Burn depth assessment by dual-wavelength light emitting diodes-excited photoacoustic imaging in rats.

Accurate burn depth assessment is crucial to determine treatment plans for burn patients. We have previously proposed a method for performing burn depth assessments based on photoacoustic (PA) imaging, and we have demonstrated the validity of this method, which allows the successful detection of PA signals originating from the blood under the bloodless burned tissue, using rat burn models. Based on these findings, we started a clinical study in which we faced two technical issues: (1) When the burn depth was shallow, PA signals due to skin contamination and/or melanin in the epidermis (surface signals) could not be distinguished from PA signals originating from the blood in the dermis; (2) the size of the system was too large. To solve these issues, we propose a burn depth diagnosis based on dual-wavelength light emitting diodes (LEDs)-excited PA imaging. The use of LEDs rendered the system compact compared to the previous one that used a conventional solid-state laser. We replicated human burned skin by applying a titrated synthetic melanin solution onto the wound surface in albino rat burn models and measured their burn depths by PA excitation at 690 and 850 nm, where melanin and haemoglobin show greatly different absorption coefficients. As a result, the surface signals were eliminated by subtracting the PA signals at 690 nm from those at 850 nm. The resultant estimated burn depths were strongly correlated with the histological assessment results. The validity of the proposed method was also examined using a burn model of rats with real melanin.

Reconsidering the H&E stain as the gold standard in assessing the depth of burn wounds.

While histological examination is considered by most as the gold standard for burn depth assessment, it has no practical use in the clinical setting. It has, however, been used in the research setting, as a mean for evaluating emerging techniques of depth measurement. Due to the limitations of the H&E stain, other stains have also been explored, such as lactate dehydrogenase (LDH), as presented in this issue, in "Improving the Histologic Characterization of Burn Depth." As the determination of burn depth is not a typical subject in dermatopathology, a summary of selected techniques and the possible role for the LDH stain in future research, is described herein.

The Novel Design of a Single-Sided MRI Probe for Assessing Burn Depth.

Burn depth assessment in clinics is still inaccurate because of the lack of feasible and practical testing devices and methods. Therefore, this process often depends on subjective judgment of burn surgeons. In this study, a new unilateral magnetic resonance imaging (UMRI) sensor equipped with a 2D gradient coil system was established, and we attempted to assess burns using unilateral nuclear magnetic resonance devices. A reduced Halbach magnet was utilized to generate a magnetic field that was relatively homogeneous on a target plane with a suitable field of view for 2D spatial localization. A uniplanar gradient coil system was designed by utilizing the mainstream target field method, and a uniplanar RF (radio frequency) coil was designed by using a timeharmonic inverse method for the UMRI sensor. A 2D image of the cross sections of a simple burn model was obtained by a fast 2D pure-phase encoding imaging method. The design details of the novel single-sided MRI probe and imaging tests are also presented.

Depth of intact vascular plexus - visualized with optical coherence tomography - correlates to burn depth in thoracic thermic injuries in children.

Objectives: Deep thermal injuries are among the most serious injuries in childhood, often resulting in scarring and functional impairment. However, accurate assessment of burn depth by clinical judgment is challenging. Optical coherence tomography (OCT) provides structural images of the skin and can detect blood flow within the papillary plexus. In this study, we determined the depth of the capillary network in healthy and thermally injured skin and compared it with clinical assessment. Methods: In 25 children between 7 months and 15 years of age (mean age 3.5 years (SD±4.14)) with thermal injuries of the ventral thoracic wall, we determined the depth of the capillary network using OCT. Measurements were performed on healthy skin and at the center of the thermal injury (16 grade IIa, 9 grade IIb). Comparisons were made between healthy skin and thermal injury. Results: The capillary network of the papillary plexus in healthy skin was detected at 0.33 mm (SD±0.06) from the surface. In grade IIb injuries, the depth of the capillary network was 0.36 mm (SD±0.06) and in grade IIa injuries 0.23 mm (SD±0.04) (Mann-Whitney U test: p<0.001). The overall prediction accuracy is 84 %. Conclusions: OCT can reliably detect and differentiate the depth of the capillary network in both healthy and burned skin. In clinical IIa wounds, the capillary network appears more superficial due to the loss of the epidermis, but it is still present in the upper layer, indicating a good prognosis for spontaneous healing. In clinical grade IIb wounds, the papillary plexus was visualized deeper, which is a sign of impaired blood flow.

In vivo monitoring of hemoglobin derivatives in a rat thermal injury model using spectral diffuse reflectance imaging.

INTRODUCTION: To demonstrate the feasibility of our previously proposed Diffuse reflectance spectral imaging (DRSI) method for in vivo monitoring of oxygenated hemoglobin, deoxygenated hemoglobin, methemoglobin, tissue oxygen saturation, and methemoglobin saturation in a rat scald burn wound model and assess whether the method could be used for differentiating the burn depth groups in rats based on the hemoglobin parameters. METHODOLOGY: Superficial dermal burns (SDBs), deep dermal burns (DDBs), and deep burns (DBs) were induced in rat dorsal skin using a Walker-Mason method. An approach based on multiple regression analysis for spectral diffuse reflectance images aided by Monte Carlo simulations for light transport was used to quantify the hemoglobin parameters. Canonical discriminant analysis (CDA) was performed to discriminate SDB, DDB, and DB. RESULTS: CDA using the total hemoglobin concentration, tissue oxygen saturation, and methemoglobin saturation as the independent variables showed good performance for discriminating the SDB, DDB, and DB groups immediately after burn injury and the SDB group from the DDB and DB groups 24-72 h after burn injury. CONCLUSIONS: The DRSI method with multiple regression analysis for quantification of oxygenated hemoglobin, deoxygenated hemoglobin, and methemoglobin proved to be reliable for monitoring these hemoglobin derivatives in the rat experimental burn injury model. The parameters of tissue oxygen saturation, methemoglobin saturation, and total hemoglobin concentration are promising for the differentiating the degree of burn injury using CDA.

Burn depth assessment using hyperspectral imaging in a prospective single center study.

BACKGROUND: The assessment of thermal burn depth remains challenging. Over the last decades, several optical systems were developed to determine burn depth. So far, only laser doppler imaging (LDI) has been shown to be reliable while others such as infrared thermography or spectrophotometric intracutaneous analysis have been less accurate. The aim of our study is to evaluate hyperspectral imaging (HSI) as a new optical device. METHODS: Patients suffering thermal trauma treated in a burn unit in Germany between November 2019 and September 2020 were included. Inclusion criteria were age ≥18 years, 2nd or 3rd degree thermal burns, written informed consent and presentation within 24 h after injury. Clinical assessment and hyperspectral imaging were performed 24, 48 and 72 h after the injury. Patients in whom secondary wound closure was complete within 21 days (group A) were compared to patients in whom secondary wound closure took more than 21 days or where skin grafting was indicated (group B). Demographic data and the primary parameters generated by HSI were documented. A Mann Whitney-U test was performed to compare the groups. A p-value below 0.05 was considered to be statistically significant. The data generated using HSI were combined to create the HSI burn index (BI). Using a logistic regression and receiver operating characteristics curve (ROC) sensitivity and specificity of the BI were calculated. The trial was officially registered on DRKS (registration number: DRKS00022843). RESULTS: Overall, 59 patients with burn wounds were eligible for inclusion. Ten patients were excluded because of a poor data quality. Group A comprised 36 patients with a mean age of 41.5 years and a mean burnt body surface area of 2.7%. In comparison, 13 patients were allocated to group B because of the need for a skin graft (n = 10) or protracted secondary wound closure lasting more than 21 days. The mean age of these patients was 46.8 years. They had a mean affected body surface area of 4.0%. 24, 48, and 72 h after trauma the BI was 1.0 ± 0.28, 1.2 ± 0.29 and 1.55 ± 0.27 in group A and 0.78 ± 0.14, 1.05 ± 0.23 and 1.23 ± 0.27 in group B. At every time point significant differences were demonstrated between the groups. At 24 h, ROC analysis demonstrated BI threshold of 0.95 (sensitivity 0.61/specificity 1.0), on the second day of 1.17 (sensitivity 0.51/specificity 0.81) and on the third day of 1.27 (sensitivity 0.92/specificity 0.71). CONCLUSION: Changes in microcirculation within the first 72 h after thermal trauma were reflected by an increasing BI in both groups. After 72 h, the BI is able to predict the need for a skin graft with a sensitivity of 92% and a specificity of 71%.

Carbon emissions from the peat fire problem-a review.

Peat fires in tropical peatland release a substantial amount of carbon into the environment and cause significant harm to peatlands and the ecology, resulting in climate change, biodiversity loss, and the alteration of the ecosystem. It is essential to understand peat fires and to develop more effective methods for controlling them. To estimate carbon emissions and monitor fires, the depth of burning can measure the overall burnt down the volume, which is proportional to the carbon emissions that are emitted to the environment. The first step is to understand the technique of measuring the depth of the burn. However, there is a lack of integrated information regarding the burning depth for peat fires. This review paper discusses the techniques used to measure the burning depth, with particular attention given to quantifying carbon emissions. The article also provides information on the types of methods used to determine the burning depths. This research contributes to the field of peat fire by providing a readily available reference for practitioners and researchers on the current state of knowledge on peat fire monitoring systems.

Real-time burn depth assessment using artificial networks: a large-scale, multicentre study.

INTRODUCTION: Early judgment of the depth of burns is very important for the accurate formulation of treatment plans. In medical imaging the application of Artificial Intelligence has the potential for serving as a very experienced assistant to improve early clinical diagnosis. Due to lack of large volume of a particular feature, there has been almost no progress in burn field. METHODS: 484 early wound images are collected on patients who discharged home after a burn injury in 48 h, from five different levels of hospitals in Hunan Province China. According to actual healing time, all images are manually annotated by five professional burn surgeons and divided into three sets which are shallow(0-10 days), moderate(11-20 days) and deep(more than 21 days or skin graft healing). These ROIs were further divided into 5637 patches sizes 224 × 224 pixels, of which 1733 shallow, 1804 moderate, and 2100 deep. We used transfer learning suing a Pre-trained ResNet50 model and the ratio of all images is 7:1.5:1.5 for training:validation:test. RESULTS: A novel artificial burn depth recognition model based on convolutional neural network was established and the diagnostic accuracy of the three types of burns is about 80%. DISCUSSION: The actual healing time can be used to deduce the depth of burn involvement. The artificial burn depth recognition model can accurately infer healing time and burn depth of the patient, which is expected to be used for auxiliary diagnosis improvement.

Optical coherence tomography provides an optical biopsy of burn wounds in children-a pilot study.

Thermic injuries are among the most severe injuries in childhood. Burn depth is the most relevant prognostic factor, and still its assessment is both difficult and controversial. This diagnostic uncertainty results in repeated wound assessments over a 10-day period and carries a relevant risk for over- and undertreatment. Precise wound assessment would thus be a significant step toward improved care. Optical coherence tomography (OCT) is a noninvasive laser-based technique with a penetration depth of ∼2 mm. It provides structural images of the skin while dynamic OCT (D-OCT) shows blood vessels. In this study, we investigated burns and scalds in 130 children with OCT and D-OCT to identify patterns of injury related to the depth of the burn wound. OCT and D-OCT images from burned skin differed consistently from normal skin. We observed several not formerly described morphologic patterns associated with burn injuries. Superficial wounds are characterized by a loss of the epidermal layer and a smooth surface. With deeper wounds, surface irregularity, loss of the dermal papillary pattern, disappearance of skin lines, and characteristic changes in the microvascular architecture were observed. This is the first systematic study of D-OCT in the assessment of burn wounds in children. A number of burn-associated patterns of injury were identified. Thus, D-OCT provided an "optical biopsy" of burn wounds that adds significant information about the severity of a burn wound.

A comparative evaluation of spectrophotometric intracutaneous analysis and laser doppler imaging in the assessment of adult and paediatric burn injuries.

INTRODUCTION: Clinical assessment of mid-dermal burns can be challenging. Currently, laser Doppler imaging (LDI) is the gold standard adjunct in the assessment of burn injuries. Although LDI has demonstrated reliable accuracy, it poses various limitations in routine use including cost and ease of use. In comparison, spectrophotometric intracutaneous analysis (SIA) is a relatively cheaper technique, which can be carried out using a modified digital camera that enables easy image acquisition. We aim to compare the accuracy of the two modalities in the assessment of mid-dermal burn injuries. METHODS: We recruited 29 patients with mid-dermal burns presenting within 2 to 5 days post burn. Forty-five burn regions of interest were identified, and the patients underwent imaging using both the modalities. Subsequent clinical outcome was followed up and showed that treatment remained unaffected by participation. Two clinicians then independently predicted the healing potential of each burn region retrospectively as per images from either modality. RESULTS: McNemar's test indicated that there is no significant difference between the accuracy of the two modalities (p = 0.61). CONCLUSION: The results suggest that the accuracy of SIA is comparable to that of LDI. Our experience with SIA indicates its potential as a cost-effective and user-friendly adjunct in decision-making.

Dermoscopic insight into skin microcirculation--Burn depth assessment.

To investigate the effectiveness of dermoscopic observation of skin microcirculation, the dermal capillary integrity of burn wounds was evaluated by dermoscopy according to a proposed algorithm that is designed to distinguish burn wounds between superficial dermal burns: SDB, and deep dermal burns: DDB. As the gold standard for comparison, two widely accepted endpoints of primary healing within 21 days (SDB) or over 21 days after injury (DDB) were used. A number of dermatologists conducted diagnostic imaging by dermoscopy. Comparison among polarized noncontact dermoscopy (PNCD), polarized contact dermoscopy (PCD) and nonpolarized contact dermoscopy (NPD) was also conducted. Images from the three modalities were evaluated for color, pattern and qualitative differences among them. The results of dermoscopy measurements according to the proposed algorithm showed accuracy of 96.7%, sensitivity of 100.0% and specificity of 94.4%. Dermoscopy measurements were significantly more accurate than clinical assessment (p<0.05). The recognition of dots increased for NPD, vessels were most clearly observed under PCD and colours tended to be more distinctly recognized under polarized light. Dermoscopy is a useful and simple tool to evaluate not only epidermal and superficial dermal skin components but also the skin microcirculation.

Variations in burn perfusion over time as measured by portable ICG fluorescence: A case series.

The early determination of healing potential in indeterminate thickness burns may be difficult to establish by visual inspection alone, even for experienced burn practitioners. This case series explores the use of indocyanine green (ICG) fluorescence using portable bedside assessment as a potential tool for early determination of burn depth. Three subjects with indeterminate thickness burns had daily perfusion assessment using ICG fluorescence assessment using the SPY machine (SPY®, Lifecell Corp., NJ, USA) in addition to standard burn care. The fluorescence was quantified as a percentage of the perfusion of intact skin, and areas of hypo- and hyper-perfusion were indicated. The study was concluded when the burn surgeon, blinded to the ICG results, made a clinical determination of the need for skin grafting or discharge. The perfusion in areas of differing depth of burn were compared over the entire study period to determine both the magnitude of difference, and the point in the time course of healing when these changes became evident. Significant differences in perfusion were noted between burned areas of varying depth. These differences were evident as early as the first post-burn day, and persisted till the completion of the study. ICG fluorescence represents a potential adjunct in burn assessment in this first longitudinal study of its use; however much more systematic research will be required to judge the feasibility of clinical implementation.

A new, fast LDI for assessment of burns: a multi-centre clinical evaluation.

INTRODUCTION: Laser Doppler imaging (LDI) provides early accurate determination of wound healing potential. LDI can scan large areas of up to 2500 cm2 within 2 min. This duration may require additional sedation in a mobile, uncooperative child. In five burn centres a faster Laser Doppler Line Scanner (LDLS) was assessed. This new imager scans 300 cm2 in 4s with potential benefit for patients and operators. The aim of this study was to assess the accuracy and convenience of the LDLS and to compare this with an established LDI imager. METHODS: Outpatients and admitted patients were included. LDI and LDLS images were obtained between 2 and 5 days post burn (PB). Photographs and records of wound and healing were obtained on day of scan and at 14 and 21 days PB. This provided data on three categories of burn wounds: healing within 14 days, 14-21 days and not healed within 21 days. RESULTS: The analysis included 596 burn areas from 204 burns patients. An accuracy of 94.2% was found with use of the LDLS compared with 94.4% for the original LDI imager. CONCLUSIONS: The high accuracy of the new line-scan imager was comparable to that of the traditional LDI. Its size and mobility enabled easier ward and outpatient use. The higher scan speed was particularly beneficial for scans in paediatric patients.