• 대한방사선기술학회지:방사선기술과학
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• 제47권3호
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• pp.175-182
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• 2024

Advanced modeled iterative reconstruction (ADMIRE) represents a repetitive reconstruction method that can adjust strength and kernel, each of which are known to affect computed tomography (CT) image quality. The aim of this study was to quantitatively analyze the noise and spatial resolution of CT images according to ADMIRE control factors. Patient images were obtained by applying ADMIRE strength 2 and 3, and kernel B40 and B59. For quantitative evaluations, the noise level, spatial resolution, and overall image quality were measured using coefficient of variation (COV), edge rise distance (ERD), and natural image quality evaluation (NIQE). The superior values for the average COV, ERD, and NIQE results were obtained for the ADMIRE reconstruction conditions of ADMIRE 2 + B40, ADMIRE 3 + B59, and ADMIRE3 + B59. NIQE, which represents the overall image quality based on no-reference, was about 6.04 when using ADMIRE 3 + B59, showing the best result among the reconstructed image acquisition conditions. The results of this study indicate that the ADMIRE strength and kernel chosen for use in ADMIRE reconstruction have a significant impact on CT image quality. This highlights the importance of adjusting to the control factors in consideration of the clinical environment.

• Korean Journal of Radiology
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• 제21권6호
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• pp.660-669
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• 2020

Objective: To evaluate the accuracy of a deep learning-based automated segmentation of the left ventricle (LV) myocardium using cardiac CT. Materials and Methods: To develop a fully automated algorithm, 100 subjects with coronary artery disease were randomly selected as a development set (50 training / 20 validation / 30 internal test). An experienced cardiac radiologist generated the manual segmentation of the development set. The trained model was evaluated using 1000 validation set generated by an experienced technician. Visual assessment was performed to compare the manual and automatic segmentations. In a quantitative analysis, sensitivity and specificity were calculated according to the number of pixels where two three-dimensional masks of the manual and deep learning segmentations overlapped. Similarity indices, such as the Dice similarity coefficient (DSC), were used to evaluate the margin of each segmented masks. Results: The sensitivity and specificity of automated segmentation for each segment (1-16 segments) were high (85.5-100.0%). The DSC was 88.3 ± 6.2%. Among randomly selected 100 cases, all manual segmentation and deep learning masks for visual analysis were classified as very accurate to mostly accurate and there were no inaccurate cases (manual vs. deep learning: very accurate, 31 vs. 53; accurate, 64 vs. 39; mostly accurate, 15 vs. 8). The number of very accurate cases for deep learning masks was greater than that for manually segmented masks. Conclusion: We present deep learning-based automatic segmentation of the LV myocardium and the results are comparable to manual segmentation data with high sensitivity, specificity, and high similarity scores.

• The Korean journal of internal medicine
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• 제39권2호
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• pp.283-294
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• 2024

Background/Aims: Epicardial adipose tissue (EAT) shares pathophysiological properties with other visceral fats and potentially triggers local inflammation. However, the association of EAT with cardiovascular disease (CVD) is still debatable. The study aimed to observe the changes and associations in EAT and risk factors over time, as well as to investigate whether EAT was associated with CVD. Methods: A total of 762 participants from Seoul National University Hospital (SNUH) and SNUH Gangnam Center were included in this study. EAT was measured using coronary computed tomography angiography. Results: Baseline EAT level was positively associated with body mass index (BMI), calcium score, atherosclerotic cardiovascular disease (ASCVD) 10-year risk score, glucose, triglycerides (TG)/high-density lipoprotein (HDL), but not with total cholesterol, low-density lipoprotein (LDL). At follow-up, EAT levels increased in all groups, with low EAT groups demonstrating a significant increase in EAT per year. Change in EAT was associated with a change in BMI, TG/HDL, and glucose, while changes in LDL, calcium score, and ASCVD 10-year risk score were not associated. Although calcium score and ASCVD 10-year risk score were associated with CVD events, baseline information of EAT, baseline EAT/body surface area, or EAT change was not available. Conclusions: Metabolic risks, e.g., BMI, TG/HDL, and glucose, were associated with EAT change per year, whereas classical CVD risks, e.g., LDL, calcium score, and ASCVD 10-year risk score, were not. The actual CVD event was not associated with EAT volume, warranting future studies combining qualitative assessments with quantitative ones.

• 대한방사선기술학회지:방사선기술과학
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• 제40권2호
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• pp.229-235
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• 2017

상복부초음파검사에서 간실질의 에코 음영증가와 불명확한 혈관경계 등으로 지방간을 진단하는데, 여러 연구들에 의하면 지방간 진단에 84~95%의 특이도와 60~90%의 민감도를 가지나 결과가 검사자에 의존적이어서 차이가 있을 수 있고 지방의 침윤 상태의 정량적인 측정이 불가능하다. 건강검진의 상복부초음파검사와 흉부 전산화단층촬영(computed tomography; CT) 검사를 같은 날에 시행한 수검자중 초음파검사에서 지방간을 진단 받은 환자의 흉부 전산화단층촬영 영상에서 간(Liver) Hounsfield Units(HU)를 측정하여 지방간 진단의 정확성을 연관분석 하고자 하였다. 연구대상 수검자 720명 중 가정의학과 전문의에게 검사를 받고 지방간 판정을 받은 자는 448명으로 62.2%였다. 지방간 판정자의 CT영상에서 간 HU를 측정한 결과 40 HU 이하의 측정값은 720명 중 175명으로 24.3%이며, 초음파에서 진단 받은 448명에 175명 중 173명이 포함되어 98.9%가 일치하였다. 이는 지방간을 초음파로 진단 시 검사자의 주관적 경험과 능력이 병변을 진단하는데 크게 영향을 미친 것으로 생각되며 검진 CT검사에서 간 HU를 측정하여 40 HU 이하는 영상저장을 통하여 지방간 진단 시 참고자료로 활용될 수 있을 것으로 사료된다.

• Journal of Korean Neurosurgical Society
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• 제63권3호
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• pp.386-396
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• 2020

Objective : To generate synthetic spine magnetic resonance (MR) images from spine computed tomography (CT) using generative adversarial networks (GANs), as well as to determine the similarities between synthesized and real MR images. Methods : GANs were trained to transform spine CT image slices into spine magnetic resonance T2 weighted (MRT2) axial image slices by combining adversarial loss and voxel-wise loss. Experiments were performed using 280 pairs of lumbar spine CT scans and MRT2 images. The MRT2 images were then synthesized from 15 other spine CT scans. To evaluate whether the synthetic MR images were realistic, two radiologists, two spine surgeons, and two residents blindly classified the real and synthetic MRT2 images. Two experienced radiologists then evaluated the similarities between subdivisions of the real and synthetic MRT2 images. Quantitative analysis of the synthetic MRT2 images was performed using the mean absolute error (MAE) and peak signal-to-noise ratio (PSNR). Results : The mean overall similarity of the synthetic MRT2 images evaluated by radiologists was 80.2%. In the blind classification of the real MRT2 images, the failure rate ranged from 0% to 40%. The MAE value of each image ranged from 13.75 to 34.24 pixels (mean, 21.19 pixels), and the PSNR of each image ranged from 61.96 to 68.16 dB (mean, 64.92 dB). Conclusion : This was the first study to apply GANs to synthesize spine MR images from CT images. Despite the small dataset of 280 pairs, the synthetic MR images were relatively well implemented. Synthesis of medical images using GANs is a new paradigm of artificial intelligence application in medical imaging. We expect that synthesis of MR images from spine CT images using GANs will improve the diagnostic usefulness of CT. To better inform the clinical applications of this technique, further studies are needed involving a large dataset, a variety of pathologies, and other MR sequence of the lumbar spine.

• 디지털융복합연구
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• 제13권9호
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• pp.431-437
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• 2015

하지 동맥 전산화단층촬영(CT) 검사 시 생리식염수 희석을 통한 조영제 사용량 감소의 효용성을 알아보고자 하였다. 조영제 125 cc 주입한 48명과 같은 양을 조영제와 생리 식염수를 7:3으로 주입한 30명을 대상으로 하였다. 각각의 영상에서 복부대동맥, 넙다리동맥, 오금동맥, 뒤정강동맥의 감쇄계수(HU)의 평균값과 신호 대 잡음비(SNR)를 정량적으로 평가 하였고, 정성적 평가는 영상의학과 전문의 2명, 방사선사 4명이 5점 척도로 4가지 평가항목을 평가하였다. 정량적 평가에서 HU와 SNR 모두 희석 전 평균값이 높게 나왔으나 독립표본 T검정에서 유의확률이 모두 p>0.05이므로 희석 전, 후의 통계적으로 유의성이 없다. 정성적 평가는 평균점수가 원액이 4.86~4.77, 희석액이 4.83~4.67로 차이가 있었으나, 유의확률이 모두 p>0.05이므로 희석 전, 후의 통계적으로 유의성이 없다. CT 하지동맥 조영 검사 시 일정 비율 희석한 조영제를 사용하여 기존 영상의 질을 유지 할 수 있고, 조영제의 총량을 줄여 단위 분자 당 요오드 함량이 낮아지므로 조영제로 인한 부작용을 줄일 수 있을 것으로 사료된다.

• Journal of Korean Neurosurgical Society
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• 제64권6호
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• pp.950-956
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• 2021

Objective : Psoas and masseter muscles are known markers of sarcopenia. However, the relative superiority of either muscle as a marker is unclear. Therefore, this study analyzed the two muscles in patients with a prognosis of traumatic brain injury (TBI). Methods : Patients with TBI visiting a regional trauma center between January 2017 and December 2018 were selected, and their medical records were reviewed. TBI patients with an abbreviated injury score (AIS) of 4 or 5 were selected. Patients with an AIS of 4 or 5 at the chest, abdomen, and extremity were excluded. Patients with a hospital stay of 1 to 2 days were excluded. Both muscle areas were measured based on the initial computed tomography. The psoas muscle index (PMI) and the masseter muscle index (MMI) were calculated by dividing both muscle areas by height in meters squared (cm²/m²). These muscle parameters along with other medical information were used to analyze mortality and the Glasgow outcome scale (GOS). Results : A total of 179 patients, including 147 males (82.1%), were analyzed statistically. The mean patient age was 58.0 years. The mortality rate was 16.8% (30 patients). The mean GOS score was 3.7. Analysis was performed to identify the parameters associated with mortality, which was a qualitative study outcome. The psoas muscle area (16.9 vs. 14.4 cm², p=0.028) and PMI (5.9 vs. 5.1 cm²/m², p=0.004) showed statistical differences between the groups. The PMI was also statistically significant as a risk factor for mortality in logistic regression analysis (p=0.023; odds ratio, 0.715; 95% confidence interval, 0.535-0.954). Quantitative analyses were performed with the GOS scores. Bivariate correlation analysis showed a statistically significant correlation between PMI and GOS scores (correlation coefficient, 0.168; p=0.003). PMI (p=0.004, variation inflation factor 1.001) was significant in multiple regression analysis. The masseter muscle area and MMI did not show significance in the study. Conclusion : Larger PMI was associated with statistically significant improved survival and GOS scores, indicating its performance as a superior prognostic marker. Further analyses involving a larger number of patients, additional parameters, and more precise settings would yield a better understanding of sarcopenia and TBI.

• Korean Journal of Radiology
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• 제19권6호
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• pp.1187-1195
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• 2018

Objective: To compare correlations between pulmonary function test (PFT) results and different reconstruction algorithms and to suggest the optimal reconstruction protocol for computed tomography (CT) quantification of low lung attenuation areas and airways in healthy individuals. Materials and Methods: A total of 259 subjects with normal PFT and chest CT results were included. CT scans were reconstructed using filtered back projection, hybrid-iterative reconstruction, and model-based IR (MIR). For quantitative analysis, the emphysema index (EI) and wall area percentage (WA%) were determined. Subgroup analysis according to smoking history was also performed. Results: The EIs of all the reconstruction algorithms correlated significantly with the forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (all p < 0.001). The EI of MIR showed the strongest correlation with FEV1/FVC (r = -0.437). WA% showed a significant correlation with FEV1 in all the reconstruction algorithms (all p < 0.05) correlated significantly with FEV1/FVC for MIR only (p < 0.001). The WA% of MIR showed the strongest correlations with FEV1 (r = -0.205) and FEV1/FVC (r = -0.250). In subgroup analysis, the EI of MIR had the strongest correlation with PFT in both eversmoker and never-smoker subgroups, although there was no significant difference in the EI between the reconstruction algorithms. WA% of MIR showed a significantly thinner airway thickness than the other algorithms ($49.7{\pm}7.6$ in ever-smokers and $49.5{\pm}7.5$ in never-smokers, all p < 0.001), and also showed the strongest correlation with PFT in both ever-smoker and never-smoker subgroups. Conclusion: CT quantification of low lung attenuation areas and airways by means of MIR showed the strongest correlation with PFT results among the algorithms used, in normal subjects.

• 한국방사선학회논문지
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• 제14권7호
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• pp.975-980
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• 2020

경추 신경공 협착은 모든 연령대의 비교적 많은 수의 사람들에게 침범하는 매우 흔한 척추 질환이다. 그러나 신경공 협착을 정량적으로 제공하는 영상검사법이 부족하므로, 본 연구는 3차원 전산화단층촬영상을 재구성하여 정량적인 측정방법을 제시하고자 한다. 3차원 영상처리 프로그램을 이용하여 경추의 후극돌기와 측돌기, 층뼈를 포함하여 신경공이 잘 관찰되도록 주변 뼈를 제거하였다. Image J를 이용하여 3차원 영상의 신경공 면적을 포함하는 관심영역을 설정하고, 신경공 면적의 화소수를 측정하였다. 측정 화소수에 화소크기를 곱하여 신경공 면적을 산출하였다. 가장 넓은 신경공 면적을 측정하기 위하여 측정 반대쪽 방향으로 40~50도 사이와, 머리쪽으로 15~20도 사이에서 측정하였다. 측정한 경추 신경공의 면적은 일관된 측정값을 보였다. 가장 크게 측정한 우측 신경공 C5-6 면적은 12.21 ㎟에서, 2년 후에 9.95 ㎟으로 18% 협착이 진행된 것을 알 수 있었다. 기존에 CT 검사 영상을 이용하여 3차원 재구성하므로 추가적인 방사선 피폭을 받지 않으며 신경공 협착 면적을 객관적으로 제시할 수 있다. 또한 3차원 영상을 보면서 신경공 협착 환자에게 설명하기 좋으며, 협착의 진행정도와 수술 후 평가에서도 사용하기 좋은 방법이라 사료된다.

• 한국방사선학회논문지
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• 제15권3호
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• pp.301-306
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• 2021

전산화단층촬영장치 (Computed tomography, CT)의 의료 방사선량을 낮추기 위한 방법으로 주석필터의 사용을 통해 직접적으로 환자의 선량을 낮추는 방법이 있다. 그러나 주석필터의 사용으로 바뀐 X선 스펙트럼으로 인해 기존의 영상과 다른 인상의 영상으로 나타나기 때문에 질병 진단에 영향을 줄 수 있다. 따라서 본 연구에서는 흉부 저선량 CT에서 주석필터의 적용 및 high pitch에 따른 영상평가를 진행함으로써 주석필터 사용 시 영상의 변화 양상을 살펴보았다. 본 연구에서는 비교를 위해 총 3개의 그룹으로 나누어 영상을 획득하였다. Group 1은 주석필터를 사용하지 않았으며, 기존에 사용하던 pitch인 0.8의 영상을 획득하였다. Group 2는 주석필터를 사용하였고, pitch는 0.8이며 Group 3은 주석필터를 사용하였으며 pitch는 2.5이다. 영상의 화질을 비교하기 위해 no-reference 기반으로 사용되는 블라인드 품질 평가 인자 중 natural image quality evaluator (NIQE)와 blind/referenceless image spatial quality evaluator (BRISQUE)를 사용하였다. 그 결과 NIQE 수치는 Group 1, Group 3, Group 2 의 순서대로 낮게 나타났다. BRISQUE 수치는 Group 3, Group 2, Group 1 의 순서대로 낮게 나타났다. 이를 통해 흉부 저선량 CT에서 주석필터 및 high pitch 기술의 영상의 우수성을 확인함으로써 특히 호흡 조절이 어려운 흉부 저선량 CT 환자에 있어서 더 정확한 영상에 대한 기대감을 가질 수 있는 기초 자료로 활용될 수 있을 것이라 사료된다.