• Nuclear Medicine and Molecular Imaging
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• 제42권2호
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• pp.98-111
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• 2008

This review introduces advances in clinical and pre-clinical single photon emission computed tomography (SPECT) and positron emission tomography (PET) providing noninvasive functional images of biological processes. Development of new collimation techniques such as multi-pinhole and slit-slat collimators permits the improvement of system spatial resolution and sensitivity of SPECT. Application specific SPECT systems using smaller and compact solid-state detector have been customized for myocardial perfusion imaging with higher performance. Combined SPECT/CT providing improved diagnostic and functional capabilities has been introduced. Advances in PET and CT instrumentation have been incorporated in the PET/CT design that provide the metabolic information from PET superimposed on the anatomic information from CT. Improvements in the sensitivity of PET have achieved by the fully 3D acquisition with no septa and the extension of axial field-of-view. With the development of faster scintillation crystals and electronics, time-of-flight (TOF) PET is now commercially available allowing the increase in the signal-to-noise ratio by incorporation of TOF information into the PET reconstruction process. Hybrid PET/SPECT/CT systems has become commercially available for molecular imaging in small animal models. The pre-clinical systems have improved spatial resolution using depth-of-interaction measurement and new collimators. The recent works on solid state detector and dual modality nuclear medicine instrumentations incorporating MRI and optical imagers will also be discussed.

• 대한영상의학회지
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• 제81권6호
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• pp.1412-1423
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• 2020

목적 본 연구는 신생아 경련 환자에서 구조적 이상이나 대사로 인한 원인이 없으면서, 확산강조영상에서 미만성 대뇌 백질의 이상을 보이는 경우의 임상적 소견과 영상 소견의 특징을 기술하고자 한다. 대상과 방법 2008년 11월에서 2017년 2월 사이에 경련에 대한 평가를 위해 56명의 생후 1주 미만의 신생아가 뇌 자기공명영상을 시행하였다. 이중 33명을 제외한 23명중, 13명에서 확산강조영상에서 미만성 대뇌 백질 이상을 보였다. 내원 시 임상 소견, 자기공명영상 소견, 추적검사 결과에 대해 후향적으로 분석하였다. 결과 확산제한을 보인 13명의 환아는 모두 만기 분만 환아였다. 대변 바이러스 검사를 시행한 10명 중 6명은 로타바이러스, 한 명은 아스트로 바이러스가 검출되었다. 확산 제한은 대뇌 백질, 시상, 중뇌에 걸쳐 다양하게 분포하였다. 결론 신생아 경련 환자에서 구조적 이상이나 대사로 인한 원인이 없으면서, 확산강조영상에서 미만성 대뇌 백질의 이상을 보이는 경우, 로타바이러스가 검출되는 경우가 흔히 있었다. 따라서 이러한 임상적, 영상의학적 소견을 보일 때, 바이러스 감염과 관련된 뇌증의 가능성을 고려할 필요가 있을 것으로 판단된다.

• Transactions on Electrical and Electronic Materials
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• 제17권6호
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• pp.375-379
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• 2016

Increasing fat tissue of obese people, increases the rate of cardiovascular disease, diabetes, metabolic syndromes and dyslipidemia. An increase in the focal tissue of pancreas is a known risk factor of these diseases. Although there exists sufficient research on the diagnosis and treatment of pancreatic cancer, studies have been done on fatty pancreas. In this study, based on ultrasound imaging and using a texture characteristic of GLCM, fatty pancreas was divided into three categories: mild, moderate and severe. We compared and analyzed the three groups was by Pancreatic ultrasonography and body characteristics, serological tests, pressure and the degree of arteriosclerosis, against normal control group. The following parameters of control and test groups were measured: WC (waist circumference),BMI (body mass index), TC (total cholesterol), TG (triglyceride), HDL-C (High-density lipoprotein cholesterol) and LDL-C (Low-density lipoprotein cholesterol), SBP (systolic blood pressure), BST (Blood Sugar Test) and aortic PWV (pulse wave velocity). We observed the values correspondingly increasing fat deposition. However, ABI (Ankle Brachial pressure index) stenosis and HDL-C levels decreased with increasing fat deposit (p <0.05); a drop in these parameters are known to be harmful to the human body. The difference in texture characteristics between normal control group and pancreatic fatty group (mild, moderate, and severe) was statistically confirmed. Ultrasound imaging of pancreatic steatosis categorized the disease as mild, moderate and severe based on the characteristic texture. In conclusion, we observed on increase in metabolic syndrome, dyslipidemia, and arteriosclerosis, proportional to the degree of pancreatic fat deposition. The escalation of these diseases was confirmed and was directly related with predictors of cardiovascular diseases.

• Imaging Science in Dentistry
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• 제41권4호
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• pp.155-159
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• 2011

Purpose : This study was performed to determine the prevalence of maxillary canine impaction on a basis of a single panoramic radiograph in Bangladeshi population. Materials and Methods : A random sample of seven hundred panoramic radiographs was collected from the patient record of a dental clinic. All the selected panoramic radiographs were taken from January 2009 to August 2010 by a single panoramic radiograph machine with the same exposure time (19 seconds) for all radiographs. One hundred and twenty panoramic radiographs were excluded to minimize the selection bias. In a dim lit room, an observer assessed the radiographs on a standard radiographic light box. The position of the impacted maxillary canine was recorded in line with the longitudinal axis of a tooth using the edge of a metal ruler. Data were subsequently put on SPSS 11.5 software and chi-square (${\chi}^2$) tests were applied to find out the association. Results : Among 580 panoramic radiographs it was found that impacted maxillary canines were present in only 7 (1.2%) radiographs. A statistical significant difference was found between the age of the patients and the vertical position of the impacted canines (p=0.000) and between the age of the patients and the horizontal position of the impacted canines (p=0.003). Conclusion : The prevalence was found to be low compared with the present study from the limitation of panoramic image. Further study needs to include three-dimensional imaging modality.

• Clinical and Experimental Pediatrics
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• 제55권10호
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• pp.397-402
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• 2012

Pelizaeus-Merzbacher disease (PMD) is a rare, X-linked recessive disorder characterized by dysmyelination in the central nervous system. PMD results from deletion, mutation, or duplication of the proteolipid protein gene (PLP1) located at Xq22, leading to the failure of axon myelination by oligodendrocytes in the central nervous system. PMD may be suspected when there are clinical manifestations such as nystagmus, developmental delays, and spasticity, and genetic analysis can confirm the diagnosis. Further diagnostic manifestations of the disease include a lack of myelination on brain magnetic resonance (MR) imaging and aberrant N-acetyl aspartate (NAA) and choline concentrations that reflect axonal and myelination abnormalities on phroton MR spectroscopy. We report 5 cases of PMD (in 1 girl and 4 boys). PLP1 duplication was detected in 2 patients. Brain MR analyses and MR spectroscopy were performed for all the patients. The brain MR images showed white matter abnormalities typical of PMD, and the MR spectroscopic images showed diverse patterns of NAA, creatinine, and choline concentrations. We propose that MR spectroscopic analysis of metabolic alterations can aid the PMD diagnosis and can contribute to a better understanding of the pathogenesis of the disease.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.291-292
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• 1998

The purpose of the study was aimed to evaluate the BOLD contrast fMRI in occipital lobe and compare this imaging with metabolite changes based on $^1H$ MRS and MRSI before and after visual stimulation. As a result, the activation map were sucessfully produced by thresholding with minimum cross-correlate value of 0.45. In MRS, NAA/Cr ratio is almost same. however, latate was elevated almost 9 times higher than before activation. Lactate metabolic images were consistent with the BOLD effect map. The BOLD contrast fMRI is not enough to detect the activation area in human brain. so, the other modality was required such as lactate metabolic map.

• 대한유전성대사질환학회지
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• 제19권1호
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• pp.26-30
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• 2019

EFMR은 뇌전증을 보이는 여자 환자에게서 지적장애가 동반된 것이 특징적인데 이들 중 PCDH19 변이와 연관이 있는 경우를 PCDH19 연관성 뇌전증으로 분류하였다. PCDH19 연관성 뇌전증은 조기에 발병하며 열에 민감하고 잘 조절되지 않는 군집발작을 보이는 것이 특징이다. 발달장애나 인지 및 행동장애를 동반할 수 있으며 정상에서부터 중증까지 다양하게 나타날 수 있다. 최근 이러한 질환에서 유전적 원인을 찾고자 하는 노력으로 뇌전증 유전자 패널을 이용하는 경우가 많아지고 있다. 저자들은 EFMR 환자에서 뇌전증 유전자 패널을 이용한 유전자 검사상 PCDH19 돌연변이가 확인된 사례를 경험하였기에 보고하는 바이다.

• Investigative Magnetic Resonance Imaging
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• 제20권1호
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• pp.53-60
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• 2016

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.

• Korean Journal of Radiology
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• 제21권5호
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• pp.588-597
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• 2020

Objective: To investigate the value of combined chemical exchange saturation transfer (CEST) and conventional magnetization transfer imaging (MT) in detecting metabolic and structural changes of renal fibrosis in rats with unilateral ureteral obstruction (UUO) at 3T MRI. Materials and Methods: Thirty-five Sprague-Dawley rats underwent UUO surgery (n = 25) or sham surgery (n = 10). The obstructed and contralateral kidneys were evaluated on days 1, 3, 5, and 7 after surgery. After CEST and MT examinations, ¹⁸F-labeled fluoro-2-deoxyglucose positron emission tomography was performed to quantify glucose metabolism. Fibrosis was measured by histology and western blots. Correlations were compared between asymmetrical magnetization transfer ratio at 1.2 ppm (MTR_asym(1.2ppm)) derived from CEST and maximum standard uptake value (SUV_max) and between magnetization transfer ratio (MTR) derived from MT and alpha-smooth muscle actin (α-SMA). Results: On days 3 and 7, MTR_asym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly different from those of contralateral kidneys (p < 0.05). On day 7, MTR_asym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly different from those of sham-operated kidneys (p < 0.05). The MTR_asym(1.2ppm) of UUO renal medulla was fairly negatively correlated with SUV_max (r = -0.350, p = 0.021), whereas MTR of UUO renal medulla was strongly negatively correlated with α-SMA (r = -0.744, p < 0.001). Conclusion: CEST and MT could provide metabolic and structural information for comprehensive assessment of renal fibrosis in UUO rats in 3T MRI and may aid in clinical monitoring of renal fibrosis in patients with chronic kidney disease.

• Asian-Australasian Journal of Animal Sciences
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• 제29권2호
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• pp.219-229
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• 2016

Fatty liver is a common metabolic disorder of dairy cows during the transition period. Historically, the diagnosis of fatty liver has involved liver biopsy, biochemical or histological examination of liver specimens, and ultrasonographic imaging of the liver. However, more convenient and noninvasive methods would be beneficial for the diagnosis of fatty liver in dairy cows. The plasma metabolic profiles of dairy cows with fatty liver and normal (control) cows were investigated to identify new biomarkers using $^1H$ nuclear magnetic resonance. Compared with the control group, the primary differences in the fatty liver group included increases in ${\beta}$-hydroxybutyric acid, acetone, glycine, valine, trimethylamine-N-oxide, citrulline, and isobutyrate, and decreases in alanine, asparagine, glucose, ${\gamma}$-aminobutyric acid glycerol, and creatinine. This analysis revealed a global profile of endogenous metabolites, which may present potential biomarkers for the diagnosis of fatty liver in dairy cows.