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noninvasive methods in dermatology. By Nashwa Naeem El-far Ass. Lecturer r. Noninvasive methods in dermatology. Instrumental tools has now entered the field of dermatology, but its application is still in full evolution.
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noninvasivemethods in dermatology By NashwaNaeem El-far Ass. Lecturerr
Noninvasive methods in dermatology Instrumental tools has now entered the field of dermatology, but its application is still in full evolution. Although some methods are already proven and commonly used, others are very slowly being introduced into current practice.
Advantages 1- The use of instruments allows us to recognize signs that are not always appreciable by sensory perception. This is the most attractive aspect of bioengineering of the skin, since some diseases are preceded by a preclinical phase, while others can go into remission for long periods. The recognition and/or monitoring of the disease in these phases would be an huge advantage with regard to both therapy and prevention.
2- It allows the collection and storage of data in quantities not easily attainable with analogical estimations. 3- It allows the comparison of data collected at different times or in different places, which is particularly important for multicentre trials. 4- Instrumental measurements can be performed by technical personnel without any clinical experience; however, this is not generalizable, but is applicable to certain procedures, such as in dermocosmetology and dermopharmacology.
Obstacles The relatively high costs of the machines may represent a considerable difficulty. Moreover, their use is not always simple, sometimes requiring specific training and the availability of specialized personnel.
Noninvasive methods in clinical dermatology • Cutaneousultrasonography • Infrared thermography • Doppler fluximetry • Digital photography and computer processing of digital images.
Ultrasonography The use of ultrasonography in the diagnosis of cutaneous pathologies is possible with scanners of appropriate frequency. Higher frequencies provide better resolution, but reduce the ability of the ultrasound bundle to penetrate in depth: The range of exploration is : • 4–5 cm for 7.5 MHz scanners, • 2–3 cm for 10 MHz scanners and • 7 mm for 20 MHz scanners.
Ultrasonography can be used for two categories of dermatological conditions: • The first type (20 MHz ), allows exploration of the epidermis, dermis and subcutaneous tissue as far as the fascia separating the skin from the underlying muscle layer. It can be used to: • Search for foreign bodies that have penetrated into the skin • To monitor the response to treatment in inflammatory diseases, such as psoriasis and scleroderma. • To assess the size and thickness of cutaneous tumors (particularly melanoma) before surgery.
The second type with 7.5–10 MHz scanners is used in the identification and characterization of lymph nodes and subcutaneous masses: • The staging and follow-up of melanoma. Subcutaneous or lymph node metastases might not be palpable owing to their small size, the distance from the skin surface or the presence of fibrosis at the site of a previous intervention or radiation treatment. • Ultrasonography can provide reliable and/or additional information about the exact position of the tumor and the conditions of the surrounding anatomical structures.
Infrared thermography Infrared thermography, commonly used to diagnose breast tumors, has recently been applied to various dermatological conditions. It allows identification of an alteration of cutaneous blood flowin the earliest phases of the disease; hence: • It is useful for the recognition and therapeutic monitoring of conditions related to defects of the cutaneous microcirculation. • To quantify the depth of skin damage from burns.
Laser Doppler fluximetry It is an excellent technique for the evaluation of the cutaneous microcirculation in physiological and pathological conditions. It is used in: • All diseases in which the skin is compromised due to altered microcirculatory conditions, such as: diabetes, arteriosclerosis. • In plastic surgery to study and monitor the vitality of skin flaps during transplantation.
Digital imaging • Simple acquisition and storage of clinical photographs, essential to document the characteristics of the case and to record its progressive response to therapy. Photographic documentation is useful not only to follow the evolution of the clinical condition in response to therapy but also for eventual medico–legal issues. • Very complex computer analyses based on specialized programs. • The availability of special lenses that provide images identical to those observable with the dermoscope has paved the way for the use of digital imaging in the study of pigmented lesions.
Confocal scanning laser microscopy(CSLM) It is an innovative technique that allows examination of skin morphology at a resolution almost equal to that of conventional microscopy, by means of images of horizontal sections of the epidermis and superficial dermis. It provides additional information that may be useful in the diagnosis of melanocytic lesions. This technology does not appear to be suitable for routine clinical use because the complexity, cost of the apparatus and the time required.
Ocular coherent tomography((OCT OCT is used widely in ophthalmology and offers interesting perspectives in dermatology. It can provide 2D images of the epidermis and dermis with a resolution reaching 2–4 μ in the most recent machines. OCT can give interesting data for the in vivo diagnosis of pigmented lesions.
Technologies and instruments for the early detection of melanoma
Noninvasive methods in dermocosmetology& dermopharmacology • Corneometry • Evaporimetry • PH-metry • Sebometry • Colorimetry • Elastometry They functionally characterize the different skin types and assess the effects of cosmetics and drugs in both normal and pathological conditions
Evaporimetry & Corneometry Corneometry measures variations of the capacitance of the stratum corneum by means of instruments that translate the biophysical data into units of skin hydration. TEWL, measured by evaporimetry, expresses the rate of evaporation of water through the skin surface and reflects the integrity of the barrier to the passage of water. In normal skin, it is usually proportional to the state of hydration, while in damaged skin it is dissociated from the water content.
Therefore, corneometry and evaporimetry are very important as parameters to assess the effects of products designed to restore normal hydration, that is, so-called moisturizers. Monitoring of skin surface homeostasis is particularly important in conditions characterized by xerosis and alterations of the barrier function, such as atopia and atopic-like states. In such circumstances, the use of delipidizing and alkalinizing products, such as soaps and similar products, could cause serious damage.
PH metry Touching the skin surface with an electrode attached to an instrument that measures pH variations. This is essential to assess the effects of cosmetic products, such as detergents and shampoos, that could modify skin pH.
Sebometer It is an extensible opaque strip situated at the end of a support that is pressed against the skin surface. Upon contact with the skin, the strip is impregnated with sebum and becomes transparent in proportion to the quantity of sebum. It can be useful to: • Monitor the effects of drugs, such as estroprogestins and retinoids, that can reduce sebaceous secretion and hypertrophy; thus, it is widely used in the treatment of acne. • Assess the effects of cosmetics designed to reduce the levels of surface lipids
Colorimetry It is used to measure skin color in normal and pathological conditions, can quantify both erythema and pigmentation. • to quantify irritation by soaps and sodium laurylsulphate, as well as erythema and UV-induced pigmentation. • to define phototypes to identify subjects at risk of actinic cancer. • The use of three-stimulus colorimetry is officially recommended by the European Cosmetic, Toiletry and Perfumery Association to determine the phototype and to quantify UV-induced erythema in determinations of the ‘skin protection factor’ of sunscreens.
Elastometry Instrumental evaluation of the mechanical properties of the skin, is useful to: • Study cutaneous diseases characterized by hardening or hyperelasticity, and to assess the efficacy of cosmetic or pharmacological treatments to counteract these conditions. • Keloids and sclerodermal lesions are conditions that habitually require the use of elastometry for objective evaluation. • Raynaud syndrome, an elastometric examination of the skin is particularly important to identify the onset of sclerodermal lesions in a preclinical phase.
