Segmentation of Pulmonary Vascular Trees from Thoracic 3D CT Images

This paper describes an algorithm for extracting pulmonary vascular trees (arteries plus veins) from three-dimensional (3D) thoracic computed tomographic (CT) images. The algorithm integrates tube enhancement filter and traversal approaches which are based on eigenvalues and eigenvectors of a Hessian matrix to extract thin peripheral segments as well as thick vessels close to the lung hilum. The resultant algorithm was applied to a simulation data set and 44 scans from 22 human subjects imaged via multidetector-row CT (MDCT) during breath holds at 85% and 20% of their vital capacity. A quantitative validation was performed with more than 1000 manually identified points selected from inside the vessel segments to assess true positives (TPs) and 1000 points randomly placed outside of the vessels to evaluate false positives (FPs) in each case. On average, for both the high and low volume lung images, 99% of the points was properly marked as vessel and 1% of the points were assessed as FPs. Our hybrid segmentation algorithm provides a highly reliable method of segmenting the combined pulmonary venous and arterial trees which in turn will serve as a critical starting point for further quantitative analysis tasks and aid in our overall goal of establishing a normative atlas of the human lung

Implantation of a Novel Cryopreserved Viable Osteochondral Allograft for Articular Cartilage Repair in the Knee

Restoration and repair of articular cartilage injuries remain a challenge for orthopaedic surgeons. The standard first-line treatment of articular cartilage lesions is marrow stimulation; however, this procedure can often result in the generation of fibrous repair cartilage rather than the biomechanically superior hyaline cartilage. Marrow stimulation is also often limited to smaller lesions, less than 2 cm2. Larger lesions may require implantation of a fresh osteochondal allograft, though a short shelf life, size-matched donor requirements, potential challenges of bone healing, limited availability, and the relatively high price limit the wide use of this therapeutic approach. We present a straightforward, single-stage surgical technique of a novel reparative and restorative approach for articular cartilage repair with the implantation of a cryopreserved viable osteochondral allograft (CVOCA). The CVOCA contains full-thickness articular cartilage and a thin layer of subchondral bone, and maintains the intact native cartilage architecture with viable chondrocytes, growth factors, and extracellular matrix proteins to promote articular cartilage repair. We report the results of a retrospective case series of three patients who presented with articular cartilage lesions more than 2 cm2 and were treated with the CVOCA using the presented surgical technique. Patients were followed up to 2 years after implantation of the CVOCA and all three patients had satisfactory outcomes without adverse events. Controlled randomized studies are suggested for evaluation of CVOCA efficacy, safety, and long-term outcomes

Development of lung tissue phantoms for bioluminescent imaging

White nylon material was chosen to make cylindrical tissue phantoms for development of bioluminescence tomography techniques. A low-level light source, delivered through an optic fiber of core diameter 200 μm, was placed at different locations on one phantom surface. The light travels through the phantom, reaches the external surface, and is captured by a liquid nitrogen-cooled CCD camera. The scattering, absorption, and anisotropy parameters of the phantom are obtained by matching the measured light transmission profiles to the profiles generated by the TracePro software. The perturbation analysis, with the homogeneous phantoms, demonstrated that the imaging system is sufficiently sensitive to capture intensity change of higher than 0.5nW/cm2 or a location shift of the light source of more than 200 microns. It is observed that the system can distinguish two point light sources with separation of about 2 mm. The perturbation analysis is also performed with the heterogeneous phantom. Based on our data, we conclude that there is inherent tomographic information in bioluminescent measures taken on the external surface of the mouse, which suggests the feasibility of bioluminescence tomography for biomedical research using the small animals, especially the mice

InGaAs PV Device Development for TPV Power Systems

Indium gallium arsenide (InGaAs) photovoltaic devices have been fabricated with bandgaps ranging from 0.75 eV to 0.60 eV on Indium Phosphide (InP) substrates. Reported efficiencies have been as high as 11.2 percent (AMO) for the lattice matched 0.75 eV devices. The 0.75 eV cell demonstrated 14.8 percent efficiency under a 1500 K blackbody with a projected efficiency of 29.3 percent. The lattice mismatched devices (0.66 and 0.60 eV) demonstrated measured efficiencies of 8 percent and 6 percent respectively under similar conditions. Low long wavelength response and high dark currents are responsible for the poor performance of the mismatched devices. Temperature coefficients have been measured and are presented for all of the bandgaps tested

In vivo tomographic imaging based on bioluminescence

The most important task for bioluminescence imaging is to identify the emission source from the captured bioluminescent signal on the surface of a small tested animal. Quantitative information on the source location, geometry and intensity serves for in-vivo monitoring of infectious diseases, tumor growth, metastases in the small animal. In this paper, we present a point-spread function-based method for reconstructing the internal bioluminescent source from the surface light output flux signal. The method is evaluated for sensing the internal emission sources in nylon phantoms and within a live mouse. The surface bioluminescent signal is taken with a highly sensitive CCD camera. The results show the feasibility and efficiency of the proposed point-spread function-based method

Development of lung tissue phantoms for bioluminescent imaging

White nylon material was chosen to make cylindrical tissue phantoms for development of bioluminescence tomography techniques. A low-level light source, delivered through an optic fiber of core diameter 200 μm, was placed at different locations on one phantom surface. The light travels through the phantom, reaches the external surface, and is captured by a liquid nitrogen-cooled CCD camera. The scattering, absorption, and anisotropy parameters of the phantom are obtained by matching the measured light transmission profiles to the profiles generated by the TracePro software. The perturbation analysis, with the homogeneous phantoms, demonstrated that the imaging system is sufficiently sensitive to capture intensity change of higher than 0.5nW/cm2 or a location shift of the light source of more than 200 microns. It is observed that the system can distinguish two point light sources with separation of about 2 mm. The perturbation analysis is also performed with the heterogeneous phantom. Based on our data, we conclude that there is inherent tomographic information in bioluminescent measures taken on the external surface of the mouse, which suggests the feasibility of bioluminescence tomography for biomedical research using the small animals, especially the mice

In vivo tomographic imaging based on bioluminescence

The most important task for bioluminescence imaging is to identify the emission source from the captured bioluminescent signal on the surface of a small tested animal. Quantitative information on the source location, geometry and intensity serves for in-vivo monitoring of infectious diseases, tumor growth, metastases in the small animal. In this paper, we present a point-spread function-based method for reconstructing the internal bioluminescent source from the surface light output flux signal. The method is evaluated for sensing the internal emission sources in nylon phantoms and within a live mouse. The surface bioluminescent signal is taken with a highly sensitive CCD camera. The results show the feasibility and efficiency of the proposed point-spread function-based method