Z1 (8.2 °F, p < 0.01; 10.9 °F, p < 0.01) or Z3 (7.3 °F, p < 0.01; 8.4 °F, p < 0.01), respectively. The best predictor of Z1 versus Z3 level of occlusion was the S/I ratio (5.2 °F, p < 0.05 vs. 3.4 °F, p = 0.27). SBIR generated qualitatively different thermal signatures among groups.

CONCLUSION

SBIR was capable of detecting thermal trends during Z1 and Z3 aortic occlusion by using an anatomical 2-point thermal ratio. There were also easily recognized qualitative differences between control and occlusion images that would allow immediate determination of adequate occlusion of the aorta. SBIR represents a potential inexpensive and accurate tool for assessing perfusion, adequate REBOA placement, and even the aortic level of occlusion.

Medical infrared thermal imaging of cats with hyperthyroidism

OBJECTIVE

To determine the usefulness of medical infrared thermal imaging (MITI) as a screening tool for hyperthyroidism in cats, evaluate the need for hair clipping over the ventral aspect of the neck to achieve optimal images, and determine whether there is a change in thermal patterns at 1 and 3 months after radioactive sodium iodide I 131 treatment.

ANIMALS

17 cats with and 12 control cats without hyperthyroidism.

PROCEDURES

All cats underwent MITI first with the hair present and then after the hair was clipped. Each cat with hyperthyroidism was subsequently appropriately treated SC with radioiodide; reevaluations, including MITI before and after hair clipping and measurement of serum thyroxine concentration, were performed 1 and 3 months after treatment.

RESULTS

The MITI had 80.5% and 87.5% accuracy in differentiating hyperthyroid cats from clinically normal cats before and after the hair over the ventral aspect of the neck was clipped. Among cats with an initial serum thyroxine concentration > 4.0 μg/dL, the success rate for MITI-detected response to radioiodide treatment at the 1-month reevaluation was 92.86% in unshaved cats and 85.71% in shaved cats. The success rate for MITI-detected response to radioiodide treatment at the 3-month reevaluation was 100% in unshaved and shaved cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that MITI was successful in differentiating between hyperthyroid cats and clinically normal cats and identifying patients with thyroxine concentration within reference interval after radioactive sodium iodide I 131 treatment.

Actinobacillus pleuropneumoniae challenge in swine: diagnostic of lung alterations by infrared thermography

BACKGROUND

Actinobacillus pleuropneumoniae (A.pp.) is the causative agent of porcine pleuropneumonia leading to high economic losses in the pig industry. Infrared thermography (IRT) of the thorax might offer a new method to select swine with lung alterations for further diagnostics. In this study 50 german landrace pigs were infected with A.pp. in an established model for respiratory tract disease, while 10 healthy pigs served as control animals. To avoid drift errors during IR measurements absolute skin temperatures and temperature differences between a thoracal and an abdominal region were assessed for its diagnostic validity.

RESULTS

IRT findings during the course of experimental A.pp.-infection were verified by computed tomography (CT) before and on days 4 and 21 after infection. Significant correlations were found between clinical scores, CT score and lung lesion score. Ambient temperature, body temperature and abdominal surface temperature were factors influencing the skin surface temperature of the thorax. On day 4 but not on day 21 after infection the right thoracal temperature was significantly higher and the difference between a thoracal region in the height of the left 10th vertebra and an abdominal region was significantly lower in infected pigs than in control pigs. At a cut off of 28°C of right thoracal temperature the specificity of the method was 100% (CI 95%: 69-100%) and the sensitivity 66% (CI 95%: 51-79%). At a cut off of 2°C temperature difference between thoracal and abdominal region on the left body site the specificity of the method was 100% (CI 95%: 69-100%) and the sensitivity 32% (CI 95%: 19-47%) with all control pigs detected negative. Orientation for lung biopsy by IRT resulted in 100% specificity and sensitivity (CI 95%: 69-100%) of bacteriological examination of tissue samples during the acute stage of infection.

CONCLUSION

IRT might be a valuable tool for the detection of inflammatory lung alterations in pigs, especially during the acute stage of infection and if ambient temperatures are constant during individual measurements. External and internal factors interfere with this method, so that its application in the field might be restricted to a selection of pigs for further diagnostic with adequate specificity.

On the Stability of Lung Parenchymal Lesions with Applications to Early Pneumothorax Diagnosis

Spontaneous pneumothorax, a prevalent medical challenge in most trauma cases, is a form of sudden lung collapse closely associated with risk factors such as lung cancer and emphysema. Our work seeks to explore and quantify the currently unknown pathological factors underlying lesion rupture in pneumothorax through biomechanical modeling. We hypothesized that lesion instability is closely associated with elastodynamic strain of the pleural membrane from pulsatile air flow and collagen-elastin dynamics. Based on the principles of continuum mechanics and fluid-structure interaction, our proposed model coupled isotropic tissue deformation with pressure from pulsatile air motion and the pleural fluid. Next, we derived mathematical instability criteria for our ordinary differential equation system and then translated these mathematical instabilities to physically relevant structural instabilities via the incorporation of a finite energy limiter. The introduction of novel biomechanical descriptions for collagen-elastin dynamics allowed us to demonstrate that changes in the protein structure can lead to a transition from stable to unstable domains in the material parameter space for a general lesion. This result allowed us to create a novel streamlined algorithm for detecting material instabilities in transient lung CT scan data via analyzing deformations in a local tissue boundary.

Evaluation of thermographic imaging of the limbs of healthy dogs

OBJECTIVE

To describe a thermographic imaging protocol, identify normal thermographic patterns (ie, color map reflecting the skin temperature distribution) for various regions of interest (ROIs) of dog limbs, and evaluate effects of clipping the coat on thermographic patterns and limb temperature in healthy dogs.

ANIMALS

10 healthy dogs.

PROCEDURES

Each dog was thermographically evaluated in the same room (ambient temperature, 21 degrees C) via ROIs that included cranial and caudal views of the body, full lateral body views, full views of the limbs, and views of various limb regions. After initial imaging, the coat was clipped on the forelimbs and hind limbs only. Each dog was then evaluated 15 and 60 minutes and 24 hours after clipping by use of the same protocol.

RESULTS

For each ROI within a category (intact coat and each time point after clipping), mean temperatures were similar among the 10 dogs. Pairwise comparisons for 15 and 60 minutes and 24 hours established patterns of temperature stabilization among the 3 time points. Temperatures did not differ significantly between the left and right limbs. There was a mean success rate of 75% for use of image pattern analysis for recognition of similar thermographic patterns in the forelimbs and hind limbs.

CONCLUSIONS AND CLINICAL RELEVANCE

Thermography can be a viable, noninvasive imaging modality that provides consistent images with reproducible thermal patterns in ROIs examined in healthy dogs. Although the coat had a predictable influence to decrease the mean temperature, thermal patterns remained fairly consistent after the coat was clipped.

Temperature measurement on tissue surface during laser irradiation

Tissue surface temperature distribution on the treatment site can serve as an indicator for the effectiveness of a photothermal therapy. In this study, both infrared thermography and theoretical simulation were used to determine the surface temperature distribution during laser irradiation of both gel phantom and animal tumors. Selective photothermal interaction was attempted by using intratumoral indocyanine green enhancement and irradiation via a near-infrared laser. An immunoadjuvant was also used to enhance immunological responses during tumor treatment. Monte Carlo method for tissue absorption of light and finite difference method for heat diffusion in tissue were used to simulate the temperature distribution during the selective laser photothermal interaction. An infrared camera was used to capture the thermal images during the laser treatment and the surface temperature was determined. Our findings show that the theoretical and experimental results are in good agreement and that the surface temperature of irradiated tissue can be controlled with appropriate dye and adjuvant enhancement. These results can be used to control the laser tumor treatment parameters and to optimize the treatment outcome. More importantly, when used with immunotherapy as a precursor of immunological responses, the selective photothermal treatment can be guided by the tissue temperature profiles both in the tumor and on the surface.

Feasibility study on using an infrared thermometer for evaluation and administration of cryosurgery

Successful performance of cryosurgery relies heavily on a quick, efficient, safe and economic imaging way to monitor the surgical advancement and then to evaluate the curative effect. However, there is currently a lack of such an imaging modality. As for the commonly adopted imaging devices such as X-CT, MRI and PET, in addition their high cost and complexity in operation, they often induce additional scathe to the patients due to their potential radiation effects. Besides, in cryosurgery, the most important parameter - temperature - can not be directly detected by these methods. Considering the above factors, infrared thermography (IRT), a rather useful yet often neglected functional imaging technique in clinics, is proposed in this paper as an efficient tool for the quick evaluation and administration of a cryosurgical treatment of tumors. Based on skin surface temperature mapping, the degree of damage to the target tissue site caused by different freezing/heating protocols, as well as the states of blood circulation and metabolic heat generation within the treated region can possibly be identified. Further, through recording the temperature variation feature at the skin surface before and after cryosurgery, IRT would help to quickly evaluate the curative effect, which is very beneficial for later treatment planning. By detecting the surface infrared image and analyzing its digital values, the patient's invisible focus and abnormal physiological states, e.g. inflammations or pneumothorax, often accompanied by cryosurgical output yet difficult to determine via conventional imaging, could also possibly be diagnosed. To test the above concepts, both typical animal and clinical experiments were performed to demonstrate the feasibility and advantages of IRT-guided cryosurgery. This study may help push forward a novel, low-cost and non-contact way for an efficient performance of cryosurgery.

Alterations of liver temperature during hepatic fibrosis

AIM: To investigate the alterations of liver temperature during hepatic fibrosis in rats induced by CCl₄.

METHODS: Liver fibrosis was induced in rats after administration of CCl₄ twice a week for 8 weeks. The rat liver temperature in 2-, 4-, 6- and 8- wk models and control group rat was detected by computer-assisted infrared thermorgraphic technology. To observe the histological change, the liver tissue microarray in every group of animals was stained by hematoxylin and eosin. Sirius red stain and polarization microscopy method was used for I and III collagen expression. Immunohistochemistry was used for detection of laminin to outline the formation of basement membrane on hepatic sinusoids.

RESULTS: The average infrared images temperature of hepatic fibrosis in rats induced by CCl₄ changed with the time of the model made. In 2-wk model group, the infrared image temperature of right liver lobe was 28.6±1.1 ℃, compared with 2-wk control group (P <0.05, t = -2.518). The temperature of 4-wk model group was 27.2±1.0 ℃. In 6-wk model group, the temperature was 30.1±1.2 ℃, compared with 6 wk control group (P <0.05, t = 3.773). The temperature of 8-wk model group was 27.4±1.0 ℃, compared with 8 wk control group (P <0.01, t = 4.998). The histological changes of liver tissue were inflammation and hepatocytic degeneration and necrosis in 2-wk model group. There was a significant increase of extracellular matrix among the necrostic hepatocytes in 4-wk model group. In 6-wk model group liver tissue showed the numbers of necrostic hepatocytes increased significantly and the septa formed around central vein and portal area. In 8 wk model group, there were wide septa expansions from the portal area to the central venous and pseudo-nodular formation. Sirius red and immunohistochemical stains showed collagen types I, III and laminin expression in liver tissues increased gradually in 2-, 4-, 6-, 8- wk model group. Collagen type III was the main collagen in 2- and 4-wk model groups. Collagen type I was the main collagen in 6- and 8-wk model groups.

CONCLUSION: The liver temperature changes regularly with hepatic tissue pathology in course of rat hepatic fibrosis induced by CCl₄.