Validation of Dynamic optical coherence tomography for non-invasive, in vivo microcirculation imaging of the skin.

OBJECTIVES: Dynamic optical coherence tomography (D-OCT) is an angiographic variation of OCT that non-invasively provides images of the in vivo microvasculature of the skin by combining conventional OCT images with flow data. The objective of this study was to investigate and report on the D-OCT technique for imaging of the vascular networks in skin as well as to validate the method by comparing the results against already accepted blood flow measuring tools. METHODS: 35 healthy subjects were recruited for the multicentre study, consisting of three experiments set up to examine the vascular blood perfusion during different induced physiologic changes in the blood flow. In order to validate the D-OCT images against existing techniques for blood flow measuring we performed consecutive D-OCT, chromametry and laser speckle contrast imager (LSCI) measurements on identical skin sites in all of the experiments. Blinded observer evaluations were performed in order to evaluate the vascular morphology in the D-OCT images. RESULTS: The results showed a statistically significant positive correlation between the D-OCT measurements and the LCSI flux measurements (rs=0.494; 95% CI [0.357, 0.615]; p<0.001), and also the redness a* measurements were positively correlated with the D-OCT measurements (r=0.48; 95% CI [0.406, 0.55]). D-OCT was able to reliably image and identify morphologic changes in the vascular network consistent with the induced physiological changes of blood flow. CONCLUSION: This study has initiated validation of the use of D-OCT for imaging of skin blood flow. Our results showed that D-OCT was able to reliably image and identify changes in the skin vasculature consistent with the induced physiological blood flow changes. These basic findings support the use of D-OCT imaging for in vivo microcirculation imaging of the skin.

Optical coherence tomography of actinic keratoses and basal cell carcinomas - differentiation by quantification of signal intensity and layer thickness.

BACKGROUND: Previous studies have shown that actinic keratoses (AKs) and basal cell carcinomas (BCCs) can be diagnosed by optical coherence tomography (OCT) based on morphological characteristics. There is a lack of systematic studies that give standardized information on signal intensity and layer thickness of AKs and BCCs. OBJECTIVE: The aim of this study was to find out if AKs and BCCs can be objectively diagnosed through standardized measurement of signal intensity and layer thickness and to use OCT as a non-invasive objective method for the diagnosis and evaluation of AKs and BCCs. Additionally, tumour and skin layer thickness were investigated in correlation with histology. METHODS: In this experimental study, 301 lesions (188 BCCs and 113 AKs) of 125 patients were clinically as well as dermoscopically diagnosed and investigated with OCT before therapy. Normal perilesional skin served as control. RESULTS: It is possible to differentiate BCCs and AKs from normal skin in OCT due to the decrease of local signal intensity in affected skin layers in relation to adjacent healthy skin. In AKs, a strong thickness increase of the stratum corneum and epidermis compared to normal skin were observed. For the distinction between AKs and BCCs, a drop of signal intensity in the dermis of AKs towards BCCs and a thicker epidermis of AKs in contrast to BCCs were registered. All results are statistically highly significant (P < 0.0001). Besides, a strong correlation of tumour and skin layer thickness of BCCs and AKs in OCT with histology was found. CONCLUSION: Through standardized measurement of signal intensity and layer thickness, BCCs and AKs can be objectively diagnosed and distinguished from each other with OCT. This will further improve the use of OCT as a non-invasive objective method for the diagnosis and treatment monitoring of these diseases.

Comparison of different optical coherence tomography devices for diagnosis of non-melanoma skin cancer.

PURPOSE: To compare the diagnostic imaging ability of three different optical coherence tomography (OCT) devices in non-melanoma skin cancer (NMSC). METHODS: Thirty actinic keratoses (AKs) and 27 basal cell carcinomas (BCCs) of 29 patients were examined with three different OCT devices, VivoSight® , Callisto® and Skintell® . RESULTS: Complete data sets were available for 16 BCCs and 10 AKs of 18 patients. All OCT devices were able to discriminate BCCs and AKs significantly from perilesional normal skin due to lower signal intensities as well as a thicker stratum corneum and epidermis in AKs. A significant decrease in the signal intensity and thickness of all skin layers was noted with Skintell® in contrast to VivoSight® and Callisto® . OCT comparisons revealed only slight differences between VivoSight® and Callisto® . Regarding BCC tumor thickness VivoSight® and Callisto® correlated well, histology did not correlate with the three OCT devices, whereas Skintell® showed no correlation with VivoSight® , Callisto® or histology. CONCLUSION: All tested OCT devices could identify BCCs and AKs objectively through standardized measurement of signal intensity and skin layer thickness. Due to their technical specifications (resolution, penetration depth), each of the OCT systems offers additional and special information on NMSC.

Confocal laser scanning microscopy as a new valuable tool in the diagnosis of onychomycosis - comparison of six diagnostic methods.

Onychomycosis is common and can mimic several different nail disorders. Accurate diagnosis is essential to choose the optimum antifungal therapy. The aim of this study was to evaluate the use of confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT) as new non-invasive diagnostic tools in onychomycosis and to compare them with the established techniques. In a prospective trial, 50 patients with suspected onychomycosis and 10 controls were examined by CLSM and OCT. Parallel KOH preparation, culture, PAS-staining and PCR were performed. PCR showed the highest sensitivity, followed by CLSM, PAS and KOH preparation. OCT offered the second best sensitivity but displayed the lowest specificity. CLSM and KOH preparation showed a high specificity and CLSM offered the best positive predictive value, similar to KOH preparation and OCT. Fungal culture showed the lowest sensitivity and the worst negative predictive value, yet culture and PCR are the only techniques able to identify genus and species. In summary, CLSM was comparable to PAS staining and superior to KOH preparation. Due to the low specificity we assess OCT not as appropriate. In the differentiation of species PCR outplays the fungal culture in terms of time and sensitivity.

Confocal laser scanning microscopy, optical coherence tomography and transonychial water loss for in vivo investigation of nails.

BACKGROUND: Nail disorders can be diagnostically challenging to the dermatologist. Noninvasive methods might help to avoid nail biopsies. More knowledge of the typical features of healthy nails with these techniques is needed for comparison with nail diseases. OBJECTIVES: To describe the typical morphology of healthy nails in optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM) and to examine the influence of exposure to water on OCT features, nail thickness as well as on transonychial water loss (TOWL) before and after a hand bath. Material and methods In the first part healthy nail plates were investigated with OCT and CLSM. The thickness of layers as well as structural details were defined. Secondly, in a prospective study 30 healthy volunteers conducted 10 hand baths with water within a 2-week period. Measurements of nail thickness and signal intensity by OCT as well as of the TOWL were performed over time. RESULTS: In OCT the unaffected nail plate appears as a band-like, layered structure, yet with some individual differences. In addition, CLSM is able to display single corneocytes and the integrity of their borders. Exposure to water led to a transient rise of TOWL and in nail thickness. CONCLUSIONS: OCT, CLSM and TOWL offer valuable noninvasive diagnostic tools for the examination of nails. Using CLSM, microscopic features like integrity of single corneocytes can be investigated. OCT allows determination of nail plate thickness and both OCT and TOWL measurements are able to detect short-term effects after exposure to water.