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Magnetic Resonance Imaging: Historical Overview, Technical Developments, and Clinical Applications
Jahng, Geon-Ho,Park, Soonchan,Ryu, Chang-Woo,Cho, Zang-Hee Korean Society of Medical Physics 2020 의학물리 Vol.31 No.3
The authors congratulate the cerebrations for the 30 years of the Korean Society of Medical Physics (http://www.ksmp.or.kr/). The paper is published to recognize the anniversary. Geon-Ho Jahng invited Professor Z. H. Cho to join to submit this manuscript because he has been one of the leaders in the field of magnetic resonance imaging (MRI) during the last 40 years. In this review, we describe the development and clinical histories of MRI internationally and domestically. We also discuss diffusion and perfusion MRI, molecular imaging using MRI and MR spectroscopy (MRS), and the hybrid systems, such as positron emission tomography-MRI (PET-MRI), MR-guided focused ultrasound surgery (MRgFUS), and MRI-guided linear accelerators (MRI-LINACs). In each part, we discuss the historical evolution of the developments, technical developments, and clinical applications.
Reaction of Ru( tpy)Cl₃ with N,N,C-Terdentates, 3,2'-Annulated-6-(2"-pyridyl)-2-phenylpyridines
Jahng, Yurngdong,Park, Jae Gyu 영남대학교 약품개발연구소 2000 영남대학교 약품개발연구소 연구업적집 Vol.10 No.-
The reactions of Ru(tpy)CI_(3)(tpy=2.2';6',2"-terpyridine) with new N, N, C-terdentate ligands, 3,2'-annulated-6-(2"-pyridyl)-2-phenylpyridines(1,HL) and the properties of their Ru(Ⅱ) complexes are described. The distri-bution ratio of the two possible Ru(Ⅱ) complexes, a pentaaza-coordinated complex [Ru(tpy)(1-N,N')CI]^(+) and a cycloruthenated complex [Ru(tpy)(La-N,N',C)]^(+) are highly dependent on the length of the polymethylene unit. The trimethylene bridge of the N,N,C-terdentate in pentaaza-coordinated complex is rigid enough to induce an asymmetry in the complex.
Jahng, Yurngdong,Park, Jae Gyu 영남대학교 약품개발연구소 1998 영남대학교 약품개발연구소 연구업적집 Vol.8 No.-
A series of 3,2'-polymethylene bridged 6-(2'-pyridyl)-2-phenylpyridines was prepared from benzo-fused cycloalkanone and β-(dimethyl-amino)vinyl 2-pyridyl ketone as potential N, N, C-terdentates. Preparations and properties of their cycloplatinated complexes were described. Even highly distorted 3, 2'-tetramethylene-6-(2"-pyridyl)-2-phenylpyridine can undergo cycloplatination. ⓒ 1998 Elsevier Science S.A.
Synthesis and Biological Activity of Conformationally Controlled 2-PAM Derivatives
Jahng, Yurngdong,Park, Jae Gyu,Yu, Jung Whey,Kim, Sun Young,Kim, Taean,Yang, Jae Ho 영남대학교 약품개발연구소 2000 영남대학교 약품개발연구소 연구업적집 Vol.10 No.-
A series of conformationally controlled 2-PAM derivatives were prepared from 2-acetylpyridine and 2,3-pyrido[b]cycloalkenones in two steps and their reactivities towards parathion poisoned AChE were evaluated. The most planar 2,3-pyrido[b]cyclohexanone oxime methiodide showed an activity comparable to 2-PAM implying E-syn is that the most active comformation of 2-PAM in the biological system.
Copper(Ⅰ) Complexes of 3,3'-Bridged 2,2'-Biquinoline-Synthesis, Properties, and Structure
Jahng, Yurngdong,Hazelrigg, John,Kimball, David,Riesgo, Elvira,Wu, Feiyue,Thummel, Randolph P. 영남대학교 약품개발연구소 1998 영남대학교 약품개발연구소 연구업적집 Vol.8 No.-
A series of 3, 3'-bridged derivatives of 2, 2'-biquinoline have been prepared where the bridge consists of one to four methylene units or a -CH=CH- moiety. The corresponding [CuL₂](ClO₄) complexes were also prepared and their structures analyzed and confirmed by ¹H NMR. Electronic absorption maxima for the metal-to-ligand transition were found to move to higher energy and oxidation potentials were found to increase as the ligands became more distorted from planarity. An X-ray analysis was carried out for the most distorted systcm having a 3, 3'-tetramethylene bridge (C_(44)H_(36)BCuF₄N₄: triclinic, P??, a = 11.605(2) Å, b = 12.622(3) Å, c = 14.524(3) Å, α = 106.05(1)˚, β = 109.06(1)˚, r = 105.37(1)˚, V = 1778 ų, Z = 2). A wide variation in Cu-N bond lengths, 1.98-2.23 Å, was observed, and the two more weakly complexed quinolines were seen to be arranged in an almost parallel fashion. Ligand exchange studies with neocuproine indicated that the strength of Cu(I) binding depends on the planarity of the system as well as the cisoid disposition of the quinoline nitrogens.
Properties of Ruthenium(Ⅱ) Complexes of 2, 2':6', 2""-Terpyridine-Related Systems
Jahng, Yurng Dong,Seoh, Byeong Chon 영남대학교 자원문제연구소 1990 資源問題硏究 Vol.9 No.-
The first unsymmetric terpyridine related ligand, 2-(2-pyridyl)-1, 10-phenanthroline(le), was prepared from 1, 10-phenanthroline in 5 steps, and converted to Ru(le)₂(PF6)₂. The redox potentials of this complex were determined to show a similiarity to those of Ru(phen)₃(원문참조), not those of Ru(tpy )₂(원문참조). The redox properties of the ruthenium complexes of 3, 3' ; 5', 3"bis-(polymethylene)-bridged 2, 2' ; 6', 2"-terpyridine (1b-d ) were also determined to show a sensitive probe of the conjugative interaction dependent on the relationship of the 2, 2' ; 6', 2"-terpyridine about the ruthenium atom. Although Ru(Ⅱ) complexes of the ligand, 1b-d. did not show any observable emission at room temperature, Ru(le)₂ shows one absorption maximum at 595 nm in aq. EtOH solution.
Jahng, Geon-Ho,Xu, Songfan Springer New York LLC 2012 BRAIN IMAGING AND BEHAVIOR Vol.6 No.3
<P>Recent studies with positron emission tomography (PET) using the Pittsburgh compound B (PIB) found widespread amyloid plaque depositions in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and even in cognitively normal (CN) subjects. The aim of this study was to investigate whether the local susceptibility gradients in brain tissue alter regional diffusion measurements using MRI in patients with AD and MCI. Two diffusion tensor (DT)-MRI data sets were acquired with alternating polarities of the external diffusion-sensitizing gradients. Three subject groups were included: 15 patients with AD, 18 patients with MCI and 16 CN. Maps of mean diffusivity (MD) and fractional anisotropy (FA) were computed separately for positive (p) and negative (n) polarities (pMD and nMD, pFA and nFA). Voxel-wise paired t-tests were performed between pMD versus nMD or between pFA versus nFA maps, separately for each subject group. We also investigated regions-of-interest (ROIs) in the brain. Based on the pair-wise comparisons, we found significant differences between pMD and nMD in all three groups. Results of ROI-based analyses showed that the non-linear behaviors of the ROI data sets were shown for all three groups. In conclusion, significant differences of MD maps between the two polarities of diffusion-sensitizing gradients were found, suggesting that the intrinsic background gradients may alter MD signals in specific regions. It can be important to take into account the effects of local gradient alterations during diffusion measurements in patients with AD, MCI and elderly controls.</P>