The interactions of single-stranded DNA (ssDNA) immobilized on gold electrodes with hexammine ruthenium(III) (RuHex) and hexammine cobalt(III) (CoHex) were investigated with chronocoulometric and electrochemical quartz crystal microbalance experiments. The modified surfaces were created by immobilizing ssDNA with tris(dithioserinol) linkers to form a compact, self-assembled monolayer, followed by passivation with 6-mercapto-1-hexanol (MCH). Upon addition of the redox indicator during a potential jump for RuHex and CoHex, we observed a dramatic increase in the frequency response in comparison to the signal observed with only low-ionic-strength hybridization buffer, 10 mM tris(hydroxymethyl)-aminomethane (Tris)/H2SO4 (pH7.4). RuHex and CoHex responded quite differently, even on a millisecond time scale. As the expected mass change is less than a factor of 35 to the observed frequency response, we concluded that the applied potential jumps lead to switching of the DNA layer viscoelasticity.

An optical imaging system is presented for preclinical bioluminescence/fluorescence imaging. By employing microlens arrays and specific electronics, the OI insert has been constructed to be MRI compatible, and be paired with an RF volume resonator.

ClearPEM-Sonic is an innovative imaging device specifically developed for breast cancer. The possibility to work in PEM-Ultrasound multimodality allows to obtain metabolic and morphological information increasing the specificity of the exam. The ClearPEM detector is developed to maximize the sensitivity and the spatial resolution as compared to Whole-Body PET scanners. It is coupled with a 3D ultrasound system, the SuperSonic Imagine Aixplorer that improves the specificity of the exam by providing a tissue elasticity map. This work describes the ClearPEM-Sonic project focusing on the technological developments it has required, the technical merits (and limits) and the first multimodal images acquired on a dedicated phantom. It finally presents selected clinical case studies that confirm the value of PEM information.

The ClearPEM-Sonic is a multimodal system dedicated to mammography, capable of providing co-registered metabolic, anatomical and structural information through combination of positron emission tomography with ultrasound elastographic imaging. The project is aimed to improve early stage detection of breast cancer through the high-resolution and high-sensitivity metabolic information provided by PEM, and the high-resolution anatomic information from US. Further improvements in the specificity of the system is provided by the ability to rule out non-cancerous findings from PEM, taking advantage of elastography imaging information. The ClearPEM-Sonic has been developed by the Crystal Clear Collaboration and is currently installed at Hopital Nord, Marseille, in the frame of CERIMED, the European Centre for Research in Medical Imaging. The detector is based on LYSO:Ce crystals, each of 2x2x20 mm3, grouped in 192 matrices of 8x4 crys- tals. BaSO4 is used as coating material and reflector. Read out is performed individually on both 2x2 mm2 faces of each crystal, using avalanche photodiodes (APDs). The detector performance has been thoroughly tested during the commissioning phase, confirming a spatial resolution of 1.5 mm, and a DOI precision of 2 mm. The co-registration software developed has proved to accurately superimpose images coming from the different modalities with a precision better than 2 mm. The clinical trial (phase 1) is being carried out on 20 patients with a known breast lesion who have been injected with FDG for a whole-body PET/CT as part of their diagnostic process. Results are compared to conventional imaging and MRI, with biopsy as a golden standard, to validate the use of ClearPEM-Sonic as a clinical imaging instrument for early detection of breast cancer.

This paper proposes an optical surface reconstruction method from multiview projectional data acquired by a multimodality imaging instrumentation. The technique is adapted for in vivo small animal imaging, specifically imaging of nude mouse in the case where the influence of CT radiation doses should be eliminated. Any potential point within the field-of-view (FOV) of a nude mouse is evaluated by a proposed photo-consistency measure utilizing sensor image information. As the superposition of adjacent projections yields depth information for any point within the FOV, the three dimensional (3D) surface of the imaged object is estimated by a graph-cuts based method through global energy minimization. The reconstructed surface is evaluated by comparing the the reconstructed surface and the CT volume of the nude mouse. The proposed surface reconstruction method demonstrates the feasibility of surface reconstruction from multiview projection, and there are still great possibilities to improve this method.

The Clear-PEM system is a dedicated PET scanner optimized for breast imaging. Because of the limited field-of-view (FOV) and the moderate timing resolution, the imaging results of the system might be degraded by random noise. This noise is more pronounced at the region that is near to the torso, which could cause false-positive or inconclusive diagnostics. Because of the high number of lines of responses (LORs) comparing to the number of acquired coincidences, list-mode reconstruction is required to maintain efficiency and accuracy. A new acquisition strategy is presented in this abstract in order to largely increase the statistics of acquired random events, without the requirement of hardware to collect single counts. During data acquisition, a large coincidence window of 90 ns is set in the readout electronics. All data within this window are collected in list-mode and, afterwards, classified by the acquisition software into prompt counts (0-4 ns), ignored counts (4-20 ns) and random counts (20-90 ns). A smooth correction image is estimated using those collected random counts. Reconstruction is afterwards performed considering the correction image with multiplication of the ratio between coincidence window width and random window width. An experimental study was performed on a breast-torso phantom. Results show that this approach can increase the statistics of recorded random coincidences over 17 folds, leading to a pronounced improvement of random correction effect. Because of the adoption of a 90 ns coincidence trigger in the hardware that can filter out most of the counts, it yields a much less computational burden to the acquisition system in comparison to the correction method using single count rate.

A method for surface recognition is presented whereby surface information is obtained considering multiview images from an MLA detector at a low number of detector projections. Simulated and experimental phantom data are presented.

This paper describes the methodology to design and conduct the performances of a fan beam collimator. This fan beam collimator was designed to use with a multi-modality small animal imaging device and the performance of the collimator was studied for a 3D geometry. Analytical expressions were formulated to calculate the parameters for the collimator. A Monte Carlo model was developed to analyze the scattering and image noises for a 3D object. The results showed that the performance of the fan beam collimator was strongly dependent on the source distribution and position. The fan beam collimator showed increased counting efficiency in comparison to a parallel hole collimator. Inside attenuating medium, the increased attenuating effect outweighed the fan beam increased counting efficiency.

We study light transport in turbid slabs by an angle-resolved transmission measurement technique. Monte Carlo results show two distinct slopes in attenuation curves, contributing to change from ballistic to diffuse regime with increasing slab thickness.

An iterative subtraction method that improves a recently developed mapping algorithm is presented. This approach allows high-resolution image calculation from acquired sensor data of a very flat optical detector assembly based on a microlens array.

This paper reports about the influence of temperature, hybridization time and convection upon the detection of osmium tetroxide bipyridine-labeled target oligonucleotides at rotating gold disk (RDE) and heated low temperature co-fired ceramics (LTCC) gold disk electrodes. We used mixed self-assembled monolayers of hexathiol-linked probe oligonucleotides and mercaptohexanol on the gold surface of the electrodes for the hybridization detection of the labeled targets by means of square-wave voltammetry. Due to protective strands, the osmium tetroxide-modified target strands were still able to hybridize with the immobilized probe strands. The hybridization of such osmium tetroxide bipyridine-modified target strands with thiol-linked probe strands immobilized on gold yielded large reversible square-wave-voltammetric signals. Rotation speed and, hence, mass transport due to convection has only marginal effects. On the other hand, temperature affects greatly the hybridization step as indicated by both heated LTCC electrode in cold and RDE in warm hybridization solution. Calculated detection limits of 3.6 and 3.1 nM targets at the RDE and the LTCC electrode, respectively, have been almost the same at both types of electrodes. Applying an appropriate temperature during hybridization is more important than mechanically enhanced mass transport.