Smartphone Thermal Imaging Research Articles

APPLICATION OF THERMAL IMAGING CAMERAS FOR SMARTPHONE: SEEK THERMAL COMPACT PRO AND FLIR ONE PRO FOR HUMAN STRESS DETECTION – COMPARISON AND STUDY

Thermography as an innovative diagnostic technique with non-contact temperature measurement is used in many industries – science, industry, medicine, and security. When using thermography in the field of health, images and images sequences obtained from thermal imaging cameras allow to record the temperature distribution in order to further recognize whether the state of the body is consistent with the defined parameters or whether there are deviations. However, it is worth paying attention to the measurement accuracy of thermal imaging cameras, their specification, and image quality of thermograms. In the case of recording stress states, measurement discrepancies between thermal imaging cameras for smartphone may affect the final results. Therefore, this article focuses on the comparison of the possibility of recording and detecting stress using two smartphone thermal imaging cameras: SEEK THERMAL Compact Pro and FLIR ONE Pro. The specifications of both cameras were compared. At the same time, the possibility of recording stress using smartphone thermal imaging cameras was confirmed on the basis of an exemplary study. The results of the comparison and analysis show that smartphone thermography can be a quick registration and diagnostic method in behavioral-biomedical issues.

Smartphone Thermal Imaging for Preoperative Perforator Mapping in Perforator Based Flaps.

To determine the diagnostic accuracy of smartphone thermal imaging for preoperative perforator mapping in perforator-based flaps, taking visual inspection as gold standard. It was a cross-validation study conducted at the Department of Plastic Surgery, Dr. Ruth K. Pfau Civil Hospital, Karachi, Pakistan, from August 2022 to January 2023. All adult patients aged 18 to 40 years of either gender undergoing perforator flap surgery were included. Each patient followed the same treatment regimen, which involved the preoperative identification of the perforator location using the FLIR One camera. Subsequently, confirmation was achieved during the surgical procedure through visual inspection. A two-by two table was used to calculate sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy. The mean age of the patients was 30.10±6.87 years, ranging from 18 to 40 years. Most of the patients were males (58.7%), and 41.3% were females. Almost 80.4% were pedicle flaps, and 19.6% were free flaps. The accuracy of thermal imaging was found to be 83.2%, with a sensitivity of 84.3%, a specificity of 80%, a PPV of 92.9%, and a NPV of 62.2%, respectively. Smartphone-based thermal imaging is useful for the diagnosis of perforators and has high sensitivity and specificity.

Clinical utility of smartphone-based digital infrared thermal imaging in predicting vascular compromise in free flaps

Abstract Background: Flap monitoring plays an important role in avoiding morbidity in free flap. Clinical monitoring is considered the gold standard, but it is subjective. Digital thermal imaging captures and displays the infrared radiation emitted from an object. This is useful in assessing temperature difference between two surfaces, as well as variation of temperature. Smartphone thermal imaging can be used to assess the tissue perfusion, which requires little training. Materials and Methods: The aim was to assess the validity of Digital Thermal Imaging in early diagnosis of flap failure, compared to conventional clinical methods. Eleven patients of microvascular-free flap reconstruction for defects following malignancy and trauma were included in the study for January 25, 2019–March 25, 2021. Flaps were monitored using three different methods – clinical monitoring, biochemical monitoring, and digital thermal imaging done at the following interval: (1) intraoperative (end of surgery), (2) hourly – for the first 48 h, (3) every 4th hourly on postoperative days 3–5, and (4) every 6th hourly on postoperative days 5–10, and the results were tabulated. Results: Flap temperature was observed to be higher compared to the surrounding skin when there was an event of venous thrombosis. The surrounding skin temperature was to be measured on the side opposite to the side where the flap was raised to do vascular anastomosis. The increase in the temperature difference almost coincided with the clinical and biochemical indicator of failing flaps. Conclusion: Monitoring of the flap temperature and comparing it with the surrounding skin temperature can be incorporated along with the gold standard. It is a simple, objective, and noncontact method compared to clinical monitoring and biochemical methods. A large sample size, multicentric, randomized controlled study is required to validate the same.

ShuffleNet and XGBoost classifier for stress reactions detection

A huge problem of the society of the present century is stress. It is not possible to eliminate it completely, but it can be controlled and actions can be taken to eliminate it or build a way of coping with stress. Stress can manifest itself in a physiological as well as psychological form. It can be visible through facial expressions, which is related to emotions. Emotions, like stress, can be positive or negative. Therefore, the observation of a person’s emotions can lead to the determination of their stress response and even the intensity of stress. Emotions allow to regulate stress sensations – increase their intensity or, on the contrary, get rid of or relieve stress. Observing the rapid development of machine learning, it is worth using the resources of neural networks for stress control and monitoring purposes. Many detection techniques use complex neural networks, which at the same time require large computer resources, are time-consuming and expensive. Therefore, it is important to use and develop lightweight neural networks that do not require huge computer resources. In addition, it is worth considering the use of expensive measuring devices, while there are many handheld devices with convergent parameters on the technical market. An example is a smartphone thermal imaging camera that can provide recording accuracy, and the acquired thermal images can be a source of data. With the whole thing in mind, in this paper, the author proposes a lightweight convolutional network drawing on ShuffleNet to detect stress from thermal images of faces expressing various emotional forms. The proposed network includes additional layers and the XGBoost classifier. As a result of the calculations, the accuracy in the multi-class classification reached 87%. The research confirmed the validity and effectiveness of the proposed network and the capabilities of the detection technique. Certainly, the subject of stress and light convolutional neural networks is developmental and will be developed by the author in the future.

Uses of Smartphone Thermal Imaging in Perforator Flaps as a Versatile Intraoperative Tool: The Microsurgeon's Third Eye

IntroductionIn this study, we evaluate the versatility of smartphone thermal imaging technology as a valuable intraoperative modality in different stages of perforator flap surgery aiming to minimize the complications and achieve the best postoperative outcome. Patients and methodsThermography was performed in 20 perforator flaps in 20 patients at different surgical stages in three different ways to identify the most dominant perforator: first, by measuring the surface temperature of the skin; second, by using the dynamic infrared thermography technique; and third, by assessing the perfusion pattern when the flap was supplied by each perforator separately. Thermography was used to help in discarding the least perfused area of the flap. After microvascular anastomosis, the flap reheating pattern was evaluated. ResultsSeventeen free and three pedicled perforator flaps were included. Intraoperatively, each of the selected perforators had a corresponding hotspot. The perforator with the hottest hotpot, best rewarming, and provision of best flap perfusion on thermography was found clinically dominant. After microvascular anastomosis in free flaps, rapid rewarming was recorded in 15 cases. In two deep inferior epigastric perforator flaps, no rapid rewarming was observed. The pedicle was kinked in one case and there was a venous insufficiency in another case that required a cephalic turndown. All flaps showed good perfusion on thermography after inset. ConclusionSmartphone thermography has proven to be a valuable, cheap, rapidly employed, and objective tool not only for the design of perforator flaps, but also for the decision making intraoperatively to achieve the best surgical outcome.

Smartphone thermal imaging for stressed people classification using CNN+MobileNetV2

Stress as a mental and physical imbalance is the experience of every human being. It can have a positive effect on human motivation and performance, as well as negatively contributing to the formation of chronic diseases. So far, stress is most often detected using EEG, ECG, GSR, BVP. A minority of researchers undertake stress detection from thermal images or video. The author, seeing the great potential in this area and looking for low-budget solutions that are more easily accessible to the average person, conducted a stress study using smartphone thermal imaging. The faces of the study participants were recorded by a low-cost thermographic camera in the smartphone version (external connection) – FLIR ONE Pro. As a stressor, arithmetic tasks with a time limit were used. The subjects additionally supplemented the MiniCOPE test to assess the level of coping with stress. These data were additional parameters that were taken into account during stress classification using CNN+MobileNetV2. The final results indicated high accuracy of stress classification based on thermal image sequences, confirming the thermal potential in stress detection.

The Use of Thermal Imaging in Free Perforator Flap Planning

Background. Preoperative planning and design of microsurgical perforator flaps are the main steps for successful operation. The aim of this study was to determine the concordance between thermographic images obtained with smartphone thermal imaging camera and hand-held Doppler in the anterolateral thigh flap (ALT) model. Methods. A concordance study of diagnostic tests was carried out in Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Plastic and Reconstructive Surgery Department during 2020–2022. Patients’ who were scheduled to undergo reconstruction with ALT flap and healthy volunteers were included in the study. Dynamic thermal images were performed with smartphone thermal camera FLIR One PRO in the typical ALT flap territory. The number and distance of hotspots in the thermogram with respect to anterior superior iliac spine were recorded in the study protocol. Later, the examination was repeated with hand-held Doppler and the control of hotspot was performed. Sensitivity, specificity and concordance index calculations were performed. Statistical analysis was performed using IMB SPSS 23.0. Results. A total of 100 ALT flap territories were examined. 266 hotspots were detected with thermal imaging and 275 perforators with hand-held Doppler. In 96.6% of cases, hotspots detected by a thermal camera were confirmed by hand-held Doppler as perforators. The sensitivity and specificity of thermography for the detection of perforators with respect to the hand-held Doppler were 93.5% and 96.9% respectively. The measure of concordance kappa index was 0.095 (p = 0.001). Conclusion. Smartphone thermal imaging have a high concordance with hand-held Doppler in perforator mapping, thus could be considered a useful adjunct to conventional methods.

Postoperative Monitoring of Free Flaps Using Smartphone Thermal Imaging May Lead to Ambiguous Results: Three Case Reports

Postoperative Monitoring of Free Flaps Using Smartphone Thermal Imaging May Lead to Ambiguous Results: Three Case Reports

How to Map All Your Flap Perforators in 2 Minutes

INTRODUCTION: Imaging modalities are changing clinical practice in plastic surgery and becoming more compact, more affordable, and easier to use. Over the last two decades, 3D imaging, ICG angiography, and virtual surgical planning have become commonplace for operative decision-making. Recently, mobile thermal imaging has demonstrated accuracy and consistency in determining perforator locations and visualizing the functional angiosomes.1 A study by Khouri et al in 1992 showed that the sensitivity of surface-temperature recording is 98%, and its predictive value is 75%.2 We sought to investigate whether recovery-enhanced mobile thermal imaging can be used to rapidly and reliably design perforator flaps. METHODS: Thermal imaging was compared with Doppler perforator mapping in five volunteers. Volunteers underwent traditional flap markings on one thigh and mobile thermal imaging (FLIR One Pro, FLIR Systems, Inc., Willsonville, Oreg.) on their contralateral thigh. In the traditional group, a line was drawn from the ASIS to the superolateral border of the patella with a 3-cm-radius circle at the midpoint, followed by perforator identification with a Doppler.3 On the contralateral thigh, ice cooling was performed for 10 seconds followed by inspection with the thermal camera. Time to identify at least three perforators, determination of perforator dominance, and perforator concordance were recorded. Additionally, in two consecutive patients undergoing anterolateral thigh flap reconstruction, flap design was examined based on traditional markings versus thermal imaging. RESULTS: Perforator identification was more rapid (136 seconds versus 232 seconds) and more likely to demonstrate perforator dominance (five versus one) using thermal imaging compared with traditional markings (P < 0.05). In both patients undergoing ALT flap reconstruction, three perforators were located with traditional and thermal imaging markings. In patient one, the middle perforator demonstrated dominance and true anastomoses to the surrounding perforators. In patient two, the transverse branch perforator demonstrated maximal intensity and poor connections to the distal perforators. After this, proximal perforator was divided and the thermal imaging worsened, resulting in resection of the proximal flap and change in flap design. Perforator location matched computed tomography angiographic findings in both patients. No postoperative flap compromise was encountered. CONCLUSIONS: Thermal imaging with ice cooling appears highly effective at rapid perforator and angiosome identification-based flap design. Recovery-enhanced thermography by ice cooling allows for dynamic visualization of angiosome perfusion area. Given improvement in technology and decreasing costs, mobile thermal imaging may become a reliable tool in flap design and flap monitoring. REFERENCES: 1. Pereira N, Valenzuela D, Mangelsdorff G, et al. Detection of perforators for free flap planning using smartphone thermal imaging. Plast Reconstr Surg. 2018;141(3):787–792. 2. Khouri RK, Shaw WW. Monitoring of free flaps with surface-temperature recordings: is it reliable? Plast Reconstr Surg. 1992;89(3):495–499; discussion 500–502. 3. Saint-Cyr M, Oni G, Lee M, et al. Simple approach to harvest of the anterolateral thigh flap. Plast Reconstr Surg. 2012;129(1):207–211.

Smartphone Thermal Imaging in the Detection of Testicular Ischemia

ObjectiveTo evaluate smartphone thermal imaging as a point of care test in the detection of testicular ischemia. Thermal imaging detects the infrared (heat) pattern of an object and the technology is now available as an inexpensive attachment to smartphones. Materials and MethodsSmartphone thermal imaging was studied as a point-of-care diagnostic test for testicular ischemia in an IACUC approved study that prioritized survival of all animal subjects. Thirty canines weighing over 12 kg were observed during elective neuter procedures with consent from owners. Randomization determined ligation of the right vs left spermatic cord. With both testicles remaining in the scrotum, blinded inspection was performed with a FLIR ONE Pro thermal imaging camera for smartphone use. The bilateral orchiectomy procedures were then completed as planned. ResultsWithin 11 minutes of ligation of the randomized spermatic cord, an obvious change in the thermal imaging pattern allowed for the correct diagnosis of the ischemic testicle in 30/30 (100%) of subjects in a blinded fashion. Temperature differences between testicles at the time of ischemia diagnosis ranged from 0.7°C to 3.7°C with an average difference of 1.79°C lower in the ischemic testicle (95% CI: [1.50, 2.08]). A thermal imaging evaluation of the testicles takes 30 seconds to perform. ConclusionSmartphone thermal imaging correctly diagnosed testicular ischemia in 100% of animal subjects in a blinded fashion. The clinical utility of this emerging point-of-care technique in the evaluation of testicular torsion is currently unknown.

Mobile Smartphone Thermal Imaging Characterization and Identification of Microvascular Flow Insufficiencies in Deep Inferior Epigastric Artery Perforator Free Flaps

BackgroundMobile smartphone thermal imaging (MTI) devices correlate with blood flow, which makes them appealing adjuncts during reconstructive surgery. MTI was assessed in the setting of deep inferior epigastric artery perforator (DIEAP) free flaps. We hypothesized that MTI can be a surrogate for blood flow to identify microvascular flow insufficiencies. MethodsNineteen patients underwent 30 DIEAP flaps for breast reconstruction. Images were obtained preoperatively, intraoperatively, and at instances of concern for flap viability. Three groups were evaluated: normal DIEAP flaps (NDFs), flaps with arterial insufficiency (AI), and flaps with venous congestion (VC). ResultsAll flaps were successful. There were significant temperature increases from max ischemia (24.5 ± 2.1°C) to 1 min after anastomosis (27.2 ± 1.6°C, P < 0.001). NDFs continued to warm until the final MTI was taken when leaving the operating room. There were no differences between MTI flap temperatures before transfer to the chest and after completion of microanastomosis. With questionable flap viability, VC and AI temperatures were found to be significantly colder than the NDF group (28.3 ± 1.9°C versus 32.2 ± 1.8°C, P = 0.003) in the VC group and (27.2 ± 0.7°C versus 32.2 ± 1.8°C, P = 0.001) in the AI group. After correction of the identified flow insufficiency, VC and AI rewarmed and temperatures were no different compared with NDF. ConclusionsMTI recognizes microanastomotic failure and is a practical adjunct in the evaluation of free flap perfusion.

Stress detection and monitoring based on low-cost mobile thermography

The high level of stress in modern life is one of the huge problems of the 21st century society, especially in the context of the Covid-19 pandemic. With the pandemic, the need for inexpensive, portable and easy-to-use health monitoring tools (mental and physical) has increased. Of particular importance here is mobile (smartphone) thermography, as it enables the initial detection and self-control of stress, which being intensified nowadays, is the cause of many diseases, depression and health problems. The smartphone thermal imaging camera responds to the strict sanitary guidelines, offering contact-free, painless and non-invasive operation. Additionally, it is included in the group of low-cost solutions available for home use. It is an alternative to commonly used (often expensive and unavailable to everyone): EMG, ECG, EEG, GSR or other high-cost stress detection tools. Thermal imaging by analyzing abnormalities or temperature changes allows for detection application. Therefore, the aim of this work is to determine the possibilities of a low-budget mobile thermal imaging camera in detecting stress, detecting and analyzing stress by identifying the characteristics of psychophysiological signals with the individual characteristics of the participants, along with the correlation. The participants’ reactions to the film introducing stress tension up to the climax of the action were recorded thermographically. Data was processed in OpenCV. In the usual observation, stress often remained unnoticed. However, the thermographic analysis provided detailed information on the impact of the film’s stressful situation on the participants, with the possibility of distinguishing the stages of stress. The results of the preliminary pilot study were presented, which indicated the variability of temperature and heart rate as important indicators of stress – with the simultaneous significance of individual characteristics of the participant. Smartphone stress thermography is a promising method of monitoring human stress, especially at home.

Smartphone Thermal Imaging Can Enable the Safer Use of Propeller Flaps.

The use of thermography for the identification of cutaneous "hot spots" that coincide with perforators is not a new concept, but the required professional cameras may be prohibitively expensive. Only relatively recently, incredibly cheap but adequate thermal imaging cameras have become available that work in concert with the ubiquitous cell phone. This can now serve as a rapid, accurate, and complementary method for finding a perforator sufficient to serve as the hub for a perforator pedicled propeller flap. In addition, the preferred direction of rotation about that hub, effect of flap insetting on perfusion, and then postoperative monitoring are possible by proper interpretation of corresponding thermograms. Every reconstructive surgeon should be able to obtain this device, and then easily learn what potential attributes for them are available when planning a propeller flap.

Smartphone thermal imaging for preoperative perforator mapping in DIEP flap breast reconstruction

Perforator-based flaps have become a mainstay of autologous breast reconstruction practice. Despite available radiological investigations ranging from Doppler ultrasound (US) to CT angiography (CTA), finding and quantitatively assessing perforators remains a time-consuming, complex process. Infrared thermographic imaging (IRT) shows promise as a novel modality for preoperative localisation of perforator vessels. Thirteen women undergoing elective breast reconstruction with deep inferior epigastric artery perforator (DIEAP) flaps were recruited between August 2017 and July 2018. All had CTA and Doppler US mapping of arterial perforators preoperatively as standard. Additional abdominal thermal images were taken using a FLIR ONE smartphone compatible camera. Thermal hotspots were compared with Doppler markings and CTA findings. Twenty-six flaps were analysed. Seventy perforators were marked by Doppler US, with a mean of 2.92 perforators per flap (± SEM 0.15, SD 0.72). Forty (57%) had a corresponding hotspot on IRT. Overall, there was a statistically significant positive correlation between the number of perforators detected by Doppler US and IRT (r = 0.573, n = 26, p = 0.003) and kappa index 0.65. Eighty-four perforators were identified by CTA, with a mean of 3.5 perforators per flap (± SEM 0.14, SD 0.66). Fifty-eight (69%) had a corresponding hotspot on IRT. There was a statistically significant positive correlation between the number of perforators detected by CTA and IRT (r = 0.504, n = 26, p = 0.012) and kappa index 0.60. Thermography is an inexpensive, portable, non-invasive imaging technique, which shows statistically significant correlation to CTA and Doppler US in mapping perforators. Level of evidence: Level IV, diagnostic study.

Dynamic infrared thermography and smartphone thermal imaging as an adjunct for preoperative, intraoperative, and postoperative perforator free flap monitoring

Dynamic infrared thermography and smartphone thermal imaging as an adjunct for preoperative, intraoperative, and postoperative perforator free flap monitoring

Smartphone Visualization of Thermal Phenomena with Thermal Imaging Accessories

Smartphone thermal cameras can be used to observe heat transfer or thermal patterns in crystallization, evaporation, mixing of liquids, and chemical reactions. The experiments described in this paper demonstrate that IR imaging can provide students with rich learning and exploring opportunities that would otherwise be infeasible or too time-consuming. The precision and sensitivity of smartphone thermal cameras are sufficient for use in chemistry education. A smartphone thermal imaging accessory is worth introducing into the teaching laboratory.

Reply: Detection of Perforators for Free Flap Planning Using Smartphone Thermal Imaging: A Concordance Study with Computed Tomographic Angiography in 120 Perforators

Reply: Detection of Perforators for Free Flap Planning Using Smartphone Thermal Imaging: A Concordance Study with Computed Tomographic Angiography in 120 Perforators

Detection of Perforators for Free Flap Planning Using Smartphone Thermal Imaging: A Concordance Study with Computed Tomographic Angiography in 120 Perforators

Diagnostic, II.

Detection of Perforators Using Smartphone Thermal Imaging.

Detection of Perforators Using Smartphone Thermal Imaging.