• Radiation Oncology Journal
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• 제31권3호
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• pp.111-117
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• 2013

Purpose: To determine whether the maximum standardized uptake value (SUV) of [$^{18}F$] fluorodeoxyglucose uptake by positron emission tomography (FDG PET) ratio of lymph node to primary tumor (mSUVR) could be a prognostic factor for node positive non-small cell lung cancer (NSCLC) patients treated with definitive radiotherapy (RT). Materials and Methods: A total of 68 NSCLC T1-4, N1-3, M0 patients underwent FDG PET before RT. Optimal cutoff values of mSUVR were chosen based on overall survival (OS). Independent prognosticators were identified by Cox regression analysis. Results: The most significant cutoff value for mSUVR was 0.9 with respect to OS. Two-year OS was 17% for patients with mSUVR > 0.9 and 49% for those with mSUVR ${\leq}0.9$ (p = 0.01). In a multivariate analysis, including age, performance status, stage, use of chemotherapy, and mSUVR, only performance status (p = 0.05) and mSUVR > 0.9 (p = 0.05) were significant predictors of OS. Two-year OS for patients with both good performance (Eastern Cooperative Oncology Group [ECOG] ${\leq}1$) and mSUVR ${\leq}0.9$ was significantly better than that for patients with either poor performance (ECOG > 1) or mSUVR > 0.9, 23% (71% vs. 23%, p = 0.04). Conclusion: Our results suggested that the mSUVR was a strong prognostic factor among patients with lymph node positive NSCLC following RT. Addition of mSUVR to performance status identifies a subgroup at highest risk for death after RT.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.776-780
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• 2017

To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a $^{99m}Tc$ gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

• Investigative Magnetic Resonance Imaging
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• 제23권2호
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• pp.100-113
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• 2019

Sarcoidosis is a multisystem disease characterized by noncaseating granulomas. Cardiac involvement is known to have poor prognosis because it can manifest as a serious condition such as the conduction abnormality, heart failure, ventricular arrhythmia, or sudden cardiac death. Although early diagnosis and early treatment is critical to improve patient prognosis, the diagnosis of CS is challenging in most cases. Diagnosis usually relies on endomyocardial biopsy (EMB), but its diagnostic yield is low due to the incidence of patchy myocardial involvement. Guidelines for the diagnosis of CS recommend a combination of clinical, electrocardiographic, and imaging findings from various modalities, if EMB cannot confirm the diagnosis. Especially, the role of advanced imaging such as cardiac magnetic resonance (CMR) imaging and positron emission tomography (PET), has shown to be important not only for the diagnosis, but also for monitoring treatment response and prognostication. CMR can evaluate cardiac function and fibrotic scar with good specificity. Late gadolinium enhancement (LGE) in CMR shows a distinctive enhancement pattern for each disease, which may be useful for differential diagnosis of CS from other similar diseases. Effectively, T1 or T2 mapping techniques can be also used for early recognition of CS. In the meantime, PET can detect and quantify metabolic activity and can be used to monitor treatment response. Recently, the use of a hybrid CMR-PET has introduced to allow identify patients with active CS with excellent co-localization and better diagnostic accuracy than CMR or PET alone. However, CS may show various findings with a wide spectrum, therefore, radiologists should consider the possible differential diagnosis of CS including myocarditis, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy, amyloidosis, and arrhythmogenic right ventricular cardiomyopathy. Radiologists should recognize the differences in various diseases that show the characteristics of mimicking CS, and try to get an accurate diagnosis of CS.

• 한국연소학회지
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• 제4권1호
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• pp.105-115
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• 1999

The structure of a non-axisymmetric propane diffusion flame was investigated. Tomographic reconstruction method to convert the line-integrated self-emission data of a fuel-rich diffusion flame with square cross-section was applied to get the spatially reconstructed emission data. Modified Shepp-Logan filter and concentric squares raster were chosen for reconstructing arbitrarily shaped object in this process. Spatially reconstructed emission data were then interpreted to several physical quantities, such as flame edge, FWHM, perimeter and 3-D flame temperature distribution. Necessary assumptions were discussed and the results were interpreted. In comparison with axisymmetric flame, flame edge was developed higher, and sooting region of upstream was broader than in this non-axisymmetric one. At some height, the flame was shrunk very rapidly and finally formed circular cross-section.

• Clinical and Experimental Pediatrics
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• 제52권7호
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• pp.804-810
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• 2009

목 적 : 영아연축은 이차성 전신간질중의 하나로 간질 병소를 발견하기 힘든 질환중의 하나이다. 이에 저자들은 $^{99m}Tc-ECD$ 추적자의 느린 점적 주사를 이용한 발작기 SPECT를 통하여 영아 연축 환아에서 간질 병소를 찾아보고자 하였다. 방 법 : 2005년 3월부터 2007년 2월까지 연세대학교 의과대학 소아과에 내원한 영아 연축 14명의 환아를 대상으로 첫 연축이 발생하는 시점에 $^{99m}Tc-ECD$ 를 2분에 걸쳐 천천히 같은 속도로 주입하였다. 발작간기와 발작기 간의 SPECT 의 차이를 비교하였으며 객관적인 비교를 위하여 SISCOM기법을 사용하였다. 또한 간질 병소를 발견할 수 있는 진단기법인 뇌파, 자기공명영상, 양전자단층촬영(PET) 등과 비교 분석하였다. 결 과 : 전체 14례의 추적자의 느린 점적 주사를 이용한 발작기 SPECT 중 10례에서 간질 병소의 혈류가 증가하였다. 비디오 뇌파와 발작기 SPECT에서 간질병소의 일치율은 Kappa=0.57, 95% confidence interval: 0.18-0.96로 높게 나왔다. 이 중 6례에서 발작기 SPECT와 비디오 뇌파에 근거하여 간질 수술을 시행하였으며 수술적 예후가 Engle class I으로 좋은 결과를 보였다. 결 론 : 추적자의 느린 점적 주사를 이용한 발작기 SPECT는 간질 병소를 찾기 어려운 영아 연축 환아에서 간질 병소를 찾아내는데 중요한 역할을 하는 것을 알 수 있었다. 그러나 보다 큰 규모의 전향적인 연구가 필요할 것으로 사료된다.

• 대한방사선기술학회지:방사선기술과학
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• 제39권3호
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• pp.369-376
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• 2016

양전자방출단영상(Positron Emission Tomography, PET)은 여러 화합물과 방사성 동위원소를 결합하여 인체 내에 주입하여 인체 내의 대사율을 정량적으로 측정할 수 있는 핵의학적 검사이다. 특히, 암 조직에서 포도당 대사가 증가되는 현상을 $^{18}F$-FDG(Fluorodeoxyglucose)를 사용하여 널리 암 진단에 활용하며, 현대에서 발병 빈도가 높은 뇌질환 중 치매 및 파킨슨 진단에도 높은 유용성을 보인다는 연구가 다수 진행되었다. 이러한 현재의 정적 정보에 시간의 동적 정보를 포함하는 동적 양전자방출단층영상(dynamic PET, dPET)을 이용할 경우, 진단을 위한 추가적인 정보가 제공되므로 진단의 정확도 향상에 기여할 수 있다. 이러한 이유로 임상 연구자 및 방사선사의 큰 관심을 받고 있으나 연구를 진행하기 위해 손쉽게 사용 가능한 도구가 부족한 실정이며, 다양하고 복잡한 수학적 알고리즘(algorithm)이나 프로그래밍(programming) 기술이 부족할 경우 연구의 활성화를 방해하는 높은 진입장벽으로 존재하게 되므로, 본 연구에서는 dPET 연구의 활성화와 손쉬운 사용을 위해서 MATLAB을 이용하여 그래픽 유저(GUI) 기반으로 하여 무료 소프트웨어를 개발하였으며, 개발된 소프트웨어인 DIA-Tool(Dynamic Image analysis-Tool)은 복잡한 수학적 영상 분석 알고리즘을 누구나 손쉽게 사용할 수 있도록 설계되었다. 향후, 많은 임상 연구자들이 DIA-Tool을 이용하여 국내의 dPET 연구 발전에 큰 도움이 될 것이라 기대된다.

• Tuberculosis and Respiratory Diseases
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• 제71권6호
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• pp.425-430
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• 2011

Background: High 2-[$^{18}F$] fluoro-2-deoxy-D-glucose (FDG) uptake on positron emission tomography-computed tomography (PET-CT) is a prognostic factor for poor survival in non-small cell lung cancer (NSCLC), especially in Stage I. We determined whether the high FDG uptake value of a primary tumor was associated with recurrence and death in patients with resected Stage I and Stage II NSCLC. Methods: We identified consecutive patients who underwent complete surgical resection for Stage I and II NSCLC between 2006 and 2009, who had preoperative PET-CT, and reviewed clinical records retrospectively. FDG uptake was measured as the maximal standardized uptake value (SUVmax) for body weight. Patients were divided into two groups based on SUVmax: (i) above or (ii) below the cut-off value (SUVmax=5.9) determined by a receiver operating characteristic (ROC) curve. Results: Of 57 patients who were enrolled consecutively, 32 (56%) had Stage I NSCLC and 25 (44%) had Stage II. The 5-year recurrence-free survival (RFS) for patients with high (${\geq}5.9$) and low (<5.9) SUVmax were 31% and 57%, respectively (p=0.014). The 5-year overall survival (OS) rates were 39% and 60%, respectively (p=0.029). In univariate analyses, SUVmax (p=0.014), T staging (p=0.025), and differentiation of tumor tissue (p=0.034) were significantly associated with RFS. But, multivariate analyses did not show that SUVmax was an independently significant factor for RFS (p=0.180). Conclusion: High FDG uptake on PET-CT is not an independent prognostic factor for poor outcomes (disease recurrence in patients with resected Stage I and II NSCLC).

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.79-85
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• 2017

본 연구는 양전자 컴퓨터단층촬영(Positron Emission Computed Tomography; PET-CT) 유방암 영상에서 질환관심영역(Region of Interest; ROI)의 대조도 대 잡음비(Contrast to Noise Ratio; CNR)와 신호 대 잡음비(Signal to Noise Ratio; SNR)를 재구성 기법별로 측정 평가하여 통계적 분석을 하고자 하였다. 연구대상은 서울소재 대학병원에서 유방 양전자 컴퓨터단층촬영(Breast PET-CT)을 검사한 환자 100명이다. 측정방법은 ImageJ 프로그램을 사용하여 표본의 인구사회학적 특성, 영상 재구성 기법별 유방암의 SNR과 CNR의 평균값, 95% 신뢰구간 값, SNR과 CNR의 평균차이 값 등을 분석하였다. SPSS Statistics21 통계프로그램으로 ANOVA 분석을 하였으며 p<0.05에서 유의한 것으로 판단하였다. 영상 재구성 기법별 분석결과는 CNR과 SNR 모두 TrueX_TOF, Iterative, Iterative-TOF, FBP-TOF 순으로 높은 값을 나타냈다(p<0.05). CNR과 SNR수치로 영상 재구성 기법의 특징을 조합하여 PET/CT 검사의 정확성과 편의성을 제공할 것이라 사료된다.

• 대한의용생체공학회:의공학회지
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• 제12권1호
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• pp.43-48
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• 1991

As the computerized methods and equipments In nuclear medicine imaging increases, quantitative information is needed on the single photon emission computed tomographic Images as well as on the conventional nuclear medicine images. In this paper, the authors investigated the effect of several clinician - friendly reconstrution filters on the resultant transverse slices of backprojected Profiles of radioisotope distribution from the Quantitative point of view, and reduced the filter parameters such as cutoff frequency and order of filter which are neces mary to minimize the quantification error using computer-generated phantoms.

• Journal of Gastric Cancer
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• 제18권3호
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• pp.218-229
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• 2018

Purpose: This study investigated whether the metabolic avidity of primary tumors and/or metastatic lymph nodes (LNs) measured by $^{18}F$-fluorodeoxyglucose ($^{18}F-FDG$) positron emission tomography/computed tomography (PET/CT) was related to survival after surgery in patients with advanced gastric cancer (AGC). Materials and Methods: One hundred sixty-eight patients with AGC who underwent preoperative $^{18}F-FDG$ PET/CT and curative resection were included. The $^{18}F-FDG$ avidity of the primary gastric tumor and LNs was determined quantitatively and qualitatively. The diagnostic performance of $^{18}F-FDG$ PET/CT was calculated, and the prognostic significance of $^{18}F-FDG$ avidity for recurrence-free survival (RFS) and overall survival (OS) was assessed. Results: In all, 51 (30.4%) patients experienced recurrence, and 32 (19.0%) died during follow-up (median follow-up duration, 35 months; range, 3-81 months); 119 (70.8%) and 33 (19.6%) patients showed $^{18}F-FDG$-avid primary tumors and LNs, respectively. $^{18}F-FDG$ PET/CT showed high sensitivity (73.8%) for the detection of advanced pathologic T ($pT{\geq}3$) stage and high specificity (92.2%) for the detection of advanced pN (${\geq}2$) stage. $^{18}F-FDG$ avidity of LNs was significantly associated with RFS (P=0.012), whereas that of primary tumors did not show significance (P=0.532). Univariate and multivariate analyses revealed that $^{18}F-FDG$ avidity of LNs was an independent prognostic factor for RFS (hazard ratio=2.068; P=0.029). Conclusions: $^{18}F-FDG$ avidity of LNs is an independent prognostic factor for predicting RFS. Preoperative $^{18}F-FDG$ PET/CT can be used to determine the risk and prognosis of patients with AGC after curative resection.