• 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.

• 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.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2367-2370
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• 2014

"Cat's eye"-shaped $[^{57}Co]CoO@SiO_2$ core-shell nanostructure was prepared by the reverse microemulsion method combined with radioisotope technique to investigate a potential imaging agent for a single photon emission computed tomography (SPECT) in nuclear medicine. The core cobalt oxide nanorods were obtained by thermal decomposition of $Co-(oleate)_2$ precursor from radio isotope Co-57 containing cobalt chloride and sodium oleate. The $SiO_2$ coating on the surface of the core cobalt oxide nanorods was produced by hydrolysis and a condensation reaction of tetraethylorthosilicate (TEOS) in the water phase of the reverse microemulsion system. In vivo test, micro SPECT image was acquired with nude mice after 30 min of intravenous injection of $[^{57}Co]CoO@SiO_2$ core-shell nanostructure.

• 대한핵의학회지
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• 제17권1호
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• pp.55-62
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• 1983

In 16 volunteers without clinical or laboratory evidence of liver disease, liver volume was determined using single-photon emission computed tomography(ECT). This technique provided excellent object contrast between the liver and its surroundings and permitted calculation of liver volume without geometric assumptions about the liver's configuration. Reproducibility of results was satisfactory, with a root-me an-square error of less than 2% between duplicate measurements in 16 individuals. The volume measurements were validated by the use of phantoms.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3943-3948
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• 2022

Single-photon emission computed tomography is one of the reliable pin-by-pin verification techniques for spent-fuel assemblies. One of the challenges with this technique is to increase the total fuel assembly verification speed while maintaining high verification accuracy. The aim of the present study, therefore, was to develop an artificial intelligence (AI) algorithm-based tomographic image analysis technique for partial-defect verification of fuel assemblies. With the Monte Carlo (MC) simulation technique, a tomographic image dataset consisting of 511 fuel-rod patterns of a 3 × 3 fuel assembly was generated, and with these images, the VGG16, GoogLeNet, and ResNet models were trained. According to an evaluation of these models for different training dataset sizes, the ResNet model showed 100% pattern estimation accuracy. And, based on the different tomographic image qualities, all of the models showed almost 100% pattern estimation accuracy, even for low-quality images with unrecognizable fuel patterns. This study verified that an AI model can be effectively employed for accurate and fast partial-defect verification of fuel assemblies.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1527-1532
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• 2023

The noise reduction algorithm using the non-local means (NLM) approach is very efficient in nuclear medicine imaging. In this study, the applicability of the NLM noise reduction algorithm in single-photon emission computed tomography (SPECT) images with a brain phantom and the optimization of the NLM algorithm by changing the smoothing factors according to various reconstruction methods are investigated. Brain phantom images were reconstructed using filtered back projection (FBP) and ordered subset expectation maximization (OSEM). The smoothing factor of the NLM noise reduction algorithm determined the optimal coefficient of variation (COV) and contrast-to-noise ratio (CNR) results at a value of 0.020 in the FBP and OSEM reconstruction methods. We confirmed that the FBP- and OSEM-based SPECT images using the algorithm applied with the optimal smoothing factor improved the COV and CNR by 66.94% and 8.00% on average, respectively, compared to those of the original image. In conclusion, an optimized smoothing factor was derived from the NLM approach-based algorithm in brain SPECT images and may be applicable to various nuclear medicine imaging techniques in the future.

• 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.

• Journal of Gynecologic Oncology
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• 제29권6호
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• pp.98.1-98.13
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• 2018

Objective: We describe a systematic review and meta-analysis of the performance of ${18}F$-fluorodeoxyglucose ($^{18}F-FDG$) positron emission tomography/computed tomography (PET/CT) for detecting metastasis in ovarian cancer. Methods: MEDLINE and Embase were searched for diagnostic accuracy studies that used $^{18}F-FDG$ PET or PET/CT for pre-treatment staging, using surgical findings as the reference standard. Sensitivities and specificities were pooled and plotted in a hierarchic summary receiver operating characteristic plot. Potential causes of heterogeneity were explored through sensitivity analyses. Results: Eight studies with 594 patients were included. The overall pooled sensitivity and specificity for metastasis were 0.72 (95% confidence interval [CI]=0.61-0.81) and 0.93 (95% CI=0.85-0.97), respectively. There was considerable heterogeneity in sensitivity ($I^2=97.57%$) and specificity ($I^2=96.74%$). In sensitivity analyses, studies that used laparotomy as the reference standard showed significantly higher sensitivity and specificity (0.77; 95% CI=0.67-0.87 and 0.96; 95% CI=0.92-0.99, respectively) than those including diagnostic laparoscopy (0.62; 95% CI=0.46-0.77 and 0.84; 95% CI=0.69-0.99, respectively). Higher specificity was shown in studies that confirmed surgical findings by pathologic evaluation (0.95; 95% CI=0.90-0.99) than in a study without pathologic confirmation (0.69; 95% CI=0.24-1.00). Studies with a lower prevalence of the FDG-avid subtype showed higher specificity (0.97; 95% CI=0.94-1.00) than those with a greater prevalence (0.89; 95% CI=0.80-0.97). Conclusion: Pre-treatment $^{18}F-FDG$ PET/CT shows moderate sensitivity and high specificity for detecting metastasis in ovarian cancer. With its low false-positive rate, it can help select surgical approaches or alternative treatment options.

• 대한정형외과학회지
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• 제56권5호
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• pp.398-403
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• 2021

목적: 연부조직 종양의 진단을 위해서는 생검이 필요하지만, 육종 등 이질성을 가진 종양들의 특징상 정확한 부위의 채취가 어려워 수술적 개방 생검으로도 진단이 어려운 경우가 많다. 이 경우 초음파 유도하 침생검이 진단율을 올릴 수 있는 방법으로 사용되고 있다. 본 연구는 자기공명 관류영상(magnetic resonance perfusion)에서 발견된 연부조직 종양을 진단하는 데 있어 초음파 유도하 침 생검의 정확도를 평가하고, 양전자방출 컴퓨터 단층촬영술(positron emission tomography-computed tomography, PET-CT)의 유용성에 대해 알고자 하였다. 대상 및 방법: 2014년 1월부터 2018년 12월까지 자기공명 관류영상에서 발견된 연부조직의 종양에 대해 초음파 유도하 침 생검을 시행한 총 152예의 환자들 중 최종 진단을 얻어 초음파 유도하 침 생검의 결과와 비교할 수 있었던 86예에 대해 그 정확도를 후향적으로 평가하였다. 총 86예의 환자를 자기공명 관류영상만을 시행한 50예와 자기공명 관류영상과 PET-CT를 함께 시행한 36예로 나누어 그 정확도를 비교, 분석하여 PET-CT가 초음파 유도하 침 생검의 정확도를 향상시킬 수 있는지 알고자 하였다. 결과: 총 86예의 환자들 중 자기공명 관류영상만을 시행한 50예 중에서는 34예에서 최종 진단과 초음파 유도하 침 생검의 결과가 일치하였으며, 자기공명 관류영상과 PET-CT를 함께 시행한 36예 중에서는 32예에서 최종 진단과 초음파 유도하 침 생검의 결과가 일치하여 초음파 유도하 침 생검의 정확도에 있어 유의한 차이를 보였다. 이 중 연부 조직 육종만 따로 분류한다면 자기공명 관류영상만을 시행한 12예 중에서 6예에서 최종 진단과 초음파 유도하 침 생검의 결과가 일치하였고 자기공명 관류영상과 PET-CT를 함께 시행한 18예 중에서는 17예에서 최종 진단과 초음파 유도하 침 생검의 결과가 일치하여 마찬가지로 초음파 유도하 침 생검의 정확도에 있어 유의한 차이를 보였다. 결론: 연부조직 종양을 진단함에 있어 초음파 유도하 침 생검은 정확도가 높은 유용한 검사로 알려져 있지만 육종의 경우 이질성이 있어 자기공명 관류영상만으로는 정확한 생검 부위를 설정하는 데 어려움이 있다. PET-CT 영상은 이러한 연부조직 종양에서 침 생검 부위를 특정하고 정확도를 유의하게 향상시킬 수 있을 것으로 생각된다.

• 대한의용생체공학회:의공학회지
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• 제26권5호
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• pp.283-294
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• 2005

The Center for Imaging Human Structures (CIH) was established in December 2002 to develop new diagnostic imaging techniques and to make them available to the greater community of biomedical and clinical researchers at Sungkyunkwan University. CIH has been involved in 5 specific activities to provide solutions for early diagnosis and improved treatment of human diseases. The five area goals include: 1) development of a digital mammography system with computer aided diagnosis (CAD); 2) development of digital radiological imaging techniques; 3) development of unified medical solutions using 3D image fusion; 4) development of multi-purpose digital endoscopy; and, 5) evaluation of new imaging systems for clinical application