Reliability of tristimulus colourimetry in the assessment of cutaneous bruise colour

Current trends in digital camera-based bioassays for point-of-care tests

Point-of-care and bedside tests are analytical devices suitable for a growing role in the current healthcare system and provide the opportunity to achieve an exact diagnosis by an untrained person and in various conditions and sites where it is necessary. Using a digital camera integrated into a well-accessible device like a smartphone brings a new way in which a colorimetric point-of-care diagnostic test can provide unbiased data. This review summarizes basic facts about the colorimetric point-of-care tests, principles of how to use a portable device with a camera in the assay, applications of digital cameras for the current tests, and new devices described in the recent papers. An overview of the recent literature and a discussion of recent developments and future trends are provided.

Pulsed Photothermal Radiometric Depth Profiling of Bruises by 532 nm and 1064 nm Lasers

Optical techniques are often inadequate in estimating bruise age since they are not sensitive to the depth of chromophores at the location of the bruise. To address this shortcoming, we used pulsed photothermal radiometry (PPTR) for depth profiling of bruises with two wavelengths, 532 nm (KTP laser) and 1064 nm (Nd:YAG laser). Six volunteers with eight bruises of exactly known and documented times of injury were enrolled in the study. A homogeneous part of the bruise was irradiated first with a 5 ms pulse at 532 nm and then with a 5 ms pulse at 1064 nm. The resulting transient surface temperature change was collected with a fast IR camera. The initial temperature-depth profiles were reconstructed by solving the ill-posed inverse problem using a custom reconstruction algorithm. The PPTR signals and reconstructed initial temperature profiles showed that the 532 nm wavelength probed the shallow skin layers revealing moderate changes during bruise development, while the 1064 nm wavelength provided additional information for severe bruises, in which swelling was present. Our two-wavelength approach has the potential for an improved estimation of the bruise age, especially if combined with modeling of bruise dynamics.

Development and Pilot Analysis of the Bruise Visibility Scale

The accuracy of assessing and documenting injuries is crucial to facilitate ongoing clinical care and forensic referrals for victims of violence. The purpose of this cross-sectional, pilot study was to evaluate the inter-rater reliability and criterion validity of a newly developed Bruise Visibility Scale (BVS). Methods: The instrument was administered to a diverse sample (n = 30) with existing bruises. Bruises were assessed under fluorescent lighting typical of an examination room by three raters who were randomly selected from a pool of eight experienced clinical nurses. Colorimetry values of the bruise and surrounding tissue were obtained using a spectrophotometer. Results: The BVS demonstrated good single (ICC = 0.71, 95% CI = 0.54 – 0.84) and average agreement (ICC = 0.88, 95% CI = 0.78 – 0.94) between raters. A significant, positive moderate correlation was found between mean BVS scores and overall color difference between the bruise and surrounding skin (Pearson’s r = 0.614, p < 0.001). Conclusion: With further research, the BVS has the potential to be a reliable and valid tool for documenting the degree of clarity in bruise appearance.

Alternate Light Source Findings of Common Topical Cosmetics and Three Removal Methods

INTRODUCTION

Alternate light sources (ALSs) are a tool used by forensic nurses to aid in the physical examination of patients. Prior research has shown some topical makeup products absorb alternate light similar to the absorption noted in bruises. Therefore, the purposes of this study were (a) to further examine the ALS findings of multiple brands and types of makeup products and (b) to compare the efficacy of three methods of makeup removal.

METHODS

Fourteen makeup products were applied to the forearms of 100 healthy adult volunteers with varying skin tones and then assessed under white light, six alternate light wavelengths, and three color filters, producing 19 total wavelength-and-filter combinations. The results were recorded before and after removal procedures by forensic nurse examiners who were blinded to the removal method. A three-arm randomized controlled trial of makeup removal methods (soap and water, isopropyl alcohol swab, makeup removal wipe) was conducted with the participants.

RESULTS

All 14 makeup products produced absorption in at least 10% of the observations. Fluorescence was observed in more than 10% of the observations for only two products. After product removal, four products continued to produce statistically significant absorption findings when viewed under an ALS. One product produced significant fluorescence after removal procedures. There were no statistically significant differences between the removal methods noted in any of these analyses.

CONCLUSION

Our findings support the importance of using alternate light as one component of a comprehensive forensic examination, including history taking and physical examination.

Quantifying the Degree of Bruise Visibility Observed Under White Light and an Alternate Light Source

BACKGROUND

Documentation of injuries associated with abuse and assault has pivotal impacts on clinical and legal outcomes. Before this study, no reliable and valid tools to consistently document the clinical visibility of bruises existed. The purpose of this study was to systematically evaluate reliability and validity of the Bruise Visibility Scale for documenting bruises visualized in normal (white) light and the Absorption Visibility Scale for documenting bruises visualized using an alternate light source (ALS).

METHODS

Bruises were induced using a paintball on the upper arms of 157 participants stratified into six skin color categories. Bruises were visualized 21 times over 4 weeks under white light and 10 ALS wavelength/goggle color combinations. Bruise size was measured using a metric ruler; bruise color was measured using a spectrophotometer. Interrater reliability was calculated using kappa and intraclass correlations coefficients. Construct validity was evaluated using generalized linear mixed modeling of associations between bruise size and color with both visibility scales.

RESULTS

Interrater agreement for bruise detection was over 90% for all but two ALS wavelength/goggle combinations. Kappa values indicated adequate interrater agreement under white light (κ = 0.76) and ALS (κ = 0.78). The visibility scale intraclass correlation coefficients were .91 for normal light and .93 for ALS. Statistical modeling showed greater bruise size was associated with higher visibility using either scale, and greater contrast in color or lightness was associated with higher Bruise Visibility Scale values.

IMPLICATIONS FOR PRACTICE

Both visibility scales showed satisfactory reliability and validity. Forensic nurses can use the scales to consistently document bruises.

Bruise dating using deep learning

The bruise dating can have important medicolegal implications in family violence and violence against women cases. However, studies show that the medical specialist has 50% accuracy in classifying a bruise by age, mainly due to the variability of the images and the color of the bruise. This research proposes a model, based on deep convolutional neural networks, for bruise dating using only images, by age ranges, ranging from 0-2 days to 17-30 days, and images of healthy skin. A 2140 experimental bruise photograph dataset was constructed, for which a data capture protocol and a preprocessing procedure are proposed. Similarly, 20 classification models were trained with the Inception V3, Resnet50, MobileNet, and MnasNet architectures, where combinations of learning transfer, cross-validation, and data augmentation were used. Numerical experiments show that classification models based on MnasNet have better results, reaching 97.00% precision and sensitivity, and 99.50% specificity, exceeding 40% precision reported in the literature. Also, it was observed that the precision of the model decreases with the age of the bruise.

Treatment of Port Wine Birthmarks in Sturge-Weber Syndrome Using Topical Timolol

Three patients with facial port wine birthmarks were randomly assigned to receive treatment with topical timolol or the placebo. Three masked observers evaluated photographs of the patients, noting improvement in patients who were treated with timolol and two controls. The photographic technique was not standardized. This pilot study suggests topical timolol warrants further evaluation for port wine birthmarks. [J Pediatr Ophthalmol Strabimus. 2021;58:e1-e4.].