Psoriasis is a common autoimmune disease with inflammatory symptoms affecting skin and joints. One way
of dealing with psoriasis is by controlled solar UV exposure treatment. However, this treatment should be
optimized to get the best possible treatment effect and to limit negative side effects such as erythema and an
increased risk of skin cancer. In this study 24 patients at Valle Marina Treatment Center in Gran Canaria were
monitored throughout a treatment period of three weeks starting at the beginning of November. The total UV
dose to the location was monitored by UV-meters placed on the roof of the treatment centere, and the patients
wore individual film dosimeters throughout the treatment period. Skin parameters were accessed by reflection
spectroscopy (400-850nm). This paper presents preliminary findings from the skin measurements in the visible
part of the spectrum, such as blood oxygenation, erythema and melanin indexes. Reflection spectroscopy was
found to be a good tool for such treatment monitoring.
Vulnerable plaques constitute a risk for serious heart problems, and are difficult to identify using existing methods. Hyperspectral imaging combines spectral- and spatial information, providing new possibilities for precise optical characterization of atherosclerotic lesions. Hyperspectral data were collected from excised aorta samples (n = 11) using both white-light and ultraviolet illumination. Single lesions (n = 42) were chosen for further investigation, and classified according to histological findings. The corresponding hyperspectral images were characterized using statistical image analysis tools (minimum noise fraction, K-means clustering, principal component analysis) and evaluation of reflectance/fluorescence spectra. Image analysis combined with histology revealed the complexity and heterogeneity of aortic plaques. Plaque features such as lipids and calcifications could be identified from the hyperspectral images. Most of the advanced lesions had a central region surrounded by an outer rim or shoulder-region of the plaque, which is considered a weak spot in vulnerable lesions. These features could be identified in both the white-light and fluorescence data. Hyperspectral imaging was shown to be a promising tool for detection and characterization of advanced atherosclerotic plaques in vitro. Hyperspectral imaging provides more diagnostic information about the heterogeneity of the lesions than conventional single point spectroscopic measurements.
Orthotopic bladder cancer model in rats mimics human bladder cancer with respect to urothelial tumorigenesis and progression. Utilizing this model at pT1 (superficial stage), we analyze the tissue responses to hexyl 5-aminolevulinate-induced photodynamic therapy (HAL-PDT). In comparison to untreated rats, HAL-PDT causes little change in tumor-free rat bladder but induces inflammatory changes with increased lymphocytes and mononuclear cell infiltration in rat bladders with tumor. Immunohistochemistry reveals that HAL-PDT is without effect on proliferating cell nuclear antigen expression within the tumor and increases caspase-3 expression in both normal urothelium and the tumor. Transmission electron microscopy reveals severe mitochondrial damage, formations of apoptotic bodies, vacuoles, and lipofuscin bodies, but no microvillus-formed niches in HAL-PDT-treated bladder cancer rats. Bioinformatics analysis of the gene expression profile indicates an activation of T-cell receptor signaling pathway in bladder cancer rats without PDT. HAL-PDT increases the expression of CD3 and CD45RA in the tumor (determined by immunohistochemistry). We suggest that pathways of action of HAL-PDT may include, at least, activations of mitochondrial apoptosis and autophagy, breakdown of cancer stem cell niches, and importantly, enhancement of T-cell activation.
OBJECTIVES: In this study, we evaluated histologically the effects of hexyl 5-aminolevulinateinduced photodynamic treatment in the AY-27 tumor cell induced rat bladder cancer model.
MATERIAL & METHODS: The animals (fischer-344 female rats) were divided into 2 groups, half of which were orthotopically implanted with 400,000 syngeniec AY-27 urothelia1 rat bladder cancer
cells and half sham implanted. 14 days post implantation 6 rats from each group were treated with hexyl 5-aminolevulinate-induced photodynamic treatment (8mM HAL and light fluence of 20 J/cm2).
Additional groups of animals were only given HAL instillation, only light treatment, or no treatment.
All animals were sacrificed 7 days after the PDT/only HAL/only light or no treatment. Each bladder was removed, embedded in paraffin and stained with hematoxylin, eosin, and saferin for histological
evaluation at high magnification for features of tissue damage by a pathologist blinded to the sample source.
RESULTS: In all animals that were AY-27 implanted and not given complete PDT treatment, viable tumors were found in the bladder mucosa and wall. In the animals treated with complete HAL-PDT
only 3 of 6 animals had viable tumor. In the 3 animals with viable tumor it was significantly reduced in volume compared to the untreated animals. It was also noted that in the PDT treated animals there was a significantly increased inflammatory response (lymphocytic and mononuclear cell infiltration) in the peri-tumor area compared to implanted animals without complete HAL-PDT.
CONCLUSION: Our results suggest that hexyl 5-aminolevulinate-induced photodynamic treatment in a rat bladder cancer model involves both direct effects on cell death (necrosis and apoptosis) and
indirect effects to evoke the host immune-response, together contributing to tumor eradication.
Imaging modalities like hyperspectral imaging create large amounts of data. Time efficient, automated analytic
techniques are therefore required to enjoy the power of such methods. In this study it was investigated if
hyperspectral imaging followed by automated noise filtering and statistical image analysis is a suitable method for
characterization of the macroscopic structure of atherosclerotic lesions. Ten human aorta samples (6×8 cm) were
collected during autopsy. Hyperspectral white light and fluorescence images and 5 - 6 biopsies were collected from
each sample. The biopsies were stained (HES, Sudan red), and grouped according to histology. All images were
noise filtered and normalized. Fluorescence spectra were collected from all biopsied regions, and used to compute
average spectra for each histological group. Supervised classification was performed using Spectral angle mapping
(SAM) with the average spectra as endmembers. K-means- and ISO-data clustering was used for unsupervised
classification. The results show that noise filtering and normalization is essential for reliable classification.
Supervised classification was in general found to perform better than unsupervised classification. However, the
SAM results strongly depend on the variation in the spectra used to compute the average endmember spectra.
The analysis show that fatty deposits, calcifications, connective tissue and hemoglobin can be identified. The
lesions were found to have a complex structure where vulnerable regions could be found next to stabile regions
within the same lesion. In conclusion hyperspectral imaging, automated filtering and -analysis was found to be
a suitable tool to classify advanced atherosclerotic lesions.
Hyperspectral imaging is a modality which combines spatial resolution and spectroscopy in one technique. Analysis of hyperspectral data from biological samples is a demanding task due to the large amount of data, and due to the complex optical properties of biological tissue. In this study it was investigated if depth information could be revealed from hyperspectral images using a combination of image analysis and analytic simulations of skin reflectance. It was also investigated if hyperspectral imaging could be utilized to monitor changes in the distribution of hemoglobin species after smoking. Hyperspectral data in the wavelength range 400-1000nm were collected from the forearm of 15 non-smokers and 5 smokers. The hyperspectral images were analyzed with respect to the distribution of hemoglobin species and vascular structures. Changes in the vascular system due to smoking were also evaluated. Principal component analysis (PCA), Spectral angle mapping (SAM), and Mixture tuned matched filtering (MTMF) were used to enhance vascular structures. Emphasis was put on identifying apparent and true absorption spectra for the present chromophores by combining image analysis and an analytical photon transport model. The results show that the depth resolution of hyperspectral images can be better understood using analytical simulations. Modulation of the chromophore spectra by the optical properties of overlying tissue was found to be an important mechanism causing the depth resolution in hyperspectral images. It was also found that hyperspectral imaging and image analysis can be successfully applied to quantify skin changes following smoking.
Monitoring of the tissue response to photodynamic therapy (PDT) can provide important information to help optimize treatment variables such as drug and light dose, and possibly predict treatment outcome. A urinary bladder cancer cell line (AY-27) was used to induce orthotopic transitional cell carcinomas (TCC) in female Fischer rats, and hexyl 5-aminolevulinate (HAL, 8 mM, 1 h)-induced PDT was performed on day 14 after instillation of the cancer cells (20 J/cm2 fluence at 635 nm). In vivo optical reflectance and fluorescence spectra were recorded from bladders before and after laser treatment with a fiberoptic probe. Calculated fluorescence bleaching and oxygen saturation in the bladder wall were examined and correlated to histology results. Reflectance spectra were analyzed using a three-layer optical photon transport model. Animals with TCC treated with PDT showed a clear treatment response; decreased tissue oxygenation and protoporphyrin IX (PpIX) fluorescence photobleaching were observed. Histology demonstrated that 3 of 6 animals with treatment had no sign of the tumor 7 days after PDT treatment. The other 3 animals had significantly reduced the tumor size. The most treatment-responsive animals had the highest PpIX fluorescence prior to light irradiation. Thus, optical spectroscopy can provide useful information for PDT. The model has proved to be very suitable for bladder cancer studies.
Determining the cause of an injury and the force behind the impact may be of crucial importance in a court case.
For non-penetrating soft tissue injuries there is a lack of information available in the literature. In this study
controlled bruises were inflicted on an anesthetized pig by high speed, low-weight paintball projectiles (diameter
17.1 mm, weight 3.15 g). The speed of the object and the impact itself were monitored using a high speed
camera. Punch biopsies (5 mm) were collected from the injury sites. A red and purple ring with a diameter of
1.5 cm appeared on the skin within 30 seconds after the paintball impact. The ring was visually fully established
after 5-10 minutes. Numerical finite element simulations performed with ABAQUS\Explicit showed a build up of
shear stresses in the skin where the ring formed. Biopsies demonstrated severe dermal vessel damage in the same
area. It is concluded that considerable shear stresses during the impact will create dermal vessel damage and
thereby cause a visible bruise. Larger forces are required for compressive stresses to inflict equivalent vascular
damage.
Studies of immediate skin reactions are important to understand the underlying biological mechanisms involved in traumatic or chemical damage to the skin. In this study the spatial and spectral information provided by hyperspectral images was used to identify and characterize non-penetrating skin injuries in a porcine model. A hyperspectral imaging system (Hyspex, Norsk Elektro Optikk AS) was used to monitor the temporal development of minor skin injuries in an anesthetized Norwegian domestic pig. Hyperspectral data were collected in the wavelength range 400-1000 nm (VNIR), with a spectral sampling interval of 3.7 nm. The measurements were initiated immediately after inflicting the injury, and were repeated at least five times at each site with irregular frequency. The last measurement was performed 4 hours after injury. Punch biopsies (5 mm), were collected from adjacent normal skin, and at the center and the margin of each injury. The study was approved by the national animal research authority. The hyperspectral data were analyzed with respect to oxy- and deoxyhemoglobin, and erythema index. The skin biopsies were examined to determine the extent of skin damage in the bruised zones. Preliminary results show that hyperspectral imaging allows discrimination between traumatized skin and normal skin in an early phase. The extent and location of the hemorrhages can be determined from hyperspectral images. These findings might contribute to a better understanding of immediate skin reactions to minor trauma, and thereby the development of a better diagnostic modality for non-penetrating skin injuries in forensic medicine.
Photodynamic therapy (PDT) is a treatment modality which has been shown to be effective for both malignant
and non-malignant diseases. New photosensitizers such as hexyl-aminolevulinate (HAL) may increase the efficiency of PDT. HAL penetrates into the cell where the photosensitizer protoporphyrin IX (PPIX) is produced
endogenously. In a previous study on HAL based PDT treatment of rat bladder cancer (AY-27 transitional cell
carcinoma), a depression of the optical reflectance spectra after treatment was observed in some of the animals.
This depression of the spectra was caused by metHemoglobin (metHb). MetHb is an indication of oxidative
stress, and can be formed as a result of for instance UV-radiation and heating of blood. The aim of this study
was to identify if metHb can be formed in vitro as a result of oxidative stress caused by singlet oxygen and
ROS produced during PDT. Methemoglobin formed during PDT might thus be used as an indirect measure of
the photochemical processes. This may help predict the PDT treatment outcome. Red blood cells mixed with
AY-27 cells exposed to HAL, or PPIX received light treatment, and the changes in the absorption spectra were
measured spectrophotometrically. The methemoglobin absorbance spectrum was also studied, and found to be
strongly dependant on pH. Hemolysis of erythrocytes by PDT was found, however no metHb was formed in
vitro.
Photodynamic therapy (PDT) is a treatment modality which has been
shown to be effective for both malignant and non-malignant diseases.
New photosensitizers such as 5-aminolevulinic acid hexylester (hALA)
may increase the efficiency of PDT. Monitoring of the tissue
response provides important information for optimizing factors such
as drug and light dose for this treatment modality. Optical
spectroscopy may be suited for this task. To test the efficacy of
hALA induced PDT, a study on rats with a superficial bladder cancer
model, in which a bladder cancer cell line (AY-27) is instilled,
will be performed. Preliminary studies have included a PDT
feasibility study on rats, fluorescence spectroscopy on AY-27 cell
suspensions, and optical reflection and fluorescence spectroscopy in
rat bladders in vivo. The results from the preliminary studies are promising, and the study on hALA induced PDT treatment
of bladder cancer will be continued.
An objective method for dating of soft tissue injuries is highly desired in forensic medicine. To achieve this, obtaining a fundamental understanding of extravascular blood behavior is necessary. Porcine blood mixed with fluorescein was inserted subcutaneously on an anaesthetized pig. The fluorescence build-up was measured as a function of time, using a fiber probe setup. Fluorescence measurements proved to be a suitable tool for
monitoring the temporal distribution of fluid in a subcutaneous hemorrhage. Reasonable values for the fluid velocity was obtained by monitoring the fluorescein distribution around the infusion point. Further theoretical work and development of the experimental technique is necessary to obtain a good understanding of subcutaneous transport of blood.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.