Current Issue
Volume 3 Issue 1 - 2016
Research Article
Matthew Getzin, Lars Gjesteby, Yen-Jun Chuang, Scott A. McCallum, Wenxiang Cong, Zhengwei Pan, Guohao Dai, Shengbai Zhang, and Ge Wang*
CT and MRI are the most widely used imaging modalities in healthcare, each with its own merits and drawbacks. Combining these techniques in one machine could provide synergy among resolution and sensitivity in a single scan, and serve as a unique platform to explore coupling of x-ray excitation and magnetic resonance. Molecular probes such as functionalized nanophosphors present a potential conduit between these modalities. Two experiments were designed such that high energy electromagnetic radiation, in the form of x-ray and UV light, was used to irradiate LiGa5O8:Cr3+ and Gd2O2S:Tb3+ semiconducting nanophosphors (NPs). Although the set-ups of these two experiments are different, the common goal was to measure MRI relaxation parameters of aqueous environments surrounding the irradiated NPs. The trends seen in the LiGa5O8:Cr3+ slurries suggest that a measurable change in T2 may occur after x-ray excitation of the nanophosphors. However, there are several experimental conditions that hinder the clarity of the results, including inter-scan variability likely due to sample instability resulting from the noncolloidal behavior of the nanoparticles over extended periods of time. In the second experimental set-up, efforts were made to control for the particle settling and variability due sample movement. Different yet equally challenging problems were encountered in this experiment, primarily the very small ROI in which parameter changes could be expected. Although we are not making definitive claims as to the MRI modulation effect of irradiated NPs, we would like to make the data available as a reference point for further analyses. Additionally, we would like this report to serve as an inspiration for further exploration into intra-modality signal modulation, especially between x-ray and MR.
Yuan Yuan, Wilfred Ngwa, Yaobo Zhang, Seyeda Yasmin-Karim, Erno Sajo, and Hengyong Yu*
Micro-Computed Tomography (micro-CT) has been widely used as a non-invasive andhigh-resolution imaging modality in preclinical research. However, soft tissues (e.g. tumors) cannot be well distinguished becausetheir densities are similar. To solve this problem, Gold Nanoparticles (AuNPs) are adopted as promising contrast agents since they are high atomic weight contrast agents and can be passively accumulated at the tumor sites. The aim of this study is to evaluate the efficacy of AuNPs as contrast agents using different energy x-rays for an in vivo study. An immune-compromised athymic nude mouse bearing a subcutaneous xenograft model of human lung cancer was imaged by a dual energy micro-CT with circular cone-beam geometry. The selected energies were 45 kVp and 65 kVp. 10g AuNPs (200 g/ml concentration) approximately 12 nm in size were injected subcutaneously into the tumor.The mouse was imaged at 0 hour, 3 hours and 24 hours post-injection. Images were reconstructed by the popular FDK algorithm. Our results show that AuNPs provided obvious greater contrast using 45 kVpx-rays at 0 hour and AuNPs were not clearly shown in the images after 3 hours and longer. The raw datasets provided in this paper can be applied to evaluate other CT reconstruction algorithms and medical image analysis methods.
Mahdieh Moghiseh*, Raja Aamir, Raj K. Panta, Niels de Ruiter, Alex Chernoglazov, Joe L. Healy, Anthony PH Butler, and Nigel G. Anderson
Imaging of biological processes in vivo is the goal of molecular imaging. Multi-energy spectral CT using a photon-counting detector has the potential to enable the imaging and quantification of tissue components, biomarker labels, and pharmaceuticals in order to monitor biological or disease processes. The aim of this study is to provide unprocessed and processed dataset from a spectral CT using Cadmium Telluride (CdTe) assembled Medipix3RX detector in Charge Summing Mode (CSM) so that others can analyse it using their familiar routines. We provide a multi-energy spectral phantom dataset with four energy bins for simultaneous discrimination of various concentrations of four high-Z materials currently used as contrast agents (iodine, gadolinium, and gold and calcium chloride (mimicking bone) in animal and human CT imaging.
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