Browsing by Subject "Contrast agent"

Now showing 1 - 3 of 3

Open Access
High‐resolution MRI of deep‐seated atherosclerotic arteries using motexafin gadolinium
(John Wiley & Sons, Inc., 2008) Brushett, C.; Qiu, B.; Atalar, Ergin; Yang, X.
Purpose: To evaluate the potential of using motexafin gadolinium (MGd) to characterize atherosclerotic plaques of deep-seated arteries with MRI. Materials and Methods: We exposed vascular endothelial cells (EC) and smooth muscle cells (SMC) in vitro to varying concentrations of MGd. The fluorescence properties of MGd were then exploited using confocal microscopy to image exposed cells. For an in vivo validation study, we performed surface coil-based and intravascular coil-based high-resolution MRI of the iliac arteries and the abdominal aorta of three atherosclerotic Yucatan pigs. Subsequently, MGd enhancement of the target vessel walls was quantitatively evaluated and MR images were correlated with histology of the target vessels. Results: The in vitro study confirmed the intracellularization of MGd in both cell types and determined the optimum MGd dosage of 0.004 mmol/kg that produced the sufficiently high intracellular fluorescent intensity. The in vivo study showed a steady increase of MGd enhancement to approximately 25% at three hours postinjection of MGd. MRI showed areas of strong enhancement along the lumen boundary, which corresponded to fibrous tissue seen in histology. Conclusion: This study provides initial evidence that MGd may enhance MR vessel wall imaging for the characterization of plaque in deep-seated arteries.
Open Access
Peptide functionalized superparamagnetic iron oxide nanoparticles as MRI contrast agents
(The Royal Society of Chemistry, 2011) Sulek, S.; Mammadov, B.; Mahcicek, D. I.; Sozeri, H.; Atalar, Ergin; Tekinay, A. B.; Güler, Mustafa O.
Magnetic resonance imaging (MRI) attracts great attention in cellular and molecular imaging due to its non-invasive and multidimensional tomographic capabilities. Development of new contrast agents is necessary to enhance the MRI signal in tissues of interest. Superparamagnetic iron oxide nanoparticles (SPIONs) are used as contrast agents for signal enhancement as they have revealed extraordinary magnetic properties at the nanometre size and their toxicity level is very low compared to other commercial contrast agents. In this study, we developed a new method to functionalize the surface of SPIONs. Peptide amphiphile molecules are used to coat SPIONs non-covalently to provide water solubility and to enhance biocompatibility. Superparamagnetic properties of the peptide-SPION complexes and their ability as contrast agents are demonstrated. In vitro cell culture experiments reveal that the peptide-SPION complexes are biocompatible and are localized around the cells due to their peptide coating.
Open Access
Semi-automatic segmentation of subcutaneous tumours from micro-computed tomography images
(Institute of Physics Publishing Ltd., 2013-10-30) Ali, R.; Gunduz Demir, C.; Szilagyi, T.; Durkee, B.; Graves, E. E.
This paper outlines the first attempt to segment the boundary of preclinical subcutaneous tumours, which are frequently used in cancer research, from micro-computed tomography (microCT) image data. MicroCT images provide low tissue contrast, and the tumour-to-muscle interface is hard to determine, however faint features exist which enable the boundary to be located. These are used as the basis of our semi-automatic segmentation algorithm. Local phase feature detection is used to highlight the faint boundary features, and a level set-based active contour is used to generate smooth contours that fit the sparse boundary features. The algorithm is validated against manually drawn contours and micro-positron emission tomography (microPET) images. When compared against manual expert segmentations, it was consistently able to segment at least 70% of the tumour region (n = 39) in both easy and difficult cases, and over a broad range of tumour volumes. When compared against tumour microPET data, it was able to capture over 80% of the functional microPET volume. Based on these results, we demonstrate the feasibility of subcutaneous tumour segmentation from microCT image data without the assistance of exogenous contrast agents. Our approach is a proof-of-concept that can be used as the foundation for further research, and to facilitate this, the code is open-source and available from www.setuvo.com. © 2013 Institute of Physics and Engineering in Medicine.