Investigation of optical attenuation imaging using optical coherence tomography for monitoring of scars undergoing fractional laser treatment

Optical attenuation coefficient of skin under low compression

In various biomedical optics therapies, knowledge of how light is absorbed or scattered by tissues is crucial. Currently, it is suspected that a low compression applied to the skin surface may improve light delivery into tissue. However, the minimum pressure needed to be applied to significantly increase the light penetration into the skin has not been determined. In this study, we used optical coherence tomography (OCT) to measure the optical attenuation coefficient of the human forearm dermis in a low compression regime (<8k P a). Our results show low pressures such as 4 kPa to 8 kPa are sufficient to significantly increase light penetration by decreasing the attenuation coefficient by at least 1.0m m ^-1.

Arterial pulsation modulates the optical attenuation coefficient of skin

Photoplethysmographic (PPG) signals arise from the modulation of light reflectivity on the skin due to changes of physiological origin. Imaging plethysmography (iPPG) is a video-based PPG method that can remotely monitor vital signs in a non-invasive manner. iPPG signals result from skin reflectivity modulation. The origin of such reflectivity modulation is still a subject of debate. Here, we have used optical coherence tomography (OCT) imaging to find whether iPPG signals may result from skin optical properties being directly or indirectly modulated by arterial transmural pressure propagation. The light intensity across the tissue was modeled through a simple exponential decay (Beer-Lambert law) to analyze in vivo the modulation of the optical attenuation coefficient of the skin by arterial pulsation. The OCT transversal images were acquired from a forearm of three subjects in a pilot study. The results show that the optical attenuation coefficient of skin changes at the same frequency as the arterial pulsation due to transmural pressure propagation (local ballistographic effect), but we cannot discard the contribution of global ballistographic effects.

Radiation-induced alterations in multi-layered, in-vitro skin models detected by optical coherence tomography and histological methods

BACKGROUND

Inflammatory skin reactions and skin alterations are still a potential side effect in radiation therapy (RT), which also need attention for patients' health care.

METHOD

In a pre-clinical study we consider alterations in irradiated in-vitro skin models of epidermal and dermal layers. Typical dose regimes in radiation therapy are applied for irradiation. For non-invasive imaging and characterization optical coherence tomography (OCT) is used. Histological staining method is additionally applied for comparison and discussion.

RESULTS

Structural features, such as keratinization, modifications in epidermal cell layer thickness and disorder in the layering-as indications for reactions to ionizing radiation and aging-could be observed by means of OCT and confirmed by histology. We were able to recognize known RT induced changes such as hyper-keratosis, acantholysis, and epidermal hyperplasia as well as disruption and/or demarcation of the dermo-epidermal junction.

CONCLUSION

The results may pave the way for OCT to be considered as a possible adjunctive tool to detect and monitor early skin inflammation and side effects of radiotherapy, thus supporting patient healthcare in the future.

Evaluation and characterization of facial skin aging using optical coherence tomography

OBJECTIVES

The skin aging exposome encompasses internal and external factors that contribute to clinical signs of facial aging. Aging skin can be characterized by distinctive features such as wrinkles, lentigines, elastosis, and roughness. Optical coherence tomography (OCT) is capable of noninvasively measuring skin characteristics. This study aimed to assess bilateral features using OCT to explore temporal skin changes among decades and potential changes in facial skin aging based on laterality.

METHODS

A total of 97 subjects between 20 and 89 years old with Fitzpatrick skin types I to IV were enrolled. VivoSight, a Multi-Beam OCT system intended to gather topographical and histological images of skin, was used to scan the area inferolateral to the lateral canthus, bilaterally. Investigators compared characteristics of skin roughness, attenuation coefficient and blood flow across age groups and based on laterality to determine any differences.

RESULTS

Only data from successful OCT scans were used. Seventy subjects, 10 from each specified decade, had successful bilateral scans and were thus included in the analysis. Chronological aging was characterized by significantly decreased dermal attenuation coefficient with increased age. Skin roughness measurements showed trends of increased roughness with age; however, no statistically significant changes were seen between groups. Qualitative differences amongst scans taken on right and left sides of the face showed no significance regarding roughness, density or blood flow at depths ranging from 0.05 to 0.5 mm.

CONCLUSIONS

OCT is an effective method for evaluating changes in aging skin. Our results illustrate a decline in skin density with chronological age. Additionally, it was illustrated that structural change in the epidermis and dermis does occur, however on a microscopic scale, there are no significant differences based on laterality. OCT holds promise as a noninvasive technique for characterization of aging skin. Its utility and application in the clinical management and treatment of aged skin requires further research; however, the technology has potential to personalize therapies based on objective findings.

A one-time pneumatic jet-injection of 5-fluorouracil and triamcinolone acetonide for treatment of hypertrophic scars-A blinded randomized controlled trial

BACKGROUND

Patients with hypertrophic scars (HTS) risk reduced quality of life due to itching, pain, poor cosmesis, and restriction of movement. Despite good clinical efficacy, patients are often reluctant to undergo repeated needle injections due to pain or needle phobia.

OBJECTIVES

To evaluate the applicability of needle-free pneumatic jet injection (PJI) and assess changes in hypertrophic scars following a single PJI treatment with 5-fluorouracil (5-FU) and triamcinolone acetonide (TAC).

METHODS

Twenty patients completed this blinded, randomized, controlled, split-scar trial. The intervention side of the HTS received a one-time treatment with PJIs containing a mixture of TAC + 5-FU injected at 5 mm intervals (mean 7 PJI per HTS); the control side received no treatment. Assessments were made at baseline and 4 weeks posttreatment. Outcome measures included change in (1) Vancouver Scar Scale (VSS) total score and subscores, (2) scar volume and surface area assessed by three-dimensional imaging, (3) skin microarchitecture measured by optical-coherence tomography (OCT), (4) photo-assessed scar cosmesis (0-100), (5) patient-reported pain and satisfaction (0-10), and (6) depiction of drug biodistribution after PJI.

RESULTS

PJI with TAC + 5-FU significantly decreased both HTS height (-1 VSS; p = 0.01) and pliability (-1 VSS; p < 0.01) with a nonstatistically significant reduction of -1 in total VSS score (0 in control; p = 0.09). On 3D imaging, a 33% decrease in scar volume (p = 0.016) and a 37% decrease in surface area (p = 0.008) was observed. OCT indicated trends towards smoother scar surface (Ra 11.1-10.3; p = 0.61), normalized dermal microarchitecture (attenuation coefficient: 1.52-1.68; p = 0.44), and a reduction in blood flow between 9% and 17% (p = 0.50-0.79). Despite advances in VSS subscores and OCT, no improved photo-assessed cosmesis was found (-3.2 treatment vs. -1.4 control; p = 0.265). Patient-reported pain was low (2/10) and 90% of the patients that had previously received needle injections preferred PJI to needle injection. Depositions of TAC + FU were imaged reaching deep into the scar at levels corresponding to the reticular dermis.

CONCLUSION

A single PJI injection containing 5-FU and TAC can significantly improve the height and pliability of HTS. PJI is favored by the patients and may serve as a complement to conventional needle injections, especially for patients with needle phobia.

Bipolar Fractional Radiofrequency Treatment of Suprapatellar Skin Assessment Using Noninvasive Devices and Microbiopsy

BACKGROUND

Noninvasive treatments for skin tightening are gaining popularity. However, no studies have assessed bipolar fractional radiofrequency treatment on suprapatellar skin.

OBJECTIVES

The purpose of this study was to evaluate the efficacy of bipolar fractional radiofrequency treatment on suprapatellar skin.

METHODS

Twenty patients received 1 bilateral suprapatellar bipolar fractional radiofrequency treatment. They returned 7 days, 3 weeks, 3 months, and 6 months posttreatment. Noninvasive measurements were obtained at each visit, including high-resolution ultrasonography, optical coherence tomography, transepidermal water loss and skin elasticity. Microbiopsies were collected in the treatment area for histologic and gene expression analyses. Three clinicians completed photographic evaluations comparing texture and laxity at baseline vs 6 months posttreatment.

RESULTS

Fifteen subjects completed all 6 visits. Both transepidermal water loss and dermal-epidermal junction roughness were increased at 3 weeks and 3 months posttreatment. Both attenuation coefficient and stiffness were increased significantly at 3 and 6 months posttreatment. Blood flow 0.5 mm below the surface and expression of epidermal hyaluronic acid and inflammatory genes IL-1b and IL-6 were significantly higher at 7 days posttreatment compared with pretreatment and 3 months posttreatment. There were no statistically significant changes in collagen- or elastin-related genes and proteins at 7 days or 3 months posttreatment. An improvement in texture and laxity was observed at 6 months posttreatment in 17.7% and 24.4% of photographs, respectively.

CONCLUSIONS

Radiofrequency treatment by microneedling of suprapatellar skin shows limited effects in decreasing skin laxity and improving skin appearance. At a molecular level, the treatment resulted in lower elastin and hyaluronic acid levels and increased dermal-epidermal junction roughness based on histology and optical coherence tomography imaging.

LEVEL OF EVIDENCE: 4

A Single-Center Trial to Evaluate the Efficacy and Tolerability of Four Microneedling Treatments on Fine Lines and Wrinkles of Facial and Neck Skin in Subjects With Fitzpatrick Skin Types I-IV: An Objective Assessment Using Noninvasive Devices and 0.33-mm Microbiopsies

BACKGROUND

Although ablative techniques are the standard of care for the treatment of fine lines and wrinkles, microneedling offers a minimally invasive alternative.

OBJECTIVES

The purpose of this study was to assess the efficacy of microneedling on facial and neck fine lines and wrinkles.

METHODS

Thirty-five subjects between 44 and 65 years old with Fitzpatrick skin types I to IV received 4 monthly microneedling treatments over the face and neck. Subjects returned 1 and 3 months posttreatment. At every visit, high-resolution ultrasonography and optical coherence tomography were performed, and transepidermal water loss and skin elasticity were measured. Microbiopsies (0.33 mm) were collected pretreatment, before the fourth treatment and 3 months posttreatment.

RESULTS

Thirty-two subjects (30 females, 2 males) completed all 7 visits. Facial dermal and epidermal density increased 101.86% and 19.28%, respectively, from baseline at 3 months posttreatment. Facial elasticity increased 28.2% from baseline at 3 months posttreatment. Facial attenuation coefficient increased 15.65% and 17.33% at 1 and 3 months posttreatment, respectively. At study completion, blood flow at a depth of 300 µm decreased 25.8% in the face and 42.3% in the neck. Relative collagen type III and elastin gene expression was statistically higher 3 months posttreatment. However, total elastin protein levels were unchanged from baseline values. Dermal muscle formation was observed in 58% of biopsies extracted 3 months posttreatment compared with 15.3% at baseline.

CONCLUSIONS

The results illustrate the effects of microneedling treatments. Noninvasive measurements and biopsy data showed changes in skin architecture and collagen/elastin gene expression, suggesting skin rejuvenation, with new extracellular matrix production and muscle formation.

LEVEL OF EVIDENCE: 3

Subjective Tools for Burn Scar Assessment: An Integrative Review

OBJECTIVE

To review the clinical and scientific literature on the subjective ways of assessing burn scars and describe their main characteristics.

DATA SOURCES

The Latin American, Caribbean Health Sciences Literature, Nursing Database, PubMed, CINAHL, and Scopus and Web of Science databases were used to search for studies published between 2014 and 2018 using descriptors in Portuguese, Spanish, and English.

STUDY SELECTION

After establishing the research question and the location and definition of the studies, as well as accounting for differences among databases and application of filters based on inclusion and exclusion criteria, 886 references remained.

DATA EXTRACTION

Investigators reviewed the titles and abstracts of the sample and selected 188 relevant studies for full review.

DATA SYNTHESIS

Twenty-six subjective forms of assessment were found; most research concerned the Patient and Observer Scar Assessment Scale and the Vancouver Scar Scale.

CONCLUSIONS

The Patient and Observer Scar Assessment Scale and the Vancouver Scar Scale are the most common scales for assessing burn scars and have similar evaluation points such as vascularization, pliability, pigmentation, and height, which are the main parameters that contribute to the general assessment and severity of a scar. There is a need to improve instructions for application of the scales to facilitate better understanding and improve agreement among evaluators.

Application of OCT-Derived Attenuation Coefficient in Acute Burn-Damaged Skin

BACKGROUND AND OBJECTIVES

There remains a need to objectively monitor burn wound healing within a clinical setting, and optical coherence tomography (OCT) is proving itself one of the ideal modalities for just such a use. The aim of this study is to utilize the noninvasive and multipurpose capabilities of OCT, along with its cellular-level resolution, to demonstrate the application of optical attenuation coefficient (OAC), as derived from OCT data, to facilitate the automatic digital segmentation of the epidermis from scan images and to work as an objective indicator for burn wound healing assessment.

STUDY DESIGN/MATERIALS AND METHODS

A simple, yet efficient, method was used to estimate OAC from OCT images taken over multiple time points following acute burn injury. This method enhanced dermal-epidermal junction (DEJ) contrast, which facilitated the automatic segmentation of the epidermis for subsequent thickness measurements. In addition, we also measured and compared the average OAC of the dermis within said burns for correlative purposes.

RESULTS

Compared with unaltered OCT maps, enhanced DEJ contrast was shown in OAC maps, both from single A-lines and completed B-frames. En face epidermal thickness and dermal OAC maps both demonstrated significant changes between imaging sessions following burn injury, such as a loss of epidermal texture and decreased OAC. Quantitative analysis also showed that OAC of acute burned skin decreased below that of healthy skin following injury.

CONCLUSIONS

Our study has demonstrated that the OAC estimated from OCT data can be used to enhance imaging contrast to facilitate the automatic segmentation of the epidermal layer, as well as help elucidate our understanding of the pathological changes that occur in human skin when exposed to acute burn injury, which could serve as an objective indicator of skin injury and healing.

Ultrasound Shear Wave Elastography and Transient Optical Coherence Elastography: Side-by-Side Comparison of Repeatability and Accuracy

Objective: We compare the repeatability and accuracy of ultrasound shear wave elastography (USE) and transient optical coherence elastography (OCE). Methods: Elastic wave speed in gelatin phantoms and chicken breast was measured with USE and OCE and compared with uniaxial mechanical compression testing. Intra- and Inter-repeatability were analyzed using Bland-Altman plots and intraclass correlation coefficients (ICC). Results: OCE and USE differed from uniaxial testing by a mean absolute percent error of 8.92% and 16.9%, respectively, across eight phantoms of varying stiffness. Upper and lower limits of agreement for intrasample repeatability for USE and OCE were ±0.075 m/s and −0.14 m/s and 0.13 m/s, respectively. OCE and USE both had ICCs of 0.9991. In chicken breast, ICC for USE was 0.9385 and for OCE was 0.9924. Conclusion: OCE and USE can detect small speed changes and give comparable measurements. These measurements correspond well with uniaxial testing.

Imaging Motion: A Comprehensive Review of Optical Coherence Tomography Angiography

Optical coherence tomography (OCT) is a three-dimensional (3-D) optical imaging technology that provides noninvasive, micrometer resolution images of structural interiors within biological samples with an approximately 1 ~ 2 mm penetration depth. Over the last decades, advances in OCT have revolutionized biomedical imaging by demonstrating a potential of optical biopsy in preclinical and clinical settings. Recently, functional OCT imaging has shown a promise as angiography to visualize cell-perfused vasculatures in the tissue bed in vivo without requiring any exogenous contrast agents. This new technology termed OCT angiography (OCTA) possesses a unique imaging capability of delineating tissue morphology and blood or lymphatic vessels down to capillaries at real-time acquisition rates. For the past 10 years since 2007, OCTA has been proven to be a useful tool to identify disorder or dysfunction in tissue microcirculation from both experimental animal studies and clinical studies in ophthalmology and dermatology. In this section, we overview about OCTA including a basic principle of OCTA explained with simple optical physics, and its scan protocols and post-processing algorithms for acquisition of angiography. Then, potential and challenge of OCTA for clinical settings are shown with outcomes of human studies.

Three-dimensional mapping of the attenuation coefficient in optical coherence tomography to enhance breast tissue microarchitecture contrast

Effective intraoperative tumor margin assessment is needed to reduce re-excision rates in breast-conserving surgery (BCS). Mapping the attenuation coefficient in optical coherence tomography (OCT) throughout a sample to create an image (attenuation imaging) is one promising approach. For the first time, three-dimensional OCT attenuation imaging of human breast tissue microarchitecture using a wide-field (up to ~45 × 45 × 3.5 mm) imaging system is demonstrated. Representative results from three mastectomy and one BCS specimen (from 31 specimens) are presented with co-registered postoperative histology. Attenuation imaging is shown to provide substantially improved contrast over OCT, delineating nuanced features within tumors (including necrosis and variations in tumor cell density and growth patterns) and benign features (such as sclerosing adenosis). Additionally, quantitative micro-elastography (QME) images presented alongside OCT and attenuation images show that these techniques provide complementary contrast, suggesting that multimodal imaging could increase tissue identification accuracy and potentially improve tumor margin assessment.

Parametric imaging of attenuation by optical coherence tomography: review of models, methods, and clinical translation

SIGNIFICANCE

Optical coherence tomography (OCT) provides cross-sectional and volumetric images of backscattering from biological tissue that reveal the tissue morphology. The strength of the scattering, characterized by an attenuation coefficient, represents an alternative and complementary tissue optical property, which can be characterized by parametric imaging of the OCT attenuation coefficient. Over the last 15 years, a multitude of studies have been reported seeking to advance methods to determine the OCT attenuation coefficient and developing them toward clinical applications.

AIM

Our review provides an overview of the main models and methods, their assumptions and applicability, together with a survey of preclinical and clinical demonstrations and their translation potential.

RESULTS

The use of the attenuation coefficient, particularly when presented in the form of parametric en face images, is shown to be applicable in various medical fields. Most studies show the promise of the OCT attenuation coefficient in differentiating between tissues of clinical interest but vary widely in approach.

CONCLUSIONS

As a future step, a consensus on the model and method used for the determination of the attenuation coefficient is an important precursor to large-scale studies. With our review, we hope to provide a basis for discussion toward establishing this consensus.

Indicators for mode of delivery in pregnant women with uteruses scarred by prior caesarean section: a retrospective study of 679 pregnant women

Background

The delivery mode for pregnant women with uteruses scarred by prior caesarean section (CS) is a controversial issue, even though the CS rate has risen in the past 20 years. We performed this retrospective study to identify the factors associated with preference for CS or vaginal birth after CS (VBAC).

Methods

Pregnant women (n = 679) with scarred uteruses from Moulay Ali Cherif Provincial Hospital, Rashidiya, Morocco, were enrolled. Gestational age, comorbidity, fetal position, gravidity and parity, abnormal amniotic fluid, macrosomia, placenta previa or abruptio, abnormal fetal presentation, premature rupture of fetal membrane with labor failure, poor progression in delivery, and fetal outcomes were recorded.

Results

Out of 679 pregnant women ≥28 gestational weeks, 351 (51.69%) had a preference for CS. Pregnant women showed preference for CS if they were older (95% CI 1.010–1.097), had higher gestational age (95% CI 1.024–1.286), and a shorter period had passed since the last CS (95% CI 0.842–0.992). Prior gravidity (95% CI 0.638–1.166), parity (95% CI 0.453–1.235), vaginal delivery history (95% CI 0.717–1.818), and birth weight (95% CI 1.000–1.001) did not influence CS preference. In comparison with fetal preference, maternal preference was the prior indicator for CS. Correlation analysis showed that pregnant women with longer intervals since the last CS and history of gravidity, parity, and vaginal delivery showed good progress in the first and second stages of vaginal delivery.

Conclusions

We concluded that maternal and gestational age and interval since the last CS promoted CS preference among pregnant women with scarred uteruses.

General model for depth-resolved estimation of the optical attenuation coefficients in optical coherence tomography

We present the proof of concept of a general model that uses the tissue sample transmittance as input to estimate the depth-resolved attenuation coefficient of tissue samples using optical coherence tomography (OCT). This method allows us to obtain an image of tissue optical properties instead of intensity contrast, guiding diagnosis and tissues differentiation, extending its application from thick to thin samples. The performance of our method was simulated and tested with the assistance of a home built single-layered and multilayered phantoms (~100 μm each layer) with known attenuation coefficient on the range of 0.9 to 2.32 mm^-1 . It is shown that the estimated depth-resolved attenuation coefficient recovers the reference values, measured by using an integrating sphere followed by the inverse adding doubling processing technique. That was corroborated for all situations when the correct transmittance value is used with an average difference of 7%. Finally, we applied the proposed method to estimate the depth-resolved attenuation coefficient for a thin biological sample, demonstrating the ability of our method on real OCT images.

Spontaneous rupture of the uterus following salpingectomy: a case report and literature review

Laparoscopic salpingectomy (LPSC) is the main treatment for ectopic pregnancy, which leads to spontaneous uterine rupture (UR) during pregnancy. We report the characteristics of a woman who had spontaneous UR during pregnancy with a history of salpingectomy. We experienced a 31-year-old woman with a UR in pregnancy with a history of LPSC twice. The patient had a successful pregnancy. We also performed a literature review including cases with spontaneous UR after LPSC. Twenty-seven case reports of 48 women were included in our review. Thirty-five (83.33%, 35/42) women previously received LPSC and 15 (31.25%) developed interstitial pregnancies. The interval between pregnancy and the last surgery did not affect the frequency of interstitial pregnancy and gestational age. Fetal outcomes in patients with UR at the third trimester were better than those at the first and second trimesters. We suggest that close observation and timely treatment by experienced clinicians lead to good outcomes of pregnant women with suspected UR.

Optical coherence tomography angiography and photoacoustic imaging in dermatology

Optical coherence tomography angiography (OCTA) is a relatively novel functional extension of the widely accepted ophthalmic imaging tool named optical coherence tomography (OCT). Since OCTA's debut in ophthalmology, researchers have also been trying to expand its translational application in dermatology. The ability of OCTA to resolve microvasculature has shown promising results in imaging skin diseases. Meanwhile, photoacoustic imaging (PAI), which uses laser pulse induced ultrasound waves as the signal, has been studied to differentiate human skin layers and to help in skin disease diagnosis. This perspective article gives a short review of OCTA and PAI in the field of photodermatology. After an introduction to the principles of OCTA and PAI, we describe the most updated results of skin disease imaging using these two optical imaging modalities. We also place emphasis on dual modality imaging combining OCTA and photoacoustic tomography (PAT) for dermatological applications. In the end, the challenges and prospects of these two imaging modalities in dermatology are discussed.

Dynamic Optical Coherence Tomography Is a New Technique for Imaging Skin Around Lower Extremity Wounds

Chronic wounds such as venous leg ulcers invariably heal slowly and recur. In the case of venous leg ulcers, poor healing of chronic wounds is variously attributed to ambulatory hypertension, impaired perfusion and diffusion, presence of chronic inflammation at wound sites, lipodermatosclerosis, and senescence. The aim of this study was to investigate whether a new technique, optical coherence tomography (OCT), which permits imaging of blood capillaries in the peri-wound skin, can provide new insights into the pathology. OCT and its recent variant, dynamic OCT, permit rapid noninvasive depth-resolved imaging of the capillaries in the superficial dermis via a handheld probe, showing the morphology and density of vessels down to 20 µm in diameter. We used dynamic OCT to investigate 15 chronic wounds and assess characteristics of the vessels at the 4 poles around the wounds, the wound bed, adjacent dermatosclerosis, and unaffected skin. The results of the study show that both vessel morphology and density in the wound edges are dramatically different from that in healthy skin, showing clusters of glomuleri-like vessels (knot-like forms or clumps) and an absence of linear branching vessels, and also greater blood perfusion. Such vessel shapes are reported to be associated with tissue growth. The OCT imaging procedure was rapid and well tolerated by patients and provided new information not available from other devices. Thus, OCT appears to have great promise as a tool for the evaluation and study of chronic ulcers.