Youngwoo Bae

Multimodal facial color imaging modality for objective analysis of skin lesions

We introduce a multimodal facial color imaging modality that provides a conventional color image, parallel and cross-polarization color images, and a fluorescent color image. We characterize the imaging modality and describe the image analysis methods for objective evaluation of skin lesions. The parallel and cross-polarization color images are useful for the analysis of skin texture, pigmentation, and vascularity. The polarization image, which is derived from parallel and cross-polarization color images, provides morphological information of superficial skin lesions. The fluorescent color image is useful for the evaluation of skin chromophores excited by UV-A radiation. In order to demonstrate the validity of the new imaging modality in dermatology, sample images were obtained from subjects with various skin disorders and image analysis methods were applied for objective evaluation of those lesions. In conclusion, we are confident that the imaging modality and analysis methods should be useful tools to simultaneously evaluate various skin lesions in dermatology.

Fabrication of double layer optical tissue phantom by spin coating method: mimicking epidermal and dermal layer

Methodologies to fabricate a solid optical tissue phantom (OTP) mimicking epidermal thin-layer have been developed for in vitro human skin experiment. However, there are cumbersome and time-consuming efforts in fabrication process such as a custom-made casting and calculation of solvent volume before curing process. In a previous study, we introduced a new methodology based on spin coating method (SCM) which is utilized to fabricate a thin-layer OTP analogous to epidermal thickness. In this study, a double layer solid OTP which has epidermal and dermal layers was fabricated to mimic the morphological and optical similarity of human tissue. The structural characteristic and optical properties of fabricated double layer OTP were measured using optical coherence tomography and inverse adding doubling algorithms, respectively. It is expected that the new methodology based on the SCM may be usefully used in the fabrication of double layer OTP.

Dermatological feasibility of multimodal facial color imaging modality for cross-evaluation of facial actinic keratosis

Background/Purpose: Digital color image analysis is currently considered as a routine procedure in dermatology. In our previous study, a multimodal facial color imaging modality (MFCIM), which provides a conventional, parallel‐ and cross‐polarization, and a fluorescent color image, was introduced for objective evaluation of various facial skin lesions. This study introduces a commercial version of MFCIM, DermaVision‐PRO, for routine clinical use in dermatology and demonstrates its dermatological feasibility for cross‐evaluation of skin lesions.

Three-dimensional stereoscopic imaging modality based on a single optical channel and detector

Abstract. A three-dimensional stereoscopic imaging modality (3D-SIM) based on a single optical channel and detector was developed to overcome some of the limitations of conventional 3D-SIM. It produces 3-D stereoscopic images by adjusting the angle of a transparent rotating deflector (TRD) to generate disparity between left and right images. The angular effect of the TRD was demonstrated to investigate the feasibility of the proposed method in 3-D stereoscopic image generation. Results indicate that image disparity increased as a function of the rotation angles of the TRD, while maintaining adequate 3-D perception. These results are expected to facilitate the practical use of a 3D-SIM in medicine.

Digital photographic imaging system for the evaluation of various facial skin lesions.

In dermatology, various imaging modalities have been developed as an assistant tool to objectively evaluate the treatment efficacy of facial skin lesion. In this study, we propose a digital photographic imaging system the evaluation of various facial skin lesions in order to maximize the clinical evaluation efficiency by integrating various independent imaging modalities. Our imaging system provides four different digital color images, such as standard digital color image, parallel and cross polarization digital color image, and UV-A induced fluorescent digital color image. In conclusion, by analyzing the color information and morphological features, we were able to simultaneously evaluate various skin lesions with one imaging system.

Characterization of a solid optical tissue phantom fabricated by a spin coating method: pilot study

Various optical tissue phantoms (OTP) have been developed and utilized for the performance test of optical device and for in vitro human skin experiments. Solid OTPs have advantages such as semi-permanent use, convenience of experimental use, and easiness of storage. However, it is difficult to fabricate epidermis layer with an extremely thin layer of about few μm thickness. This study suggests a spin coating method to fabricate a thin layer which is similar to epidermis layer thickness of human skin (about 50 μm). By controlling specific parameters such as the concentration of matrix solution and the spin velocity for spin coating, we could design a solid OTP with extremely thin layer of about few μm and a good degree of planarization. Quantitative analysis was performed to evaluate both the spin velocity and the concentration of OTP matrix solution used to control specific thickness of OTP. By using optimal combination of parameters a specific thin layered OTP was fabricated with a thickness of less than 50 μm. In further studies, optimal combination of parameters needs to be studied to fabricate desired thickness of layer, depending on purpose.

Comparison of a digital color and hyper-spectral, camera for dental plaque detection

In this study, a hyper-spectral camera (HSC) was used lo find an optimal wavelength for the quantitative assessment of dental plaque area. The result confirmed that HSC provided superior images contrast compared to that of digital color camera and presented usefulness of hyper-spectral image for the quantitative and automatic assessment of dental plaque area.

5-ALA induced fluorescent image analysis of actinic keratosis

In this study, we quantitatively analyzed 5-ALA induced fluorescent images of actinic keratosis using digital fluorescent color and hyperspectral imaging modalities. UV-A was utilized to induce fluorescent images and actinic keratosis (AK) lesions were demarcated from surrounding the normal region with different methods. Eight subjects with AK lesion were participated in this study. In the hyperspectral imaging modality, spectral analysis method was utilized for hyperspectral cube image and AK lesions were demarcated from the normal region. Before image acquisition, we designated biopsy position for histopathology of AK lesion and surrounding normal region. Erythema index (E.I.) values on both regions were calculated from the spectral cube data. Image analysis of subjects resulted in two different groups: the first group with the higher fluorescence signal and E.I. on AK lesion than the normal region; the second group with lower fluorescence signal and without big difference in E.I. between two regions. In fluorescent color image analysis of facial AK, E.I. images were calculated on both normal and AK lesions and compared with the results of hyperspectral imaging modality. The results might indicate that the different intensity of fluorescence and E.I. among the subjects with AK might be interpreted as different phases of morphological and metabolic changes of AK lesions.

Multimodal digital color imaging system for facial skin lesion analysis

In dermatology, various digital imaging modalities have been used as an important tool to quantitatively evaluate the treatment effect of skin lesions. Cross-polarization color image was used to evaluate skin chromophores (melanin and hemoglobin) information and parallel-polarization image to evaluate skin texture information. In addition, UV-A induced fluorescent image has been widely used to evaluate various skin conditions such as sebum, keratosis, sun damages, and vitiligo. In order to maximize the evaluation efficacy of various skin lesions, it is necessary to integrate various imaging modalities into an imaging system. In this study, we propose a multimodal digital color imaging system, which provides four different digital color images of standard color image, parallel and cross-polarization color image, and UV-A induced fluorescent color image. Herein, we describe the imaging system and present the examples of image analysis. By analyzing the color information and morphological features of facial skin lesions, we are able to comparably and simultaneously evaluate various skin lesions. In conclusion, we are sure that the multimodal color imaging system can be utilized as an important assistant tool in dermatology.

Optical Polarimetry Probe for Glucose Monitoring

Optical measurement techniques were continuously applied for glucose sensing for several years. Optical polarimetry is an effect method for the measurement of glucose concentration. In this paper, we introduce a new optical polarimetry probe system which has a variable optical path length.