Steady-state total diffuse reflectance with an exponential decaying source

The increasing preclinical and clinical utilization of digital cameras for photographic measurements of tissue conditions motivates the study of reflectance measurements obtained with planar illumination. We examine herein a formula that models the total diffuse reflectance measured from a semi-infinite medium using an exponentially decaying source, assuming continuous plane wave epi-illumination. The model is validated with experimental reflectance measurements from tissue mimicking phantoms. The need for adjusting the blood absorption spectrum due to pigment packaging is discussed along with the potential applications of the proposed formulation.This research PBGA was supported in part by a Marie Curie Intra European Fellowship within the 7th European Community Framework Program. J. R. acknowledges a Marie Curie CIG grant

Tackling standardization in fluorescence molecular imaging.

The emerging clinical use of targeted fluorescent agents heralds a shift in intraoperative imaging practices that overcome the limitations of human vision. However, in contrast to established radiological methods, no appropriate performance specifications and standards have been established in fluorescence molecular imaging. Moreover, the dependence of fluorescence signals on many experimental parameters and the use of wavelengths ranging from the visible to short-wave infrared (400–1,700 nm) complicate quality control in fluorescence molecular imaging. Here, we discuss the experimental parameters that critically affect fluorescence molecular imaging accuracy, and introduce the concept of high-fidelity fluorescence imaging as a means for ensuring reliable reproduction of fluorescence biodistribution in tissue

Robust overlay schemes for the fusion of fluorescence and color channels in biological imaging.

ABSTRACT. Molecular fluorescence imaging is a commonly used method in various biomedical fields and is undergoing rapid translation toward clinical applications. Color images are commonly superimposed with fluorescence measurements to provide orientation, anatomical information, and molecular tissue properties in a single image. New adaptive methods that produce a more robust composite image than conventional lime green alpha blending are presented and demonstrated herein. Moreover, visualization through temporal changes is showcased as an alternative for real-time imaging systems

RENAL INVOLVEMENT IN SICKLE CELL-BETA THALASSEMIA

Renal function studies were performed in 41 patients with sickle cell-beta thalassaemia (S/b thal) and compared to 14 normal controls and 8 sickle cell (SS) patients. Polyuria, hyposthenuria and mild proteinuria were common in both S/b thal and SS patients. A renal concentrating defect was manifest in all patients studied, and in 4 of the 7 S/b thal patients tested, an abnormal acidification test was found. A statistically significant negative correlation (n = 19, r = -0.48. p < 0.05) was noted between creatinine clearance (CCr) and age for the patients over 30 years. There was no correlation between hemoglobin and CCr; on the contrary, a statistically significant negative correlation was found between CCr and hemoglobin F (n = 29, r = -0.428, p < 0.05) Our S/b thal and SS patients showed a decreased daily excretion of sodium, calcium, phosphate and magnesium and lower serum magnesium levels than the controls. One third of the S/b thal patients showed hyperuricosuria, and a statistically significant negative correlation was noted between serum uric acid and its fractional excretion in all S/b thal patients (n = 41, r = -0.450, p < 0.01). Serum phosphate levels were independent of age. A statistically significant positive correlation was found between the tubular reabsorptive capacity for phosphate and the number of painful crises per year (n = 33, r = 0.836, p < 0.001). We conclude that renal involvement in the double heterozygous state is as severe as in homozygous sickle cell disease

Pushing the optical Imaging limits of cancer with multi-frequency-band Raster-Scan Optoacoustic Mesoscopy (RSOM).

Angiogenesis is a central cancer hallmark, necessary for supporting tumor growth and metastasis. In vivo imaging of angiogenesis is commonly applied, to understand dynamic processes in cancer development and treatment strategies. However, most radiological modalities today assess angiogenesis based on indirect mechanisms, such as the rate of contrast enhancement after contrast agent administration. We studied the performance of raster-scan optoacoustic mesoscopy (RSOM), to directly reveal the vascular network supporting melanoma growth in vivo, at 50 MHz and 100 MHz, through several millimeters of tumor depth. After comparing the performance at each frequency, we recorded, for the first time, high-resolution images of melanin tumor vasculature development in vivo, over a period of several days. Image validation was provided by means of cryo-slice sections of the same tumor after sacrificing the mice. We show how optoacoustic (photoacoustic) mesoscopy reveals a potentially powerful look into tumor angiogenesis, with properties and features that are markedly different than other radiological modalities. This will facilitate a better understanding of tumor's angiogenesis, and the evaluation of treatment strategies

Imaging melanin cancer growth <em>in-vivo</em> using Raster-Scan Optoacoustic Mesoscopy (RSOM) at 50 MHz and 100 MHz .

We used raster-scan optoacoustic mesoscopy (RSOM) at 50 MHz, and at 100 MHz, to monitor tumor growth, and tumor angiogenesis, which is a central hallmark of cancer, in-vivo. In this study we compared the performance, and the effect of the 50 MHz, and the 100 MHz frequencies on the quality of the final image. The system is based on a reflection-mode implementation of RSOM. The detectors used are custom made, ultrawideband, and spherically focused. The use of such detectors enables light coupling from the same side as the detector, thus reflection-mode. Light is in turn coupled using a fiber bundle, and the detector is raster scanned in the xy-plane. Subsequently, to retrieve small features, the raw data are reconstructed using a multi-bandwidth, beamforming reconstruction algorithm. Comparison of the system performance at the different frequencies shows as expected a higher resolution in case of the 100 MHz detector compared to the 50 MHz. On the other hand the 50 MHz has a better SNR, can detect features from deeper layers, and has higher angular acceptance. Based on these characteristics the 50 MHz detector was mostly used. After comparing the performance we monitored the growth of B16F10 cells, melanin tumor, over the course of 9 days. We see correspondence between the optoacoustic measurements and the cryoslice validations. Additionally, in areas close to the tumor we see sprouting of new vessels, starting at day 4-5, which corresponds to tumor angiogenesis

Artifact-free deconvolution in light field microscopy.

The sampling patterns of the light field microscope (LFM) are highly depth-dependent, which implies non-uniform recoverable lateral resolution across depth. Moreover, reconstructions using state-of-the-art approaches suffer from strong artifacts at axial ranges, where the LFM samples the light field at a coarse rate. In this work, we analyze the sampling patterns of the LFM, and introduce a flexible light field point spread function model (LFPSF) to cope with arbitrary LFM designs. We then propose a novel aliasing-aware deconvolution scheme to address the sampling artifacts. We demonstrate the high potential of the proposed method on real experimental data

Serial sectioning and mulstispectral imaging system for versatile biomedical applications.

Serial sectioning combined with microscopy provides high resolution volumetric data to complement in-vivo imaging modalities and aid ex-vivo diagnostics. We describe the design of a fully-automated cryomicrotome combined with a multispectral reflection and fluorescence imaging system that enables high-throughput analyses of biological specimens with a large field of view and cellular resolution while keeping the manufacturing and running costs low. We show the performance of the system for representative applications in high-resolution volumetric imaging of reporter animals and multispectral tissue analysis. Furthermore, we demonstrate the versatility of the economical imaging system in applications such as in vivo epifluorescence imaging, histology slide scanning, cell counting and gel electrophoresis documentation