Melanoma diagnosis by Raman spectroscopy and neural networks: structure alterations in proteins and lipids in intact cancer tissue.

Melanoma is the most aggressive skin cancer. The specificity and sensitivity of clinical diagnosis varies from around 40% to 80%. Here, we investigated whether the chemical changes in the melanoma tissue detected by Raman spectroscopy and neural networks can be used for diagnostic purposes. Near-infrared Fourier transform Raman spectra were obtained from samples of melanoma (n=22) and other skin tumors that can be clinically confused with melanoma: pigmented nevi (n=41), basal cell carcinoma (n=48), seborrheic keratoses (n=23), and normal skin (n=89). A sensitivity analysis of spectral frequencies used by a neural network was performed to determine the importance of the individual components in the Raman spectra. Visual inspection of the Raman spectra suggested that melanoma could be differentiated from pigmented nevi, basal cell carcinoma, seborrheic keratoses, and normal skin due to the decrease in the intensity of the amide I protein band around 1660 cm-1. Moreover, melanoma and basal cell carcinoma showed an increase in the intensity of the lipid-specific band peaks around 1310 cm-1 and 1330 cm-1, respectively. Band alterations used in the visual inspection were also independently identified by a neural network for melanoma diagnosis. The sensitivity and specificity for diagnosis of melanoma achieved by neural network analysis of Raman spectra were 85% and 99%, respectively. We propose that neural network analysis of near-infrared Fourier transform Raman spectra could provide a novel method for rapid, automated skin cancer diagnosis on unstained skin samples.

Detection of skin cancer by classification of Raman spectra.

Skin lesion classification based on in vitro Raman spectroscopy is approached using a nonlinear neural network classifier. The classification framework is probabilistic and highly automated. The framework includes a feature extraction for Raman spectra and a fully adaptive and robust feedforward neural network classifier. Moreover, classification rules learned by the neural network may be extracted and evaluated for reproducibility, making it possible to explain the class assignment. The classification performance for the present data set, involving 222 cases and five lesion types, was 80.5%+/-5.3% correct classification of malignant melanoma, which is similar to that of trained dermatologists based on visual inspection. The skin cancer basal cell carcinoma has a classification rate of 95.8%+/-2.7%, which is excellent. The overall classification rate of skin lesions is 94.8%+/-3.0%. Spectral regions, which are important for network classification, are demonstrated to reproduce. Small distinctive bands in the spectrum, corresponding to specific lipids and proteins, are shown to hold the discriminating information which the network uses to diagnose skin lesions.

Skin changes following defibrillation. The effect of high voltage direct current.

Previously, electrical injuries have been suggested caused only by the concomitant heat developed during the passage of an electrical current. Recent experimental studies on fully anesthetized pigs and the study of one human case have, however, shown typical electrical alterations. The purpose of the present study was further to evaluate the histology of electrically induced changes in the skin in humans. In addition, supplementary in vivo methods for evaluation of skin changes as high-frequency ultrasound and Raman spectroscopy were used. The skin of 11 patients treated with a defibrillation of the heart was examined for macroscopic changes, the skin of eight of them also for histologic changes and for changes observable via supplementary methods. Immediately and 7 days after the defibrillation, fractions of a narrow red ring were observed along the periphery of the tin-foil electrode. Epidermis showed signs previously observed following electrical influence: segmental alterations often related to the openings of sweat ducts, darkstaining or "empty" nuclei and homogeneous cytoplasm, eosinophilic or pale. Dermis did not show the specific sign of electrical influence: deposits of calcium salts on dermal fibres, neither via histologic examination nor via high-frequency ultrasonography and Raman spectroscopy. Fractions of a narrow red ring along the periphery of the electrode showing histological signs of electric influence in epidermis thus appear to be characteristic of high voltage electrical injury.

Near-infrared Fourier transform Raman spectroscopic analysis of proteins, water and lipids in intact normal stratum corneum and psoriasis scales.

Previous biochemical studies demonstrated differences in the structure of lipids in normal skin and psoriatic lesions. Raman spectroscopy provides a unique possibility of studying the molecular structure of proteins, lipids and water in intact skin. Near-infrared Fourier transform Raman spectroscopy was used to study changes in molecular structure and conformation of proteins and lipids of stratum corneum in healthy persons and patients with psoriasis. In vitro Raman spectra were obtained from intact psoriatic scales in 11 patients and from normal stratum corneum of forearm, elbow and heel in a group of age-matched healthy persons. The spectra of stratum corneum differed between psoriasis and normal skin but not between investigated regions. No major changes of lipid band positions in Raman spectra were found, but the crystalline lipid structure was disrupted in psoriatic scales (assessed as the ratio of the symmetric methylene C-H stretching-mode intensities, S(lat)). Major spectral differences were seen in the molecular structure of the proteins. In the spectra of psoriatic scales, the peak position of the amide I band, in comparison with the normal skin, was shifted to higher wavenumbers, suggesting unfolding of proteins. Moreover, alterations in the disulfide stretch bonds of proteins were found in psoriasis scales, resulting in a less energetically favourable gauche-gauche-trans conformation (band around 520 cm(-1)). Psoriatic scales and normal stratum corneum did not statistically differ in their water content. The findings further define the molecular abnormalities in the stratum corneum in psoriasis.

Ultrasonido de alta resolucion (15 MHz) en el estudio de la u¤a psoriatica / High resolution ultrasound in the study of psoriatic nail

Antecedentes. La Psoriasis es una enfermedad frecuente en la practica dermatológica. En EE.UU., 7 millones de personas (2-3por ciento) la padecen. El 5 por ciento de los pacientes con psoriasis ungueal no tienen manifestaciones cutáneas. Entre 10-20 por ciento de los pacientes con psoriasis cutanea tienen artritis psoriatica. De los pacientes con artritis psoriatica, el 53-86 por ciento presentan compromiso ungueal. Objetivo. Estudiar los cambios visibles al ultrasonido de alta resolución, en la u¤a de los pacientes psoriaticos. Material y metodo. Se utilizo equipo de ultrasonido Philips ATL 5000 equipado con SonoCT, XRES, campo de visión extendida y transductores de 15-7 MHz y 12-5 MHz. Se estudiaron 15 pacientes, 9 controles normales y 6 psoriaticos con compromiso ungueal. Mujeres n=9 y hombres n=6, promedio de edad 47,7 a¤os. Se exploraron las 2 manos en todos los pacientes (150 u¤as) y se midieron en cada paciente las distancias entre ambas placas ungueales como también entre la placa ungueal ventral y el margen óseo de la falange distal en la u¤a del dedo indice derecho. Resultados. Se describe la anatomia ultrasonografica normal de la u¤a y cuatro patrones de alteraciones visibles en el compromiso por psoriasis que incluyen: compromiso focal hipere-cogenico de la placa ventral sin compromiso de placa dorsal, perdida de definición de la placa ventral con placa dorsal indemne, ondulación de ambas placas y perdida de definición de ambas placas. Se encontró una diferencia significativa (p= 0.02) entre el promedio de distancia placa ventral ungueal y margen óseo de la falange distal para u¤as normales (1,5 mm) y para psoriasis (3,0 mms). Conclusión: El ultrasonido de alta resolución permite un estudio no invasivo de la u¤a, describiendo su anatomia y cambios morfológicos en pacientes normales y psoriaticos con compromiso ungueal. Ello puede ser útil en la monitorización de los efectos del tratamiento de psoriasis en sus distintas mani-festaciones, ya que existen cambios imperceptibles en su magnitud y ubicación para el clinico, que pueden observarse sin esperar el recambio ungueal total. Las diferencias de distancia entre las placas de la u¤a, incluyendo la distancia con el margen óseo de la falange distal, en los pacientes normales y psoriaticos, en nuestro conocimiento, no han sido previamente publicadas.