A pilot study of fluorescence diagnosis of basal cell carcinoma using a digital flash light-based imaging system.

BACKGROUND/PURPOSE: Fluorescence diagnosis (FD) is a promising method for the non-invasive detection of tumor boundaries. We aimed to investigate the clinical utility of a flash light-based fluorescence imaging system. METHODS: Sixteen patients with basal cell carcinomas were included in this pilot study. FD was performed using a 20% 5-aminolevulinic acid (ALA) cream. The FD tumor area was determined 3 h after the ALA application using a digital flash light-based fluorescence imaging system and an image analysis system. The tumor area was also assessed by means of the clinical diagnosis (CD) based on the normal colored picture. The tumors were excised following the FD procedure, but according to the clinically diagnosed lesional area. RESULTS: Though there was a very strong correlation between the tumor areas assessed by FD and CD, the mean tumor area that was visualized by FD was significantly smaller than the tumor area determined by CD. The mean+/-SD FD/CD ratio was 0.78+/-0.11 in total. In 81.3% of cases, complete tumor excision was achieved. CONCLUSION: This pilot study indicates that the FD technology may be less sensitive than CD, and refinements of the technique along with larger systematic trials on the sensitivity and specificity of FD are required.

Characterization of benign and malignant melanocytic skin lesions using optical coherence tomography in vivo.

BACKGROUND: Although optical coherence tomography (OCT) is a promising noninvasive imaging technique for the micromorphology of the skin, OCT has not been studied systematically in skin cancer such as malignant melanoma (MM). OBJECTIVE: We sought to visualize and characterize melanocytic skin lesions (MSL) by using OCT in vivo, compare OCT features of benign nevi (BN) and MM, and histologically validate the OCT findings. METHODS: In all, 75 patients with 92 MSL, including 52 BN and 40 MM, were included in this study. MSL were investigated by OCT in vivo and consecutive histology. We compared the OCT images with the corresponding histologic slices of BN and MM. To ascertain accuracy of correlation between OCT images and histologic sections, the excised lesions were tattooed according to the level of OCT scanning. For every MSL, serial histologic slices were prepared. RESULTS: MM often showed a marked architectural disarray (P = .036) and rarely displayed a clear dermoepidermal border (P = .0031) when compared with BN. OCT of MM infrequently demonstrated a dermoepidermal junction zone with finger-shaped elongated rete ridges as typically seen in BN (P = .011). Compared with BN, the papillary and superficial reticular dermis in MM frequently displayed a more diffuse or patchy reflectivity with loss of the typical bright horizontal linear structures (P = .022). However, more or less large vertical, icicle-shaped structures were the most striking OCT feature of MM, which were not observed in BN (P < .001). LIMITATIONS: The diagnostic performance of OCT in the diagnosis of MSL could not be fully determined. Sensitivity and specificity studies also including other skin tumors have not been performed. CONCLUSION: In this study, distinct OCT features of MSL could be correlated to histopathologic findings. With regard to the micromorphologic features visualized by OCT, we detected significant differences between BN and MM. These OCT features might serve as useful discriminating parameters of MSL.

Preoperative ultrasonic assessment of thin melanocytic skin lesions using a 100-MHz ultrasound transducer: a comparative study.

BACKGROUND: It has been shown that tumor thickness (TT) of melanocytic skin lesions (MSL) of less than 1 mm vertical thickness assessed by 20 MHz are often incorrectly evaluated. OBJECTIVE: We aimed to evaluate the accuracy of 100-MHz ultrasound for the determination of TT of thin MSL, compared with conventional 20-MHz ultrasound and histologic findings. METHODS: Thirty-seven patients with 50 suspicious MSL, including tumor diameter up to 1 cm and maximum vertical TT of less than 1 mm, were recruited. The agreement between the histologically and ultrasographically measured TT was analyzed using Bland and Altman plots. RESULTS: Compared to histology, 20-MHz ultrasound (33.9 microm) as well as 100-MHz (16 microm) resulted in overestimation of TT that was twofold higher for 20-MHz ultrasound. The latter also revealed wider 95% limits of agreement (4.9 to 63 microm) than 100-MHz ultrasound (3.5 to 28.7 microm). CONCLUSION: Analysis of agreement clearly demonstrated that the performance of 100-MHz ultrasound is superior to conventional 20-MHz ultrasound, even though a relatively small positive bias was observed in 100-MHz ultrasound, indicating a systematic error. We consider 100-MHz ultrasound a useful tool for the noninvasive determination of TT of thin MSL in vivo.

In vivo optical coherence tomography of basal cell carcinoma.

BACKGROUND: Optical coherence tomography (OCT) is a promising non-invasive imaging technique that has not systematically been studied in skin cancer such as basal cell carcinoma (BCC). OBJECTIVE: We aimed, first, to describe the in vivo histologic features of BCC by using OCT, and second, to find out whether it is possible to differentiate BCC subtypes by means of OCT. METHODS: Prior to the excision, the BCCs (n=43) as well as adjacent non-lesional skin sites were assessed by OCT in vivo. The lesional area of interest was marked prior to OCT and tattooed after excision, respectively, in order to enable topographical concordance between the cross-sectional OCT images and the histologic sections. RESULTS: Compared to non-lesional skin, a loss of normal skin architecture and disarrangement of the epidermis and upper dermis was observed in the OCT images of BCCs. Features that were frequently identified by OCT and correlated with histology included large plug-like signal-intense structures, honeycomb-like signal-free structures, and prominent signal free cavities in the upper dermis. With regard to the aforementioned OCT features, no statistically significant (P<0.05) difference was found between nodular, multifocal superficial, and infiltrative BCCs, respectively. CONCLUSIONS: OCT is capable to visualize altered skin architecture and histopathological correlates of BCC. However, there is not at this time sufficient data supporting the clinical use of OCT for the differentiation of BCC subtypes.

In vivo data of epidermal thickness evaluated by optical coherence tomography: effects of age, gender, skin type, and anatomic site.

BACKGROUND: The knowledge of epidermal thickness (ET) is of great significance in many areas of medical and biological research. OBJECTIVES: We aimed to assess optical coherence tomography (OCT) in terms of precision, and to investigate the influence of several constitutional factors, such as age, gender, skin type, and anatomic site, on the mean ET using OCT in vivo. METHODS: Eighty-three subjects were studied using OCT in vivo. Intra- and inter-day repeatability measurements were performed. The mean ET was assessed in six different body sites of young (20-40 years old) and old (60-80 years old) Caucasians, respectively. An ethnic group was included into the study. RESULTS: OCT proved to be a precise technique in terms of repeatability and reproducibility as expressed in low coefficients of variation. Comparison of young and old Caucasians demonstrated a significant decrease of ET with age in all anatomic sites investigated. ET assessed in males and females did not significantly differ, except for forehead skin which is significantly thinner in old females than in males. ET observed in Caucasians did not significantly differ from ET measured in ethnic individuals. Anatomic sites insignificantly influenced ET on an inter-individual level. However, differences of ET between body sites on an intra-individual level are significant. CONCLUSIONS: This was the first systematic in vivo study on ET investigating several influencing parameters of the epidermal dimension in a reasonable study sample by means of OCT. The results presented here may serve as ET reference data in a variety of clinical and experimental matters.

Topical tacrolimus neither prevents nor abolishes ultraviolet-induced erythema.

A dose- and vehicle-controlled study on the pretreatment and posttreatment effect of 0.1% tacrolimus ointment on erythema induced by solar-simulated ultraviolet (UV) radiation was performed. Surprisingly, comparisons of clinical erythema scores and colorimetric data obtained 24 and 72 hours after UV exposure did not reveal significant differences between the control, tacrolimus, and vehicle preirradiation and postirradiation treated sites (P > .05). Our data strongly indicate that topical tacrolimus neither prevents nor abolishes UV-induced erythema in a clinical meaningful degree.

Erbium:YAG laser-assisted preparation of a combined dermal/full thickness sandwich skin graft.

BACKGROUND: Skin grafting is a common procedure to close defects after tumor resection. However, delicate areas such as the heel or the sole of the foot can be closed with a specially designed graft as described in this article. OBJECTIVE: To describe a surgical technique by means of erbium:YAG laser-assisted preparation of a combined dermal/full-thickness sandwich skin graft that facilitates the closure of defects, especially at mechanically stressed anatomic sites. METHODS: Tumor defects on the sole of the foot of 28 patients were closed with a new dermal/full-thickness sandwich skin graft. To obtain this special graft, half of a full-thickness skin graft twice the size of the wound defect was deepithelialized with an erbium:YAG laser. After complete defatting of the transplant, the deepithelialized part was folded beneath the full-thickness part (upside down) resulting in a sandwich graft, enabling contact of the papillary dermis with the wound surface. Graft results were graded as excellent when more than 75%, good if 50-75%, fair if 25-50%, and poor if less than 25% of the transplant healed. RESULTS: Results were graded as excellent in 32%, good in 54%, fair in 11%, and poor in 3% of the patients. Total graft loss was experienced in 1 of 28 patients. Complications such as bulky margins or infection were encountered in 14% of the patients. CONCLUSION: The laser-assisted preparation of the combined dermal/full-thickness sandwich skin graft is a new technique that facilitates the closure of defects in delicate anatomic locations with high mechanical stress like the plantar sole.

A comparative pilot study on ultraviolet-induced skin changes assessed by noninvasive imaging techniques in vivo.

The effects of acute and chronic ultraviolet (UV) on the morphology of human skin have been extensively studied ex vivo by means of histological investigations. However, innovative skin imaging techniques enable visualization of micromorphological structures in vivo. We aimed to perform a correlation study evaluating in vivo dose and time dependent skin changes following solar-simulated irradiation using noninvasive techniques such as optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM). The forearms of 10 healthy subjects were exposed to 1 minimal erythema dose (MED) and 3 MED of solar-simulated radiation. Noninvasive measurements were performed before and 24 h and 72 h after UV exposures. We demonstrate definite OCT and CLSM findings obtained from UV-exposed skin, including an increase in epidermal thickness (hyperproliferation, acanthosis), a reduction in dermal reflectivity (dermal edema), an increase in brightness of the basal layer (pigmentation), and an increase in vessel diameter within the dermal papillae (vasodilatation). A moderate to strong linear association between the methods employed was observed. In conclusion, noninvasive high-resolution imaging techniques such as OCT and CLSM may be promising tools for photobiological studies aimed at assessing photoadaptive and/or phototoxic processes in vivo. However, larger studies are needed to demonstrate the applicability of the findings presented in this pilot study.

Acute skin alterations following ultraviolet radiation investigated by optical coherence tomography and histology.

Optical coherence tomography (OCT) appears to be a promising technique to study skin in vivo. As part of an exploratory study to investigate UV induced effects non-invasively we aimed to evaluate the kinetics of acute UVB- as well as UVA1 induced skin alterations by means of OCT, and to correlate the results obtained with routine histology. Twelve healthy subjects received daily 60 J/cm2 of UVA1 and 1.5 minimal erythema doses of UVB on their upper back over three consecutive days. One day (24 h) after the last UV exposure, OCT measurements and skin biopsies were performed in four subjects (day 1) on the centre of the irradiated sites and an adjacent non-irradiated control site. The same procedure was performed in four subjects 3 days and 6 days after irradiation, respectively. Prior to OCT assessment two waterproof marks were drawn on the centre of UVB and UVA1 exposed sites and the control site. The OCT scanner, SkinDex 300, was used in the RI1D measurement modus in order to investigate morphological features, epidermal thickness, and scattering coefficients. Immediately after OCT assessment, 4 mm punch biopsies were taken from the previously marked sites. OCT as well as histological examinations performed on day 1, 3, and 6, revealed markedly higher values for epidermal thickness on UVB exposed skin sites, and slightly increased epidermal thickening in UVA1 exposed sites. UVB exposed sites showed disruption of the entrance signal in the B-scan of OCT resulting in a thickened layer with a signal-poor centre corresponding to hyperkeratosis and parakeratosis as confirmed by routine histology. Surprisingly, the mean scattering coefficients of the epidermis were slightly lower on UVA1 exposed sites, as compared to non-irradiated skin. By contrast, the scattering coefficient of the upper dermis of UVA1 irradiated skin was hardly altered. Moreover, the scattering coefficient of the upper dermis assessed on UVB exposed skin on day 1 was clearly smaller than the scattering coefficient observed on non-irradiated and UVA1 exposed skin. Conclusively, it was possible to demonstrate by means of OCT differences of epidermal thickness and pathological features of the stratum corneum following UV exposure. UVA1 induced epidermal pigmentation as well as UVB induced dermal inflammation may affect the light attenuation in the tissue indicated by a decrease of the scattering coefficient. OCT seems to be a useful tool to monitor UV induced effects in vivo.

Comparison of histometric data obtained by optical coherence tomography and routine histology.

There is a lack of systematic investigations comparing optical coherence tomography (OCT) with histology. OCT assessments were performed on the upper back of 16 healthy subjects. Epidermis thickness (ET) was assessed using three methods: first, peak-to-valley analysis of the A-scan (ET-OCT-V); second, manual measurements in the OCT images (ET-OCT-M); third, light microscopic determination using routine histology (ET-Histo). The relationship between the different methods was assessed by means of the Pearson correlation procedure and Bland and Altman plots. We observed a strong correlation between ET-Histo (79.4+/-21.9 microm) and ET-OCT-V (79.2+/-15.5 microm, r=0.77) and ET-OCT-M (82.9+/-15.8 microm, r=0.75), respectively. Bland and Altman plots revealed a bias of -0.19 microm (95% limits of agreement: -27.94 microm to 27.56 microm) for ET-OCT-V versus ET-Histo and a bias of 3.44 microm (95% limits of agreement: -24.9 microm to 31.78 microm) for ET-OCT-M versus ET-Histo. Despite the strong correlation and low bias observed, the 95% limits of agreement demonstrated an unsatisfactory numerical agreement between the two OCT methods and routine histology indicating that these methods cannot be employed interchangeably. Regarding practicability, precision, and indication spectrum, ET-OCT-V and ET-OCT-M are of different clinical value.

Applications of optical coherence tomography in dermatology.

Histology represents the gold standard for morphological investigation of the skin, though biopsy may alter the original morphology, is non-repeatable on the same site and always requires an iatrogenic trauma. In the past decade, advances in optics, fibre as well as laser technology have enabled the development of a novel non-invasive optical biomedical imaging technique, optical coherence tomography (OCT). The latter is based on a classic optical measurement method known as low-coherence interferometry that enables non-invasive, high resolution, two- or three-dimensional, cross-sectional imaging of microstructural morphology in biological tissue in situ. Using conventional OCT with a lateral resolution of 10-15 microm, the stratum corneum of glabrous skin (palmoplantar), the epidermis and the upper dermis can usually be identified, as well as skin appendages and blood vessels. For example, non-invasive monitoring of cutaneous inflammation, hyperkeratotic conditions and photoadaptive processes is possible by means of OCT. Furthermore, the development of high-output broadband light sources, e.g. femtosecond Ti:sapphire laser, might soon enable ultrahigh image resolutions of about 1 microm in order to investigate skin tissue on the cellular level, which could potentially allow the differentiation between benign and malignant tissues. Beyond a high resolution morphology in OCT images, tissue characterization by additional local physical parameters, such as the scattering coefficient and refractive index may be of great value, in particular in cosmetics and the pharmaceutical industry. Functional OCT imaging based on spectroscopy, tissue birefringence, elastography and Doppler flow reveals further information on tissue properties and represents an important progress of OCT technique in the field of dermatology. Therefore, the advanced versions of OCT technique might not only lead to significant new insights in skin physiology and pathology, but also in diagnosis and therapeutic control of cutaneous disorders with respect to non-invasive diagnosis of conditions and monitoring of disease activity in addition to treatment effects over time.

Correlation between clinical scoring of allergic patch test reactions and optical coherence tomography.

Noninvasive imaging techniques might be of particular diagnostic value for studying and monitoring cutaneous inflammatory conditions such as contact dermatitis. We evaluate acute allergic contact dermatitis (AACD) by means of optical coherence tomography (OCT) and correlate the clinical grading of patch test reactions with the findings obtained from OCT. Twenty positive patch test reactions (+, n = 6; ++, n = 7; +++, n = 7) are investigated using a conventional OCT scanner. In comparison to the control sites, OCT of AACD showed pronounced skin folds, thickened and/or disrupted entrance signals, and a significant increase in epidermal thickness. Moreover, clearly demarcated signal-free cavities within the epidermis and considerable reduction of dermal reflectivity are demonstrated by OCT. Notably, the latter findings strongly correlate with the clinical patch test grading. OCT may be a useful tool for visualization of micromorphological features of AACD. However, before OCT can be employed as an objective parameter in grading severity of patch test reactions, larger studies are required that correlate clinical patch test readings and OCT findings with histopathology.