DOT corrected fluorescence molecular tomography using targeted contrast agents for small animal tumor imaging.

PURPOSE: To demonstrate diffuse optical tomography (DOT) corrected fluorescence molecular tomography (FMT) for quantitatively imaging tumor-targeted contrast agents in a 4T1 mouse mammary tumor model. PROCEDURES: In the first set of experiments, we validated our DOT corrected FMT method using subcutaneously injected 4T1 cells pre-labeled with a near-infrared (NIR) Cy 5.5 dye labeled recombinant amino-terminal fragment (ATF) of the receptor binding domain of urokinase plasminogen activator (uPA), which binds to uPA receptor (uPAR) that is highly expressed in breast cancer tissues. Next, we apply the DOT corrected FMT method to quantitatively evaluate the ability of sensitive tumor imaging after systemic delivery of new uPAR-targeted optical imaging probes in the mice bearing 4T1 mammary tumors. These uPAR-targeted optical imaging probes are ATF peptides labeled with a newly developed NIR-830 dye being conjugated to magnetic iron oxide nanoparticles (IONPs). RESULTS: Our results have shown that DOT corrected FMT can accurately quantify and localize the injected imaging probe labeled 4T1 cells. Following systemic delivery of the targeted imaging nanoprobes into the mice bearing orthotopic mammary tumors, specific accumulation of the imaging probes in the orthotopic mammary tumors was detected in the mice that received uPAR targeted NIR-830-ATF-IONP probes but not in the mice injected with non-targeted NIR-830-mouse serum albumin (MSA)-IONPs. Additionally, DOT corrected FMT also enables the detection of both locally recurrent tumor and lung metastasis in the mammary tumor model 72 hrs after systemic administration of the uPAR-targeted NIR-830-labeled ATF peptide imaging probes. CONCLUSIONS: DOT corrected FMT and uPAR-targeted optical imaging probes have great potential for detection of breast cancer, recurrent tumor and metastasis in small animals.

Quantitative bioluminescence tomography guided by diffuse optical tomography.

We present for the first time experimental evidence that the quantitative accuracy of bioluminescence tomography (BLT) can be significantly improved by incorporating prior spatial distribution of optical properties of heterogeneous media obtained from diffuse optical tomography (DOT). A series of experiments were conducted using a CCD-based scanning system where millimeter-size bioluminescent targets were embedded in a 3 x 3 x 5 cm optically heterogeneous scattering medium. The results show that the BLT images with the recovered optical property distribution in place are considerably better reconstructed compared to that without such prior information, in terms of the location, size and source strength of the targets.

DOT guided fluorescence molecular tomography of arbitrarily shaped objects.

The authors demonstrate an approach for truly quantitative three-dimensional fluorescence molecular tomography (FMT) of arbitrarily shaped objects where the distribution of optical properties is obtained using diffuse optical tomography (DOT). The method is tested and evaluated using phantom geometries mimicking mouse anatomic structures. The experiments were conducted using the authors' optical-fiber-free, multiangle transmission system. The results indicate that with the knowledge of optical property distribution, the accuracy of the recovered fluorophore absorption coefficient (mu(a(x-->m of indocyanine green is improved significantly over that without such a priori information using the authors' finite element reconstruction approach. In particular, the absolute value of mu(a(x-->m)) from their DOT guided FMT is quantitatively consistent with that obtained with spectroscopic methods.

Biosensor for the determination of sorbitol based on molecularly imprinted electrosynthesized polymers.

Despite the increasing number of applications of biosensors in many fields, the construction of a steady biosensor remains still challenging. The high selectivity and stability of molecularly imprinted polymers for the template molecule make them ideal alternatives as recognition elements for sensors. In this work, the fabrication and characterization of biosensor based on molecularly imprinted electrosynthesized polymers is reported as the first case of imprinting sorbitol. A relevant molecularly imprinted film is prepared by o-phenylenediamine (o-PD) using the electrochemical method. Quartz crystal microbalance is employed as a sensitive apparatus of biosensor for the determination of sorbitol. An equation is deduced to characterize the interaction between molecularly imprinted films and the template. A linear relationship between the frequency shift and the concentration of analyte in the range of 1-15 mM was found. The detection limit is about 1mM.

In vivo monitoring of stem cells in Drosophila pupae using the radiative transfer equation-based fluorescence molecular tomography.

PURPOSE: The aim of this study is to realize in vivo monitoring of DSRed-expressing cell distribution in Drosophila pupae using fluorescence molecular tomography (FMT). PROCEDURES: The radiative transfer equation (RTE)-based FMT reconstruction algorithm is implemented using finite element method for mesoscopic- or millimeter-scale imaging. The RTE algorithm is validated using both simulated and phantom experimental data. For the in vivo experiments, DsRed fluorescent reporter was inserted into the middle of irradiation-responsive enhancer region (IRER) of Drosophila pupae and expressed only in IRER-open cells. RESULTS: Quantitatively accurate fluorescence images can be reconstructed from both simulated and phantom data. The in vivo images obtained agree well with the in vitro images obtained from confocal microscopy both qualitatively and semi-quantitatively. CONCLUSION: DsRed-bearing stem cells in Drosophila pupae can be markedly imaged using our FMT approach. This study suggests that the technique described can be used for dynamic in vivo monitoring of biological events in mesoscopic-scale animals and facilitates basic biologic research such as genetics, epigenetics, and stem cells.

An optical reflected device using a molecularly imprinted polymer film sensor.

A novel and highly selective optical sensor with molecularly imprinted polymer (MIP) film was fabricated and investigated. The optical sensor head employing a medium finesse molecularly imprinted polymer film has been fabricated and characterised. A blank polymer and formaldehyde imprinted polymer were using methacrylic acid as the functional monomer and the ethylene glycol dimethacrylate as a crosslinker. The transduction mechanism is discussed based on the changes of optical intensity of molecularly imprinted polymer film acting as an optical reflected sensor. Template molecules, which diffused into MIP, could cause film density, and refractive index change, and then induce measurable optical reflective intensity shifts. Based on the reflective intensity shifts, an optical reflection detection of formaldehyde was achieved by illuminating MIP with a laser beam. For the same MIP, the reflective intensity shift was proportional to the amount of template molecule. This optical sensor, based on an artificial recognition system, demonstrates long-time stability and resistance to harsh chemical environments. As the research moves forward gradually, we establish the possibilities of quantitative analysis primly, setting the groundwork to the synthesis of the molecular imprinted optical fiber sensor. The techniques show good reproducibility and sensitivity and will be of significant interest to the MIP community.

Diffuse optical tomography guided quantitative fluorescence molecular tomography.

We describe a method that combines fluorescence molecular tomography (FMT) with diffuse optical tomography (DOT), which allows us to study the impact of heterogeneous optical property distribution on FMT, an issue that has not been systemically studied. Both numerical simulations and phantom experiments were performed based on our finite-element reconstruction algorithms. The experiments were conducted using a noncontact optical fiber free, multiangle transmission system. In both the simulations and experiments, a fluorescent target was embedded in an optically heterogeneous background medium. The simulation results clearly suggest the necessity of considering the absorption coefficient (mu(a)) and reduced scattering coefficient (mu'(s)) distributions for quantitatively accurate FMT, especially in terms of the accuracy of reconstructed fluorophore absorption coefficient (mu(a(x-->m))). Subsequent phantom experiments with an indocyanine green (ICG)-containing target confirm the simulation findings. In addition, we performed a series of phantom experiments with low ICG concentration (0.1, 0.2, 0.4, 0.6 and 1.0 microM) in the target to systematically evaluate the quantitative accuracy of our FMT approach. The results indicate that, with the knowledge of optical property distribution, the accuracy of the recovered fluorophore concentration is improved significantly over that without such a priori information. In particular absolute value of mu(a(x-->m) ) from our DOT guided FMT are quantitatively consistent with that obtained using spectroscopic methods.

Auto-analysis system for graphite morphology of grey cast iron.

The current method to classify graphite morphology types of grey cast iron is based on traditional subjective observation, and it cannot be used for quantitative analysis. Since microstructures have a great effect on the mechanical properties of grey cast iron and different types have totally different characters, six types of grey cast iron are discussed and an image-processing software subsystem that performs the classification and quantitative analysis automatically based on a kind of composed feature vector and artificial neural network (ANN) is described. There are three kinds of texture features: fractal dimension, roughness and two-dimension autoregression, which are used as an extracted feature input vector of ANN classifier. Compared with using only one, the checkout correct precision increased greatly. On the other hand, to achieve the quantitative analysis and show the different types clearly, the region segmentation idea was applied to the system. The percentages of the regions with different type are reported correctly. Furthermore, this paper tentatively introduces a new empirical method to decide the number of ANN hidden nodes, which are usually considered as a difficulty in ANN structure decision. It was found that the optimum hidden node number of the experimental data was the same as that obtained using the new method.