• Asian Pacific Journal of Cancer Prevention
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• 제15권18호
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• pp.7821-7824
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• 2014

Background: We investigated the correlation between standardized uptake value (SUVmax), tumor size and Fuhrman grade in patients with renal cell carcinoma (RC). Materials and Methods: We retrospectively analyzed the data of 54 patients with clear cell renal cell carcinoma histopathologically diagnosed who underwent fluorine-18 fluoro-2 deoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) between January 2005 and March 2014. Results: Avarage tumor sizes were $5.64{\pm}1.85$, $6.85{\pm}2.24$ and $7.98{\pm}2.45$ in low, medium and high SUVmax groups, respectively. The Spearman's correlation coefficient between the tumor size and SUVmax was 0.385 (p=0.004) and between the Fuhrman grade and SUVmax was 0.578 (p<0.001). Conclusions: SUVmax appears highly correlated with tumor size and Fuhrman grade in patients with histopathologically confirmed clear cell RC. Multicenter studies are needed to provide larger series for more accurate results.

• Biomolecules & Therapeutics
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• 제26권1호
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• pp.81-92
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• 2018

It is widely accepted that altered metabolism contributes to cancer growth and has been described as a hallmark of cancer. Our view and understanding of cancer metabolism has expanded at a rapid pace, however, there remains a need to study metabolic dependencies of human cancer in vivo. Recent studies have sought to utilize multi-modality imaging (MMI) techniques in order to build a more detailed and comprehensive understanding of cancer metabolism. MMI combines several in vivo techniques that can provide complementary information related to cancer metabolism. We describe several non-invasive imaging techniques that provide both anatomical and functional information related to tumor metabolism. These imaging modalities include: positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS) that uses hyperpolarized probes and optical imaging utilizing bioluminescence and quantification of light emitted. We describe how these imaging modalities can be combined with mass spectrometry and quantitative immunochemistry to obtain more complete picture of cancer metabolism. In vivo studies of tumor metabolism are emerging in the field and represent an important component to our understanding of how metabolism shapes and defines cancer initiation, progression and response to treatment. In this review we describe in vivo based studies of cancer metabolism that have taken advantage of MMI in both pre-clinical and clinical studies. MMI promises to advance our understanding of cancer metabolism in both basic research and clinical settings with the ultimate goal of improving detection, diagnosis and treatment of cancer patients.

• The Korean Journal of Medicine
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• 제93권6호
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• pp.571-574
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• 2018

니볼루맙을 사용하는 도중 폐렴이 발생할 수 있고, 폐렴이 의심되면 치료하기 이전에 바이러스를 포함한 감염 여부와 림프관성 암의 진행 상태 및 울혈성 심장 기능 상실 여부 등의 감별이 필요하며 폐렴의 등급과 중증도를 평가하여 스테로이드를 경험적으로 쓰는 것이 중요하다. 본 증례에서는 감염을 배제하기 위하여 기관지 폐포세척을 시행한 후 폐포자충 폐렴이 진단된 사례로 드물기는 하지만 페포자충 폐렴의 감별이 필요함을 보여주어 증례로 보고하는 바이다.

• Nuclear Medicine and Molecular Imaging
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• 제40권6호
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• pp.309-315
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• 2006

목적: 두경부 편평상피암 환자에서 경부림프절전이에 대한 F-18 FDG PET/CT의 진단성적을 평가하고 CT/MRI와 비교하였다. 대상 및 방법: 수술전 조직검사로 편평상피암으로 진단받은 17명(남: 15명, 여: 2명, 평균나이: $59{\pm}11$세)의 환자를 대상으로 F-18 FDG PET/CT를 시행하였다. 경부림프절의 F-18 FDG섭취 정도는 세 등급(1=배후방사능, 2=간방사능보다 낮거나 같은 경우, 3=간방사능보다 높은 경우)으로 나누었고, 3등급일 때 전이로 진단하였다. 경부림프절전이에 대한 F-18 FDG PET/CT의 예민도와 특이도를 CT/MRI와 비교하였다. 결과: 17명의 환자에서 123개의 경부림프절이 절제되었고 이 중 29개가 전이로 확진되었다. F-18 FDG PET/CT의 예민도는 69%(20/29), 특이도는 99%(93/94), CT/MRI의 예민도는 62%(18/29), 특이도는 96%(90/94)로 경부림프절전이에 대한 두 검사의 진단성적은 유의한 차이가 없었다. 그러나 F-18 FDG PET/CT는 각각의 환자에서 간에 생긴 이차성 원발암과 늑골전이를 발견할 수 있었다. 결론: 두경부 편평상피암에서 경부림프절 전이에 대한 F-18 FDG PET/CT의 특이도는 매우 높았지만 예민도는 비교적 낮았고 CT/MRI와 유의하게 다르지 않았다. F-18 FDG PET/CT의 비교적 낮은 예민도의 원인은 최근 많이 절제되고 있는 잠재 전이의 가능성이 있는 작은 경부림프절을 발견하지 못하는 F-18 FDG PET/CT 의 한계 때문이었다. 그러나 F-18 FDG PET/CT는 이차성 원발암과 원격전이를 부가적으로 평가할 수 있어 환자의 치료 방침 결정에 유용하였다.

• 대한방사성의약품학회지
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• 제2권2호
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• pp.73-83
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• 2016

Imaging hypoxia using positron emission tomography (PET) is of great importance for cancer therapy. [$^{18}F$] Fluoromisonidazole (FMISO) was the first PET agent used for imaging tumor hypoxia. Various radiolabeled nitroimidazole derivatives such as [$^{18}F$]fluoroerythronitroimidazole (FETNIM), [$^{18}F$]1-${\alpha}$-D-(2-deoxy-2-fluoroarabinofuranosyl)-2-nitroimidazole(FAZA), 2-(2-nitroimidazol-1-yl)-N-(3,3,3-[18F]-trifluoropropyl)acetamide ([$^{18}F$]EF-3), [$^{18}F$]2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl) acetamide (EF-5), 3-[$^{18}F$]fluoro-2-(4-((2-nitro-1H-imidazol-1-yl)methyl)-1H-1,2,3,-triazol-1-yl)-propan-1-ol ([$^{18}F$]HX-4), and [$^{18}F$]fluoroetanidazole (FETA) were developed successively. However, these imaging agents still produce PET images with limited resolution; the lower blood flow in hypoxic tumors compared to normoxic tumors results in low uptake of the agents in hypoxic tumors. Thus, the development of better imaging agents is necessary.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (B)
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• pp.376-378
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• 2006

본 논문에서는 소동물 양전자방출단층촬영 영상(Positron Emission Tomography, PET) 내 종양영역을 자동분할하고 분할된 윤곽선주변의 기하학적 위험구간에 따른 종양의 형태특성을 분석하기 위한 방법을 제시한다. PET 영상내 검출된 종양영역의 신뢰성을 위해 위음성(False negative, FN) 및 위양성(False positive, FP)의 위험구간을 같이 제공하는 것이 필요하다. 따라서, 방사선 특이적 특성이 반영된 명암값을 기반으로 Fuzzy C-Means(FCM) 클러스터링을 수행하여 종양영역을 자동 분할한다. 분활된 종양영역의 위험구간은 클러스터 간 공유되는 영역의 소속값을 이용하여 위음성, 위양성을 계산한다. 또한, 임의의 소속값 임계치 변화를 통해 위험구간의 변화에 따른 종양의 형태적 특성변화를 관측한다. 이러한 지역적 변화의 관측을 통해 위험구간의 형태학적 위치를 판단할 수 있어 위험구간에 따른 추가적인 잔여 암의 위치 및 형태 파악을 용이하게 한다.

• Nuclear Medicine and Molecular Imaging
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• 제43권6호
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• pp.526-534
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• 2009

목적: 무증상 성인을 대상으로 시행된 PET과 PET/CT 검사 결과를 분석하여 이들 검사의 암 조기 진단을 위한 선별검사로서의 유용성을 평가하고자 하였다. 대상 및 방법: 1998년 3월부터 2008년 2월까지 서울 소재 1개 대학병원에서 건강검진 프로그램의 일부로 시행된 PET과 PET/CT 검사자 중 1년 이상 추적관찰이 이루어진 5,091명을 대상으로 하였다. PET과 PET/CT 시행 후 1년 이내에 암이 확진된 경우를 조사하여 PET과 PET/CT의 판독결과와 비교하고 민감도와 특이도를 평가하였으며, 판독에서 명확한 결론을 내기 어려워 추가 검사를 권고한 경우를 분석하였다. 결과: PET 또는 PET/CT 검사 시행 후 1년이내에 암을 진단 받은 경우는 총 86건으로 전체 조사 대상의 1.7%(86/5,091)였다. PET과 PET/CT 검사를 합친 전체검사의 민감도는 48.8%였으며 특이도는 81.1%였다. PET 단독검사의 민감도와 특이도는 각각 46.2%, 81.4% 였으며, PET/CT 단독 검사의 민감도와 특이도는 각각 75.0%, 78.5%였다. 판독에서 암이 의심되었던 경우와 판독에서 암이 의심되지 않았던 경우를 비교하여 보았으나 암부위, 조직학적 진단, 암 병기 등에서 두 군 사이에 통계학적으로 유의한 차이가 없었다. PET과 PET/CT에서 양성 혹은 악성의 의미 있는 병변이 의심되거나 양성 및 악성을 구분하기 어려워 추가 검사를 권고한 경우는 전체의 19.3%(981/5,091)였다. 이중에서 두경부 및 상부 위장관 부위에 대한 추가 검사를 권고한 경우가 가장 많았다. 결론: 무증상 성인의 건강검진에서 사용한 PET과 PET/CT 의 암 진단 정확도는 중간 정도로 평가되었다. PET과 PET/CT의 효용성을 높이기 위해서는 검사 대상집단의 연령이나 위험요인과 같은 임상적 특성을 고려해야 할 것이다. 또한 검사법과 판독 기술의 향상이 필요하며, 검사에 대한 충분한 이해를 바탕으로 수진자가 현명한 선택을 하도록 하여야 한다.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1764-1773
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• 2018

A-PET is a quad-head PET scanner developed for use in small-animal imaging. The dimensions of its volumetric field of view (FOV) are $46.1{\times}46.1{\times}46.1mm^3$ and the gap between the detector modules has been minimized in order to provide a highly sensitive system. However, such a small FOV together with the quad-head geometry causes image quality degradation. The main factor related to image degradation for the quad-head PET is the mispositioning of events caused by the penetration effect in the detector. In this paper, we propose a precise method for modelling the system at the high spatial resolution of the A-PET using a LOR (line of response) based ML-EM (maximum likelihood expectation maximization) that allows for penetration effects. The proposed system model provides the detection probability of every possible ray-path via crystal sampling methods. For the ray-path sampling, the sub-LORs are defined by connecting the sampling points of the crystal pair. We incorporate the detection probability of each sub-LOR into the model by calculating the penetration effect. For comparison, we used a standard LOR-based model and a Monte Carlo-based modeling approach, and evaluated the reconstructed images using both the National Electrical Manufacturers Association NU 4-2008 standards and the Geant4 Application for Tomographic Emission simulation toolkit (GATE). An average full width at half maximum (FWHM) at different locations of 1.77 mm and 1.79 mm are obtained using the proposed system model and standard LOR system model, which does not include penetration effects, respectively. The standard deviation of the uniform region in the NEMA image quality phantom is 2.14% for the proposed method and 14.3% for the LOR system model, indicating that the proposed model out-performs the standard LOR-based model.

• 한국의학물리학회지:의학물리
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• 제13권3호
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• pp.139-148
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• 2002

The measured attenuation correction with transmission (Tx) scans produced quantitatively accurate images. However, it was not clear for optimal emission (Ex) and Tx scan time in PET imaging. This study was to evaluate acceptable Ex and Tx scan time by simulating clinical situations using various phantoms. Cylindrical and NEMA phantom were used for $^{18}$ F-PET scan using 2D protocol in GE Advance PETTM scanner. Cylindrical phantom was filled with 136 MBq 18F, and five regions of interests (ROI) were drawn on 23 slices. NEMA phantom had three inserts containing water, air and polytetrafluoro-ethylene (PTFE). Outside of these inserts were filled with 309 MBq of $^{18}$ F, and total 12 ROIs were drawn on 23 slices. Scans were carried out according to five Ex scan times: 2, 5, 10, 15, and 30 min, and nine Tx scan times: 2, 3, 4, 5, 7, 10, 15, 20, and 30 min. Images were reconstructed using measured attenuation correction, and ROI analyses were performed for all images, and mean, standard deviation (SD), coefficient of variation and percent errors were calculated. For cylindrical phantom study, ROI mean and SD were decreased as Ex and Tx time increased. Coefficients of variation were kept constant, when Tx was greater than 10 min. The amount of error decreased for the increment of Ex time from 10 min to 15 min was almost the same to that from 15 min to 30 min. In NEMA phantom Tx 15 min showed the lowest er개r level when the percent errors for three inserts were summed for all of the Ex times. This study suggested that Ex 15 min and Tx 15 min were acceptable as optimal scan time for the scanning protocol and the dose of radiopharmaceuticals used in these phantom study.

• 대한방사선기술학회지:방사선기술과학
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• 제44권6호
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• pp.655-661
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• 2021

Positron emission tomography (PET) images is affected by acquisition time, short acquisition times results in low gamma counts leading to degradation of image quality by statistical noise. Noise2Void(N2V) is self supervised denoising model that is convolutional neural network (CNN) based deep learning. The purpose of this study is to evaluate denoising performance of N2V for PET image with a short acquisition time. The phantom was scanned as a list mode for 10 min using Biograph mCT40 of PET/CT (Siemens Healthcare, Erlangen, Germany). We compared PET images using NEMA image-quality phantom for standard acquisition time (10 min), short acquisition time (2min) and simulated PET image (S2 min). To evaluate performance of N2V, the peak signal to noise ratio (PSNR), normalized root mean square error (NRMSE), structural similarity index (SSIM) and radio-activity recovery coefficient (RC) were used. The PSNR, NRMSE and SSIM for 2 min and S2 min PET images compared to 10min PET image were 30.983, 33.936, 9.954, 7.609 and 0.916, 0.934 respectively. The RC for spheres with S2 min PET image also met European Association of Nuclear Medicine Research Ltd. (EARL) FDG PET accreditation program. We confirmed generated S2 min PET image from N2V deep learning showed improvement results compared to 2 min PET image and The PET images on visual analysis were also comparable between 10 min and S2 min PET images. In conclusion, noisy PET image by means of short acquisition time using N2V denoising network model can be improved image quality without underestimation of radioactivity.