Absorption and reduced scattering coefficients in epidermis and dermis from a Swedish cohort study.

Significance: Knowledge of optical properties is important to accurately model light propagation in tissue, but in vivo reference data are sparse. Aim: The aim of our study was to present in vivo skin optical properties from a large Swedish cohort including 3809 subjects using a three-layered skin model and spatially resolved diffuse reflectance spectroscopy (Periflux PF6000 EPOS). Approach: Diffuse reflectance spectra (475 to 850 nm) at 0.4 and 1.2 mm source-detector separations were analyzed using an inverse Monte Carlo method. The model had one epidermis layer with variable thicknesses and melanin-related absorptions and two dermis layers with varying hemoglobin concentrations and equal oxygen saturations. The reduced scattering coefficient was equal across all layers. Results: Median absorption coefficients (mm-1) in the upper dermis ranged from 0.094 at 475 nm to 0.0048 at 850 nm and similarly in the lower dermis from 0.059 to 0.0035. The reduced scattering coefficient (mm-1) ranged from 3.22 to 1.20, and the sampling depth (mm) ranged from 0.23 to 0.38 (0.4 mm separation) and from 0.49 to 0.68 (1.2 mm separation). There were differences in optical properties across sex, age groups, and BMI categories. Conclusions: Reference material for skin optical properties is presented.

Reconstruction of dermal layers evaluated by high-frequency ultrasound following treatment for skin fibrosis.

Background: Lymphedema is a chronic, progressive clinical condition that evolves with intense fibrosis, the most advanced stage of which is stage III (lymphostatic fibrosclerosis). Aim: The aim of the present study was to show the possibility to reconstruct the dermal layers with the intensive treatment of fibrosis using the Godoy method. Case description: A 55-year-old patient with an eight-year history of edema of the lower limb of the leg had constant episodes of erysipelas, despite regular treatments. The edema progressed continually, associated with a change in the color of the skin and the formation of a crust. Intensive treatment (eight hours per day for three weeks) was proposed with the Godoy method. The ultrasound was performed and results revealed substantial improvement in the skin, with the onset of the reconstruction of the dermal layers. Conclusion: It is possible to reconstruct the layers of the skin in fibrotic conditions caused by lymphedema.

Sodium concentration imaging in dermis layer by square-wave open electrical impedance tomography (SW-oEIT) with spatial voltage thresholding (SVT).

In this study, sodium concentration in the dermis layer is imaged by the square wave open electrical impedance tomography (SW-oEIT) with spatial voltage thresholding (SVT). The SW-oEIT with SVT consists of three steps which are (1) voltage measurement, (2) spatial voltage thresholding, and (3) sodium concentration imaging. In the 1st step, the root mean square voltagevis calculated based on the measured voltagevunder the square wave currentIthrough the planar electrodes on the skin domain Ω. In the 2nd step, them-th measured voltagevis converted to a compensated voltagev*based on the voltage electrodes distancedvand threshold distancedΓin order to highlight the region of interest of the dermis layerΩd.In the 3rd step, sodium concentration is imaged by the Gauss-Newton reconstruction method. The SW-oEIT with SVT was applied to multi-layer skin simulation andex-vivoexperiments under various dermis sodium concentrationscin the range of 5-50 mM. As an image evaluation result, the spatial mean conductivity distributionσ*inΩdis successfully determined as increasingcon both simulations and experiments. The relationship between〈σ*〉andcwas evaluated by the determination coefficientR2and the normalized sensitivity〈S〉.The optimizeddΓwith the highest evaluation values ofR2=0.84 and〈S〉=0.83 is under the condition ofdΓ= 2 mm. Based on the signal evaluation, the SW-oEIT with SVT has a 15.32% higher correlation coefficientCCcompared to the conventionaloEIT based on sinewave injection.

Subcutaneous fat infiltration into the dermal layer induces wrinkle formation.

BACKGROUND: Wrinkles appear with aging, producing an aged impression, but the mechanism of wrinkle formation has not yet been fully elucidated. We recently reported that subcutaneous fat infiltrates into the dermal layer with aging and impairs skin elasticity, but the contribution of this process to wrinkle formation is still unclear. PURPOSE: We aimed to clarify the contribution of dermal fat infiltration to wrinkle formation by analyzing the relationship between them in the forehead of female volunteers. METHODS: We measured the severity of fat infiltration in the forehead of 29 middle-aged female volunteers by means of ultrasonography. Fixed wrinkles present when the eyes were closed and wrinkles transiently formed when the eyes were open were evaluated using a photograph-based 6-grade evaluation system for each type of wrinkle. RESULTS: Fat infiltration at the forehead area was observed similarly to that in the cheek area as we reported previously. We found that opening the eyes induced the formation of stable transient wrinkles, the grade of which was significantly related to fat infiltration severity. Furthermore, fat infiltration was also significantly related to the severity of fixed wrinkles. Moreover, the severity of transient wrinkles was significantly related to that of fixed wrinkles. CONCLUSIONS: Our results suggest that fat infiltration into the dermal layer enhances transient wrinkle formation during facial expression by impairing the ability of the skin to resist deformation, thereby promoting fixed wrinkle formation. Therefore, fat infiltration is a critical cause of wrinkle formation.

Tattoo Pigments Are Localized Intracellularly in the Epidermis and Dermis of Fresh and Old Tattoos: In vivo Study Using Two-Photon Excited Fluorescence Lifetime Imaging.

BACKGROUND: The knowledge about the location and kinetics of tattoo pigments in human skin after application and during the recovery is restricted due to the limitation of in vivo methods for visualizing pigments. Here, the localization and distribution of tattoo ink pigments in freshly and old tattooed human skin during the regeneration of the epidermis and dermis were investigated in vivo. METHODS: Two-photon excited fluorescence lifetime imaging (TPE-FLIM) was used to identify tattoo ink pigments in human skin in vivo down to the reticular dermis. One subject with a freshly applied tattoo and 10 subjects with tattoos applied over 3 years ago were investigated in the epidermal and dermal layers in vivo. One histological slide of tattooed skin was used to localize skin-resident tattoo pigment using light microscopy. RESULTS: The carbon black particles deposited around the incision have still been visible 84 days after tattoo application, showing delayed recovery of the epidermis. The TPE-FLIM parameters of carbon black tattoo ink pigments were found to be different to all skin components except for melanin. Distinction from melanin in the skin was based on higher fluorescence intensity and agglomerate size. Using TPE-FLIM in vivo tattoo pigment was found in 75% of tattoos applied up to 9 years ago in the epidermis within keratinocytes, dendritic cells, and basal cells and in the dermis within the macrophages, mast cells, and fibroblasts. Loading of highly fluorescent carbon black particles enables in vivo imaging of dendritic cells in the epidermis and fibroblasts in the dermis, which cannot be visualized in native conditions. The collagen I structures showed a higher directionality similar to scar tissue resulting in a greater firmness and decreased elasticity of the tattooed skin. CONCLUSIONS: Here, we show the kinetics and location of carbon black tattoo ink pigment immediately after application for the first time in vivo in human skin. Carbon black particles are located exclusively intracellularly in the skin of fresh and old tattoos. They are found within macrophages, mast cells, and fibroblasts in the dermis and within keratinocytes, dendritic cells, and basal cells in the continuously renewed epidermis even in 9-year-old tattoos in skin showing no inflammation.

Use of new microcirculation software allows the demonstration of dermis vascularization.

AIMS: Current ultrasound (US) Doppler techniques cannot demonstrate the vascularization of the dermis. The purpose of this study was to investigate whether the new Superb Vascular Imaging (SMI) and Microvascular Flow (MV-Flow) techniques improve the detection of normal dermis vessels. SMI and MV-Flow were compared side-by-side to conventional power-Doppler (PD) imaging. METHODS: By using US, 50 healthy volunteers were evaluated at level of five body areas: forehead, forearm, palm, buttock, and thigh. Two off-site operators evaluated the images to assess the difference between SMI and PD imaging and between MV-Flow and PD imaging in terms of dermis flow amount. A 0-3 scoring system was adopted. RESULTS: SMI scored grade 0 in 0% of body areas, grade 1 in 58%, grade 2 in 33%, and grade 3 in 9%. In comparison with SMI, PD scored grade 0 in 38% of body areas, grade 1 in 56%, grade 2 in 6%, and grade 3 in 0%. MV-Flow scored grade 0 in 0% of body areas, grade 1 in 52%, grade 2 in 43%, and grade 3 in 6%. Comparted to MV-Flow, PD scored grade 0 in 53% of body areas, grade 1 in 34%, grade 2 in 13%, and grade 3 in 0%. The difference in terms of sensitivity was statistically significant for all the body areas investigated. CONCLUSIONS: We found both SMI and MV-Flow to be superior to PD imaging and capable to demonstrate normal vascularization of the dermis.

Three-dimensional fine structure of fibroblasts and other mesodermally derived tissues in the dermis of adults of the Bahamas lancelet (Chordata, Cephalohordata), as seen by serial block-face scanning electron microscopy.

Tissues of adult cephalochordates include sparsely distributed fibroblasts. Previous work on these cells has left unsettled such questions as their developmental origin, range of functions, and even their overall shape. Here, we describe fibroblasts of a cephalochordate, the Bahamas lancelet, Asymmetron lucayanum, by serial block-face scanning electron microscopy to demonstrate their three-dimensional (3D) distribution and fine structure in a 0.56-mm length of the tail. The technique reveals in detail their position, abundance, and morphology. In the region studied, we found only 20 fibroblasts, well separated from one another. Each was strikingly stellate with long cytoplasmic processes rather similar to those of a vertebrate telocyte, a possibly fortuitous resemblance that is considered in the discussion section. In the cephalochordate dermis, the fibroblasts were never linked with one another, although they occasionally formed close associations of unknown significance with other cell types. The fibroblasts, in spite of their name, showed no signs of directly synthesizing fibrillar collagen. Instead, they appeared to be involved in the production of nonfibrous components of the extracellular matrix-both by the release of coarsely granular dense material and by secretion of more finely granular material by the local breakdown of their cytoplasmic processes. For context, the 3D structures of two other mesoderm-derived tissues (the midline mesoderm and the posteriormost somite) are also described for the region studied.

In vivo stiffness measurement of epidermis, dermis, and hypodermis using broadband Rayleigh-wave optical coherence elastography.

Traveling-wave optical coherence elastography (OCE) is a promising technique to measure the stiffness of biological tissues. While OCE has been applied to relatively homogeneous samples, tissues with significantly varying elasticity through depth pose a challenge, requiring depth-resolved measurement with sufficient resolution and accuracy. Here, we develop a broadband Rayleigh-wave OCE technique capable of measuring the elastic moduli of the 3 major skin layers (epidermis, dermis, and hypodermis) reliably by analyzing the dispersion of leaky Rayleigh surface waves over a wide frequency range of 0.1-10 kHz. We show that a previously unexplored, high frequency range of 4-10 kHz is critical to resolve the thin epidermis, while a low frequency range of 0.2-1 kHz is adequate to probe the dermis and deeper hypodermis. We develop a dual bilayer-based inverse model to determine the elastic moduli in all 3 layers and verify its high accuracy with finite element analysis and skin-mimicking phantoms. Finally, the technique is applied to measure the forearm skin of healthy volunteers. The Young's modulus of the epidermis (including the stratum corneum) is measured to be ∼ 4 MPa at 4-10 kHz, whereas Young's moduli of the dermis and hypodermis are about 40 and 15 kPa, respectively, at 0.2-1 kHz. Besides dermatologic applications, this method may be useful for the mechanical analysis of various other layered tissues with sub-mm depth resolution. STATEMENT OF SIGNIFICANCE: To our knowledge, this is the first study that resolves the stiffness of the thin epidermis from the dermis and hypodermis, made possible by using high-frequency (4 - 10 kHz) elastic waves and optical coherence elastography. Beyond the skin, this technique may be useful for mechanical characterizations of various layered biomaterials and tissues.

Three-Dimensional Skin CT Based on Intelligent Algorithm in the Analysis of Skin Lesion Sites Features in Children with Psoriasis.

This research was to explore the application value of three-dimensional computed tomography (CT) based on artificial intelligent algorithm in analyzing the characteristics of skin lesions in children with psoriasis. In this study, 15 children with psoriasis were selected as the observation group, and 15 children with other skin diseases were selected as the control group. The CT images were optimized, and the feature selection was carried out based on artificial intelligent algorithm. Firstly, the results were compared with the results of simple skin three-dimensional CT to determine the effectiveness. Then, the two groups of three-dimensional skin CT image features of skin psoriasis-like hyperplasia, Munro microabscess, dermal papillary vascular dilation, and squamous epithelium based on intelligent algorithms were compared. After comparison, the detection rate of psoriasis-like hyperplasia, Munro microabscess, dermal papillary vascular dilation, and squamous epithelium in the observation group was higher than that in the control group, with significant difference and statistical significance (P < 0.05). In addition, the sensitivity of psoriasis-like hyperplasia, Munro microabscess, dermal papilla vascular dilatation, and squamous epithelium in children with psoriasis was 80.0%, 86.7%, 80.0%, and 93.3%, respectively. The specificity of psoriasis-like hyperplasia, Munro microabscess, dermal papilla vascular dilatation, and squamous epithelium in children with psoriasis was 86.7%, 93.3%, 60.0%, and 73.3%, respectively. The results showed that Munro microabscess and psoriasis-like hyperplasia had high sensitivity and specificity in all diagnostic items, which could be used as important features of skin lesion sites in the diagnosis of psoriasis in children. The research provides a basis for the clinical diagnosis of psoriasis in children, which is worthy of clinical promotion.

In Vivo Quantitative Ultrasound on Dermis and Hypodermis for Classifying Lymphedema Severity in Humans.

This study investigated the ability of in vivo quantitative ultrasound (QUS) assessment to evaluate lymphedema severity compared with the gold standard method, the International Society of Lymphology (ISL) stage. Ultrasonic measurements were made around the middle thigh (n = 150). Radiofrequency data were acquired using a clinical scanner and 8-MHz linear probe. Envelope statistical analysis was performed using constant false alarm rate processing and homodyned K (HK) distribution. The attenuation coefficient was calculated using the spectral log-difference technique. The backscatter coefficient (BSC) was obtained by the reference phantom method with attenuation compensation according to the attenuation coefficients in the dermis and hypodermis, and then effective scatterer diameter (ESD) and effective acoustic concentration (EAC) were estimated with a Gaussian model. Receiver operating characteristic curves of QUS parameters were obtained using a linear regression model. A single QUS parameter with high area under the curve (AUC) differed between the dermis (ESD and EAC) and hypodermis (HK) parameters. The combinations with ESD and EAC in the dermis, HK parameters in the hypodermis and typical features (dermal thickness and echogenic regions in the hypodermis) improved classification performance between ISL stages 0 and ≥I (AUC = 0.90 with sensitivity of 75% and specificity of 91%) in comparison with ESD and EAC in the dermis (AUC = 0.82) and HK parameters in the hypodermis (AUC = 0.82). In vivo QUS assessment by BSC and envelope statistical analyses can be valuable for non-invasively classifying an extremely early stage of lymphedema, such as ISL stage I, and following its progression.

Infiltration of subcutaneous adipose layer into the dermal layer with aging.

BACKGROUND: The elasticity of the dermal layer decreases with aging, leading to ulcer formation and wrinkling, but the mechanism of this change is not fully understood, because it is difficult to access the complex three-dimensional (3D) internal structure of the dermis. OBJECTIVE: To clarify age-dependent changes in the overall 3D structure of the dermal layer by means of 3D analysis technology. METHODS: We observed sun-protected human skin by means of X-ray micro CT, identified the layers of the skin, and reconstructed the 3D structure on computer. Age-dependent structural changes of the dermal layer were evaluated by statistical comparison of young and aged skin. RESULTS: Histological observations suggested the presence of two types of ectopic fat deposits, namely infiltrated subcutaneous fat and isolated fat, in the lower region of the reticular dermal layer in aged skin. To elucidate their nature, we observed skin specimens by X-ray microCT. The epidermis, dermal layer, and subcutaneous adipose layer were well differentiated on CT images, and 3D skin was digitally reconstructed on computer. This method clearly showed that the isolated fat observed histologically was in fact connected to the subcutaneous fat, namely all ectopic fat is connected to the subcutaneous adipose layer. Statistical analysis showed that the severity of fat infiltration into dermal layer is significantly increased in aged skin compared with young skin. CONCLUSION: Our findings indicate that subcutaneous fat infiltrates into the dermal layer of aged skin. Our 3D analysis approach is advantageous to understand changes of complex internal skin structures with aging.

Application of Cellular Resolution Full-Field Optical Coherence Tomography in vivo for the Diagnosis of Skin Tumours and Inflammatory Skin Diseases: A Pilot Study.

BACKGROUND: Optical coherence tomography (OCT) has been shown to provide non-invasive diagnosis of common skin neoplasms, especially basal cell carcinoma. OCT produces a cross-sectional view of the tissue, similar to a traditionally sectioned histopathological view, but the resolution of conventional OCT is low and thus limits clinical application. OBJECTIVES: This study aimed to investigate the application ability of a full-field (FF)OCT system which was newly developed to scan the skin at the cellular level. METHODS: Patients with skin tumours or inflammatory lesions warranting biopsy were consecutively enrolled. All lesions underwent clinical, dermoscopic, and OCT assessment, followed by routine biopsy. The adjacent normal skin was scanned for comparison. OCT images were interpreted (blinded to the biopsy results) and then compared with the histopathological diagnosis. RESULTS: A total of 111 patients with 115 lesions completed the protocol, including 80 skin tumours, 28 inflammatory diseases, and 7 other diseases. Of the OCT images, 43.5% were of good quality and show expected features. Identifiable features of actinic keratosis, Bowen's disease, basal cell carcinoma, extramammary Paget's disease, seborrheic keratosis, large cell acanthoma, bullous pemphigoid, interface dermatitis, lichenoid tissue reaction, and psoriasis were demonstrated. Lesions are located deeply, and so some features were out of the field of view, accounting for 40.0% (46/115). CONCLUSIONS: This study expanded the ability of FFOCT for the clinical diagnosis of various skin conditions. This new optical technique can clearly visualise skin lesions located in the epidermis and upper dermis. It provided an effective way to perform digital skin biopsy in superficial skin diseases.

Improving dermal level images from reflectance confocal microscopy using wavelet-based transformations and adaptive histogram equalization.

OBJECTIVES: Reflectance confocal microscopy (RCM) generates scalar image data from serial depths in the skin, allowing in vivo examination of cellular features. The maximum imaging depth of RCM is approximately 250 µm, to the papillary dermis, or upper reticular dermis. Frequently, important diagnostic features are present in the dermis, hence improved visualization of deeper levels is advantageous. METHODS: Low contrast and noise in dermal images were improved by employing a combination of wavelet-based transformations and contrast-limited adaptive histogram equalization. RESULTS: Preserved details, noise reduction, increased contrast, and feature enhancement were observed in the resulting processed images. CONCLUSIONS: Complex and combined wavelet-based enhancement approaches for dermal level images yielded reconstructions of higher quality than less sophisticated histogram-based strategies. Image optimization may improve the diagnostic accuracy of RCM, especially for entities with dermal findings.

Seeing the unseen with superb microvascular imaging: Ultrasound depiction of normal dermis vessels.

PURPOSE: Current color- and power-Doppler techniques cannot demonstrate vascularization of the dermis. Aim of this prospective study was to investigate whether the new superb vascular imaging (SMI) technique improves the ultrasound (US) depiction of dermis vessels in healthy volunteers. SMI was compared side-by-side to conventional power-Doppler (PD) imaging. METHODS: Thirty adult subjects (18 men and 12 women, mean age 45 years old) were evaluated with US at level of five body areas: forehead, forearm, palm, buttock, and thigh. The vascular index (VI) was employed to objectively quantify the difference between SMI and PD imaging in terms of dermis flow amount. RESULTS: Forehead VI was higher for SMI than for PD in 93% of cases, forearm VI was higher for SMI than for PD in 97% of cases, palm VI was higher for SMI than for PD in 87% of cases, buttock VI was higher for SMI than for PD in 100% of cases, thigh VI was higher for SMI than for PD in 100% of cases. SMI-detected vascular signals in 100% of the body areas. PD failed to show any flow signals from the forehead in 23% of cases, forearm in 37% of cases, palm in 33% of cases, buttock in 47% of cases, and thigh in 50% of cases. CONCLUSION: SMI can demonstrate normal dermis vascularization whereas conventional PD cannot. SMI is a sensitive and promising technique in the study of dermis abnormalities, particularly when quantifying the disease activity is important.

Scanning electron microscopy of murine skin ultrathin sections and cultured keratinocytes.

Generating high-quality electron microscopy images of the skin and keratinocytes can be challenging. Here we describe a simple protocol for scanning electron microscopy (SEM) of murine skin. The protocol enables characterization of the ultrastructure of the epidermis, dermis, hair follicles, basement membrane, and cell-cell junctions. We detail the specific steps for sample preparation and highlight the critical need for proper orientation of the sample for ultrathin sectioning. We also describe the isolation and preparation of primary keratinocyte monolayers for SEM. For complete details on the use and execution of this protocol, please refer to Biswas et al. (2021).

Delineating papillary dermis around basal cell carcinomas by high and ultrahigh resolution optical coherence tomography-A pilot study.

Bedside diagnosis of skin cancer remains a challenging task. The real-time noninvasive technology of optical coherence tomography (OCT) masters a high diagnostic accuracy in basal cell carcinoma (BCC) but a lower specificity in recognizing imitators and other carcinomas. We investigate the delicate signal of papillary dermis using an in-house developed ultrahigh resolution OCT (UHR-OCT) system with shadow compensation and a commercial multi-focus high resolution OCT (HR-OCT) system for clinical BCC imaging. We find that the HR-OCT system struggled to resolve the dark band signal of papillary dermis where the UHR-OCT located this in all cases and detected changes in signal width. UHR-OCT is able to monitor extension and position of papillary dermis suggesting a novel feature for delineating superficial BCCs in pursuit of a fast accurate diagnosis. Comprehensive studies involving more patients are imperative in order to corroborate results.

Sodium in the dermis colocates to glycosaminoglycan scaffold, with diminishment in type 2 diabetes mellitus.

BACKGROUND: Dietary sodium intake mismatches urinary sodium excretion over prolonged periods. Our aims were to localize and quantify electrostatically bound sodium within human skin using triple-quantum-filtered (TQF) protocols for MRI and magnetic resonance spectroscopy (MRS) and to explore dermal sodium in type 2 diabetes mellitus (T2D). METHODS: We recruited adult participants with T2D (n = 9) and euglycemic participants with no history of diabetes mellitus (n = 8). All had undergone lower limb amputations or abdominal skin reduction surgery for clinical purposes. We used 20 µm in-plane resolution 1H MRI to visualize anatomical skin regions ex vivo from skin biopsies taken intraoperatively, 23Na TQF MRI/MRS to explore distribution and quantification of freely dissolved and bound sodium, and inductively coupled plasma mass spectrometry to quantify sodium in selected skin samples. RESULTS: Human dermis has a preponderance (>90%) of bound sodium that colocalizes with the glycosaminoglycan (GAG) scaffold. Bound and free sodium have similar anatomical locations. T2D associates with a severely reduced dermal bound sodium capacity. CONCLUSION: We provide the first evidence to our knowledge for high levels of bound sodium within human dermis, colocating to the GAG scaffold, consistent with a dermal "third space repository" for sodium. T2D associates with diminished dermal electrostatic binding capacity for sodium.

Non-invasive intradermal imaging of cystine crystals in cystinosis.

IMPORTANCE: Development of noninvasive methodology to reproducibly measure tissue cystine crystal load to assess disease status and guide clinical care in cystinosis, an inherited lysosomal storage disorder characterized by widespread cystine crystal accumulation. OBJECTIVE: To develop an unbiased and semi-automated imaging methodology to quantify dermal cystine crystal accumulation in patients to correlate with disease status. DESIGN, SETTING AND PARTICIPANTS: 101 participants, 70 patients and 31 healthy controls, were enrolled at the University of California, San Diego, Cystinosis Clinics, Rady Children's Hospital, San Diego and at the annual Cystinosis Research Foundation family conference for an ongoing prospective longitudinal cohort study of cystinosis patients with potential yearly follow-up. EXPOSURES: Intradermal reflectance confocal microscopy (RCM) imaging, blood collection via standard venipuncture, medical record collection, and occasional skin punch biopsies. MAIN OUTCOMES AND MEASURES: The primary outcome was to establish an automated measure of normalized confocal crystal volume (nCCV) for each subject. Secondary analysis examined the association of nCCV with various clinical indicators to assess nCCV's possible predictive potential. RESULTS: Over 2 years, 57 patients diagnosed with cystinosis (median [range] age: 15.1 yrs [0.8, 54]; 41.4% female) were intradermally assessed by RCM to produce 84 image stacks. 27 healthy individuals (38.7 yrs [10, 85]; 53.1% female) were also imaged providing 37 control image stacks. Automated 2D crystal area quantification revealed that patients had significantly elevated crystal accumulation within the superficial dermis. 3D volumetric analysis of this region was significantly higher in patients compared to healthy controls (mean [SD]: 1934.0 µm3 [1169.1] for patients vs. 363.1 µm3 [194.3] for controls, P<0.001). Medical outcome data was collected from 43 patients with infantile cystinosis (media [range] age: 11 yrs [0.8, 54]; 51% female). nCCV was positively associated with hypothyroidism (OR = 19.68, 95% CI: [1.60, 242.46], P = 0.02) and stage of chronic kidney disease (slope estimate = 0.53, 95%CI: [0.05, 1.00], P = 0.03). CONCLUSIONS AND RELEVANCE: This study used non-invasive RCM imaging to develop an intradermal cystine crystal quantification method. Results showed that cystinosis patients had increased nCCV compared to healthy controls. Level of patient nCCV correlated with several clinical outcomes suggesting nCCV may be used as a potential new biomarker for cystinosis to monitor long-term disease control and medication compliance.

Subdermal Dissection for Elevation of Pure Skin Perforator Flaps and Superthin Flaps: The Dermis as a Landmark for the Most Superficial Dissection Plane.

BACKGROUND: Pure skin perforator and superthin flaps have been reported and are becoming popular, as they allow one-stage thin skin reconstruction even from a thick donor site. However, currently reported elevation procedures use proximal-to-distal dissection requiring free-style perforator selection and primary thinning procedures. With distal-to-proximal dissection using the dermis as a landmark for dissection plane, it is expected that elevation of pure skin perforator or superthin flaps can be simplified. METHODS: Patients who underwent pure skin perforator or superthin flap transfers with the subdermal dissection technique were included. Flaps were designed based on location of pure skin perforators visualized on color Doppler ultrasound, and elevated just below the dermis under an operating microscope. Medical charts were reviewed to obtain clinical and intraoperative findings. Characteristics of the patients, flaps, and postoperative courses were evaluated. RESULTS: Thirty-six flaps were transferred in 34 patients, all of which were elevated as true perforator flaps (superficial circumflex iliac artery perforator flap in 29 cases, other perforator flaps in seven cases). Mean ± SD flap thickness was 2.24 ± 0.77 mm (range, 1.0 to 4.0 mm). Skin flap size ranged from 3.5 × 2 cm to 27 × 8 cm. Time for flap elevation was 27.4 ± 11.6 minutes. All flaps survived without flap atrophy/contracture 6 months after surgery, except for two cases of partial necrosis. CONCLUSION: The subdermal elevation technique allows straightforward and direct elevation of a pure skin perforator or superthin flap within 30 minutes on average without the necessity of primary thinning. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.