Multi-Component Relaxation Study of Human Brain Using Relaxographic Analysis

Chang, Yongmin,Han, Bong Soo,Kang, Bong Seok,Jeon, Kyungnyeo,Bae, Kyungsoo,Kim, Yong-Sun,Kang, Duk-Sik 경북대학교 병원 2003 경북대학교병원의학연구소논문집 Vol.7 No.1

목적 : 자기공명영상과 자기이완분포 분석법을 통합적으로 이용하는 경우 기존의 자기이완시간 분석기법에서 제공할 수 없었던 자기이완시간의 분포 및 해당 분포의 상대적인 물분자 함유량등의 추가적인 정보를 제공할 수 있음을 보이고자 하였다. 대상 및 방법 : 자기이완분포 분석법(CONTIN)의 정확도 및 신뢰성을 검증하기 위하여 먼저 자기이완시간이 일정한 분포를 가지도록 고안된 모의 자기이완 데이터를 사용하였다. 다음으로 지질의 함유량이 99% 이상인 식용유와 증류수를 일정비율(0, 10, 20, 30%)로 혼합한 실험 팬텀을 제작하고 inversion-recovery 시퀸스(TI: 40-1160 msec, TR/TE=2200/20msec)를 사용하여 MR 영상을 획득하여 CONTIN을 사용하여 각 관심영역에서의 자기이완분포를 분석하였다. 결과 : 신호대잡음비를 달리한 모의 자기이완 데이터의 분석결과 자기이완시간의 위치에 대한 오차는 신호대잡음비에 관계없이 긴 자기이완시간(T₁=600msec)에 비해 짧은 자기이완시간(T₁=150msec)에서 크게 나타났으며 반대로 자기이완시간 분포면적에 대해서는 긴 자기이완시간(T₁=600msec)의 면적오차가 짧은 자기이완시간(T₁=150msec)에 비해 큰 것으로 나타났다. 실험 팬톰을 이용한 분석결과는 실제 오일대 증류수의 비율을 1:2:3으로 한 팬톰들에서 분석결과는 1:1.3:1.9 으로 나타났다. 자원자의 뇌영상에서는 CSF의 경우에는 하나의 T₁ 자기이완시간만이 나타난 반면 백질과 회백질에서는 2개의 T₁ 자기이완분포를 가지는 것으로 분석되었다. CSF와 백질의 평균 자기이완시간은 기존의 보고된 값들과 잘 일치 하였다. 결론 : 자기공명영상과 자기이완분포 분석법을 통합적으로 이용하는 경우 기존의 자기이완시간 분석기법에서 제공할 수 없었던 자기이완시간의 분포 및 해당 분포의 상대적인 물분자 함유량등의 추가적인 정보를 제공한다는 사실을 규명하였고 이러한 추가적인 정보들은 임상적 유용성이 있을 것으로 추정된다. Purpose : To demonstrate that the relaxographic method provides additional information such as the distribution of relaxation times and water content which are poentially applicable to clinical medicine. Materials and Methods : First, the computer simulation was performed with the generated relaxation data to verify the accuracy and reliablility of the relaxographic method(CONTIN). Secondly, in order to see how well the CONTIN quantifies and resolves the two different T₁ environments, we calculated the oil to water peak area ratios and identified peak positions of T₁-distribution curve of the phantom solutions, which consist of four centrifugal tubes(10㎖) filled with the compounds of 0, 10, 20, 30% of corn oil and distilled water, using CONTIN, Finally, inversion recovery MR images for a volunteer are acquired for each TI ranged from 40 to 1160 msec with TR/TE=2200/20 msec. From the 3 different ROIs(GM, WM, CSF), CONTIN analysis was performed to obtain the T₁-distribution curves, which gave peak positions and peak area of each ROI location. Results : The simulation result shows that the errors of peak positions were less in the higher peak(centered T₁=600msec) than in the lower peak(centered T₁=150msec) for all SNR but the errors of peak areas were larger in the higher peak than in the lower peak. The CONTIN analysis of the measured relaxation data of phantoms revealed two peaks between 20 and 60msec and between 500 and 700msec. The analysis gives the peak area ratio as oil 10%: oil 20%: oil 30%=1:1.3:1.9, which is different from the exact ratio, 1:2:3. For human brain, in ROI 3(CSF), only one component of -distributions was observed whereas in ROI 1(GM) and in ROI 2(WM) we observed two components of T₁ -distribution. For the WM and CSF there was great agreement between the observed T₁ -relaxation times and reported values. Conclusion : we demonstrated that the relaxographic method provided additional information such as the distribution of relaxation times and water content, which were not available in the routine relaxometry and T₁/T₂ mapping techniques. In addition, these additional information provided by relaxographic analysis may have clinical importance.

Altered white matter integrity in primary restless legs syndrome patients: diffusion tensor imaging study.

Chang, Yongmin,Paik, Jong Soo,Lee, Hui Joong,Chang, Hyuk Won,Moon, Hye-Jin,Allen, Richard P,Earley, Christopher J,Cho, Yong Won Butterworths [etc.] 2014 Neurological research Vol.36 No.8

<P>A prior diffusion tensor imaging (DTI) of restless legs syndrome (RLS) subjects found alterations in brain white matter (WM). The aim of this study was to explore the possible mechanism of altered integrity of brain WM in RLS patients.</P>

Voxel-Wise Analysis of Diffusion Tensor Imaging for Clinical Outcome of Cochlear Implantation: Retrospective Study

Chang, Yongmin,Lee, Hye-Ryung,Paik, Jong-Soo,Lee, Kyu-Yup,Lee, Sang-Heun Korean Society of Otorhinolaryngology-Head and Nec 2012 Clinical and Experimental Otorhinolaryngology Vol.5 No.-

<P><B>Objectives</B></P><P>To evaluate retrospectively, the possible difference in diffusion tensor imaging (DTI) metric of fractional anisotropy (FA) between good and poor surgical outcome cochlear implantation (CI) patients using investigator-independent voxel-wise analysis.</P><P><B>Methods</B></P><P>Eighteen patients (11 males, 7 females; mean age, 5.9 years) with profound sensorineural hearing loss underwent DTI scans using a 3.0 Tesla magnetic resonance scanner. Among the 18 patients, 10 patients with categories of auditory performance (CAP) score over 6 were classified into the good outcome group and 8 patients with CAP score below 6 were classified into the poor outcome group. The diffusion tensor scalar measure was calculated from the eigenvalues of the tensor on a voxel-by-voxel basis from each subject and two-sample <I>t</I>-test evaluation between good and poor outcome subjects were performed for each voxel of FA values, across the entire brain, with a voxel-wise intensity threshold of <I>P</I><0.0005 (uncorrected) and a contiguous cluster size of 64 voxels. Individual values of FA were measured by using the region-of-interest based analysis for correlation analysis with CAP scores, open sentence and open word scores.</P><P><B>Results</B></P><P>Two-sample <I>t</I>-test evaluation using SPM voxel-wise analysis found significantly higher FA values at the several brain areas including Broca's area, genu of the corpus callosum, and auditory tract in good outcome subjects compared to poor outcome subjects. Correlation analyses between FA and CAP scores, open sentence and open word scores revealed strong correlations at medial geniculate nucleus, Broca's area, genu of the corpus callosum and auditory tract.</P><P><B>Conclusion</B></P><P>Investigator-independent voxel-based analysis of DTI image demonstrated that good outcome subjects showed better neural integrity at brain areas associated with language and auditory functions, suggesting that the conservation of microstructural integrity of these brain areas is important. Preoperative functional imaging may be helpful for CI.</P>

Neural correlates of motor imagery for elite archers.

Chang, Yongmin,Lee, Jae-Jun,Seo, Jee-Hye,Song, Hui-Jin,Kim, Yang-Tae,Lee, Hui Joong,Kim, Hye Jung,Lee, Jongmin,Kim, Woojong,Woo, Minjung,Kim, Jin Gu Heyden Son ; John Wiley Sons Inc 2011 NMR in biomedicine Vol.24 No.4

<P>Motor imagery is a mental rehearsal of simple or complex motor acts without overt body movement. It has been proposed that the association between performance and the mental rehearsal period that precedes the voluntary movement is an important point of difference between highly trained athletes and beginners. We compared the activation maps of elite archers and nonarchers during mental rehearsal of archery to test whether the neural correlates of elite archers were more focused and efficiently organised than those of nonarchers. Brain activation was measured using functional MRI in 18 right-handed elite archers and 18 right-handed nonarchers. During the active functional MRI imagery task, the participants were instructed to mentally rehearse their archery shooting from a first-person perspective. The active imagery condition was tested against the nonmotor imagery task as a control condition. The results showed that the premotor and supplementary motor areas, and the inferior frontal region, basal ganglia and cerebellum, were active in nonarchers, whereas elite archers showed activation primarily in the supplementary motor areas. In particular, our result of higher cerebellar activity in nonarchers indicates the increased participation of the cerebellum in nonarchers when learning an unfamiliar archery task. Therefore, the difference in cerebellar activation between archers and nonarchers provides evidence of the expertise effect in the mental rehearsal of archery. In conclusion, the relative economy in the cortical processes of elite archers could contribute to greater consistency in performing the specific challenge in which they are highly practised.</P>

Incidental magnetization transfer effects in multislice brain MRI at 3.0T

Chang, Yongmin,Bae, Sung Jin,Lee, Young Ju,Hwang, Moon Jung,Lee, Sang Heun,Lee, Jongmin,Lee, Sang Kwon,Woo, Seongku RADIOLOGICAL SOCIETY OF NORTH AMERICA INC 2007 JOURNAL OF MAGNETIC RESONANCE IMAGING Vol.25 No.4

<B>Purpose</B><P>To evaluate the effect of incidental magnetization transfer (iMT) in multislice brain imaging at 3.0T.</P><B>Materials and Methods</B><P>The contribution of iMT to multislice brain MRI was evaluated at 3.0T. In 10 normal subjects we obtained multislice fast spin-echo (FSE) MR images using a 16-echo pulse train without an off-resonance MT pulse at 3.0T and 1.5T. We quantified the extent of iMT by calculating the iMT ratio (iMTR).</P><B>Results</B><P>We found that the iMT contrast (iMTC) has a greater effect at 3.0T. As the number of slices increased in multislice FSE imaging, the difference between two field strengths became larger. Compared to WM structures, however, the difference in iMT effect between 1.5T and 3.0T was smaller in the case of GM structures.</P><B>Conclusion</B><P>The iMTC has a greater effect at 3.0T. The strength of the iMT is different for different tissue types and also varies according to the number of slices used. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.</P>

Diffusion Tensor Imaging and Fiber Tractography of Patients with Cervical Spinal Cord Injury

Chang, Yongmin,Jung, Tae-Du,Yoo, Dong Soo,Hyun, Jung Keun Mary Ann Liebert 2010 JOURNAL OF NEUROTRAUMA - Vol.27 No.11

Pallidal index measured with three-dimensional T1-weighted gradient echo sequence is a good predictor of manganese exposure in welders

Chang, Yongmin,Woo, Seung-Tae,Kim, Yangho,Lee, Jae-Jun,Song, Hui-Jin,Lee, Hui Joong,Kim, Suk Hwan,Lee, Hun,Kwon, Young Joo,Ahn, Joon-Ho,Park, Sin-Jae,Chung, In-Sung,Jeong, Kyoung Sook Wiley Subscription Services, Inc., A Wiley Company 2010 JOURNAL OF MAGNETIC RESONANCE IMAGING Vol.31 No.4

<B>Purpose:</B><P>To evaluate which T1-wieghted technique between 3D gradient-echo (FSPGR) and conventional spin-echo (SE) sequence is more sensitive predictor of neurobehavioral dysfunction found in welders with chronic manganese (Mn) acquired at 3 Tesla.</P><B>Materials and Methods:</B><P>Forty-three current male welders and 29 age- and gender-matched, nonwelding production workers (control individuals) were recruited to the present study. Each subject underwent neurological examination, blood sample collection, and neurobehavioral tests, in addition to magnetic resonance imaging (MRI) examination. The MRI examinations were performed using a 3.0 Tesla whole-body scanner. T1-weighted axial images were obtained using SE and FSPGR with a 180° inversion recovery prepared pulse, and the corresponding pallidal indices (PI), PI (SE), and PI (FSPGR), were calculated.</P><B>Results:</B><P>Both PI (SE) and PI (FSPGR) were well correlated with blood Mn level, but only PI (FSPGR) was significantly correlated with air Mn concentration (P = 0.007). Of the neurobehavioral performance indicators, after controlling for covariates, PI (FSPGR) was significantly associated with cognitive components, such as the digit symbol score, the digit span backward score, the Stroop test score and also with the grooved pegboard (dominant hand) score, whereas PI (SE) was associated only with grooved pegboard (dominant hand) score.</P><B>Conclusion:</B><P>PI using a T1-weighted 3D FSPGR sequence shows the best correlation with neurobehavioral performance indicators and is the best measure for detection of blood and airborne Mn concentrations in welders exposed to excessive occupational Mn. J. Magn. Reson. Imaging 2010;31:1020–1026. ©2010 Wiley-Liss, Inc.</P>

Gadolinium agents for theragnosis of malignant tumors

Chang, Yongmin,Chae, Kwon Seok,Lee, Gang Ho Thomas Telford Ltd. 2016 Bioinspired, biomimetic and nanobiomaterials Vol.5 No.4

In Situ Analyses of Carbon Dissolution into Ni-YSZ Anode Materials

Kim, Yongmin,Kim, Jung Hyun,Bae, Joongmyeon,Yoon, Chang Won,Nam, Suk Woo American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.24

<P>A combination of in situ analyses, including measurement of both electrical resistance and volumetric expansion, and thermogravimetric analysis (TGA) was employed to elucidate the deactivation process of a nickel-yttria-stabilized zirconia (Ni-YSZ) cermet (60 wt % NiO-YSZ) upon exposure to methane at 750 °C. In conjunction with the aforementioned in situ techniques, a number of ex situ analyses, including scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and Raman spectroscopy, revealed that carbon deposition initially occurred at the Ni centers, followed by carbon dissolution into the Ni-YSZ cermet after an induction period of 200 min, which then led to three-dimensional expansion. The structural change of the Ni-based cermet induced increases in electrical resistance of the material. The increased electrical resistance likely originated from the breakage of the Ni–Ni conducting network as well as from the formation of microscopic cracks within the Ni-YSZ material, resulting from the observed process of carbon dissolution. Moreover, a combination of TGA involving measurements of electrical resistance was demonstrated to be useful for determining amounts of carbon deposits critical for carbon dissolution. These results strongly suggest that changes in electrical resistance can be utilized to monitor the extent of carbon dissolution into the Ni-YSZ catalysts in situ, which would be helpful for the development of an efficient curing system for solid oxide fuel cells (SOFCs).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-24/jp3035693/production/images/medium/jp-2012-035693_0002.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3035693'>ACS Electronic Supporting Info</A></P>

Sequential ¹H MR Spectroscopy(MRS) Studies of Kaolin-Induced Hydrocephalic Cat Brain

김명진,황성규,황정현,장용민,김용선,김승래,Kim, Myung Jin,Hwang, Sung Kyoo,Hwang, Jeong Hyun,Chang, Yongmin,Kim, Yong Sun,Kim, Seung Lae The Korean Neurosurgical Society 2000 Journal of Korean neurosurgical society Vol.29 No.11

목 적 : 실험적으로 유발된 고양이 수두증 모델을 통하여 양자 자기공명 분광상의 수두증에서의 임상적 적응과 경시적 뇌 대사산물의 변화를 규명하는데 목적이 있다. 대상 및 방법 : 30마리의 고양이에서 뇌대조내에 kaolin을 주입후 수두증을 유발한후 양자 자기공명 분광상을 이용하여 kaolin 주입전, 주입후 1, 3, 7, 14, 21, 28일째에 주요 대사산물인 N-acetyl aspartate(NAA), creatine(Cr), choline (Cho), lactate(Lac)의 분광상을 분석하였다. 결 과 : 30마리의 고양이에서 모두 수두증이 유발되었고, 급성기에 NAA/Cr비가 감소하는 소견보였으며, 1마리에서 lactate peak이 관찰되었다. 만성기(>14 days)까지 생존한 4마리의 고양이에서 NAA/Cr비의 증가가 관찰되었으며 이는 임상적 증상의 회복과 상응하는 결과를 나타내었다. 결 론 : Kaolin 유발 수두증모델에서 양자 자기공명 분광상은 급성기의 진단적 정보의 제공과 수두증에서의 뇌대사 및 생화학적 결과를 반영해 준다. 그리고, 급성기에서 lactate peak없이 NAA/Cr비의 감소와 만성기의 NAA/Cr비의 회복은 수두증으로인한 뇌실질의 손상이 신경세포 자체보다는 축색손상을 의미한다. 급성기말까지 초기 NAA/Cr비 감소가 회복없이 lactate peak이 동반되는 경우는 불량한 예후인자가 된다. 만성기의 NAA/Cr비의 정상화는 NAA/ Cr비의 감소를 보이는 뇌피질위축의 경우와의 감별진단에 실마리를 제공한다. Objectives : The aim of this study is to evaluate the sequential metabolic changes in experimental hydrocephalus and the clinical applicability to the diagnosis and prognosis of hydrocephalus using proton MR spectroscopy. Methods : Hydrocephalus was experimentally induced in 30 cats(2-3kg body weight) by injecting 1ml of sterile kaolin suspension(250mg/ml) into the cisterna magna. Proton MRS was performed with a 1.5 T MRI/MRS unit (Vision Plus, Siemens) at pre-treatment and at 1, 3, 7, 14, 21, and 28 days after the kaolin injection. PRESS(TR/TE=1500/270msec) technique was employed. The major metabolites which include N-acetyl aspartate (NAA), creatine(Cr), choline(Cho), and lactate(Lac) were quantitatively analyzed and the relative concentrations ratios were evaluated. Multislice $T_2$-weighted images were also obtained using fast spin echo sequence(TR/TE= 2500/96msec) to monitor the morphologic changes along with progression of hydrocephalus. Results : Hydrocephalus was successfully induced in all 30 cats. Twenty five cats died within 3 days and one at the end of the second week. In all animals, the NAA/Cr ratios initially decreased during the acute stage. In 4 surviving cats, the NAA/Cr ratios initially decreased during the acute stage(<14 days) and then gradually increased to the prekaolin level as follows : pre-kaolin($1.49{\pm}0.04$), day 1($1.11{\pm}0.07$), day 7($1.17{\pm}0.04$), day 14($1.40{\pm}0.03$), day 21 ($1.46{\pm}0.06$), day 28($1.43{\pm}0.03$). These levels were relatively well correlated with the symptomatologic improvement. Lactate peak, which reflects the evidence of ischemia, did not appear throughout the entire period except in one case which expired at the end of the second week. Conclusions : The NAA/Cr ratio of the sequential proton MRS in kaolin-induced hydrocephalic cats reflects a metabolic aspect of the hydrocephalus at each stage. A decreased NAA level at the early stage is from both neuronal and axonal damage which may provide diagnostic information in the acute stage of hydrocephalus. In addition, the initial fall of NAA/Cr ratio and recovery in the late stage, when no lactate peak emerges, may suggest that the main insult of the parenchyma is not to the neuron itself but to the axon, which may be related to a good prognosis. However, emergence of the lactate peak and unrecoverable NAA/Cr at the end of the acute phase may be a poor prognostic factor. In the chronic stage, recovery of NAA/Cr ratio may provide a diagnostic clue for the differentiation between hydrocephalus and cortical atrophy.