In vivo quantification of photosensitizer fluorescence in the skin-fold observation chamber using dual-wavelength excitation and NIR imaging

A major challenge in biomedical optics is the accurate quantification of in vivo fluorescence images. Fluorescence imaging is often used to determine the pharmacokinetics of photosensitizers used for photodynamic therapy. Often, however, this type of imaging does not take into account differences in and changes to tissue volume and optical properties of the tissue under interrogation. To address this problem, a ratiometric quantification method was developed and applied to monitor photosensitizer meso-tetra (hydroxyphenyl) chlorin (mTHPC) pharmacokinetics in the rat skin-fold observation chamber. The method employs a combination of dual-wavelength excitation and dualwavelength detection. Excitation and detection wavelengths were selected in the NIR region. One excitation wavelength was chosen to be at the Q band of mTHPC, whereas the second excitation wavelength was close to its absorption minimum. Two fluorescence emission bands were used; one at the secondary fluorescence maximum of mTHPC centered on 720 nm, and one in a region of tissue autofluorescence. The first excitation wavelength was used to excite the mTHPC and autofluorescence and the second to excite only autofluorescence, so that this could be subtracted. Subsequently, the autofluorescence-corrected mTHPC image was divided by the autofluorescence signal to correct for variations in tissue optical properties. This correction algorithm in principle results in a linear relation between the corrected fluorescence and photosensitizer concentration. The limitations of the presented method and comparison with previously published and validated techniques are discussed

The status of in vivo autofluorescence spectroscopy and imaging for oral oncology

Autofluorescence spectroscopy and imaging have been studied for the early detection and classification of (pre)malignancies of the oral mucosa. In the present review we will give an overview of the literature on autofluorescence imaging and spectroscopy for various clinical questions. From the studies performed so far we hope to conclude whether autofluorescence spectroscopy and imaging are helpful in the diagnosis of lesions of the oral mucosa, and if this is the case: for which clinical questions they are suitable. A strong emphasis is put on in vivo human studies of the oral mucosa. (C) 2004 Elsevier Ltd. All rights reserved

Effects of individual characteristics on healthy oral mucosa autofluorescence spectra

Autofluorescence spectroscopy is a tool. for detecting tissue alterations in vivo. In a previous study, we found spectral differences between clinically normal mucosa of different patient groups. These are possibly caused by associated patient characteristics. In the present study, we explore the influences of volunteer characteristics on healthy oral mucosa autofluorescence. Autofluorescence spectra were recorded in 96 volunteers with no clinically observable oral lesions. We applied principal components analysis to extract the relevant information. We used multivariate linear regression techniques to estimate the effect of volunteer characteristics on principal component scores. Statistically significant differences were found for all factors but age. Skin color strongly affected autofluorescence intensity. Gender differences were found in blood absorption. Alcohol consumption was associated with porphyrin-like peaks. However, all differences but those associated with skin color were of the same order of magnitude as standard deviations within categories. The effects of volunteer characteristics on autofluorescence spectra of the oral mucosa are measurable. Only the effects of skin color were large. Therefore, in lesion classification, skin color should be taken into account. (C) 2004 Elsevier Ltd. All rights reserved

Optical detection of (pre-)malignant lesions of the oral mucosa:autofluorescence characteristics of healthy mucosa

Previous clinical results demonstrate the potential of in vivo autofluorescence spectroscopy for early detection of (pre-)malignant lesions of the oral mucosa. For reliable diagnosis, it is necessary to study auto fluorescence spectra of healthy mucosa first. We measured excitation-emission maps in healthy subjects and subjects with a history of cancer in the head-neck region. Our results show that different anatomical locations produce distinct autofluorescence spectra. Influences of, among others, smoking and drinking habits require further investigation

Upper cervical intramedullary spinal metastasis of ovarian carcinoma: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Currently there is no generalized approach to treating patients with intra-medullary spinal metastasis. High cervical spinal cord lesions can be particularly challenging cases, and may even be considered inoperable by some.</p> <p>Case report</p> <p>We present what is, to the best of our knowledge, the first reported case of ovarian carcinoma (managed primarily with surgery) in a 65-year-old Caucasian woman metastasizing to the upper cervical spinal cord; we also review the relevant literature and discuss management strategies.</p> <p>Conclusions</p> <p>Due to improving systemic cancer therapies, patients with cancer now often survive longer and are more likely to develop central nervous system metastases. Therefore, neurosurgical oncologists are often challenged with difficult decisions about how to surgically manage these patients. We recommend individualized multidisciplinary management based on patient functional status, the need for definitive diagnosis for possible additional adjuvant therapies, and consideration of extent of systemic disease impacting on desirable quality and length of survival.</p

Autofluorescence and diffuse reflectance spectroscopy for oral oncology

Background and Objectives: Autofluorescence and diffuse reflectance spectroscopy have been used separately and combined for tissue diagnostics. Previously, we assessed the value of autofluorescence spectroscopy for the classification of oral (pre-)malignancies. In the present study, we want to determine the contributions of diffuse reflectance and autofluorescence spectroscopy to diagnostic performance. Study Design/Materials and Methods: Autofluorescence and diffuse reflectance spectra were recorded from 172 oral lesions and 70 healthy volunteers. Autofluorescence, spectra were corrected in first order for blood absorption effects using diffuse reflectance spectra. Principal Components Analysis (PCA) with various classifiers was applied to distinguish (1) cancer and (2) all lesions from healthy oral mucosa, and (3) dysplastic and malignant lesions from benign lesions. Autofluorescence and diffuse reflectance spectra were evaluated separately and combined. Results: The classification of cancer versus healthy mucosa gave excellent results for diffuse reflectance as well as corrected autofluorescence (Receiver Operator Characteristic (ROC) areas up to 0.98). For both autofluorescence and diffuse reflectance spectra, the classification of lesions versus healthy mucosa was successful (ROC areas up to 0.90). However, the classification of benign and (pre-)malignant lesions was not successful for raw or corrected autofluorescence spectra (ROC areas <0.70). For diffuse reflectance spectra, the results were slightly better (ROC areas up to 0.77). Conclusions: The results for plain and corrected autofluorescence as well as diffuse reflectance spectra were similar. The relevant information for distinguishing lesions from healthy oral mucosa is probably sufficiently contained in blood absorption and scattering information, as well as in corrected autofluorescence. However, neither type of information is capable of distinguishing benign from dysplastic and malignant lesions. Combining autofluorescence and reflectance only slightly improved the results. (c) 2005 Wiley-Liss, Inc

Autofluorescence and Raman microspectroscopy of tissue sections of oral lesions

Autofluorescence spectroscopy and Raman spectroscopy have been suggested for lesion diagnostics. We investigate the information contained in autofluorescence and Raman spectra recorded from oral tissue slices of various lesion types. Thirty-seven human oral mucosa lesions were biopsied and freeze-dried. Complete autofluorescence images and spectra were recorded from 20 mu m sections. Raman spectra were acquired from the same positions for 12 of the sections. Cluster analysis was applied to find any relationship between spectral shape and lesion type or cell layer. Autofluorescence images showed high intensities for keratin layers and connective tissue, but hardly any for the epithelium. Autofluorescence spectra were centered around 520 nm and did not show specific spectral features. No clustering with regard to lesion type or cell layer was observed. Raman spectra allowed for reliable classification into cell layers, but differences between lesion types were not significant in this study. Autofluorescence spectra of freeze-dried oral mucosa sections did not contain useful information. A more comprehensive study is required for Raman spectra