Sterenborg, H.J.C.M.

Photodynamic therapy with systemic meta-tetrahydroxyphenylchlorin in the treatment of anal intraepithelial neoplasia, grade 3 (Article)

2012-10-01T00:00:00Z

Background and Objective Anal cancer and preneoplastic anal lesions (anal intraepithelial neoplasia, AIN) rising especially in men having sex with men (MSM). There are no widely accepted treatment standards for AIN. Photodynamic therapy (PDT) using the systemic sensitizer meta-tetrahydroxyphenylchlorin (mTHPC) has the potential to treat the anal area even when the exact borders of the preneoplastic anal lesion cannot easily be visualized. Study Design/Materials and Methods In this prospective intervention study, 15 HIV-positive MSM with AIN 3 were treated in 25 PDT-sessions using mTHPC intravenously administered at drug doses of 0.075-0.15 mg ml-1and illumination at 48 hours. The illumination was performed using a custom made applicator using either red light (652 nm) to a measured intended fluence of 10 and 20 J cm-2and green light (532 nm) to a measured intended fluence of 105, 210, and 340 J cm-2. Red and green illuminations were performed at a (green) equivalent fluence rate of 105 mW cm-2. Results Initial complete response was seen in 7/25 (28%) of treatments and another 4/25 (16%) initial partial responses. After an average 8 months, recurrences were detected in 7/11 (64%) of sessions that initially showed response. A total 4/25 (16%) showed persistent complete response 6-15 months after green light illumination. Red light illuminations caused more significant side effects combined with no persistent complete response. Reported side effects were intense pain, bloody and purulent rectal discharge, and anal stricture formation, in one patient. Conclusion The results show that the use of systemic mTHPC is partially effective for the treatment of AIN 3. Lasers Surg.

Temoporfin mediated photodynamic therapy in patients with local persistent and recurrent nasopharyngeal carcinoma after curative radiotherapy: A feasibility study (Article)

2012-09-01T00:00:00Z

Background: The treatment of persistent and recurrent nasopharyngeal carcinoma (NPC) remains a challenge, especially in Indonesia. We investigated the safety and efficacy of temoporfin mediated photodynamic therapy (PDT) for patients with local persistent and recurrent NPC. Material and methods: Twenty-two patients with persistent and recurrent NPC (maximum tumor depth <10mm) underwent PDT under local anesthesia with use of a nasopharyngeal light applicator. Three different drug doses and light intervals have been administered: treatment arm A: 0.15mg/kg Foscan®; 96h drug-light interval; B: drug dose of 0.10mg/, 48h drug-light interval; C: drug dose of 0.075mg/kg, 24h drug-light interval. Toxicity was measured by using the CTCAE 3.1 scale. Results: Arm A consisted of eight patients, arms B and C consisted of seven patients. The treatment procedure was well tolerable under local anesthesia. The most common grade III toxicities for all groups is headache (n=7; 33%). No grade IV toxicity was seen. One patient died 2 days after treatment due to a misdiagnosed pneumonia. In 17 of the 22 patients a biopsy was performed after 40 weeks and showed no tumor in all biopsies. Arm A seems, in addition to comparable toxicity, clinically more effective than arms B and C. Conclusion: The present study demonstrated that temoporfin mediated photodynamic therapy is a relatively simple technique that can be utilized to treat residual or recurrent nasopharyngeal cancer, restricted locally to the nasopharynx.

The future of medical diagnostics: Review paper (Article)

2011-08-30T00:00:00Z

While histopathology of excised tissue remains the gold standard for diagnosis, several new, non-invasive diagnostic techniques are being developed. They rely on physical and biochemical changes that precede and mirror malignant change within tissue. The basic principle involves simple optical techniques of tissue interrogation. Their accuracy, expressed as sensitivity and specificity, are reported in a number of studies suggests that they have a potential for cost effective, real-time, in situ diagnosis. We review the Third Scientific Meeting of the Head and Neck Optical Diagnostics Society held in Congress Innsbruck, Innsbruck, Austria on the 11th May 2011. For the first time the HNODS Annual Scientific Meeting was held in association with the International Photodynamic Association (IPA) and the European Platform for Photodynamic Medicine (EPPM). The aim was to enhance the interdisciplinary aspects of optical diagnostics and other photodynamic applications. The meeting included 2 sections: oral communication sessions running in parallel to the IPA programme and poster presentation sessions combined with the IPA and EPPM posters sessions.

Image-guided surgery in head and neck cancer: Current practice and future directions of optical imaging (Article)

2011-04-06T00:00:00Z

A key aspect for the postoperative prognosis of patients with head and neck cancer is complete tumor resection. In current practice, the intraoperative assessment of the tumor-free margin is dependent on visual appearance and palpation of the tumor. Optical imaging has the potential of traversing the gap between radiology and surgery by providing real-time visualization of the tumor, thereby allowing for image-guided surgery. The use of the near-infrared light spectrum offers 2 essential advantages: increased tissue penetration of light and an increased signal-to-background ratio of contrast agents. In this review, the current practice and limitations of image-guided surgery by optical imaging using intrinsic fluorescence or contrast agents are described. Furthermore, we provide an overview of the various molecular contrast agents targeting specific hallmarks of cancer that have been used in other fields of oncologic surgery, and we describe perspectives on its future use in head and neck cancer surgery.

Fractionated illumination at low fluence rate photodynamic therapy in mice (Article)

2010-09-01T00:00:00Z

Photodynamic therapy (PDT) for actinic field cancerization is effective but painful. Pain mechanisms remain unclear but fluence rate has been shown to be a critical factor. Lower fluence rates also utilize available oxygen more efficiently. We investigated PDT effect in normal SKH1-HR mice using low and high fluence rate aminolevulinic acid (ALA) PDT and a fractionated illumination scheme. Six groups of six mice with different light treatment parameters were studied. Visual skin damage was assessed up to 7 days post-PDT. Fluorescence and reflectance spectroscopy during illuminations provided us with real-time information about protoporphyrin IX (PpIX) photobleaching. A novel dosing approach was introduced in that we used a photobleaching percentage instead of a preset fluence. Data show similar total and maximum damage scores in high and low fluence rate groups. Photobleaching of PpIX in the low fluence rate groups shows a trend toward more efficient photobleaching. Results indicate that low fluence rate PDT is as effective as and more efficient than high fluence rate PDT in normal mouse skin. Low fluence rate PDT light protocols need to be explored in human studies in search for an effective and well-tolerated treatment for actinic field cancerization.

A Telemetric light delivery system for metronomic photodynamic therapy (mPDT) in rats (Article)

2010-06-30T00:00:00Z

Light delivery and monitoring during photodynamic therapy (PDT) is often limited by the need for a physical link between the light source, detectors and the treatment volume. This paper reports on the first in vivo experiments performed with a fully implantable telemetric system, designed for a rat glioblastoma model. In this system, light delivery is performed using a solid state optode containing 2 LEDs, and 4 photodiodes which will be used to monitor light delivery in future experiments. Powering and communication is achieved by means of an inductive link. The implant may remain in the animal for extended time periods, making it particularly interesting for performing metronomic PDT. In this paper, we demonstrate the feasibility of in vivo light delivery and biocompatibility of the device.. Activation of the inductive link as well as illumination of the brain by the LED did not influence animal behavior during or after treatment. We show that the implant can remain in the animal for two weeks without causing serious biological reactions.

Differential path-length spectroscopy: a tool for quantitative assessment of blood oxygen saturation in microvessels (Article)

2010-05-01T00:00:00Z

A dedicated applicator for light delivery and monitoring of PDT of intra-anal intraepithelial neoplasia (Article)

2010-03-01T00:00:00Z

The objective of this study was to develop an applicator for delivery of light and monitoring of photodynamic therapy (PDT) in the anal cavity for treatment of anal intraepithelial neoplasia grade III (AIN III), which can progress to invasive anal cancer. Forty-eight hours before treatment, patients participating in the study were injected with 0.03 (n = 2) or 0.075 (n = 2) mg kg-1m-THPC. For light delivery and monitoring of PDT, an applicator based on standard anoscopy equipment was developed which facilitates, in addition to a light treatment fiber, fiber optic probes to monitor blood saturation, blood volume, fluorescence and fluence (rate) at two different locations in situ. Patients were given a light dose of 10-17 J cm-2at a fluence rate of 45-50 mW cm-2based on in situ measured light treatment parameters. We demonstrate that the applicator does not influence the fluence rate profile of the light treatment fiber. Furthermore this study shows the possibility of monitoring blood saturation, blood volume, fluorescence and fluence (rate) during therapeutic illumination without changing the light treatment protocol.

Monitoring interstitial m-THPC-PDT in vivo using fluorescence and reflectance spectroscopy (Article)

2009-11-01T00:00:00Z

Background and Objective: In order to understand the mechanisms of photodynamic therapy (PDT) it is important to monitor parameters during illumination that yield information on deposited PDT dose. The aim of this study is to investigate the possibility of monitoring implicit parameters, such as photobleaching, in addition to monitoring explicit parameters (fluence (rate), oxygenation, photosensitizer concentration) directly or indirectly. These parameters are monitored during PDT without interrupting the therapeutic illumination. Materials and Methods: Rats were injected with 0.3 mg kg-1m-THPC. Sixteen hours after administration the abdominal muscle in rats was irradiated for 1,500 seconds using clinically relevant fluence rates of 50, 100, and 250 mW cm-1of diffuser length at 652 nm. In addition to the linear diffuser for delivering treatment light, isotropic fiber-optic probes and fiber-optic probes for differential path-length spectroscopy (DPS) were placed on both sides of the muscle to monitor tissue physiological parameters, fluence rate, and fluorescence. Results: The m-THPC treatment groups show a decrease in fluence rate throughout PDT of 16%, 19%, and 27% for the 50, 100, and 250 mW cm-1groups, respectively. Both during and post-PDT differences in vascular response between treatment groups and animals within the same treatment group are observed. Furthermore we show fluence rate dependent bleaching of m-THPC up to a measured fluence rate of 100 mW cm-1. Conclusion: The data presented in this study show the possibility of simultaneously monitoring fluence (rate), fluorescence, hemoglobin oxygen saturation, and blood volume during PDT without interruptions to the therapeutic illumination. Differences in saturation profiles between animals and treatment groups indicate differences in vascular response during illumination. Furthermore, the relationship between fluence rate andm-THPCfluorescence photobleaching is complex in an interstitial environment.

Noninvasive measurement of oxygen saturation of the microvascular blood in Barrett's dysplasia by use of optical spectroscopy (Article)

2009-07-01T00:00:00Z

Background: Current investigations into endoscopic screening for the early detection of Barrett's esophageal adenocarcinoma have focused on visualization of the microvascular morphology by using narrow-band imaging (NBI). Adjustment of the center wavelength, particularly of the NBI blue imaging filter, may lead to improved image contrast, depending on the oxygen saturation of the microvascular blood of dysplastic and early cancerous Barrett's mucosa. Objective: To perform in vivo, noninvasive measurements of the oxygen saturation of the microvascular blood for different pathologic grades of Barrett's mucosa by using differential path-length spectroscopy (DPS). Design: DPS measurements were made on normal (n = 7), low-grade dysplastic (n = 10), high-grade dysplastic (n = 7), and cancerous (n = 4) Barrett's mucosa by using a fiber-optic probe, and were correlated to the histologic outcome of biopsy specimens taken from the same location. Setting: Academic medical center. Patients: Fifteen patients with Barrett's esophagus who were undergoing gastroscopy. Interventions: Biopsy specimens were taken from suspicious areas in the esophagus. Main Outcome Measurements: The oxygen saturation of the microvascular blood of different pathologic grades of Barrett's mucosa was assessed. Results: The oxygen saturation of the microvascular blood remains high (approximately 90%) throughout the metaplasia-dysplasia-adenocarcinoma sequence. Limitation: The small number of patients. Conclusions: The current NBI blue imaging filter, centered on the peak absorption of oxyhemoglobin (415 nm), is well chosen, and little improvement in image contrast is to be expected from changes in this center wavelength.

Heel de mens met licht (Inaugural Lecture)

2009-05-28T00:00:00Z

Rede, in verkorte vorm uitgesproken ter gelegenheid van het aanvaarden van het ambt van bijzonder hoogleraar met als leeropdracht Fotodynamische Therapie aan het Erasmus MC, faculteit van de Erasmus Universiteit Rotterdam op 28 mei 2009

Empirical model of the photon path length for a single fiber reflectance spectroscopy device (Article)

2009-01-19T00:00:00Z

A reflectance spectroscopic device that utilizes a single fiber for both light delivery and collection has advantages over classical multi-fiber probes. This study presents a novel empirical relationship between the single fiber path length and the combined effect of both the absorption coefficient, μa(range: 0.1-6 mm-1), and the reduced scattering coefficient, μ′s(range: 0.3-10 mm-1), for different anisotropy values (0.75 and 0.92), and is applicable to probes containing a wide range of fiber diameters (range: 200-2000 μm). The results indicate that the model is capable of accurately predicting the single fiber path length over a wide range (r = 0.995; range: 180-3940 μm) and predictions do not show bias as a function of either μaor μ′s.

In vivo nonlinear spectral imaging microscopy of visible and ultraviolet irradiated hairless mouse skin tissues (Article)

2008-11-06T00:00:00Z

We demonstrate the capability of nonlinear spectral imaging microscopy (NSIM) in investigating ultraviolet and visible light induced effects on albino Skh:HR-1 hairless mouse skin non-invasively.

Monitoring ALA-induced PpIX photodynamic therapy in the rat esophagus using fluorescence and reflectance spectroscopy (Article)

2008-11-01T00:00:00Z

The presence of phased protoporphyrin IX (PpIX) bleach kinetics has been shown to correlate with esophageal response to 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) in animal models. Here we confirm the existence of phased PpIX photobleaching by increasing the temporal resolution of the fluorescence measurements using the therapeutic illumination and long wavelength fluorescence detection. Furthermore fluorescence differential pathlength spectroscopy (FDPS) was incorporated to provide information on the effects of PpIX and tissue oxygenation distribution on the PpIX bleach kinetics during illumination. ALA at a dose of 200 mg kg-1was orally administered to 15 rats, five rats served as control animals. PDT was performed at an in situ measured fluence rate of 75 mW cm-2using a total fluence of 54 J cm-2. Forty-eight hours after PDT the esophagus was excised and histologically examined for PDT-induced damage. Fluence rate and PpIX photobleaching at 705 nm were monitored during therapeutic illumination with the same isotropic probe. A new method, FDPS, was used for superficial measurement on saturation, blood volume, scattering characteristics and PpIX fluorescence. Results showed two-phased PpIX photobleaching that was not related to a (systematic) change in esophageal oxygenation but was associated with an increase in average blood volume. PpIX fluorescence photobleaching measured using FDPS, in which fluorescence signals are only acquired from the superficial layers of the esophagus, showed lower rates of photobleaching and no distinct phases. No clear correlation between two-phased photobleaching and histologic tissue response was found. This study demonstrates the feasibility of measuring fluence rate, PpIX fluorescence and FDPS during PDT in the esophagus. We conclude that the spatial distribution of PpIX significantly influences the kinetics of photobleaching and that there is a complex interrelationship between the distribution of PpIX and the supply of oxygen to the illuminated tissue volume.

Microscopic localisation of protoporphyrin IX in normal mouse skin after topical application of 5-aminolevulinic acid or methyl 5-aminolevulinate (Article)

2008-08-21T00:00:00Z

Light fractionation does not enhance the response to photodynamic therapy (PDT) after topical methyl-aminolevulinate (MAL) application, whereas it is after topical 5-aminolevulinic acid (ALA). The differences in biophysical and biochemical characteristics between MAL and ALA may result in differences in localisation that cause the differences in response to PDT. We therefore investigated the spatial distribution of protoporphyrin IX (PpIX) fluorescence in normal mouse skin using fluorescence microscopy and correlated that with the PDT response histologically observed at 2.5, 24 and 48 h after PDT. As expected high fluorescence intensities were observed in the epidermis and pilosebaceous units and no fluorescence in the cutaneous musculature after both MAL and ALA application. The dermis showed localised fluorescence that corresponds to the cytoplasma of dermal cells like fibroblast and mast cells. Spectral analysis showed a typical PpIX fluorescence spectrum confirming that it is PpIX fluorescence. There was no clear difference in the depth and spatial distribution of PpIX fluorescence between the two precursors in these normal mouse skin samples. This result combined with the conclusion of Moan et al. that ALA but not MAL is systemically distributed after topical application on mouse skin [Moan et al., Pharmacology of protoporphyrin IX in nude mice after application of ALA and ALA esters, Int. J. Cancer 103 (2003) 132-135] suggests that endothelial cells are involved in increased response of tissues to ALA-PDT using light fractionation. Histological analysis 2.5 h after PDT showed more edema formation after ALA-PDT compared to MAL-PDT that was not accompanied by a difference in the inflammatory response. This suggests that endothelial cells respond differently to ALA and MAL-PDT. Further investigation is needed to determine the role of endothelial cells in ALA-PDT and the underlying mechanism behind the increased effectiveness of light fractionation using a dark interval of 2 h found after ALA but not after MAL-PDT.

Ex vivo quantification of mTHPC concentration in tissue: Influence of chemical extraction on the optical properties (Article)

2008-05-29T00:00:00Z

A method for the quantification of the concentration of the photosensitizer meso-tetra(hydroxyphenyl) chlorin (mTHPC) in tissue samples is presented. The technique is an extension of a previously published method based on alkaline hydrolysis of tissue, using Solvable™ as a tissue solubilizer. mTHPC quantification was achieved by subsequent fluorescence spectroscopy. Since the original extraction method involved multiple steps in which water dilution of the sample was implemented, we studied the spectral characteristics of mTHPC in different Solvable™/water mixtures. Using UV-VIS absorption and fluorescence spectroscopy, it was demonstrated that the spectral characteristics of mTHPC vary for different Solvable™ concentrations. In the range of 20-100% Solvable™, the fluorescence intensity of mTHPC did not change, while dramatic changes in the mTHPC fluorescence intensity were observed for lower Solvable™ concentrations (< 20%) due to increasing hydrophilicity of the environment, combined with pH alterations. We also demonstrated that the absorption and fluorescence spectra of the dissolved tissue were time-dependent. Longer incubation of the samples resulted in a significant increase of the native tissue chromophore fluorescence. This implies that for the correct quantification of photosensitizer concentrations, the fluorescence of native tissue chromophores must be accounted for.

Fractionated aminolevulinic acid-photodynamic therapy provides additional evidence for the use of PDT for non-melanoma skin cancer (Article)

2008-04-01T00:00:00Z

Background: Photodynamic therapy (PDT) is an accepted treatment for superficial basal cel carcinoma (sBCC) and Bowens disease. In Rotterdam, extensive preclinical research has lead to an optimized twofold illumination scheme for aminolevulinic acid-PDT (ALA-PDT). Objective: To provide additional evidence of ALA-PDT for sBCC, Bowens disease (BD), nodular BCC (nBCC) and actinic keratosis (AK) using a 2-fold illumination scheme after a single application of ALA. Methods: Five hundred fifty-two lesions (430 sBCC, 20 nBCC, 32 BD, 70 AK) were treated with ALA-PDT using a twofold illumination scheme. ALA was applied topically for 4 h. Lesions were treated with two light fractions of 20 and 80 J/cm2separated by a 2-h dark interval. Results: After a minimum follow-up of 12 months, in average follow-up of 2 years, an overall complete response of 95% was seen for all lesions. For sBCC, the complete response at 2 years was 97% (for AK 98%, for BD 84% and for nBCC 80% after 2 years). A sub-analysis of the results of lesions larger than 2 cm showed CR at 2 years of 89% for all lesions (n = 57). Cosmetic outcome was good to excellent in 95% of the treated lesions. Conclusion: ALA-PDT using a twofold illumination scheme of 20 plus 80 J/cm2separated by a 2-h dark interval leads to high complete response rates at 2 years and can be regarded as an evidence-based treatment modality for superficial growing non-melanoma skin cancer and the (pre)malignant AK. The Rotterdam fractionated approach should be included in future guidelines. © Journal compilation

Non-invasive measurement of the morphology and physiology of oral mucosa by use of optical spectroscopy (Article)

2008-01-01T00:00:00Z

Differential path-length spectroscopy (DPS) was used to non-invasively determine the superficial optical properties of oral mucosa in vivo. DPS yields information on physiological parameters such as the mucosal blood content, the microvascular blood oxygenation and the average micro-vessel diameter as well as on morphological parameters such as the scattering slope and scattering amplitude. DPS measurements were made on normal and cancerous oral mucosa using a novel fiber-optic probe, and were correlated to the histological outcome of punch biopsies taken from the same location. Our data shows that the mucosa of oral squamous cell carcinoma is characterised by a significant decrease in microvascular oxygenation and increase in mucosal blood content compared to normal oral mucosa as well as a significant decrease in scattering amplitude and increase in scattering slope.

Performance of a dedicated light delivery and dosimetry device for photodynamic therapy of nasopharyngeal carcinoma: Phantom and volunteer experiments (Article)

2007-09-01T00:00:00Z

The objective of this study was to develop a light delivery and measurement device for photodynamic therapy (PDT) in the nasopharyngeal cavity, which achieves a homogeneous and reproducible fiuence rate distribution to a target area and provides proper shielding of predefined risk areas. Materials and Methods: A flexible silicone applicator was developed, incorporating light delivery and dosimetry fibers. The applicator can be inserted through the mouth and fixed in the nasopharyngeal cavity. Tissue optical phantoms were prepared on the basis of optical properties measured in vivo using diffuse reflectance spectroscopy (DRS). The fluence rate over the length of the applicator surface was measured in air, in tissue optical phantoms and in five healthy volunteers. Results: The fluence rate distribution over the applicator surface in air and tissue optical phantom was found to be more homogeneous (SD/mean 3.8% and 18.3%, respectively) than the fluence rate distribution in five volunteers (SD/mean ranging from 19% up to 52%). The maximum observed fiuence rate build-up in the nasopharynx varied between subjects and ranged from a factor of 4.1-6.9. Shielding of the risk area such as the soft palate and tongue was effective. Conclusions: In air and in tissue optical phantoms the fluence rate distribution of the device was highly homogeneous. The observed inter-subject and intra-subject variations in fluence rate in healthy volunteers originated from differences in optical properties and nasopharyngeal geometry. Light delivery based on a single tissue surface measurement will not be adequate. In situ dosimetric measurements are required to determine the light fluence delivered to a geometrically complex site such as the nasopharynx. These observations should be taken in consideration when developing light applicators for PDT of the nasopharynx and other non-uniform surfaces.

In vivo quantification of fluorescent molecular markers in real-time: A review to evaluate the performance of five existing methods (Article)

2007-09-01T00:00:00Z

With the advent of molecular-targeted fluorescent markers, there is a renewed interest in fluorescence quantification methods that are based on continuous wave excitation and multi-spectral image acquisition. However, little is known about their in vivo quantification performance. We reviewed the performance of five selected methods by analytically describing these and varying input parameters of irradiance, excitation geometry, collection efficiency, autofluorescence, melanin content, blood volume, blood oxygenation and tissue scattering using optical properties representing those for human skin. We identified one method that corrects for variations in all parameters. This requires image acquisition before and after marker administration, under identical geometry. Hence, it is suited for applications where the site of interest can be relocated (e.g. anaesthetized animals and dermatology). For applications where relocation is not possible, we identified a second method where the uncertainty in the fluorescence signal was ±20%. Hence, use of these methods can substantially aid in vivo fluorescence quantification compared to use of the raw fluorescence signal, as this changed by more than 3 orders of magnitude. Since these methods can be computed in real-time, they are of particular interest for applications where direct feedback is critical, as diagnostic screening or image-guided surgery.

Spectrally resolved multiphoton imaging of in vivo and excised mouse skin tissues (Article)

2007-08-01T00:00:00Z

The deep tissue penetration and submicron spatial resolution of multiphoton microscopy and the high detection efficiency and nanometer spectral resolution of a spectrograph were utilized to record spectral images of the intrinsic emission of mouse skin tissues. Autofluorescence from both cellular and extracellular structures, second-harmonic signal from collagen, and a narrowband emission related to Raman scattering of collagen were detected. Visualization of the spectral images by wavelength-to-RGB color image conversion allowed us to identify and discriminate tissue structures such as epidermal keratinocytes, lipid-rich corneocytes, intercellular structures, hair follicles, collagen, elastin, and dermal cells. Our results also showed morphological and spectral differences between excised tissue section, thick excised tissue, and in vivo tissue samples of mouse skin. Results on collagen excitation at different wavelengths suggested that the origin of the narrowband emission was collagen Raman peaks. Moreover, the oscillating spectral dependency of the collagen second-harmonic intensity was experimentally studied. Overall, spectral imaging provided a wealth of information not easily obtainable with present conventional multiphoton imaging systems.

In vivo quantification of fluorescent molecular markers in real-time by ratio imaging for diagnostic screening and image-guided surgery (Article)

2007-08-01T00:00:00Z

Future applications of "molecular diagnostic screening" and "molecular image-guided surgery" will demand images of molecular markers with high resolution and high throughput (∼≥30 frames/second). MRI, SPECT, PET, optical fluorescence tomography, hyper-spectral fluorescence imaging, and bioluminescence imaging do not offer such high frame rates. 2D optical fluorescence imaging can provide surface images with high resolution and high throughput. The ability to accurately quantify the fluorescence in vivo is critical to extract functional information of the disease state, however few methods are available. Here, a ratiometric 2D quantification method is introduced. Through mathematical modeling the performance was evaluated using optical properties that resembled biological tissues with the fluorescent marker Protoporhyrin IX. Experimentally the performance was evaluated in optical phantoms with different optical properties employing a novel prototype clinical imaging system. The clinical feasibility of real-time, image-guided surgery was demonstrated in patients undergoing prostatectomy. Discussed are the reasons why the introduced method leads to an increased quantification performance followed by modifications so it can be applied to novel fluorescent molecular markers as phthalocyanine 4 and dual-fluorescent markers. These offer additional advantages as these can provide a linear response to marker concentration and further minimize the dependence on autofluorescence and optical properties, as demonstrated through modeling.

Measurement of hypoxia-related parameters in bronchial mucosa by use of optical spectroscopy. (Article)

2005-05-15T00:00:00Z

RATIONALE: Tumor hypoxia has both prognostic and therapeutic consequences for solid tumors. We developed a novel noninvasive technique, differential path-length spectroscopy (DPS), which allows the measurement of hypoxia-related parameters in the superficial microvasculature of tissue. OBJECTIVES: The aim of this study was to measure the microvascular oxygenation of histologically normal endobronchial mucosa and of neoplastic lesions during bronchoscopy using DPS. METHODS: Sixty-four patients with known or suspected malignancies of the lung were studied. One hundred and five endobronchial lesions (38 histologically normal, 37 metaplastic/mild dysplastic lesions, and 30 invasive carcinomas) were detected by white and/or autofluorescence bronchoscopy and measured using DPS. RESULTS: We observed that bronchial tumors are characterized by a lower blood oxygen saturation and a higher blood content than normal mucosa. No differences were observed between normal and metaplastic/mild dysplastic mucosa. CONCLUSION: DPS is a new optical technique allowing the noninvasive study of endobronchial tumor hypoxia.

5-aminolevulinic acid photodynamic therapy versus argon plasma coagulation for ablation of Barrett's oesophagus: a randomised trial (Article)

2004-01-01T00:00:00Z

BACKGROUND: Photochemical and thermal methods are used for ablating Barrett's oesophagus (BO). The aim of this study was to compare 5-aminolevulinic acid induced photodynamic therapy (ALA-PDT) with argon plasma coagulation (APC) with respect to complete reversal of BO. METHODS: Patients with BO (32 no dysplasia and eight low grade dysplasia) were randomised to one of three treatments: (a) ALA-PDT as a single dose of 100 J/cm(2) at four hours (PDT100; n = 13); (b) ALA-PDT as a fractionated dose of 20 and 100 J/cm(2) at one and four hours, respectively (PDT20+100; n = 13); or (c) APC at a power setting of 65 W in two sessions (APC; n = 14). If complete elimination of BO was not achieved by the designated treatment, the remaining BO was treated by a maximum of two sessions of APC. RESULTS: Mean endoscopic reduction of BO at six weeks was 51% (range 20-100%) in the PDT100 group, 86% (range 0-100%) in the PDT20+100 group, and 93% (range 40-100%) in the APC group (PDT100 v PDT20+100, p<0.005; PDT100 v APC, p<0.005; and PDT20+100 v APC, NS) with histologically complete ablation in 1/13 (8%) patients in the PDT100 group, 4/12 (33%) in the PDT20+100 group, and 5/14 (36%) in the APC group (NS). Remaining BO was additionally treated with APC in 23/40 (58%) patients. Histological examination at 12 months revealed complete ablation in 9/11 (82%) patients in the PDT100 group, in 9/10 (90%) patients in the PDT20+100 group, and in 8/12 (67%) patients in the APC group (NS). At 12 months, no dysplasia was detected. Side effects (that is, pain (p<0.01), and nausea and vomiting (p<0.05)) and elevated liver transaminases (p<0.01) were more common after PDT than APC therapy. One patient died three days after treatment with PDT, presumably from cardiac arrhythmia. CONCLUSION: APC alone or ALA-PDT in combination with APC can lead to complete reversal of Barrett's epithelium in at least two thirds of patients when administered in multiple treatment sessions. As the goal of treatment should be complete reversal of Barrett's epithelium, we do not recommend these techniques for the prophylactic ablation of BO.