Michail Ilias

Phototesting based on a divergent beam--a study on normal subjects.

In a previous publication from our group, phototesting based on a single exposure to a divergent UVB beam with radially decreasing irradiance values was suggested. The aim of the present study was to evaluate technical, practical and biological aspects of the suggested method in normal subjects. Twenty healthy volunteers were provoked on the back with both a collimated beam (four fixed doses, in circular areas with a diameter of 1.5 cm) and the divergent beam (a continuous, radially attenuating dose spectrum covering an area with a diameter of 4.5 cm). Eleven of the subjects were subjected to double provocation with the divergent beam. Assessment was carried out at 6 and 24 h after exposure by measuring the diameter of the reactions both visually and by mapping the skin blood flow change with laser Doppler perfusion imaging (LDPI). Minimal erythemal dose (MED) was determined for both the collimated and the divergent provocation. The reaction diameters were used to decide MED by combination to a mm for mm mapped dose spectrum of the divergent beam profile. Dose‐response curves were plotted using the quantitative response data of the LDPI‐images against the corresponding dosimetry data. No systematic difference could be proven between LDPI and visual diameters and a 95% confidence interval for the mean difference was calculated to (‐0.8, 2.0). Slightly greater diameters were found at the visual assessment performed at 6 h compared to 24 h (95% confidence interval (‐0.1, 2.8)). Double provocation showed a good reproducibility both for the visual and the LDPI assessment (P<0.05). The divergent beam provocation allowed a more detailed discrimination of MED compared to the collimated beam provocation. The MED values determined with the divergent beam were, however, generally higher, especially in the lower range of MED values. Technical factors related to the beam divergence and the correct measurement of erythemal effective irradiance are believed to be the explanation for this phenomenon, which is thus correctable. In conclusion, the results from this study support our belief that the phototesting protocol based on a divergent beam constitutes a good opportunity for improved phototesting, since MED and dose‐response characteristics may be extracted in more detail from a single UV exposure.

Evaluation of a fiber-optic fluorescence spectroscopy system to assist neurosurgical tumor resections

The highly malignant brain tumor, glioblastoma multiforme, is difficult to totally resect without aid due to its infiltrative way of growing and its morphological similarities to surrounding functioning brain under direct vision in the operating field. The need for an inexpensive and robust real-time visualizing system for resection guiding in neurosurgery has been formulated by research groups all over the world. The main goal is to develop a system that helps the neurosurgeon to make decisions during the surgical procedure. A compact fiber optic system using fluorescence spectroscopy has been developed for guiding neurosurgical resections. The system is based on a high power light emitting diode at 395 nm and a spectrometer. A fiber bundle arrangement is used to guide the excitation light and fluorescence light between the instrument and the tissue target. The system is controlled through a computer interface and software package especially developed for the application. This robust and simple instrument has been evaluated in vivo both on healthy skin but also during a neurosurgical resection procedure. Before surgery the patient received orally a low dose of 5-aminolevulinic acid, converted to the fluorescence tumor marker protoporphyrin IX in the malignant cells. Preliminary results indicate that PpIX fluorescence and brain tissue autofluorescence can be recorded with the help of the developed system intraoperatively during resection of glioblastoma multiforme.

Inter-observer variability in reading of phototest reactions with sharply or diffusely delineated borders

Background: In both clinical and experimental phototesting, naked eye assessment of erythema has been the main assessment parameter. As with all subjective assessment, variability in recorded results due to variable circumstances around the performance and reading of tests influences reliability and utility of data whether they be interpreted for an individual patient or for a group of research subjects.

Visible hyperspectral imaging evaluating the cutaneous response to ultraviolet radiation

In vivo diagnostics of skin diseases as well as understanding of the skin biology constitute a field demanding characterization of physiological and anatomical parameters. Biomedical optics has been successfully used, to qualitatively and quantitatively estimate the microcirculatory conditions of superficial skin. Capillaroscopy, laser Doppler techniques and spectroscopy, all elucidate different aspects of microcirculation, e.g. capillary anatomy and distribution, tissue perfusion and hemoglobin oxygenation. We demonstrate the use of a diffuse reflectance hyperspectral imaging system for spatial and temporal characterization of tissue oxygenation, important to skin viability. The system comprises: light source, liquid crystal tunable filter, camera objective, CCD camera, and the decomposition of the spectral signature into relative amounts of oxy- and deoxygenized hemoglobin as well as melanin in every pixel resulting in tissue chromophore images. To validate the system, we used a phototesting model, creating a graded inflammatory response of a known geometry, in order to evaluate the ability to register spatially resolved reflectance spectra. The obtained results demonstrate the possibility to describe the UV inflammatory response by calculating the change in tissue oxygen level, intimately connected to a tissues metabolism. Preliminary results on the estimation of melanin content are also presented.

Phototesting with a divergent UVB beam in the investigation of anti-inflammatory effects of topically applied substances

Background: Phototesting based on a single exposure to a divergent ultraviolet B (UVB) beam with radially decreasing UVB doses can be used to determine an individuals minimal erythema dose (MED). Laser Doppler perfusion imaging (LDPI) data can be combined with dosimetry data to produce objective dose–response plots in addition to the MED. The aim of this study was to investigate whether the divergent beam protocol could be used to demonstrate and quantify the anti‐inflammatory effects of clobetasol diproprionate (Dermovate®), pharmaceutical‐grade acetone and a gel vehicle, applied after skin provocation by UVB.

A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin.

Introduction: The colour of tissue is often of clinical use in the diagnosis of tissue homeostasis and physiological responses to various stimuli. Determining tissue colour changes and borders, however, often poses an intricate problem and visual examination, constituting clinical praxis, does not allow them to be objectively characterized or quantified. Demands for increased inter‐ and intra‐observer reproducibility have been incentives for the introduction of objective methods and techniques for tissue colour (e.g. erythema) evaluation. The aim of the present paper was to study the border zone of a UVB‐provoked erythematous response of human skin in terms of blood volume and oxygenation measured by means of diffuse reflectance spectroscopy using a commercial probe.

Single exposure phototesting utilizing a divergent ultraviolet beam

Background/aims: Confident diagnosis of photosensitivity in patients with light dermatoses requires skin exposure to well determined ultraviolet (UV) light doses, most often from a solar simulator. The traditional test procedure results in a rough classification of skin sensitivity based on the minimal erythema dose (MED) found for each patient. The limited number of constant irradiance doses used during phototesting decreases the precision of the MED value. In the present study we aimed at developing the technical system for the determination of MED by using a single, centrifugally attenuating, UVB provocation.

Biomedical Engineering Education, Virtual Campuses and the Bologna Process

Higher education in Europe can be divided into before and after the Bologna Declaration, the most revolutionary process in modern education. Biomedical engineering, an emerging “subject” during the last 40 years, strongly interdisciplinary, fragmented and lacking of international coordination, may benefit from this harmonization process. An early initiative such as BIOMEDEA has made a contribution through proposing biomedical engineering foundations for building a common curriculum among higher education institutions. A common curriculum would presumably contribute to student and teacher mobility, certification and accreditation and as a consequence promote increased international employability. The virtual campus action extends or adds values to already existing educational exchange networks such as Erasmus, important in student mobility and educational harmonization and recognition. A virtual education dimension is added to European co-operation, encouraged through the development of new organisational models for European institutions, promoting virtual mobility and recognition. Virtual campuses may have a possibility to bridge the gaps in national BME curricula all with respect to the action towards a consensus on European guidelines for the harmonization. The evaluation of the e-curricula is conformant with the roadmap of BME courses as defined by BIOMEDEA. Most courses are classified as second cycle courses on a Master level, supporting that studies in BME could be a continuation from cycle one. Learning environment and the students learning outcome, points towards a strong teacher-centred approach to learning. The transparency at all levels are low, a factor that might influence recruiting potential students to a programme, especially those students with working experience and an international background. To fulfil the Bologna Declaration and other steering documents for the higher education in an expanding European future there are still tasks to be solved regarding recognition, legalisation, pedagogical issues and employability looking for a harmonized solution.