Preferential accumulation of 5-aminolevulinic acid-induced protoporphyrin IX in breast cancer: a comprehensive study on six breast cell lines with varying phenotypes

We describe the potential of 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence as a source of contrast for margin detection in commonly diagnosed breast cancer subtypes. Fluorescence intensity of PpIX in untreated and ALA-treated normal mammary epithelial and breast cancer cell lines of varying estrogen receptor expression were quantitatively imaged with confocal microscopy. Percentage change in fluorescence intensity integrated over 610-700 nm (attributed to PpIX) of posttreated compared to pretreated cells showed statistically significant differences between four breast cancer and two normal mammary epithelial cell lines. However, a direct comparison of post-treatment PpIX fluorescence intensities showed no differences between breast cancer and normal mammary epithelial cell lines due to confounding effects by endogenous fluorescence from flavin adenine dinucleotide (FAD). Clinically, it is impractical to obtain pre- and post-treatment images. Thus, spectral imaging was demonstrated as a means to remove the effects of endogenous FAD fluorescence allowing for discrimination between post-treatment PpIX fluorescence of four breast cancer and two normal mammary epithelial cell lines. Fluorescence spectral imaging of ALA-treated breast cancer cells showed preferential PpIX accumulation regardless of malignant phenotype and suggests a useful contrast mechanism for discrimination of residual cancer at the surface of breast tumor margins.

Noninvasive monitoring of tissue hemoglobin using UV-VIS diffuse reflectance spectroscopy: a pilot study

We conducted a pilot study on 10 patients undergoing general surgery to test the feasibility of diffuse reflectance spectroscopy in the visible wavelength range as a noninvasive monitoring tool for blood loss during surgery. Ratios of raw diffuse reflectance at wavelength pairs were tested as a first-pass for estimating hemoglobin concentration. Ratios can be calculated easily and rapidly with limited post-processing, and so this can be considered a near real-time monitoring device. We found the best hemoglobin correlations were when ratios at isosbestic points of oxy- and deoxyhemoglobin were used, specifically 529/500 nm. Baseline subtraction improved correlations, specifically at 520/509 nm. These results demonstrate proof-of-concept for the ability of this noninvasive device to monitor hemoglobin concentration changes due to surgical blood loss. The 529/500 nm ratio also appears to account for variations in probe pressure, as determined from measurements on two volunteers.

A robust Monte Carlo model for the extraction of biological absorption and scattering in vivo

We have a toolbox to quantify tissue optical properties that is composed of specialized fiberoptic probes for UV-visible diffuse reflectance spectroscopy and a fast, scalable inverse Monte Carlo (MC) model. In this paper, we assess the robustness of the toolbox for quantifying physiologically relevant parameters from turbid tissue-like media. In particular, we consider the effects of using different instruments, fiberoptic probes, and instrument-specific settings for a wide range of optical properties. Additionally, we test the quantitative accuracy of the inverse MC model for extracting the biologically relevant parameters of hemoglobin saturation and total hemoglobin concentration. We also test the effect of double-absorber phantoms (hemoglobin and crocin to model the absorption of hemoglobin and beta carotene, respectively, in the breast) for a range of absorption and scattering properties. We include an assessment on which reference phantom serves as the best calibration standard to enable accurate extraction of the absorption and scattering properties of the target sample. We found the best reference-target phantom combinations to be ones with similar scattering levels. The results from these phantom studies provide a set of guidelines for extracting optical parameters from clinical studies.

A strategy for quantitative spectral imaging of tissue absorption and scattering using light emitting diodes and photodiodes

A diffuse reflectance spectroscopy system was modified as a step towards miniaturization and spectral imaging of tissue absorption and scattering. The modified system uses a tunable source and an optical fiber for illumination and a photodiode in contact with tissue for detection. Compared to the previous system, it is smaller, less costly, and has comparable performance in extracting optical properties in tissue phantoms. Wavelength reduction simulations show the feasibility of replacing the source with LEDs to further decrease system size and cost. Simulated crosstalk analysis indicates that this evolving system can be multiplexed for spectral imaging in the future.

Cost-effective diffuse reflectance spectroscopy device for quantifying tissue absorption and scattering in vivo

A hybrid optical device that uses a multimode fiber coupled to a tunable light source for illumination and a 2.4-mm photodiode for detection in contact with the tissue surface is developed as a first step toward our goal of developing a cost-effective, miniature spectral imaging device to map tissue optical properties in vivo. This device coupled with an inverse Monte Carlo model of reflectance is demonstrated to accurately quantify tissue absorption and scattering in tissue-like turbid synthetic phantoms with a wide range of optical properties. The overall errors for quantifying the absorption and scattering coefficients are 6.0+/-5.6 and 6.1+/-4.7%, respectively. Compared with fiber-based detection, having the detector right at the tissue surface can significantly improve light collection efficiency, thus reducing the requirement for sophisticated detectors with high sensitivity, and this design can be easily expanded into a quantitative spectral imaging system for mapping tissue optical properties in vivo.

Diffuse reflectance spectroscopy with a self-calibrating fiber optic probe

Calibration of the diffuse reflectance spectrum for instrument response and time-dependent fluctuation as well as interdevice variations is complicated, time consuming, and potentially inaccurate. We describe a novel fiber optic probe with a real-time self-calibration capability that can be used for tissue optical spectroscopy. The probe was tested in a number of liquid phantoms over a relevant range of tissue optical properties. Absorption and scattering coefficients are extracted with an average absolute error and standard deviation of 6.9%+/-7.2% and 3.5%+/-1.5%, respectively.

Breast cancer detection using neutron stimulated emission computed tomography: prominent elements and dose requirements

Neutron stimulated emission computed tomography (NSECT) is being developed to noninvasively determine concentrations of trace elements in biological tissue. Studies have shown prominent differences in the trace element concentration of normal and malignant breast tissue. NSECT has the potential to detect these differences and diagnose malignancy with high accuracy with dose comparable to that of a single mammogram. In this study, NSECT imaging was simulated for normal and malignant human breast tissue samples to determine the significance of individual elements in determining malignancy. The normal and malignant models were designed with different elemental compositions, and each was scanned spectroscopically using a simulated 2.5 MeV neutron beam. The number of incident neutrons was varied from 0.5 million to 10 million neutrons. The resulting gamma spectra were evaluated through receiver operating characteristic (ROC) analysis to determine which trace elements were prominent enough to be considered markers for breast cancer detection. Four elemental isotopes (133Cs, 81Br, 79Br, and 87Rb) at five energy levels were shown to be promising features for breast cancer detection with an area under the ROC curve (A(Z)) above 0.85. One of these elements--87Rb at 1338 keV--achieved perfect classification at 10 million incident neutrons and could be detected with as low as 3 million incident neutrons. Patient dose was calculated for each gamma spectrum obtained and was found to range from between 0.05 and 0.112 mSv depending on the number of neutrons. This simulation demonstrates that NSECT has the potential to noninvasively detect breast cancer through five prominent trace element energy levels, at dose levels comparable to other breast cancer screening techniques.

Introduction to neutron stimulated emission computed tomography

Neutron stimulated emission computed tomography (NSECT) is presented as a new technique for in vivo tomographic spectroscopic imaging. A full implementation of NSECT is intended to provide an elemental spectrum of the body or part of the body being interrogated at each voxel of a three-dimensional computed tomographic image. An external neutron beam illuminates the sample and some of these neutrons scatter inelastically, producing characteristic gamma emission from the scattering nuclei. These characteristic gamma rays are acquired by a gamma spectrometer and the emitting nucleus is identified by the emitted gamma energy. The neutron beam is scanned over the body in a geometry that allows for tomographic reconstruction. Tomographic images of each element in the spectrum can be reconstructed to represent the spatial distribution of elements within the sample. Here we offer proof of concept for the NSECT method, present the first single projection spectra acquired from multi-element phantoms, and discuss potential biomedical applications.

[Clinical features of cerebral toxoplasmosis in Cuban patients with AIDS]

INTRODUCTION

Neurotoxoplasmosis (NTX) is one of the commonest opportunist infections in patients infected by the human immunodeficiency virus. It presents with a variety of clinical features in the immunocompromised patient.

PATIENTS AND METHODS

We made a horizontal retrospective descriptive study of 88 patients with a diagnosis of NTX treated in the Pedro Kour Institute during a three years period. Our aim was to find which were the most common forms of clinical presentation in our setting and to evaluate the use of paraclinical examinations in reaching the presumptive diagnosis. The patients had clinical examinations, CSF studies, detection of indirect immunofluorescence titres (IFI) for Toxoplasma, imaging studies (CAT) and lymphocyte counts.

RESULTS

The commonest symptoms were: headache in 79%, fever in 55.68%, motor defect in 44.31% and disorders of consciousness in 29.54% of the patients. The IFI titres were negative in 31.54% of the patients, between 1/16 and 1/32 in 38.34% and between 1/64 and 1/1,024 in only 30.07% of cases. The T CD4+ lymphocyte count was less than 200 cells in 66.7% of the patients; 72% of imaging studies showed typical lesions, in association with other disorders in 38% of the cases (lymphomas, cryptococcosis, tuberculous meningoencephalitis and cytomegalovirus encephalitis).

CONCLUSIONS

NTX in a patient with AIDS often presents in our setting with headache and fever, motor deficit and alterations of consciousness. The diagnosis should be confirmed by immunological or imaging studies since in this disease serology and CSF studies are less specific.

The use of carbamazepine to treat benzodiazepine withdrawal in a geriatric population

Rapid withdrawal of short to intermediate half-life benzodiazepines may be hazardous, particularly in the elderly. The use of carbamazepine to facilitate withdrawal has been reported in younger patients. We describe four elderly patients (average age, 72.5 years) who had each experienced at least one unsuccessful attempt at alprazolam withdrawal and who were subsequently successfully withdrawn via the use of carbamazepine over a period ranging from 2 to 6 days. These geriatric patients experienced no major withdrawal symptoms, but mild symptoms were common. There was no correlation between dose or duration of alprazolam use and extent of withdrawal symptoms. We recommend use of this treatment regimen in a hospital setting only, where close monitoring can occur.