Search Results (12)

Background/Objectives: Rhinophyma, an advanced form of rosacea, is characterized by significant nasal tissue enlargement and deformation, leading to aesthetic and psychosocial challenges. Traditional treatments are often invasive with variable outcomes, emphasizing the need for improved therapeutic approaches. This study evaluates the efficacy of a dual-laser therapy (CO₂ and dye lasers) in treating rhinophyma. An innovative diagnostic algorithm using multispectral imaging guided treatment decisions, while Optical Coherence Tomography (OCT) was utilized to analyze post-treatment vascular and collagen changes. Methods: A prospective study was conducted involving 20 patients with rhinophyma. Multispectral imaging was used to guide the tailored application of CO₂ laser, dye laser, or both, depending on the predominant vascular or glandular components in the nasal tissue. Post-treatment analysis employed OCT to assess changes in vascular and collagen density, providing insights into the tissue modifications induced by laser therapy. Results: The treatment significantly reduced vascular density from 35,526.75 to 26,577.55 at 300 microns and from 46,916.25 to 35,509.25 at 500 microns. Collagen density decreased from 81.35 to 66.34. All reductions were statistically significant, with highly significant p-values. These findings highlight the dual-laser therapy’s effectiveness in addressing the pathological features of rhinophyma. Conclusions: Dual-laser therapy guided by multispectral imaging provides a targeted and effective treatment for rhinophyma, addressing its vascular and glandular components. The use of OCT enhances understanding of laser-induced tissue changes and confirms significant reductions in vascular and collagen density. This approach represents a significant advancement in the management of rhinophyma, offering improved precision and therapeutic outcomes. Full article

Multispectral imaging can provide objective quantitative data on various clinical pathologies, e.g., abnormal content of bio-substances in human skin. Performance of diagnostics increases with decreased spectral bandwidths of imaging; from this point, ultra-narrowband laser spectral line imaging is well suited for diagnostic applications. In this study, 40 volunteers participated in clinical validation tests of a newly developed prototype device for triple laser line whole-body skin imaging. The device comprised a vertically movable high-resolution camera coupled with a specific illumination unit—a side-emitting optical fiber spiral that emits simultaneously three RGB laser spectral lines at the wavelengths 450 nm, 520 nm, and 628 nm. The prototype’s design details, skin spectral image processing, and the obtained first clinical data are reported and discussed. Full article

A 17th century wall painting, representing the Virgin between two Saints, in a noble Italian renaissance palace, the Palazzo Gallo in Bagnaia (Viterbo, Italy), was restored in 2021 in the context of a wider restoration campaign involving the main room of the palace built by cardinal Sansoni Riario. Diagnostic analyses performed using traditional characterization techniques (optical microscopy on micro-stratigraphic sections, X-ray fluorescence spectroscopy and Fourier transform infrared spectroscopy) provided the identification of both the original painting and its restoration materials, while imaging investigations using the ultraviolet fluorescence photography, false color images and multispectral mapping provided by the hypercolorimetric multispectral imaging (HMI) technique enabled the evaluation of the state of conservation, the location of restoration interventions and supported the monitoring of the cleaning procedure. An altered protective Paraloid^®-based coating dating from the early 2000s had to be removed due to the unpleasant glossy finishing it had given to the painted surface, making the scene barely readable. To pursue a restoration protocol based on environmental sustainability and green chemistry, enzyme-based gels marketed by the Nasier-Brenta© and CTS© companies were tested in different protocols for the cleaning of the mixture (known as beverone) covering the painting. Although some interesting results were observed, the enzymatic cleaning had limited effectiveness, and was more timing-consuming than was reasonable. Traditional chemical solvents such as Dowanol PM (methoxy propanol) and benzyl alcohol were necessary to complete the cleaning of the painting surface. Full article

The aim of this clinical study was to compare the diagnostic performance of dual short wavelength infrared (SWIR) occlusal transillumination and reflectance multispectral imaging with conventional visual assessment and radiography for caries detection on premolars scheduled for extraction for orthodontics reasons. Polarized light microscopy (PLM) and micro-computed tomography (microCT) performed after tooth extraction were used as gold standards. The custom-fabricated imaging probe was 3D-printed and the imaging system employed a SWIR camera and fiber-optic light sources emitting light at 1300 nm for occlusal transillumination and 1600 nm for reflectance measurements. Teeth (n = 135) on 40 test subjects were imaged in vivo using the SWIR imaging prototype in the study and teeth were extracted after imaging. Our study demonstrates for the first time that near-simultaneous real-time transillumination and reflectance video can be successfully acquired for caries detection. Both SWIR imaging modalities had markedly higher sensitivity for lesions on proximal and occlusal surfaces compared to conventional methods (visual and radiographic). Reflectance imaging at 1600 nm had higher sensitivity and specificity than transillumination at 1300 nm. The combined SWIR methods yielded higher specificity but the combined sensitivity was lower than for each individual method. Full article

Skin optical inspection is an imperative procedure for a suspicious dermal lesion since very early skin cancer detection can guarantee total recovery. Dermoscopy, confocal laser scanning microscopy, optical coherence tomography, multispectral imaging, multiphoton laser imaging, and 3D topography are the most outstanding optical techniques implemented for skin examination. The accuracy of dermatological diagnoses attained by each of those methods is still debatable, and only dermoscopy is frequently used by all dermatologists. Therefore, a comprehensive method for skin analysis has not yet been established. Multispectral imaging (MSI) is based on light–tissue interaction properties due to radiation wavelength variation. An MSI device collects the reflected radiation after illumination of the lesion with light of different wavelengths and provides a set of spectral images. The concentration maps of the main light-absorbing molecules in the skin, the chromophores, can be retrieved using the intensity values from those images, sometimes even for deeper-located tissues, due to interaction with near-infrared light. Recent studies have shown that portable and cost-efficient MSI systems can be used for extracting skin lesion characteristics useful for early melanoma diagnoses. This review aims to describe the efforts that have been made to develop MSI systems for skin lesions evaluation in the last decade. We examined the hardware characteristics of the produced devices and identified the typical structure of an MSI device for dermatology. The analyzed prototypes showed the possibility of improving the specificity of classification between the melanoma and benign nevi. Currently, however, they are rather adjuvants tools for skin lesion assessment, and efforts are needed towards a fully fledged diagnostic MSI device. Full article

(1) Background. The aim of this work is to combine non-invasive imaging with chemical characterization analyses to study original and restoration materials of a late 16th-century painting on a canvas representing the “Coronation of the Virgin with the Saints Ambrose and Jerome”, preserved in the Diocesan archive of Orte, a town in the district of Viterbo (Italy). The diagnostic campaign was addressed to support the restoration activities and the choice of the most suitable cleaning operations. (2) Methods. Both traditional analytical techniques and innovative multispectral imaging were applied to solve the diagnostic issues and best address the restoration of the painting. Specifically, hypercolorimetric multispectral imaging (HMI), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), optical microscopy, and gas chromatography coupled with mass spectrometry (GC-MS) were combined to obtain information on the general conservation state of the artwork and the characterization of pigments, organic binders, and superimposed materials, these last being particularly important to identify ancient and not-documented restoration intervention, enabling the correct choice of the most suitable and effective cleaning intervention. (3) Results. Multispectral data allowed us to differentiate and map original materials through infrared and ultraviolet false color images and spectral reflectance-based similarity maps, suggesting pigment attribution and focusing point analysis for characterization. This approach was particularly successful to identify and locate the presence of unaltered smalt blue in the first painting coat, which had been covered with other pigments, and to suggest the use of organic dye in mixtures with cinnabar and ochres. Spectroscopic and chromatographic techniques enabled us to identify the painting palette and confirm the use of oil-based binder for the pigments and characterize the altered top layers, made with a natural resin and an animal glue. (4) Conclusions. The characterization of the artwork’s materials was essential to select the most suitable methods and materials for the bio-cleaning, based on bacteria, experimented with during the restoration activities. Full article

We present spectroscopic diagnostic methods that allow us to estimate the gas and the electron temperature in emerged lightning stroke channels (from thunderclouds) observed by the photometers and cameras of the Atmosphere Space Interaction Monitor (ASIM). We identify the species (molecules, atoms and ions) producing light emission in different wavelengths, and how the blue (337 ± 2 nm), red (777.4 ± 2.5 nm) and ultraviolet (180–230 nm) optical emissions captured by ASIM photometers change as a function of the temperature in the lightning stroke channel. We find good agreement between the light curves of the emerged lightning observed by ASIM and the synthetic ones obtained from calculated spectra. Our results suggest that (i) early stage (high temperature > 20,000 K) emerged lightning strokes at high altitude can contribute to the optical signals measured by the PH2 photometer (180–230 nm), (ii) intermediate stage (mid temperatures, 6000–21,000 K) emerged lightning strokes can produce 777.4 nm near-infrared radiation (observable by PH3) exhibiting higher intensity than PH1 observable N${}_2$ SPS between ∼6000 K and ∼8000 K, and than ion optical emissions (336.734 nm and 337.714 nm) between ∼16,000 K and ∼21,000 K, (iii) from ∼16,000 K to 35,000 K, neutral oxygen 777.4 nm radiation and ion emissions at 336.734 nm and 337.714 nm can be simultaneoulsy observed but 777.4 nm dominates only between ∼16,000 K and ∼21,000 K, (iv) the availability of detections with a narrow 0.5 nm gap filtered photometer (336.75–337.25 nm), with the same or better sensitivity than PH1 in ASIM-MMIA but with a central wavelength at exactly 337.0 nm (the strongest N${}_2$ SPS transition), would give access to the late stage of lightning strokes (emerged or not) when temperatures are between 8000 K and 5000 K (or lower for a photometer with better sensitivity than PH1 in ASIM-MMIA) when the production of nitrogen oxides (NO${}_x$) and hydroxyl radicals (OH) maximizes. Full article

The Operational Land Imager (OLI) onboard Landsat 8 has found successful application in inland and coastal water remote sensing. Its radiometric specification and high spatial resolution allows quantification of water-leaving radiance while resolving small water bodies. However, its limited multispectral band set restricts the range of water quality parameters that can be retrieved. Identification of cyanobacteria biomass has been demonstrated for sensors with a band centered near 620 nm, the absorption peak of the diagnostic pigment phycocyanin. While OLI lacks such a band in the orange region, superposition of the available multispectral and panchromatic bands suggests that it can be calculated by a scaled difference. A set of 428 in situ spectra acquired in diverse lakes in Belgium and The Netherlands was used to develop and test an orange contra-band retrieval algorithm, achieving a mean absolute percentage error of 5.39% and a bias of −0.88% in the presence of sensor noise. Atmospheric compensation error propagated to the orange contra-band was observed to maintain about the same magnitude (13% higher) observed for the red band and thus results in minimal additional effects for possible base line subtraction or band ratio algorithms for phycocyanin estimation. Generality of the algorithm for different reflectance shapes was tested against a set of published average coastal and inland Optical Water Types, showing robust retrieval for all but relatively clear water types (Secchi disk depth > 6 m and chlorophyll a $<1.6$ mg m ${}^{-3}$ ). The algorithm was further validated with 79 matchups against the Ocean and Land Colour Imager (OLCI) orange band for 10 globally distributed lakes. The retrieved band is shown to convey information independent from the adjacent bands under variable phycocyanin concentrations. An example application using Landsat 8 imagery is provided for a known cyanobacterial bloom in Lake Erie, US. The method is distributed in the ACOLITE atmospheric correction code. The contra-band approach is generic and can be applied to other sensors with overlapping bands. Recommendations are also provided for development of future sensors with broad spectral bands with the objective to maximize the accuracy of possible spectral enhancements. Full article

The Advanced Spaceborne Thermal Emission and Reflection Radiometer is one of five instruments operating on the National Aeronautics and Space Administration (NASA) Terra platform. Launched in 1999, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) has been acquiring optical data for 20 years. ASTER is a joint project between Japan’s Ministry of Economy, Trade and Industry; and U.S. National Aeronautics and Space Administration. Numerous reports of geologic mapping and mineral exploration applications of ASTER data attest to the unique capabilities of the instrument. Until 2000, Landsat was the instrument of choice to provide surface composition information. Its scanners had two broadband short wave infrared (SWIR) bands and a single thermal infrared band. A single SWIR band amalgamated all diagnostic absorption features in the 2–2.5 micron wavelength region into a single band, providing no information on mineral composition. Clays, carbonates, and sulfates could only be detected as a single group. The single thermal infrared (TIR) band provided no information on silicate composition (felsic vs. mafic igneous rocks; quartz content of sedimentary rocks). Since 2000, all of these mineralogical distinctions, and more, could be accomplished due to ASTER’s unique, high spatial resolution multispectral bands: six in the SWIR and five in the TIR. The data have sufficient information to provide good results using the simplest techniques, like band ratios, or more sophisticated analyses, like machine learning. A robust archive of images facilitated use of the data for global exploration and mapping. Full article

Hyperspectral/Multispectral imaging (HSI/MSI) technologies are able to sample from tens to hundreds of spectral channels within the electromagnetic spectrum, exceeding the capabilities of human vision. These spectral techniques are based on the principle that every material has a different response (reflection and absorption) to different wavelengths. Thereby, this technology facilitates the discrimination between different materials. HSI has demonstrated good discrimination capabilities for materials in fields, for instance, remote sensing, pollution monitoring, field surveillance, food quality, agriculture, astronomy, geological mapping, and currently, also in medicine. HSI technology allows tissue observation beyond the limitations of the human eye. Moreover, many researchers are using HSI as a new diagnosis tool to analyze optical properties of tissue. Recently, HSI has shown good performance in identifying human diseases in a non-invasive manner. In this paper, we show the potential use of these technologies in the medical domain, with emphasis in the current advances in gastroenterology. The main aim of this review is to provide an overview of contemporary concepts regarding HSI technology together with state-of-art systems and applications in gastroenterology. Finally, we discuss the current limitations and upcoming trends of HSI in gastroenterology. Full article

Optical tissue imaging has several advantages over the routine clinical imaging methods, including non-invasiveness (it does not change the structure of tissues), remote operation (it avoids infections) and the ability to quantify the tissue condition by means of specific image parameters. Dermatologists and other skin experts need compact (preferably pocket-size), self-sustaining and easy-to-use imaging devices. The operational principles and designs of ten portable in-vivo skin imaging prototypes developed at the Biophotonics Laboratory of Institute of Atomic Physics and Spectroscopy, University of Latvia during the recent five years are presented in this paper. Four groups of imaging devices are considered. Multi-spectral imagers offer possibilities for distant mapping of specific skin parameters, thus facilitating better diagnostics of skin malformations. Autofluorescence intensity and photobleaching rate imagers show a promising potential for skin tumor identification and margin delineation. Photoplethysmography video-imagers ensure remote detection of cutaneous blood pulsations and can provide real-time information on cardiovascular parameters and anesthesia efficiency. Multimodal skin imagers perform several of the abovementioned functions by taking a number of spectral and video images with the same image sensor. Design details of the developed prototypes and results of clinical tests illustrating their functionality are presented and discussed. Full article

A terahertz (THz) imaging system based on narrow band microbolometer sensors (NBMS) and a novel diffractive lens was developed for spectroscopic microscopy applications. The frequency response characteristics of the THz antenna-coupled NBMS were determined employing Fourier transform spectroscopy. The NBMS was found to be a very sensitive frequency selective sensor which was used to develop a compact all-electronic system for multispectral THz measurements. This system was successfully applied for principal components analysis of optically opaque packed samples. A thin diffractive lens with a numerical aperture of 0.62 was proposed for the reduction of system dimensions. The THz imaging system enhanced with novel optics was used to image for the first time non-neoplastic and neoplastic human colon tissues with close to wavelength-limited spatial resolution at 584 GHz frequency. The results demonstrated the new potential of compact RT THz imaging systems in the fields of spectroscopic analysis of materials and medical diagnostics. Full article