• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.154-154
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• 2012

지표에서의 토양수분은 작은 구성비를 가짐에도 불구하고 여러 수문 현상을 연계하는 매우 중요한 인자로써 최근 관련 연구가 활발하게 진행되고 있다. 토양수분은 침투나 침루를 통하여 강우와 지하수를 연결하는 기능을 함과 동시에 강우사상에 따른 유출특성에 직접적인 영향을 미치며 증발산을 통하여 에너지 순환을 연결하는 중요한 기능을 한다. 토양수분을 측정하는 방법에는 세타 탐침(Theta Probe), 장력계, TDR(Time Domain Reflectrometry) 등이 이용되고 있으며, 광역 토양수분자료의 보다 정확한 공간 변동성의 관측을 위하여 항공원격탐사와 인공위성 원격탐사기술이 개발되어 적용되고 있다. 인공위성 영상은 자료의 분석이 간편하며, 공간자료이므로 공간 변화를 분석하는 데 있어 매우 편리하다. 그 중 MODIS(Moderate Resolution Imaging Spectroradiometer) 위성영상은 저해상도 영상으로 극궤도 위성인 Terra와 Aqua 위성에 장착되어 있으며, NASA에서 필요한 정보를 받아 사용할 수 있다. 본 연구에서는 유역의 물리적 지형자료와 같은 방대한 양의 자료 수집 없이도, 모형이 구축되면 인공위성자료와 강우자료만으로도 신뢰성 높은 결과를 단시간 내에 효율적으로 산정할 수 있는 자료 지향형 모형인 ANFIS(Adaptive Neuro-Fuzzy Inference System)를 사용하였다. 사용된 퍼지변수로는 시험유역의 토양수분 관측자료와 강수량 및 인공위성 자료인 MODIS NDVI(Normalize Difference Vegetation Index), MODIS LST(Land-Surface Temperature) 영상을 이용하였다. MODIS NDVI는 시간 해상도 8일, 공간해상도 250 인 Level 3 영상이며, MODIS LST는 시간 해상도 1일, 공간해상도 1 km인 Level 3 영상을 사용하였다. 위성자료를 사용하기 위해 Korea TM 좌표체계로 변환한 뒤, 토양수분 관측지점이 속한 각 셀의 속성값을 추출하였다. 위성자료와 수집된 자료 및 토양수분자료와의 관계를 분석하기 위하여 입력자료를 다양한 방법으로 구성하여 입력 변수를 생성하였다. 생성된 입력 변수와 ANFIS 모형을 연계하여 각각의 토양수분 산정모형을 구축하고 대상지점에 대한 토양수분을 산정 및 비교 분석하였다.

• Korean Journal of Radiology
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• v.22 no.3
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• pp.405-414
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• 2021

Objective: To compare two clinically available MR volumetry software, NeuroQuant^® (NQ) and Inbrain^® (IB), and examine the inter-method reliabilities and differences between them. Materials and Methods: This study included 172 subjects (age range, 55-88 years; mean age, 71.2 years), comprising 45 normal healthy subjects, 85 patients with mild cognitive impairment, and 42 patients with Alzheimer's disease. Magnetic resonance imaging scans were analyzed with IB and NQ. Mean differences were compared with the paired t test. Inter-method reliability was evaluated with Pearson's correlation coefficients and intraclass correlation coefficients (ICCs). Effect sizes were also obtained to document the standardized mean differences. Results: The paired t test showed significant volume differences in most regions except for the amygdala between the two methods. Nevertheless, inter-method measurements between IB and NQ showed good to excellent reliability (0.72 < r < 0.96, 0.83 < ICC < 0.98) except for the pallidum, which showed poor reliability (left: r = 0.03, ICC = 0.06; right: r = -0.05, ICC = -0.09). For the measurements of effect size, volume differences were large in most regions (0.05 < r < 6.15). The effect size was the largest in the pallidum and smallest in the cerebellum. Conclusion: Comparisons between IB and NQ showed significantly different volume measurements with large effect sizes. However, they showed good to excellent inter-method reliability in volumetric measurements for all brain regions, with the exception of the pallidum. Clinicians using these commercial software should take into consideration that different volume measurements could be obtained depending on the software used.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.124-135
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• 2012

Purpose : The objective of this study was to investigate the differences of hippocampal volume and shape as well as the functional change between long life experienced taxi drivers and controls of Korean population. Materials and Methods: Three-dimensional T1-weighted images and blood oxygen level dependent functional MRI(fMRI) were obtained from 8 subjects, consisting of 4 experienced (20-30 years) taxi drivers and 4 age-matched controls. The hippocampal volume and shape were analyzed with three-dimensional T1-weighted images. In addition, neuronal activities of brain were analyzed using a blood oxygen level dependent fMRI between the two groups. Results: The hippocampal volume showed no statistically significant difference between the two groups (p > 0.05). The left hippocampi of the taxi drivers were slightly elongated with larger head and tail portions than those of the controls (p < 0.05, uncorrected). For the functional MRI, fusiform gyrus was specifically activated in taxi drivers, compared with the control group. Conclusion: The structural and functional changes of taxi driver's hippocampus indicate the functional differentiation as a result of occupational dependence on spatial navigation. In other words, the continuous usage of spatial navigation performance may diminish degeneration of hippocampus and the related brain regions.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.83-90
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• 2011

To prospectively determine the diagnostic performance a combination of standard bolus-chase magnetic resonance (MR) angiography and MR angiography with time-resolved imaging of contrast kinetics (TRICKS) for depicting severity of the head and neck vascular diseases. Over a period of two months, A total of 100 patients(average ages : $50{\pm}8$, male : 60, female : 40) with head and neck vascular diseases were performed on the GE excite 3.0 T units with 8-channel head coil and 4-channel NV coil. Imaging parameters for a typical study were as follow: SBC(TR/ TE/ FA/ SliceThicken./ Slab/ Freq./ FOV/ BW/Scan Time) = 5.4/ min/ 30/ 2/ zip2/ 70/ $224{\times}448$/ 30/ 62.50/ 28, TRICKS(TR/ TE/ FA/ Slice Thicken/Slab/ Freq./ FOV/ BW/ Temp Res./ Scan Time = 3.6/ min/ 25/ 4/ 30/ $160{\pm}384$, zip512/ 30/ 100/ 1 to 1.5/ 23). The analysis of all MR images, which have respect-ively classified two techniques into some diseases. The results of the former were divided into two groups(SBC, TRICKS)with 4 grading of two reader, respectively. Wilcoxon signed rank test was used to determine if a significant difference between imaging techniques existed(p < 0.05). In 33 of 100 patients, arterio-venous malformation was 11% at TRICKS, subclavian vein stenosis : 8%, fistular sinus : 4%, jugular vein stenosis:6%, Middle Cerebral Artery bypass surgery : 4%, p < 0.05). The rest of 67 patients were considered as the results of SBC(14% in the basilar artery stenosis, carotid stenosis : 16%, vertebral stenosis : 17%, central neuro-cytoma : 5%, meningioma : 5%, Not appliable : 10%, p < 0.05). Sensitivity and specificity of TRICKS MR angiography in SVS, FS, JVS, MCABS were improved compared with those at standard MR angiography. In SBS MR angiography which were improved in BAS, CS, VS, CN, Meningioma. In conclusion, TRICKS MR angiography of the SVS, FS, JVS, MCABS is superior to standard MR angiography regarding the number of diagnostic grading. The SBS MR angiography were improved in BAS, CS, VS, CN, Meningioma. and assessment of the degree of luminal narrowing on both TRICKS and SBS.

• Korean Journal of Radiology
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• v.24 no.6
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• pp.553-563
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• 2023

Objective: Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging-derived tractography (DTI-t) contribute to the localization of language areas, but their accuracy remains controversial. This study aimed to investigate the diagnostic performance of preoperative fMRI and DTI-t obtained with a simultaneous multi-slice technique using intraoperative direct cortical stimulation (DCS) or corticocortical evoked potential (CCEP) as reference standards. Materials and Methods: This prospective study included 26 patients (23-74 years; male:female, 13:13) with tumors in the vicinity of Broca's area who underwent preoperative fMRI and DTI-t. A site-by-site comparison between preoperative (fMRI and DTI-t) and intraoperative language mapping (DCS or CCEP) was performed for 226 cortical sites to calculate the sensitivity and specificity of fMRI and DTI-t for mapping Broca's areas. For sites with positive signals on fMRI or DTI-t, the true-positive rate (TPR) was calculated based on the concordance and discordance between fMRI and DTI-t. Results: Among 226 cortical sites, DCS was performed in 100 sites and CCEP was performed in 166 sites. The specificities of fMRI and DTI-t ranged from 72.4% (63/87) to 96.8% (122/126), respectively. The sensitivities of fMRI (except for verb generation) and DTI-t were 69.2% (9/13) to 92.3% (12/13) with DCS as the reference standard, and 40.0% (16/40) or lower with CCEP as the reference standard. For sites with preoperative fMRI or DTI-t positivity (n = 82), the TPR was high when fMRI and DTI-t were concordant (81.2% and 100% using DCS and CCEP, respectively, as the reference standards) and low when fMRI and DTI-t were discordant (≤ 24.2%). Conclusion: fMRI and DTI-t are sensitive and specific for mapping Broca's area compared with DCS and specific but insensitive compared with CCEP. A site with a positive signal on both fMRI and DTI-t represents a high probability of being an essential language area.

• Current Optics and Photonics
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• v.3 no.3
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• pp.256-262
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• 2019

Extensive tumor resection accompanied by radiotherapy and chemotherapy is the standard of care for malignant gliomas. However, there is a significant obstacle to the complete resection of the tumor due to the difficulty of distinguishing tumor and normal brain tissue with a conventional surgical microscope. Recently, multiple studies have shown the possibility of fluorescence-guided surgery in malignant gliomas. The most used fluorescence dyes for brain tumor surgery are 5-aminolevulinic acid (5-ALA) and indocyanine green (ICG). In this paper, a new fluorescence guided operation system, which can detect both 5-ALA and ICG fluorescent images simultaneously, is presented. This operation system consists of light emitting diodes (LEDs) which emits 410 nm and 740 nm wavelengths. We have performed experiments on rats in order to verify the operation of the newly developed operation system. Oral administration and imaging were performed to observe the fluorescence of 5-ALA and ICG fluorescence in rats. When LEDs at wavelengths of 410 nm and 740 nm were irradiated on rats, 628 nm wavelength with a violet fluorescence color and 825 nm wavelength with a red fluorescence color were expressed in 5-ALA and ICG fluorescent material, respectively, thus we were able to distinguish the tumor tissues easily. Previously, due to the poor resolution of the conventional surgical microscope and the fact that the color of the vein is similar to that of the tumor, the tumor resection margin was not easy to observe, thus increasing the likelihood for cancer recurrence. However, when the tumor is observed through the fluorescence guided operation system, it is possible to easily distinguish the color with the naked eye and it can be completely removed. Therefore, it is expected that surgical removal of cancerous tumors will be possible and surgical applications and surgical microscopes for cancer tumor removal surgery will be promising in the future.

• Korean Journal of Radiology
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• v.24 no.8
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• pp.784-794
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• 2023

Objective: To determine whether dynamic susceptibility contrast-enhanced (DSC) perfusion magnetic resonance imaging (MRI) can be used to evaluate posterior cerebral circulation in pediatric patients with moyamoya disease (MMD) who underwent anterior revascularization. Materials and Methods: This study retrospectively included 73 patients with MMD who underwent DSC perfusion MRI (age, 12.2 ± 6.1 years) between January 2016 and December 2020, owing to recent-onset clinical symptoms during the follow-up period after completion of anterior revascularization. DSC perfusion images were analyzed using a dedicated software package (NordicICE; Nordic NeuroLab) for the middle cerebral artery (MCA), posterior cerebral artery (PCA), and posterior border zone between the two regions (PCA-MCA). Patients were divided into two groups; the PCA stenosis group included 30 patients with newly confirmed PCA involvement, while the no PCA stenosis group included 43 patients without PCA involvement. The relationship between DSC perfusion parameters and PCA stenosis, as well as the performance of the parameters in discriminating between groups, were analyzed. Results: In the PCA stenosis group, the mean follow-up duration was 5.3 years after anterior revascularization, and visual disturbances were a common symptom. Normalized cerebral blood volume was increased, and both the normalized time-topeak (nTTP) and mean transit time values were significantly delayed in the PCA stenosis group compared with those in the no PCA stenosis group in the PCA and PCA-MCA border zones. TTP_PCA (odds ratio [OR] = 6.745; 95% confidence interval [CI] = 2.665-17.074; P < 0.001) and CBV_PCA-MCA (OR = 1.567; 95% CI = 1.021-2.406; P = 0.040) were independently associated with PCA stenosis. TTP_PCA showed the highest receiver operating characteristic curve area in discriminating for PCA stenosis (0.895; 95% CI = 0.803-0.986). Conclusion: nTTP can be used to effectively diagnose PCA stenosis. Therefore, DSC perfusion MRI may be a valuable tool for monitoring PCA stenosis in patients with MMD.

• Clinical and Experimental Pediatrics
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• v.45 no.9
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• pp.1055-1058
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• 2002

뇌종양 치료성적은 점차 향상되고 있지만 백혈병 등 다른 소아암에 비해 향상 속도가 느리다. 하지만, 근래 MRI, PET scan 등 neuro-imaging 기술의 발달, 뇌종양의 분자유전학적 연구, 외과 수술 방법의 진전, 치료방사선요법의 다양화 등 많은 분야에서 꾸준한 발전을 보이고 있다. 그리고 여러 가지 신약개발에 의한 제 1, 제 2상의 약제시험, antiangiogenesis 약제의 임상시험, gene therapy 등의 연구가 활발하게 진행되고 있으므로, 이에 따른 환자의 치료 성적도 향상될 것으로 기대하고 있다. 외국에서는 여러 대학이 함께 참여하여 작성한 공동의 치료 protocol에 의한 치료가 활발하게 진행되어 생존율을 높이는데 반해, 우리나라에서는 아직까지 각 기관의 협조체제가 구축되지 못한 형편이다. 하지만 금년에 처음으로 여러 대학에서 임상각과가 참석하는 한국소아 뇌종양연구회가 탄생되어 우리나라 뇌종양 환아들의 치료 protocol 개발에 기여할 것을 기대하고 있다. 뇌종양 치료 후 생존하는 아이들을 위한 정밀한 추적관찰이 필수사항인데 여기에 소아과 의사들의 역할은 클 것으로 사료된다. 지능장애, 부적절한 대인관계, 사회적응의 어려움, 치료 후 발생한 내분비계통의 후유증 그리고 2차 암의 발생 등의 정확한 진단 및 치료가 소아과 의사들의 몫으로 남는다. 또한, 이러한 장애가 있는 환아들이 사회에 잘 적응하도록 하기 위해서는 재활교육에 대한 사회적인 관심과 그에 적절한 지원제도의 확립이 절실히 요구된다. 이 점에 있어서도 소아과 의사들의 관심과 지원이 필요하다.

• Journal of Veterinary Clinics
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• v.40 no.5
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• pp.360-364
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• 2023

A 7-year-old castrated male Yorkshire Terrier presented for a palpable mass of the right neck with ophthalmic signs of conjunctival hyperemia and anisocoria with fixed mydriatic pupil of the right eye. Clinical examination findings included the absence of direct and consensual pupillary light reflexes, external and internal ophthalmoplegia, and corneal hypoesthesia with incomplete blinking of the right eye. Magnetic resonance imaging and computed tomography revealed a mass extending from the right cavernous sinus to the orbital fissure with neighboring bone lysis. Cytological examination of fine-needle aspiration samples of the mass revealed a neuroendocrine tumor. The owner declined further diagnosis and did not wish to care for the dog receiving chemotherapy. This study describes the importance of investigating neuro-ophthalmic findings, which might provide clues for the localization of lesions, including tumors, to aid in diagnosis.

• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1545-1555
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• 2021

Purpose The purpose of this study was to evaluate the rates of unacceptable diagnosis and clinically significant diagnostic discrepancy in radiology sections and imaging modalities through a peer review of teleradiology. Materials and Methods Teleradiology peer reviews in a Korean teleradiology clinic in 2018 and 2019 were included. The peer review scores were classified as acceptable and unacceptable diagnoses and clinically insignificant and significant diagnostic discrepancy. The diagnostic discrepancy rates and clinical significance were compared among radiology sections and imaging modalities using the chi-square test. Results Of 1312 peer reviews, 117 (8.9%) cases had unacceptable diagnoses. Of 462 diagnostic discrepancies, the clinically significant discrepancy was observed in 104 (21.6%) cases. In radiology sections, the unacceptable diagnosis was highest in the musculoskeletal section (21.4%) (p < 0.05), followed by the abdominal section (7.3%) and neuro section (1.3%) (p < 0.05). The proportion of significant discrepancy was higher in the chest section (32.7%) than in the musculoskeletal (19.5%) and abdominal sections (17.1%) (p < 0.05). Regarding modalities, the number of unacceptable diagnoses was higher with MRI (16.2%) than plain radiology (7.8%) (p < 0.05). There was no significant difference in significant discrepancy. Conclusion Peer review provides the rates of unacceptable diagnosis and clinically significant discrepancy in teleradiology. These rates also differ with subspecialty and modality.