Ultrasound assessment of skin and wound tissue: comparison with histology

Quantitative evaluation of rat sciatic nerve degeneration using high-frequency ultrasound

In this study, we evaluated the utility of using high-frequency ultrasound to non-invasively track the degenerative process in a rat model of peripheral nerve injury. Primary analyses explored spatial and temporal changes in quantitative backscatter coefficient (BSC) spectrum-based outcomes and B-mode textural outcomes, using gray level co-occurrence matrices (GLCMs), during the progressive transition from acute to chronic injury. As secondary analyses, correlations among GLCM and BSC spectrum-based parameters were evaluated, and immunohistochemistry were used to suggest a structural basis for ultrasound outcomes. Both mean BSC spectrum-based and mean GLCM-based measures exhibited significant spatial differences across presurgical and 1-month/2-month time points, distal stumps enclosed proximity to the injury site being particularly affected. The two sets of parameters sensitively detected peripheral nerve degeneration at 1-month and 2-month post-injury, with area under the receiver operating charactersitic curve > 0.8 for most parameters. The results also indicated that the many BSC spectrum-based and GLCM-based parameters significantly correlate with each other, and suggested a common structural basis for a diverse set of quantitative ultrasound parameters. The findings of this study suggest that BSC spectrum-based and GLCM-based analysis are promising non-invasive techniques for diagnosing peripheral nerve degeneration.

Comparison of digital and traditional skin wound closure assessment methods in mice

BACKGROUND

Chronic skin wounds are a common complication of many diseases such as diabetes. Various traditional methods for assessing skin wound closure are used in animal studies, including wound tracing, calliper measurements and histological analysis. However, these methods have poorly defined wound closure or practical limitations. Digital image analysis of wounds is an increasingly popular, accessible alternative, but it is unclear whether digital assessment is consistent with traditional methods. This study aimed to optimise and compare digital wound closure assessment with traditional methods, using a diabetic mouse model. Diabetes was induced in male C57BL/6J mice by high-fat diet feeding combined with low dose (65 mg/kg of body weight) streptozotocin injections. Mice fed normal chow were included as controls. After 18 weeks, four circular full-thickness dorsal skin wounds of 4 mm diameter were created per mouse. The wounds were photographed and measured by callipers. Wound closure rate (WCR) was digitally assessed by two reporters using two methods: wound outline (WCR-O) and re-epithelialisation (WCR-E). Wounded skin tissues were collected at 10-days post-wounding and wound width was measured from haematoxylin and eosin-stained skin tissue.

RESULTS

Between reporters, WCR-O was more consistent than WCR-E, and WCR-O correlated with calliper measurements. Histological analysis supported digital assessments, especially WCR-E, when wounds were histologically closed.

CONCLUSIONS

WCR-O could replace calliper measurements to measure skin wound closure, but WCR-E assessment requires further refinement. Small animal studies of skin wound healing can greatly benefit from standardised definitions of wound closure and more consistent digital assessment protocols.

The evaluation of podiatrists, with knowledge and training in diagnostic musculoskeletal ultrasound, to describe sonographic images of diabetic foot wounds in the United Kingdom and Australia

AIMS

Currently, wound management decisions are based largely on visual observations such as photographs, descriptors or measurements which can lack detail and do not always capture the sub-wound area. A previous case series suggests that there is benefit in using ultrasound imaging (USI) to evaluate diabetic foot ulcers (DFU) at point-of-care, however no guidance exists to inform its use. This scoping exercise explores the capacity of podiatrists with experience in interpreting musculoskeletal structures using USI to interpret sonographic images of DFU.

METHODS

Following a short briefing session, podiatrists with previous musculoskeletal (MSK) USI training were asked to review and report on previously recorded static sonographic images (n = 8) of active DFU. Content analysis was utilised to identify recurring keywords within the podiatrists' reports which were coded and assigned to categories to gain context to the data.

RESULTS

Seven podiatrists participated in the study. Four categories were constructed for the purposes of analysis: 1) Frequency of reporting, 2) Language used in reporting, 3) Observations, 4) Clinical impression Frequently, the reported findings between podiatrists were found to be similar, especially those related to bone morphology. However greater variability was seen in the reporting of wound specific soft-tissue observations.

CONCLUSION

This scoping exercise has shown that podiatrists can translate their existing USI skills to make rudimentary reports on clinical findings in DFU. All participants were consistently able to identify and describe characteristics associated with DFU from a single b mode static wound ultrasound image. Findings from this investigation can be used as a foundation for further work to establish accuracy and reliability to validate DFU sonography. In conjunction the development of protocols and training materials will enable the adoption of USI to assess DFU in clinical practice. This will in turn, contribute to improved patient care and establish a new paradigm for wound surveillance which is translatable to other wound types.

Synthetic Aperture Radar Imaging for Burn Wounds Diagnostics

The need for technologies to monitor the wound healing under dressing materials has led us to investigate the feasibility of using microwave and millimetre wave radiations due to their sensitivity to water, non- ionising nature, and transparency to dressing materials and clothing. This paper presents synthetic aperture radar (SAR) images obtained from an active microwave and millimetre wave scanner operating over the band 15–40 GHz. Experimental images obtained from porcine skin samples with the presence of dressing materials and after the application of localised heat treatments reveal that SAR images can be used for diagnosing burns and for potentially monitoring the healing under dressing materials. The experimental images were extracted separately from the amplitude and phase measurements of the input reflection coefficient (S₁₁). The acquired images indicate that skin and burns can be detected and observed through dressing materials as well as features of the skin such as edges, irregularities, bends, burns, and variation in the reflectance of the skin. These unique findings enable a microwave and millimetre-wave scanner to be used for evaluating the wound healing progress under dressing materials without their often-painful removal: a capability that will reduce the cost of healthcare, distress caused by long waiting hours, and the healthcare interventional time.

The relationship between pressure offloading and ischial tissue health in individuals with spinal cord injury: An exploratory study

Objectives: To compare thickness and texture measures of tissue overlying the ischial region in able-bodied (AB) individuals vs. individuals with spinal cord injury (SCI) and to determine if there is a relationship between pressure offloading of the ischial tuberosities (IT) and tissue health in individuals with SCI. Design: Exploratory cross-sectional study. Setting: University setting and rehabilitation hospital. Outcome Measures: Thickness and texture measurements from ultrasound images of tissues overlying the IT were obtained from AB individuals (n = 10) and individuals with complete or incomplete traumatic and non-traumatic SCI American Spinal Injury Association Impairment Scale (AIS) classification A-D (n = 15). Pressure offloading was measured in individuals with SCI and correlated with tissue health measurements. Results: The area overlying the IT occupied by the muscle was significantly greater in the SCI when compared with AB cohort. The area occupied by the muscle in individuals with SCI appeared to lose the striated appearance and was more echogenic than nearby skin and subcutaneous tissue (ST). There was no correlation between offloading times and thickness, echogenicity and contrast measurements of skin, ST and muscle in individuals with SCI. Conclusion: Changes in soft tissues overlying the ischial tuberosity occur following SCI corresponding to the loss of striated appearance of muscle and increased thickness of the area occupied by the muscle. Further studies using a larger sample size are recommended to establish if thickness and tissue texture differ between individuals with SCI who sustain pressure injuries vs. those who do not.

Use of platelet-rich plasma to facilitate wound healing

Platelet-rich plasma (PRP) is widely used nowadays in different fields of medicine, affecting physiological processes including tissue regeneration. The use of PRP in maxillofacial surgical interventions and its efficiency in the improvement of postoperative wound healing were analysed. Patients undergoing plastic and reconstructive surgeries in the maxillofacial region were recruited: 50 patients were enrolled into a control group (received no PPRP injection) and 50 patients were enrolled into a treatment group, where PRP was applied during the surgical procedure. Evaluation of treatment outcomes was carried out by determination of IL-1β, TNFα, and IL-6 cytokines levels in the wound-drain fluid. The stages of wound healing were assessed by cytological analyses and ultrasound within a month period. The use of the PRP has substantially positive effects, contributing to the improvement of the healing process. In the treatment group, fibroblasts, macrophages, and collagen fibres appeared and their quantities increased earlier than when compared with control group patients. The concentration of IL-1β and TNFα in wound fluid on day 1 and day 5 after operation was higher for the treatment group as opposed to the control group, which was linked to the influence of PRP on inflammatory and granulation phases of the healing process. An ultrasound examination showed less oedema and infiltration in the tissues around the wound of the treatment group.

Ultrasonographic findings of re-epithelialized skin after partial-thickness burns

Background

This study aimed to investigate the difference between ultrasonographic findings of normal skin and those of re-epithelialized skin after partial-thickness burns and to evaluate the relationship between these findings and clinical outcomes.

Methods

This study retrospectively analysed the ultrasound images of re-epithelialized skin after partial-thickness burns and contralateral normal skin from January 2016 to December 2016. A total of 155 lesions from 148 patients were analysed with ultrasound images, and healing time was documented. The scar status of each lesion was evaluated through medical records and photographs. We analysed the difference in ultrasonographic findings between normal skin and re-epithelialized skin after partial-thickness burns and statistically analysed the relationship between healing time, scar status and ultrasonographic findings.

Results

The re-epithelialized skin after partial-thickness burns was significantly thicker than the contralateral normal skin, and the echogenicity was significantly lower. The ultrasound images of the re-epithelialized skin after partial-thickness burns showed the characteristic findings of low-echogenic bands (LEB), and the proportion of LEB thickness is strongly correlated with healing time. In the multivariate analysis of scar status, only the proportion of LEB thickness was statistically significant.

Conclusion

In this study, we found that there were ultrasonographic differences between re-epithelialized skin after partial-thickness burns and normal skin and that an LEB of varying thickness was formed after re-epithelialization. The thickness of the LEB in re-epithelialized skin after partial-thickness burns increased with healing time and was related to scar status.

In vivo estimation of the Young's modulus in normal human dermis

Skin elastic properties change during a cutaneous disorder or in the aging process. Deep knowledge of skin layers helps monitoring and diagnosing structural changes. High frequency ultrasound (HF-US) has been recently introduced to diagnose and evaluate some dermatological disorders in the clinical practice. US elastography adds elasticity information of the analyzed tissue. In particular, harmonic elastography estimates the speed of shear waves produced by external vibration sources, in order to relate the shear wave speed to the Young's modulus. In the epidermis and dermis layers, shear waves are not generated; in contrast, surface acoustic waves (SAWs) exist as they propagate in the top of the tissue. This study uses crawling wave sonoelastography for the estimation of SAWs in human thigh dermis in vivo. Experiments were performed in ten volunteers in the range of 200 - 500 Hz. As other studies suggest, SAW speed needs to be compensated to reach shear wave speed, for calculating the Young's modulus. Thus, the SAW speed estimated was corrected when it propagates in solidUS gel interface. Specifically, the elasticity modulus found was $18.35 \pm 1.04$ KPa for a vibration frequency of 200 Hz. Results suggest that the elasticity modulus can be estimated in vivo using crawling wave HF-US for skin application and shows potential for future application in skin disorders.

Quantitative ultrasound imaging over the ischial tuberosity: An exploratory study to inform tissue health

BACKGROUND

Characterization of ischial tissue health using a standardized diagnostic ultrasound protocol capturing thickness and gray scale analysis has not been established.

OBJECTIVES

This study evaluates inter-participant and inter-trial reliability of thickness and gray scale analysis of ultrasound images of tissues overlying the ischial tuberosity. It provides recommendations for the number of images required to minimize the standard error of measurement (SEM) and determines the number of images required for thickness, gray scale and contrast values that exceed an a-priori minimal detectable change (MDC) for repeated tissue assessment.

METHODS

Brightness mode ultrasound images using a 12 MHz linear probe were collected on the dominant limb in the side lying position for ten healthy participants and partitioned into three regions of interest: skin, subcutaneous tissue and muscle. Thickness and gray scale measures of skin, muscle and subcutaneous tissue were calculated using a customized MATLAB program. Contrast of each region of interest was calculated using the Gray Scale Level Co-Occurrence Matrix. Generalizability theory was used to quantify indices of dependability and corresponding SEMs and MDCs with 90% Confidence Intervals.

RESULTS

Participants accounted for most of the total variance (75.56% to 94.78%). Coefficient of dependability (ϕ) for thickness, grey scale and contrast measures was greater than 0.80 when more than two images were averaged. In order to detect a MDC of 21% in thickness and echogenicity measures, at least three images are required, while at least 5 images are required for a MDC of 25% for contrast measures.

CONCLUSIONS

Obtaining reliable thickness, echogenicity and contrast measures of tissue overlying the ischial tuberosity can be achieved from two ultrasound images by a single therapist on an individual participant however three and five images are required to use a MDC of 21% for thickness measures and MDC of 25% for contrast measures respectively.

Skin thickness as a potential marker of gestational age at birth despite different fetal growth profiles: A feasibility study

BACKGROUND

New methodologies to estimate gestational age (GA) at birth are demanded to face the limited access to obstetric ultrasonography and imprecision of postnatal scores. The study analyzed the correlation between neonatal skin thickness and pregnancy duration. Secondarily, it investigated the influence of fetal growth profiles on tissue layer dimensions.

METHODS AND FINDINGS

In a feasibility study, 222 infants selected at a term-to-preterm ratio of 1:1 were assessed. Reliable information on GA was based on the early ultrasonography-based reference. The thicknesses of the epidermal and dermal skin layers were examined using high-frequency ultrasonography. We scanned the skin over the forearm and foot plantar surface of the newborns. A multivariate regression model was adjusted to determine the correlation of GA with skin layer dimensions. The best model to correlate skin thickness with GA was fitted using the epidermal layer on the forearm site, adjusted to cofactors, as follows: Gestational age (weeks) = -28.0 + 12.8 Ln (Thickness) - 4.4 Incubator staying; R2 = 0.604 (P<0.001). In this model, the constant value for the standard of fetal growth was statistically null. The dermal layer thickness on the forearm and plantar surfaces had a negative moderate linear correlation with GA (R = -0.370, P<0.001 and R = -0.421, P<0.001, respectively). The univariate statistical analyses revealed the influence of underweight and overweight profiles on neonatal skin thickness at birth. Of the 222 infants, 53 (23.9%) had inappropriate fetal growths expected for their GA. Epidermal thickness was not fetal growth standard dependent as follows: 172.2 (19.8) μm for adequate for GA, 171.4 (20.6) μm for SGA, and 177.7 (15.2) μm for LGA (P = 0.525, mean [SD] on the forearm).

CONCLUSIONS

The analysis highlights a new opportunity to relate GA at birth to neonatal skin layer thickness. As this parameter was not influenced by the standard of fetal growth, skin maturity can contribute to clinical applications.

Utility of high-frequency ultrasound: moving beyond the surface to detect changes in skin integrity

Ultrasound imaging is a versatile modality frequently used in clinical medicine, most likely due to its low cost, low risk to patients, and the ability to provide images in real time. Ultrasound used typically in clinical settings has frequencies between 2 and 12 MHz. Lower frequencies produce greater resolution but are limited in depth penetration; higher frequencies produce greater resolution, but depth of penetration is limited. High-frequency ultrasound (HFUS) shows promise for detection of certain changes in the skin and this has implications for early detection of changes associated with pressure ulcer formation and wound healing. The purpose of this article was to provide an overview of where HFUS has been used with the skin and provide some discussion on its utility with detecting skin changes related to pressure.

Stress predicts the trajectory of wound healing in living kidney donors as measured by high-resolution ultrasound

BACKGROUND

Psychological stress has been shown to be an influential factor on the rate of wound healing; however these findings have been demonstrated predominantly on artificially created wounds. Due to the absence of major co-morbidities, living kidney donors are a unique group in which to study this relationship. This study investigated the effect of preoperative stress and personality on surgical wound healing through the use of high-resolution ultrasound.

METHODS

Living kidney donors due to undergo a hand-assisted laparoscopic donor nephrectomy were asked to complete the Perceived Stress Scale, the Life Orientation Test-Revised and the Ten Item Personality Inventory prior to surgery. High-resolution ultrasound scans of surgical wounds were performed on the first three post-operative days and once following discharge (mean=15.3 days; s.d. 2.8). Two measurements from each image were obtained: wound width (size of wound) and median intensity (a marker of tissue fluid). Latent Growth Curve Models (LGCMs) were used to evaluate wound healing.

RESULTS

52 living kidney donors participated. Higher pre-operative life stress, lower optimism and lower conscientiousness were associated with delayed wound healing in living kidney donors for both outcomes. Increased emotional stability was associated with faster wound healing as demonstrated by a change in median intensity. Possible confounding factors, such as age, BMI, smoking status, local anaesthetic use and wound drain placement were not influential.

CONCLUSIONS

This study, which measured wound healing in a novel patient sample using a novel technique, has demonstrated a negative association between stress and wound healing and the positive influence of optimism, conscientiousness and emotional stability.

The utility of musculoskeletal ultrasound in rehabilitation settings

Aside from its prompt use in musculoskeletal injuries (sports lesions, degenerative/inflammatory joint disorders, and peripheral nerve pathologies), ultrasonographic imaging can be used quite conveniently in various types of rehabilitation conditions as well. If used in a rehabilitation setting, ultrasound can significantly contribute to the diagnostic/therapeutic algorithm of rehabilitation patients. Accordingly, in this article, the authors focus on the diagnostic/interventional utility of ultrasound particularly for shoulder problems, overuse injuries of wheelchair users, heterotopic ossification, amputee follow-up, peripheral nerve and botulinum toxin injections, and diaphragm imaging/electromyography.

Automatic evaluation of pressure sore status by combining information obtained from high-frequency ultrasound and digital photography

In this study, the different phases of pressure sore generation and healing are investigated through a combined analysis of high-frequency ultrasound (20 MHz) images and digital color photographs. Pressure sores were artificially induced in guinea pigs, and the injured regions were monitored for 21 days (data were obtained on days 3, 7, 14, and 21). Several statistical features of the images were extracted, relating to both the altering pattern of tissue and its superficial appearance. The features were grouped into five independent categories, and each category was used to train a neural network whose outputs were the four days. The outputs of the five classifiers were then fused using a fuzzy integral to provide the final decision. We demonstrate that the suggested method provides a better decision regarding tissue status than using either imaging technique separately. This new approach may be a viable tool for detecting the phases of pressure sore generation and healing in clinical settings.

Scarring occurs at a critical depth of skin injury: precise measurement in a graduated dermal scratch in human volunteers

BACKGROUND

The association between scarring and the depth of dermal injury or burn is clinically recognized but not quantified. The authors tested the hypothesis that there is a critical depth beyond which a fibrous scar develops.

METHODS

A novel jig produced a wound that was deep dermal at one end and superficial dermal at the other. Pilot studies in cadaveric and ex vivo breast skin confirmed the depth of injury. Healthy volunteers had a standardized dermal wound made on the lateral aspect of the hip. Digital photography recorded the surface appearance of wound healing and scar development. High-frequency ultrasound demonstrated the depth of the healing wound and subsequent scar in vivo.

RESULTS

One hundred thirteen human subjects participated in the clinical study. Mean length of follow up was 28.6 +/- 13.2 weeks. The deep dermal end of the wound healed with a visible scar and the superficial end had no visible residual mark after week 18. The initial length of injury was 51.3 +/- 0.6 mm, which reduced to a scar of 34.9 +/- 1.0 mm at 36 weeks (corresponding areas were 196.6 +/- 7.5 mm and 92.7 +/- 9.4 mm). High-frequency ultrasound analysis showed a gradual reduction in scar thickness at the deep end and no detectable scar at the shallow end. The transition point between scar and no scar marked the threshold depth for scarring. This was calculated as 0.56 +/- 0.03 mm, or 33.1 percent of normal hip skin thickness.

CONCLUSIONS

The dermal scratch provides a well-tolerated, standardized, and reproducible wound model for investigating the healing response to dermal injury of different depths. There is a threshold depth of dermal injury at which scarring develops.

Use of High-Resolution, High-Frequency Diagnostic Ultrasound to Investigate the Pathogenesis of Pressure Ulcer Development

OBJECTIVES

To investigate the pathogenesis of pressure ulcers utilizing high-resolution ultrasound and to explore the utility of this technology for the detection of incipient pressure ulcers prior to visual clinical signs.

DESIGN

An observational prospective study comparing high-resolution ultrasound images obtained from 119 long-term-care facility residents determined to be at risk for pressure ulcer development (Braden Scale score of 18 or less) with images obtained from 15 healthy volunteers (medical students and medical residents). Common pressure ulcer sites were scanned, including the heels, sacrum, and ischial tuberosity.

SETTING

A medical center and a long-term-care facility.

INTERVENTION

Anatomic sites universally accepted as at risk for pressure ulcer development were scanned using high-resolution ultrasound; the sites did not have visual evidence of skin breakdown. The images obtained from the long-term-care facility residents were compared with images considered normal that were obtained from healthy volunteers. In addition, documentation of the clinical assessment finding for erythema was reviewed, recorded, and compared with the high-resolution ultrasound finding for each specific site.

MEASUREMENTS

The images obtained were classified as not readable, normal, or abnormal. The images classified as abnormal were further classified by depth of abnormal finding: pattern 1 (deep) or pattern 2 (superficial). The images classified with the abnormal finding pattern 1 (deep) were further classified and subdivided by anatomic location of abnormal finding(s): subgroup 1, abnormal findings in the subdermal area only; subgroup 2, subdermal and dermal abnormal findings; and subgroup 3, subdermal, dermal, and subepidermal edema. Pattern 2 (superficial) included images with abnormal findings limited to the dermal/epidermal junction.

RESULTS

630 (55.3%) of the images obtained from the long-term-care residents were different from the images obtained from the healthy volunteers. The healthy volunteers' images classified as normal had the expected ultrasound findings for homogeneous pattern of ultrasound reflections, allowing for visualization of various skin layers (epidermis, superficial papillary dermis, deep reticular dermis, and hypodermis) and subcutaneous tissue (subdermal). However, many images (55.3%) obtained from the residents at risk for pressure ulcer development had patterns where areas within the various skin layers were not visible, interrupted by areas indicative of fluid or edema. Moreover, most images (79.7%) with abnormal ultrasound patterns did not have documentation of erythema.

CONCLUSION

High-resolution ultrasound is an effective tool for the investigation of skin and soft tissue changes consistent with the documented pathogenesis of pressure ulcers. A progressive process for pressure ulcer development from deep subdermal layers to superficial dermal then epidermal layers can be inferred. Dermal edema was only present with subdermal edema. In other words, there was never evidence of dermal edema in the absence of subdermal edema. A better understanding of the pathogenesis of pressure ulcers through the use of high-resolution ultrasound to detect soft tissue damage and edema before visible clinical signs could lead to earlier and more focused pressure ulcer prevention programs, resulting in reduced pain and suffering for improved patient quality of life and wound care cost savings.

Ultrasound imaging demonstration of the improvement of non-ablative laser remodeling by concomitant daily topical application of 0.05% retinaldehyde

BACKGROUND

Retinaldehyde has been proven to be effective in the reduction of facial wrinkles. It has also demonstrated its usefulness when used before and after laser skin resurfacing.

OBJECTIVE

A monocentric, comparative, randomized, double-blind study was performed to evaluate the efficacy of retinaldehyde versus excipient in combination with non-ablative laser remodeling treatment.

METHODS

A total of 16 female patients (mean age 45 years) were enrolled for neck line and forehead rhytid treatment. They were randomly assigned into two groups. The RAL group (eight patients) was treated with a non-ablative laser (1540 nm Er:glass, 10 J/cm2 per pulse, three pulses, 2 Hz repetition rate, 4 mm spot, +5 degrees C cooling) and daily topical application of 0.05% retinaldehyde immediately after the first laser treatment and up to 3 months after the fifth treatment. The CTRL group (eight patients) was treated under similar conditions, except with a daily application of excipient. The thickness of the skin (forehead and neck) was measured by ultrasound imaging before the first treatment, 1 month after the third treatment, 1 month after the fifth treatment and 3 months after the fifth treatment.

RESULTS

An increase of dermal thickness was observed for all patients treated by laser (groups RAL and CTRL) on the forehead and neck. However, the increase was greater for the RAL group (retinaldehyde) when compared with the CTRL group (excipient). Three months after the fifth treatment, the increase in dermal thickness (%) was, respectively, 5.27 versus 1.13 for the forehead and 10.54 versus 3.57 for the neck. The difference between groups was statistically significant in favor of the retinaldehyde group for the forehead (p<0.05) and of limited significance for the neck (p=0.08).

CONCLUSION

When considering the reduced number of patients in each group, the statistical analysis demonstrates an evident advantage of using retinaldehyde versus excipient. This study demonstrates that irradiation with a 1540 nm Er:glass laser can be potentiated with concomitant daily topical application of 0.05% retinaldehyde.

Collagen remodeling after 585-nm pulsed dye laser irradiation: an ultrasonographic analysis

BACKGROUND AND OBJECTIVES

Nonablative dermal remodeling is an evolving technology that has generated great interest among both laser surgeons and patients. Evidence indicates that dermal collagen formation is the key mechanism of action for the nonablative techniques. We studied, with ultrasound, new collagen formation after nonablative laser irradiation.

METHODS

Ten patients with facial rhytids underwent a single treatment with a 585-nm pulsed dye laser. The patients were all female, ranging in age from 47 to 67, and were Fitzpatrick skin types I-III. Laser parameters were as follows: an energy fluence of 2.4 to 3.0 J/cm2, a pulse duration of 350 microsec, and a spot size of 5 mm with no overlap. Ultrasonographic assessments of dermal collagen were taken at baseline and at 30 and 90 days after treatment.

RESULTS

Ultrasonography demonstrated an increase in dermal collagen after a single treatment with the 585-nm pulsed dye laser. The greatest degree of neocollagenesis occurred periocularly.

CONCLUSION

A single treatment with a 585-nm pulsed dye laser appears to increase dermal collagen. This increase in dermal collagen can be assessed with noninvasive cutaneous ultrasound.

Wound healing assessment using 20 MHz ultrasound and photography

BACKGROUND/AIMS

To compare two non-invasive techniques of assessing wound healing, photography and high resolution ultrasound (HRUS) scanning, in experimentally induced full-thickness human skin wounds.

METHODS

Punch biopsy wounds, 4 mm in diameter, were made aseptically through locally anaesthetised skin on the anterior (volar) surface of the non-dominant forearm, 3 cm below the base of the cubital fossa, of 20 human participants. The wounds were treated with a topical antibiotic and covered for 3 days with Mepore sterile dressings. Wound healing was assessed on post-operative days 3, 7, 14 and 21 from photographs and HRUS B-scans. All photographs were taken of the wound site and adjacent intact skin under standardised conditions. The prints obtained were examined visually and digitised. Digital HRUS B-scans were taken through the centre of the wound bed and the adjacent intact skin parallel to the epidermis. Using the scanner's calibrated linear measurement capability, the wound width was measured adjacent to the deep surface of the scab, at the base of the wound, and midway between these two levels.

RESULTS

The wound margins were more clearly defined in the HRUS scans than in the photographs of the wounds; in some of the latter the scab masked the wound margins. Changes in the surface width of the wound were affected by the time of scab dehiscence, which varied between volunteers. There was less individual variation in the width of the base of the wound, as measured from the HRUS scans.

CONCLUSIONS

In contrast to photography, which allows recording of changes in the superficial aspect of the wound only, HRUS scanning permits the quantitative assessment of structural changes deep within the wound. Temporal changes in the width of the base of the wound can be used as an indication of the progress of repair.

Nonablative remodeling: clinical, histologic, ultrasound imaging, and profilometric evaluation of a 1540 nm Er:glass laser

BACKGROUND

Nonablative remodeling has been recently proposed as an alternative to CO2 and Er:YAG resurfacing.

OBJECTIVE

To evaluate the efficacy and safety of a 1540 nm Er:glass laser with contact cooling in nonablative skin remodeling, focused on perioral and periorbital rhytides.

METHODS

Sixty patients (mean age 47 years), Fitzpatrick skin types I-IV were treated four times over 6-week intervals. Patients were evaluated using digital photographs, histology, ultrasound imaging, and profilometry with silicone imprints in order to quantitate the degree of clinical improvement.

RESULTS

All subjects reported subjective improvement in the quality and visual aspect of their skin. This was confirmed by a 40.2% reduction of anisotropy (P <.001) 6 weeks after the fourth treatment. Ultrasound imaging demonstrated a 17% increase of dermis thickness (P <.005). Biopsy specimens showed evidence of new collagen formation.

CONCLUSION

This study has clearly demonstrated that irradiation with 1540 nm Er:glass laser can lead to new collagen formation, dermis thickening, reduction of anisotropy of the skin, and clinical improvements. The lack of adverse effects confirmed that this 1540 nm laser emitting in a pulsed mode coupled with an efficient cooling system is safe.

Use of thigh pressure cuffs to modulate simulated microgravity-induced changes in the skin measured with high-resolution B-scan ultrasound

OBJECTIVE

The aim of the present study was to evaluate the fluid shift in a simulated microgravity experiment and to test the use of thigh cuffs to help alleviate the problem.

METHODS

The change in skin thickness was assessed by a 20 MHz B-scan ultrasound device. This was performed on eight volunteers who underwent two successive 7-day periods of -6 degrees anti-orthostatic bed-rest, with or without the daytime use of thigh cuffs. The thigh cuffs were used to counteract the development of facial oedema.

RESULTS

In the control group (without thigh cuffs), the results showed a steady increase in skin thickness of the combined dermis and hypodermis of the forehead and a reduction of the thickness of this tissue on the tibia. For the countermeasure group, although thigh cuffs were only employed during the daytime - being removed at night - their use reduced the amplitude and kinetics of the fluid shift, resulting in greater beneficial effects at the end of the day than early in the morning.

CONCLUSION

These results of objective measurements of skin made using a non-invasive high frequency ultrasonography method confirm reports by cosmonauts of a reduction in facial oedema and a more 'comfortable' adaptation to microgravity by the use of thigh cuffs during space flight. This system is potentially promising for investigating fluid shifts in the skin and may prove useful in the evaluation of some oedematous skin diseases, as well as their therapy.