• Investigative Magnetic Resonance Imaging
• /
• v.25 no.4
• /
• pp.209-217
• /
• 2021

Magnetic resonance angiography (MRA) plays an important role in accurate diagnosis and appropriate treatment planning for patients with arterial disease. Contrast-enhanced (CE) MRA is fast and robust, offering hemodynamic information of arterial flow, but involves the risk of a side effect called nephrogenic systemic fibrosis. Various non-contrast-enhanced (NCE) MRA techniques have been developed by utilizing the fact that arterial blood is moving fast compared to background tissues. NCE MRA is completely free of any safety issues, but has different drawbacks for various approaches. This review article describes basic principles of CE and NCE MRA techniques with a focus on how to generate angiographic image contrast from a pulse sequence perspective. Advantages, pitfalls, and key applications are also discussed for each MRA method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.4
• /
• pp.2199-2206
• /
• 2014

This research, used an contrast agent, which weighs about 1mmol/mL, of twice as much amount of gadolinum, per unit, for the test of magnetic-resonance shoulder arthrography. the reasearch which was carried out from January, of the year 2012 to August of the year 2013. consisted, of target of 41, patients including 20 ones, of whom an original, contrast agent of amount of 0.5mmol/mL, 21, ones of whom, a new, of amount of 1mmol/mL was used on, were the test target, in order to figure out the differences, according to the amount of gadolinum, according to the test results, the SNR of the contrast agent, of amount of 1mmol/mL, which is of high amount of gadolinum, was noticeably higher than the one of amount of 0.5mmol/mL(the percentage of joint space 38.01%, the supraspinous muscle 8.40%, head of humerus 12.78%). and CNR of the contrast agent, of amount of 1mmol/mL, which is of high amount of gadolinum, was higher than the one of amount of 0.5mmol/mL(the percentage of joint space and supraspinous muscle 48.96%, the one of joint space and head of humerus 42.00%). In conclusion, one of the methods of increasing the reducing effect of T1, is to use contrast agent of amount of 1mmol/mL, in order to increase the reducing effect of T1, acquire the visual of high testing quality.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.1-1
• /
• 2011

We developed a new generalized synthetic procedure, called as "heat-up process," to produce uniform-sized nanocrystals of many transition metals and oxides without a size selection process. We were able to synthesize uniform magnetite nanocrystals as much as 1 kilogram-scale from the thermolysis of Fe-oleate complex. Clever combination of different nanoscale materials will lead to the development of multifunctional nano-biomedical platforms for simultaneous targeted delivery, fast diagnosis, and efficient therapy. In this presentation, I would like to present some of our group's recent results on the designed fabrication of multifunctional nanostructured materials based on uniform-sized magnetite nanoparticles and their medical applications. Uniform ultrasmall iron oxide nanoparticles of <3 nm were synthesized by thermal decomposition of iron-oleate complex in the presence of oleyl alcohol. These ultrasmall iron oxide nanoparticles exhibited good T1 contrast effect. In in vivo T1 weighted blood pool magnetic resonance imaging (MRI), iron oxide nanoparticles showed longer circulation time than commercial gadolinium complex, enabling high resolution imaging. We used 80 nm-sized ferrimagnetic iron oxide nanocrystals for T2 MRI contrast agent for tracking transplanted pancreatic islet cells and single-cell MR imaging. We reported on the fabrication of monodisperse magnetite nanoparticles immobilized with uniform pore-sized mesoporous silica spheres for simultaneous MRI, fluorescence imaging, and drug delivery. We synthesized hollow magnetite nanocapsules and used them for both the MRI contrast agent and magnetic guided drug delivery vehicle.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.3
• /
• pp.639-644
• /
• 2010

Amphiphilic porphyrin derivatives have been synthesized and characterized by $^1H$ NMR and MALDI-TOF-MS. All porphyrin derivatives showed very high solubility to aqueous medium as well as hydrophobic organic solvent. The UV-vis absorption of the porphyrin derivatives showed significant broadness and decrease of maximum intensity of absorption in aqueous solution. SEM experiment showed the formation of spherical micellar structure. The $T_1$ relaxation time of aqueous medium was drastically decreased in the presence of Mn(III)-porphyrin derivative, indicating that the supramolecular micelle has strong possibility to use as a $T_1$ contrast agent.

• Journal of Veterinary Clinics
• /
• v.17 no.1
• /
• pp.243-246
• /
• 2000

A 3-year old female Poodle dog was presented with a history of anorexia, vomiting, abdominal pain and depression for 2 days. After physical and blood examination, excretory urogram(EU) and ultrasonography of the abjomen were conducted. On radiographs and ultrasonographs, dilation of diverticulum, sinus, proximal ureter of right kidney and mild dilation of left renal medullar were found. And there was some leakage of contrast agent in the proximal ureter area of right kidney. So this was diagnosed as a rupture of right proximal ureter. This dog was undertaken a surgery of nephrectomy of right kidney. On surgery, dilation of right kidney and hemorrhage, adhesion were found at the proximal ureter and some calculi were also found in the pelvis of right kidney. There were no complications after surgery.

• Journal of the Korean Society of Visualization
• /
• v.3 no.1
• /
• pp.26-35
• /
• 2005

The combination of ultrasound echo images with digital particle image velocimetry (DPIV) method has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window of offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow and pulsatile flow showed good agreement with both optical PIV measurements and the known analytic solution. These studies indicate that echo PIV is a promising technique for the non-invasive measurement of velocity profiles and shear stress.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.7
• /
• pp.617-621
• /
• 2012

This paper studies asymptotic consensus problem for linear multi-agent systems. We propose a distributed state feedback control algorithm for solving the problem under fixed and undirected network communication. In contrast with the conventional algorithms that use global information (e.g., graph connectivity), the proposed algorithm only uses local information from neighbors. The principle for achieving asymptotic consensus is that, for each agent, a distributed update law gradually increases the coupling gain of LQR-type feedback and thus, the overall stability of the multi-agent system is recovered by the gain margin of LQR.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.16 no.1
• /
• pp.25-38
• /
• 1998

The developing agent is the materials which first acts on silver grain and make it into metallic silver by reducing reaction. There are several types in developing agent, and according to Lumiere-Andresen principle, substitution product which has amino or hydroxyl group in benzen nucleus has a developing power, but all reduing substances are not in used. In the developing effect, not only the role of developing agent but also that of assistant materials are important. But in this work, we have studied effect, change by lith developing agent which require high contrast image. We made an developing experiment after having manufactured developing solution used hydroquinone and another developing agents like chlorohydroquinone, pyrocatechol and pyrogallol as developing agent. And we added that did in addition of diethanolamine and ascorbic acid, and then we examined the possibility of use.

• 제어로봇시스템학회:학술대회논문집
• /
• 1999.10a
• /
• pp.292-297
• /
• 1999

Evolving in artificial agent is an extremely difficult problem, but on the other hand, a challenging task. At present the studies mainly centered on single agent learning problem. In our case, we use simulated soccer to investigate multi-agent cooperative learning. Consider the fundamental differences in learning mechanism, existing reinforcement learning algorithms can be roughly classified into two types-that based on evaluation functions and that of searching policy space directly. Genetic Programming developed from Genetic Algorithms is one of the most well known approaches belonging to the latter. In this paper, we give detailed algorithm description as well as data construction that are necessary for learning single agent strategies at first. In following step moreover, we will extend developed methods into multiple robot domains. game. We investigate and contrast two different methods-simple team learning and sub-group loaming and conclude the paper with some experimental results.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.1
• /
• pp.87-92
• /
• 2014

The work is directed toward the synthesis of a series of DO3A conjugates of tranexamates (1c-e) and their Gd complexes (2c-e) for use as a liver-specific MRI CA. All these complexes show thermodynamic and kinetic stabilities comparable to those of structurally related clinical agents such as Dotarem$^{(R)}$. Their $R_1$ relaxivities also compare well with those of commercial agent, ranging 3.68-4.84 $mM^{-1}s^{-1}$. In vivo MR images of mice with 2a-e reveal that only 2a exhibits liver-specificity. Although 2b and 2c show strong enhancement in liver, yet no bile-excretion is observed to be termed as a liver-specific agent. The rest behaves much like ordinary ECF CAs like Dotarem$^{(R)}$. The new series possess no toxicity to be employed in vivo.