Computer-Aided Detection of Metastatic Brain Tumors Using Magnetic Resonance Black-Blood Imaging

Yang, Seungwook,Nam, Yoonho,Kim, Min-Oh,Kim, Eung Yeop,Park, Jaeseok,Kim, Dong-Hyun Lippincott Williams Wilkins, Inc. 2013 Investigative radiology Vol.48 No.2

OBJECTIVES: The objective of this study was to develop a computer-aided detection system for automated brain metastases detection using magnetic resonance black-blood imaging and compare its applicability with conventional magnetization-prepared rapid gradient echo (MP-RAGE) imaging. MATERIALS AND METHODS: Twenty-six patients with brain metastases were imaged with a contrast-enhanced, 3-dimensional, whole-brain magnetic resonance black-blood pulse sequence. Approval from the institutional review board and informed consent from the patients were obtained. Preprocessing steps included B1 inhomogeneity correction and brain extraction. The computer-aided detection system used 3-dimensional template matching, which measured normalized cross-correlation coefficient to generate possible metastases candidates. An artificial neural network was used for classification after various volume features were extracted. The same detection procedure was tested with contrast-enhanced MP-RAGE, which was also acquired from the same patients. RESULTS: The performance of the proposed detection method was measured by the area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity values. In the black-blood case, detection process displayed an AUROC of 0.9355, a sensitivity value of 81.1%, and a specificity value of 98.2%. Magnetization-prepared rapid gradient echo data showed an AUROC of 0.6508, a sensitivity value of 30.2%, and a specificity value of 99.97%. CONCLUSIONS: The results demonstrate that accurate automated detection of metastatic brain tumors using contrast-enhanced black-blood imaging sequence is possible compared with using conventional contrast-enhanced MP-RAGE sequence.

Alternating Acquisition Technique for Quantification of in vitro Hyperpolarized [1-¹³C] Pyruvate Metabolism

Yang, Seungwook,Lee, Joonsung,Joe, Eunhae,Lee, Hansol,Song, Ho-Taek,Kim, Dong-Hyun Korean Society of Magnetic Resonance in Medicine 2016 Investigative Magnetic Resonance Imaging Vol.20 No.1

Purpose: To develop a technique for quantifying the $^{13}C$-metabolites by performing frequency-selective hyperpolarized $^{13}C$ magnetic resonance spectroscopy (MRS) in vitro which combines simple spectrally-selective excitation with spectrally interleaved acquisition. Methods: Numerical simulations were performed with varying noise level and $K_p$ values to compare the quantification accuracies of the proposed and the conventional methods. For in vitro experiments, a spectrally-selective excitation scheme was enabled by narrow-band radiofrequency (RF) excitation pulse implemented into a free-induction decay chemical shift imaging (FIDCSI) sequence. Experiments with LDH / NADH enzyme mixture were performed to validate the effectiveness of the proposed acquisition method. Also, a modified two-site exchange model was formulated for metabolism kinetics quantification with the proposed method. Results: From the simulation results, significant increase of the lactate peak signal to noise ratio (PSNR) was observed. Also, the quantified $K_p$ value from the dynamic curves were more accurate in the case of the proposed acquisition method compared to the conventional non-selective excitation scheme. In vitro experiment results were in good agreement with the simulation results, also displaying increased PSNR for lactate. Fitting results using the modified two-site exchange model also showed expected results in agreement with the simulations. Conclusion: A method for accurate quantification of hyperpolarized pyruvate and the downstream product focused on in vitro experiment was described. By using a narrow-band RF excitation pulse with alternating acquisition, different resonances were selectively excited with a different flip angle for increased PSNR while the hyperpolarized magnetization of the substrate can be minimally perturbed with a low flip angle. Baseline signals from neighboring resonances can be effectively suppressed to accurately quantify the metabolism kinetics.

반가 식품인 청육장 제조 중 아이소플라본 분포 변화

이승욱(SeungWook Lee),박영우(YongWoo Park),한양선(Yang Sun Han),장판식(Pahn-Shick Chang),이종미(Jong-Mee Lee),김영석(Young Suk Kim),이재환(JaeHwan Lee) 한국식품과학회 2009 한국식품과학회지 Vol.41 No.2

청육장은 볶은 대두를 이용하여 제조된 청국장에 해산물, 육류를 함께 가열한 반가 식품의 일종이다. 140과 220℃에서 각각 21.0과 6.0분 간 볶은 대두와 이를 이용한 청국장, 청육장의 총 아이소플라본을 HPLC로 분석하였다. 총 아이소플라본 함량(μmol/g)은 생 대두 대비 약 79-80, 56-65, 47-50%이었다. 볶음 공정으로 인해 malonyl-β-glucosides 함량은 유의적으로 감소한 반면 acetyl-β-glucosides와 β-glucosides의 함량은 유의적으로 증가하였다(p < 0.05). 청국장과 청육장의 주된 아이소플라본은 β-glucosides이었다. 생 대두와 볶은 대두에서는 succinyl-β-daidzin과 succinyl-β-genistin은 검출되지 않았고, 청국장과 청육장에서 succinyl-β-genistin의 peak area는 succinyl-β-daidzin 보다 더 높게 검출되었다. Cheongyukjang, a Banga food, is a heavy soy-soup prepared by boiling cheonggukjang, sea foods, and meats. Soybeans roasted at 140℃ for 21.0 min and 220℃ for 6.0 min, respectively, were used for cheonggukjang preparation. Distributions of isoflavones in raw soybeans, roasted soybeans, cheonggukjang, and cheongyukjang were analyzed by high performance liquid chromatography. The total isoflavones in roasted soybeans, cheonggukjang and cheongyukjang were about 79-80, 56-65, and 47-50% of those in raw soybeans, respectively. Roasting caused significant increases in acetyl derivatives and β-glucoside isoflavones, and significant decreases in malonyl derivatives (p < 0.05). The major isoflavones in cheonggukjang and cheongyukjang were β-glucosides. Succinyl-β-daidzin and succinyl-β-genistin, which are recognized as new metabolites of isoflavones, were not detected in raw and roasted soybeans. Peak areas of succinyl-β-genistin were higher than thse of succinyl-β-daidzin, in both cheongyukjang and cheonggukjang.

Succinyl Daidzin and Succinyl Genistin are New Isoflavone Derivatives Found in Cheonggukjang

SeungOk Yang,SeungWook Lee,YoungWoo Park,SangJun Lee,Pahn-Shick Chang,Sung-Seen Choi,JaeHwan Lee 한국식품과학회 2008 Food Science and Biotechnology Vol.17 No.1

Two new fermentation products were separated from cheonggukjang by high performance liquid chromatography (HPLC) and tentatively identified as succinyl daidzin and succinyl genistin by HPLC-mass spectrometry (MS). Both succinyl daidzin and succinyl genistin were detected in all 4 commercially available and one laboratory prepared cheonggukjang and 1 commercially available natto. However, these compounds were not detected in commercially available 4 home-made and 4 factory-produced doenjang. Peak areas of succinyl genistin were about 1.95-2.45 times higher than those of succinyl daidzin in cheonggukjang, which may be due to the higher concentration of genistin derivatives than daidzin derivatives in soybeans. This is the first report on the succinyl derivatives as isoflavone metabolites from cheonggukjang and these 2 isoflavone derivatives could be characteristic indicators for cheonggukjang.

Steric Effects on the Formation of Self‐Assembled Monolayers of Alicyclic Thiol Derivatives on Au(111)

Seong Sicheon,Kwon Seungwook,Han Seulki,Son Young Ji,Lee Gaeun,Yang Taeho,Lee Nam‐Suk,Noh Jaegeun 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.9

To understand the steric effects on the formation of alicyclic thiolate self-assembled monolayers on Au(111), the surface structures and reductive desorption behaviors of self-assembled monolayers on Au(111) derived from cyclohexanethiol (CHT) and 1-methylcyclohexanethiols (MCHT) were characterized using scanning tunneling microscopy (STM) and cyclic voltammetry. STM observations showed that the adsorption of CHT on Au(111) resulted in the formation of well-organized monolayers with an unit cell of a = 14.5 0.3 Å and b = 10.2 0.3 Å, while the adsorption of MCHT with a methyl substituent bonded to the 1-position of the cyclohexyl ring resulted in the formation of a disordered phase. The reductive desorption potentials for CHT and MCHT monolayers on Au electrodes were observed at 0.984 and 0.974 V, respectively. This difference in potentials can be attributed to the difference in lateral interactions, which depend on the structural order of monolayers.

Determination of Optimal Scan Time for the Measurement of Downstream Metabolites in Hyperpolarized ¹³C MRSI

Lee, Hansol,Lee, Joonsung,Joe, Eunhae,Yang, Seungwook,Choi, Young-suk,Wang, Eunkyung,Song, Ho-Taek,Kim, Dong-Hyun Korean Society of Magnetic Resonance in Medicine 2015 Investigative Magnetic Resonance Imaging Vol.19 No.4

Purpose: For a single time-point hyperpolarized $^{13}C$ magnetic resonance spectroscopy imaging (MRSI) of animal models, scan-time window after injecting substrates is critical in terms of signal-to-noise ratio (SNR) of downstream metabolites. Pre-scans of time-resolved magnetic resonance spectroscopy (MRS) can be performed to determine the scan-time window. In this study, based on two-site exchange model, protocol-specific simulation approaches were developed for $^{13}C$ MRSI and the optimal scan-time window was determined to maximize the SNR of downstream metabolites. Materials and Methods: The arterial input function and conversion rate constant from injected substrates (pyruvate) to downstream metabolite (lactate) were precalibrated, based on pre-scans of time-resolved MRS. MRSI was simulated using two-site exchange model with considerations of scan parameters of MRSI. Optimal scan-time window for mapping lactate was chosen from simulated lactate intensity maps. The performance was validated by multiple in vivo experiments of BALB/C nude mice with MDA-MB-231 breast tumor cells. As a comparison, MRSI were performed with other scan-time windows simply chosen from the lactate signal intensities of pre-scan time-resolved MRS. Results: The optimal scan timing for our animal models was determined by simulation, and was found to be 15 s after injection of the pyruvate. Compared to the simple approach, we observed that the lactate peak signal to noise ratio (PSNR) was increased by 230%. Conclusion: Optimal scan timing to measure downstream metabolites using hyperpolarized $^{13}C$ MRSI can be determined by the proposed protocol-specific simulation approaches.

Dual Component Analysis for In Vivo T₂^* Decay of Hyperpolarized ¹³C Metabolites

Joe, Eunhae,Lee, Joonsung,Lee, Hansol,Yang, Seungwook,Choi, Young-Suk,Wang, Eunkyung,Song, Ho-Taek,Kim, Dong-Hyun Korean Society of Magnetic Resonance in Medicine 2017 Investigative Magnetic Resonance Imaging Vol.21 No.1

Purpose: To investigate the exchange and redistribution of hyperpolarized $^{13}C$ metabolites between different pools by temporally analyzing the relative fraction of dual $T_2{^*}$ components of hyperpolarized $^{13}C$ metabolites. Materials and Methods: A dual exponential decay analysis of $T_2{^*}$ is performed for [1-$^{13}C$] pyruvate and [1-$^{13}C$] lactate using nonspatially resolved dynamic $^{13}C$ MR spectroscopy from mice brains with tumors (n = 3) and without (n = 4) tumors. The values of shorter and longer $T_2{^*}$ components are explored when fitted from averaged spectrum and temporal variations of their fractions. Results: The $T_2{^*}$ values were not significantly different between the tumor and control groups, but the fraction of longer $T_2{^*}$ [1-$^{13}C$] lactate components was more than 10% in the tumor group over that of the controls (P < 0.1). The fraction of shorter $T_2{^*}$ components of [1-$^{13}C$] pyruvate showed an increasing tendency while that of the [1-$^{13}C$] lactate was decreasing over time. The slopes of the changing fraction were steeper for the tumor group than the controls, especially for lactate (P < 0.01). In both pyruvate and lactate, the fraction of the shorter $T_2{^*}$ component was always greater than the longer $T_2{^*}$ component over time. Conclusion: The exchange and redistribution of pyruvate and lactate between different pools was investigated by dual component analysis of the free induction decay signal from hyperpolarized $^{13}C$ experiments. Tumor and control groups showed differences in their fractions rather than the values of longer and shorter $T_2{^*}$ components. Fraction changing dynamics may provide an aspect for extravasation and membrane transport of pyruvate and lactate, and will be useful to determine the appropriate time window for acquisition of hyperpolarized $^{13}C$ images.

현대자동차 LPG 액상분사 시스템 개발

이우직(Woojik Lee),김인탁(Intak Kim),양승욱(Seungwook Yang) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

LPG, which has relatively high hydrogen-to-carbon ratio compared to gasoline, provides a substantial low emissions of CO₂ and also has an advantages on HC emissions by comparable low wall wetting. Inspite of these merits, however, the conventional LPG feedback-mixing system has also certain disadvantages to a gasoline engines with respect to cold startability, low engine power and poor air-to-fuel control. To solve such problems, HMC has now developed the world's first mono LPI system to make up for the shortcomings of FBM vehicles.

인젝터 누설량에 의한 시동성 영향에 대한 실험적 연구

김현유(Hyeongyoo Kim),유승묵(Seungmook You),양승욱(Seungwook Yang) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The start-ability is one of the most important factors for developing a vehicle and is strongly dependent on the essential sensors and actuators such as an air flow meter and injectors. So far we've been making every effort to calibrate data related to start-ability according to the flow rate of an injector. But, we've not focused on the influence of the injector-leakage on start-ability. In this study, we made several combinations of injectors which have different leakage levels and then tested the start-ability with them. As a result of the experiments, the starting was delayed in some cases, and we conclude the relationship between the injector-leakage and the delay of starting. To resolve the start-delay problem caused by the injector-leakage, it is recommended to reduce the fuel quantities during engine starting, but this fuel reduction can also affect the start-ability using low RVP fuels of under the other conditions. And we found experimentally the specification of injector-leakage and the minimal reduction ratio of fuel needed to start an engine stably even with low RVP fuels and high leakage injectors.

고남산 화성복합체와 관련된 Fe-Ti (-V) 광화작용의 형성과 기원

이지현(Jihyun Lee),김의준(Euijun Kim),양석준(Seokjun Yang),신승욱(Seungwook Shin),조성준(Seongjun Cho),신동복(Dongbok Shin) 대한지질학회 2020 대한지질학회 학술대회 Vol.2020 No.10