• Korean Journal of Radiology
• /
• 제21권12호
• /
• pp.1367-1373
• /
• 2020

Objective: To assess diffusion tensor imaging (DTI) parameters of the hepatic parenchyma for the differentiation of biliary atresia (BA) from Alagille syndrome (ALGS). Materials and Methods: This study included 32 infants with BA and 12 infants with ALGS groups who had undergone DTI. Fractional anisotropy (FA) and mean diffusivity (MD) of the liver were calculated twice by two separate readers and hepatic tissue was biopsied. Statistical analyses were performed to determine the mean values of the two groups. The optimum cut-off values for DTI differentiation of BA and ALGS were calculated by receiver operating characteristic (ROC) analysis. Results: The mean hepatic MD of BA (1.56 ± 0.20 and 1.63 ± 0.2 × 10^-3 mm²/s) was significantly lower than that of ALGS (1.84 ± 0.04 and 1.79 ± 0.03 × 10^-3 mm²/s) for both readers (r = 0.8, p = 0.001). Hepatic MD values of 1.77 and 1.79 × 10^-3 mm²/s as a threshold for differentiating BA from ALGS showed accuracies of 82 and 79% and area under the curves (AUCs) of 0.90 and 0.91 for both readers, respectively. The mean hepatic FA of BA (0.34 ± 0.04 and 0.36 ± 0.04) was significantly higher (p = 0.01, 0.02) than that of ALGS (0.30 ± 0.06 and 0.31 ± 0.05) for both readers (r = 0.80, p = 0.001). FA values of 0.30 and 0.28 as a threshold for differentiating BA from ALGS showed accuracies of 75% and 82% and AUCs of 0.69 and 0.68 for both readers, respectively. Conclusion: Hepatic DTI parameters are promising quantitative imaging parameters for the detection of hepatic parenchymal changes in BA and ALGS and may be an additional noninvasive imaging tool for the differentiation of BA from ALGS.

• Journal of Radiation Protection and Research
• /
• 제37권1호
• /
• pp.25-34
• /
• 2012

본 연구는 진단용 X-선 촬영에서 부가필터 두께에 따라 피폭 선량 및 의료영상저장전송시스템에 저장된 영상을 비교 평가하여 환자에게 가장 적은 방사선 피폭을 주면서 진단에 적절한 영상을 얻을 수 있는 촬영 조건을 알아보고자 하였다. 그 결과 면적선량($mGy{\cdot}cm^2$)과 입사표면선량($mGy$)은 1 mmAl+0.2 mmCu의 부가필터에서 가장 낮은 피폭 선량값을, 그리고 0 mmAl (No Filter)에서 가장 높은 피폭 선량 값을 보였다. 그러나 의료영상저장전송시스템으로 전송된 영상을 수치 해석 소프트웨어(MATLAB)로 구현한 히스토그램 결과 영상의 질에는 크게 영향을 미치지 않았다. 따라서 진단용 X-선 촬영 장치를 이용한 영상의학적 검사에서 영상의 질에 영향을 미치지 않고 피폭선량을 경감할 수 있는 최적의 부가필터를 사용함으로서 환자의 피폭 선량을 예측하고 검사 조건을 조절하는 데 있어 유용하게 이용될 수 있을 것으로 판단되었다.

• Journal of Gastric Cancer
• /
• 제19권3호
• /
• pp.254-277
• /
• 2019

Inflammation can be a causative factor for carcinogenesis or can result from a consequence of cancer progression. Moreover, cancer therapeutic interventions can also induce an inflammatory response. Various inflammatory parameters are used to assess the inflammatory status during cancer treatment. It is important to select the most optimal biomarker among these parameters. Additionally, suitable biomarkers must be examined if there are no known parameters. We briefly reviewed the published literature for the use of inflammatory parameters in the treatment of patients with cancer. Most studies on inflammation evaluated the correlation between host characteristics, effect of interventions, and clinical outcomes. Additionally, the levels of C-reactive protein, albumin, lymphocytes, and platelets were the most commonly used laboratory parameters, either independently or in combination with other laboratory parameters and clinical characteristics. Furthermore, the immune parameters are classically examined using flow cytometry, immunohistochemical staining, and enzyme-linked immunosorbent assay techniques. However, gene expression profiling can aid in assessing the overall peri-interventional immune status. The checklists of guidelines, such as STAndards for Reporting of Diagnostic accuracy and REporting recommendations for tumor MARKer prognostic studies should be considered when designing studies to investigate the inflammatory parameters. Finally, the data should be interpreted after adjusting for clinically important variables, such as age and cancer stage.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
• /
• pp.252-255
• /
• 2005

가스터빈 엔진은 작동시간이 축적됨에 따라 엔진 주요부품의 성능이 점차적으로 저하되며, 내부구성부품 사이에 결함이 발생하기도 한다. 이러한 엔진의 손상여부를 진단하기 위해 가스경로해석(GPA, Gas Path Analysis)이 사용되고 있다. 본 연구에서는 상용 프로그램에 의존하지 않고, 각 성능변수들과 측정 변수들과의 열역학적 민감도를 이용하여 엔진성능진단 코드를 개발하였으며, 스마트무인기용 터보축 엔진에 적용하여 엔진의 단일 성능 저하를 예측하여 보았다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2005년도 제25회 추계학술대회논문집
• /
• pp.289-292
• /
• 2005

가스터빈 엔진은 운용시간이 축적됨에 따라 압축기, 연소기, 터빈 등 엔진의 여러 핵심 구성요소의 성능이 저하하게 된다. 따라서, 가스터빈 엔진의 운용에 있어서 높은 신뢰성과 운용비용의 최소화는 엔진 제작자나 사용자 모두에게 있어 중요한 문제이다 본 연구에서는 상용 프로그램에 의존하지 않고, 각 성능 변수들과 측정 변수들과의 열역학적 민감도를 이용하여 엔진성능진단 코드를 개발하였으며, 터보축 엔진에 적용하여 엔진의 단일 성능 저하를 예측하였다.

• 대한임상검사과학회지
• /
• 제37권2호
• /
• pp.88-95
• /
• 2005

Even though the echocardiograph has been recognized as the method of choice among various diagnostic tools to detect congestive heart failure (CHF), there were some limitations in relation to the consumption of time, labor and process. We analyzed results of N-terminal probrain-type natriuretic peptide (NT-proBNP) and various parameters of the echocardiographic findings to clarify the diagnostic usefulness of NT-proBNP in detecting patients with CHF. We analyzed the sera from total of 242 cases from in-patients and out-patients, which were requested from the cardiovascular section of department of Internal Medicine at Chungnam National University Hospital from March 2003 to May 2004. The procedures were performed in order as shown below; sampling, NT-proBNP analysis, data acquisition and data analysis. All data including personal information and echocardiographic findings ware acquired by medical record review. When classifying the study population into six groups according to the degree of left ventricular ejection fraction (LVEF), the serum level of NT-proBNP was higher in the group with 51-60% of LVEF (P=0.023). There were low correlation between the serum level of NT-proBNP and various parameters of the echocardiographic findings with LVESD (r=0.1513), LVEDD (r=0.0831), LVEF (r=0.2035), IVST (r=0.03) and LVPWT (r=0.0728), respectively. When comparing NT-proBNP with atrial and/or ventricular enlargement, the patient group with both left atrial and left ventricular enlargement (p=0.186) or only left atrial (p=0.105) or only left ventricular enlargement (p=0.256) showed higher level of NT-proBNP without statistical significance than patient group with no enlargement. Searching the optimal cutoff of the serum level of NT-proBNP, the sensitivity (98.9%) and the specificity (100%) was highest at the cutoff of 300 pg/mL than any other cutoffs. These findings suggested that the analysis of NT-proBNP in serum might detect the patients with CHF earlier than with the echocardiograph, especially in patients with asymptomatic or mild symptomatic CHF. In conclusion, NT-proBNP test was proved to be clinically useful to diagnose CHF patients.

• 대한한의진단학회지
• /
• 제20권2호
• /
• pp.51-65
• /
• 2016

Objectives This study was conducted to suggest a standard operating procedure (SOP) in order to improve the reliability of tongue-image analysis system. Methods An affecting-factors list was made, which may affect the diagnostic parameters of the tongue-image analysis system. They were sub-classified into two groups: controllable and uncontrollable. Only the controllable factors, which could affect the results and easily set-up, were included into the SOP draft. Affecting factors control experiment was performed to investigate the effects of controllable factors, whose influence on diagnostic parameters of the tongue-image analysis system is ambiguous: rehearsal for tongue extrusion; alignment of camera axis; and presentation of a guideline. Three subjects volunteered for this experiment. Each of three variables was implemented twice in a random order by two operators on the subjects. Finally, 96 tongue images obtained in the aggregate. The diagnostic parameter set as a primary outcome in this experiment was the percentage of tongue coating. Results All of the control variables were not significant in both operators; however, the presentation of a guideline was relatively more affect than two other variables. Interaction effects among the variables were also insignificant. Therefore, the presentation of a guideline was included in the final SOP and the other variables were not included. Conclusions We suggested the SOP which could be used for both experimenter and subject. Moreover, Each of the SOPs applied to various types of tongue-image analysis system should be developed in order to improve the reliability.

• Journal of Yeungnam Medical Science
• /
• 제36권3호
• /
• pp.231-240
• /
• 2019

Background: We sought to determine the value of combining diffusion-weighted (DW) and perfusion-weighted (PW) sequences with a conventional magnetic resonance (MR) sequence to assess solid components of borderline ovarian tumors (BOTs) and stage I carcinomas. Methods: Conventional, DW, and PW sequences in the tumor imaging studies of 70 patients (BOTs, n=38; stage I carcinomas, n=32) who underwent surgery with pathologic correlation were assessed. Two independent radiologists calculated the parameters apparent diffusion coefficient (ADC), $K^{trans}$ (vessel permeability), and $V_e$ (cell density) for the solid components. The distribution on conventional MR sequence and mean, standard deviation, and 95% confidence interval of each DW and PW parameter were calculated. The inter-observer agreement among the two radiologists was assessed. Area under the receiver operating characteristic curve (AUC) and multivariate logistic regression were performed to compare the effectiveness of DW and PW sequences for average values and to characterize the diagnostic performance of combined DW and PW sequences. Results: There were excellent agreements for DW and PW parameters between radiologists. The distributions of ADC, $K^{trans}$, and $V_e$ values were significantly different between BOTs and stage I carcinomas, yielding AUCs of 0.58 and 0.68, 0.78 and 0.82, and 0.70 and 0.72, respectively, with ADC yielding the lowest diagnostic performance. The AUCs of the DW, PW, and combined PW and DW sequences were $0.71{\pm}0.05$, $0.80{\pm}0.05$, and $0.85{\pm}0.05$, respectively. Conclusion: Combining PW and DW sequences to a conventional sequence potentially improves the diagnostic accuracy in the differentiation of BOTs and stage I carcinomas.

• 대한기계학회논문집A
• /
• 제39권1호
• /
• pp.37-43
• /
• 2015

압전소자(Piezoelectric transducer, PZT)는 구조물의 안정성 평가를 목적으로 하는 구조 건전성 모니터링 기법(Structural Health Monitoring, SHM)의 센서(sensor) 및 구동기(actuator)로 많이 활용되고 있다. 사용되는 센서 및 구동기의 성능을 사전에 파악하고, 잔존수명 및 결함을 탐지하는 센서 자가 진단법은 안정적인 SHM의 결과를 얻기 위해 매우 중요한 절차이다. 본 연구에서는 Admittance 값을 기반으로 한 센서 자가 진단절차를 통하여 압전체 센서의 결함을 탐지하였으며, 센서 진단과정에 영향을 줄 수 있는 접합층 및 온도 등의 영향인자에 대해 실험적 분석을 실시하였다. 분석 결과 Admittance와 온도 및 접착제의 상관관계를 파악할 수 있었으며, admittance를 기반으로 한 센서 자가 진단 절차를 통해 센서의 접착상태와 접착제의 성능평가가 가능함을 검증하였다.

• Journal of Gastric Cancer
• /
• 제16권3호
• /
• pp.141-151
• /
• 2016

Purpose: The aim of the present study was to elucidate the clinicopathological significance and diagnostic accuracy of immunohistochemistry (IHC) for determining the mesenchymal epidermal transition (c-MET) expression in patients with gastric cancer (GC). Materials and Methods: The present meta-analysis investigated the correlation between c-MET expression as determined by IHC and the clinicopathological parameters in 8,395 GC patients from 37 studies that satisfied the eligibility criteria. In addition, a concordance analysis was performed between c-MET expression as determined by IHC and c-MET amplification, and the diagnostic test accuracy was reviewed. Results: The estimated rate of c-MET overexpression was 0.403 (95% confidence interval [CI], 0.327~0.484) and it was significantly correlated with male patients, poor differentiation, lymph node metastasis, higher TNM stage, and human epidermal growth factor receptor 2 (HER2) positivity in IHC analysis. There was a significant correlation between c-MET expression and worse overall survival rate (hazard ratio, 1.588; 95% CI, 1.266~1.992). The concordance rates between c-MET expression and c-MET amplification were 0.967 (95% CI, 0.916~0.987) and 0.270 (95% CI, 0.173~0.395) for cases with non-overexpressed and overexpressed c-MET, respectively. In the diagnostic test accuracy review, the pooled sensitivity and specificity were 0.56 (95% CI, 0.50~0.63) and 0.79 (95% CI, 0.77~0.81), respectively. Conclusions: The c-MET overexpression as determined by IHC was significantly correlated with aggressive tumor behavior and positive IHC status for HER2 in patients with GC. In addition, the c-MET expression status could be useful in the screening of c-MET amplification in patients with GC.