• Korean Journal of Radiology
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• 제20권4호
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• pp.599-608
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• 2019

Objective: To evaluate the effectiveness of computed tomography (CT) Hounsfield unit histogram analysis (HUHA) in postoperative pancreatic fistula (PF) prediction. Materials and Methods: Fifty-four patients (33 males and 21 females; mean age, 65.6 years; age range, 37-89 years) who had undergone preoperative CT and pancreaticoduodenectomy were included in this retrospective study. Two radiologists measured mean CT Hounsfield unit (CTHU) values by drawing regions of interest (ROIs) at the level of the pancreaticojejunostomy site on preoperative pre-contrast images. The HUHA values were arbitrarily divided into three categories, comprising HUHA-A ≤ 0 HU, 0 HU < HUHA-B < 30 HU, and HUHA-C ≥ 30 HU. Each HUHA value within the ROI was calculated as a percentage of the entire area using commercial 3-dimensional analysis software. Pancreas texture was evaluated as soft or hard by manual palpation. Results: Fifteen patients (27.8%) had clinically relevant PFs. The PF group had significantly higher HUHA-A (p < 0.01) and significantly lower mean CTHU (p < 0.01) values than those of the non-PF group. The HUHA-A value had a moderately strong correlation with PF occurrence (r = 0.60, p < 0.01), whereas the mean CTHU had a weak negative correlation with PF occurrence (r = -0.27, p < 0.01). The HUHA-A and mean CTHU areas under the curve (AUCs) for predicting PF occurrence were 0.86 and 0.65, respectively, with significant difference (p < 0.01). The HUHA-A and mean CTHU AUCs for predicting pancreatic softness were 0.86 and 0.64, respectively, with significant difference (p < 0.01). Conclusion: The HUHA-A values on preoperative pre-contrast CT images demonstrate a strong correlation with PF occurrence.

• Asian-Australasian Journal of Animal Sciences
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• 제20권12호
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• pp.1901-1908
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• 2007

The aim of this series of experiments was to examine the opportunity for application of X-ray computer tomography (CT) in cattle production. Firstly, tissue composition of M. longissimus dorsi (LD) cuts between the $11-13^{th}$ ribs (in Exp 1. between the $9-11^{th}$ ribs), was determined by CT and correlated with tissue composition of intact half carcasses prior to dissection and tissue separation. Altogether, 207 animals of different breeds and genders were used in the study. In Exp. 2 and 3, samples were taken from LD cuts, dissected and chemical composition of muscle homogenates was analysed by conventional procedures. Correlation coefficients were calculated among slaughter records, tissues in whole carcasses and tissue composition of rib samples. Results indicated that tissue composition of rib samples determined by CT closely correlated with tissue composition results by dissection of whole carcasses. The findings revealed that figures obtained by CT correlate well with the dissection results of entire carcasses (meat, bone, fat). Close three-way coefficients of correlation (r = 0.80-0.97) were calculated among rib eye area, volume of cut, pixel-sum of adipose tissue determined by CT and intramuscular fat or adipose tissue in entire carcasses. Estimation of tissue composition of carcasses using equations including only CT-data as independent variables proved to be less reliable in prediction of lean meat and bone in carcass ($R^2 = 0.51-0.86$) than for fat (($R^2 = 0.83-0.89$). However, when cold half carcass weight was also included in the equation, the coefficient of determination exceeded $R^2 = 0.90$. In Exp. 3 tissue composition of rib samples by CT were compared to the results of EUROP carcass classification. Findings revealed that CT analysis has higher predictive value in estimation of actual tissue composition of cattle carcasses than EUROP carcass classification.

• 한국의학물리학회지:의학물리
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• 제28권1호
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• pp.27-32
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• 2017

We investigated the effect of a commercial iterative reconstruction technique (iDose, Philips) on the image quality and the dose calculation for the treatment plan. Using the electron density phantom, the 3D CT images with five different protocols (50, 100, 200, 350 and 400 mAs) were obtained. Additionally, the acquired data was reconstructed using the iDose with level 5. A lung phantom was used to acquire the 4D CT with the default protocol as a reference and the low dose (one third of the default protocol) 4D CT using the iDose for the spine and lung plans. When applying the iDose at the same mAs, the mean HU value was changed up to 85 HU. Although the 1 SD was increased with reducing the CT dose, it was decreased up to 4 HU due to the use of iDose. When using the low dose 4D CT with iDose, the dose change relative to the reference was less than 0.5% for the target and OARs in the spine plan. It was also less than 1.1% in the lung plan. Therefore, our results suggests that this dose reduction technique is applicable to the 4D CT image acquisition for the radiation treatment planning.

• Journal of Yeungnam Medical Science
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• 제12권2호
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• pp.400-404
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• 1995

국소 결절성 과형성은 섬유성 격막에 의해 나누어지는 간세포와 Kupffer 세포의 결절로 이루어진 양성 종괴이다. 방사선학적으로 다른 종괴와 유사한 소견을 보이나 그 예후와 치료는 달라 감별이 요구된다. 저자들이 경험한 증례는 조영 후 영상을 조영전기영상과 조영후기영상으로 분리함으로써 종괴의 혈류형태를 관찰할 수 있는 급속조영 CT를 설시하여 감별진단에 도움을 받을 수 있었고 병리조직학적으로 국소 결절성 과형성으로 확인된, 급속조영 CT 설시 후 국내에서 보고되는 최초의 증례이다.

• 한국방사선학회논문지
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• 제13권2호
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• pp.305-311
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• 2019

본 연구에서는 이중 시간 PET/CT 검사에서 지연검사 시간이 다른 두 그룹의 40명의 췌장암 환자에 대한 SUV 데이터의 통계 분석을 통해 최적의 지연검사 시간을 제시하였다. 췌장암의 유무를 확인해야 될 이중 시간 PET/CT 검사에서 새로운 수학적 예측 모델을 만들어 정확도 높은 최적의 지연검사 시간을 제시하였다. 시간에 따른 포도당 대사를 적용한 방사능 붕괴식을 예측 모델로 제시하였다. 지연검사 시간이 다른 두 그룹의 데이터를 가지고 시뮬레이션한 결과 PET/CT에서 췌장암 판별을 위한 최적의 지연검사 시간이 131.5분으로 제시하였다. 제안된 지연검사 시간은 췌장암 결정에 적용될 수 있는 통계적 유의 수준을 보였다(p<0.05). 제안된 지연 검사 시간 131.5분을 결정하여 검사를 진행할 때, 췌장암 조기 판별에 도움을 줄 수 있을 것으로 사료된다.

• 대한방사선기술학회지:방사선기술과학
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• 제46권4호
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• pp.295-301
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• 2023

In addition to protocol adjustments during CT examinations, the height of the CT table can also affect image quality. Therefore, this study aimed to investigate the change in image quality depending on the height of the table in brain CT, which accounts for a large proportion of CT examinations, by measuring signal to contrast to noise ratio (CNR) and noise power spectrum (NPS) using the head phantom and evaluating them. The head phantom images were acquired using Philips Brilliance iCT 256. When the image was acquired, the table height was adjusted to 815, 865, 915, 965, 1015, and 1030 mm, respectively, and each scan was performed 3 times for each height. The CNR result showed the highest value at 965 mm, which is the height adjacent to the center of the head phantom. NPS showed the lowest NPS at 915 mm, the center of the head phantom in the low frequency region. From these results, it can be seen that the height of the table in CT examination is closely related to the image quality, and it can be seen the characteristics of image quality according to CT table through quantitative evaluation methods such as CNR and NPS.

• 핵의학기술
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• 제17권2호
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• pp.10-14
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• 2013

Purpose: Due to developed simultaneous PET/MRI, it has become possible to obtain more anatomical image information better than conventional PET/CT. By the way, in the PET/CT, the linear absorption coefficient is measured by X-ray directly. However in case of PET/MRI, the value is not measured from MRI images directly, but is calculated by dividing as 4 segmentation ${\mu}-map$. Therefore, in this paper, we will evaluate the SUV's difference of attenuation correction PET images from PET/MRI and PET/CT. Materials and Methods: Biograph mCT40 (Siemens, Germany), Biograph mMR were used as a PET/CT, PET/MRI scanner. For a phantom study, we used a solid type $^{68}Ge$ source, and a liquid type $^{18}F$ uniformity phantom. By using VIBE-DIXON sequence of PET/MRI, human anatomical structure was divided into air-lung-fat-soft tissue for attenuation correction coefficient. In case of PET/CT, the hounsfield unit of CT was used. By setting the ROI at five places of each PET phantom images that is corrected attenuation, the maximum SUV was measured, evaluated %diff about PET/CT vs. PET/MRI. In clinical study, the 18 patients who underwent simultaneous PET/CT and PET/MRI was selected and set the ROI at background, lung, liver, brain, muscle, fat, bone from the each attenuation correction PET images, and then evaluated, compared by measuring the maximum SUV. Results: For solid $^{68}Ge$ source, SUV from PET/MRI is measured lower 88.55% compared to PET/CT. In case of liquid $^{18}F$ uniform phantom, SUV of PET/MRI as compared to PET/CT is measured low 70.17%. If the clinical study, the background SUV of PET/MRI is same with PET/CT's and the one of lung was higher 2.51%. However, it is measured lower about 32.50, 40.35, 23.92, 13.92, 5.00% at liver, brain, muscle, fat, femoral head. Conclusion: In the case of a CT image, because there is a linear relationship between 511 keV ${\gamma}-ray$ and linear absorption coefficient of X-ray, it is possible to correct directly the attenuation of 511 keV ${\gamma}-ray$ by creating a ${\mu}$map from the CT image. However, in the case of the MRI, because the MRI signal has no relationship at all with linear absorption coefficient of ${\gamma}-ray$, the anatomical structure of the human body is divided into four segmentations to correct the attenuation of ${\gamma}-rays$. Even a number of protons in a bone is too low to make MRI signal and to localize segmentation of ${\mu}-map$. Therefore, to develope a proper sequence for measuring more accurate attenuation coefficient is indeed necessary in the future PET/MRI.

• 한국방사선학회논문지
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• 제10권7호
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• pp.503-510
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• 2016

소아는 방사선 감수성이 어른에 비해 높고 몸의 크기가 작아 어른과 같은 양의 방사선에 노출 되더라도 유효선량은 어른에 비해 더 높기 때문에 불필요한 피폭 방사선량을 줄이는 것이 매우 중요하다. 따라서 본 연구에서는 소아 두부 CT 검사에 있어서 피폭 방사선량을 경감할 수 있는 방법을 모색하고자 부산지역 병원들에서 시행된 년 간 소아 두부 CT 검사에 대한 CT 선량지표(CTDI)를 국내 진단참고준위와 비교하여 분석함으로써 제안점을 도출하고자 하였다. 이를 위하여 부산시내에 설치된 CT 장비 중 소아 두부 CT 검사를 시행하며, 선량보고서를 PACS로 전송하는 24개 병원 28대 CT 장비를 대상으로 하여 소아 두부 CT 검사를 의뢰받은 10세 미만의 소아 2,043명을 후향적으로 조사하였다. 결과적으로 전체병원의 소아 두부 CT의 선량지표 CTDIvol의 평균값은 31.18 mGy, DLP는 $444.73mGy{\cdot}cm$로 나타나 진단참고준위를 초과하는 것으로 나타났다. 연령이 낮을수록 방사선에 대한 관리가 더욱 필요하다고 할 수 있는데 연구결과 6-10세 이하의 연령에 비해 더 낮은 다른 두 연령별에서 진단참고준위를 초과하는 환자수와 초과되는 비율이 높게 나타났다. 따라서 불필요한 방사선 노출을 줄이고 선량관리를 위한 노력들이 필요하다. 이를 위해 본 연구에서는 진단참고준위를 벗어나는 선량의 정도를 파악하고 초과되는 선량지표의 원인을 분석하여 선량감소를 위한 방안을 마련하고자 한다.

• 대한영상의학회지
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• 제84권6호
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• pp.1324-1336
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• 2023

목적 이첨 대동맥 판막의 아형과 판막 석회화의 정도에 따른 심장 CT와 경흉부심초음파의 이첨 대동맥 판막 진단 능력을 비교해 보고자 한다. 대상과 방법 대동맥 판막 치환술 전 심장 CT와 경흉부 심초음파를 시행한 266명의 환자(이첨 대동맥 판막, 106명; 삼첨 대동맥 판막, 166명)를 후향적으로 포함하였다. 심장 CT를 이용하여 판막의 모양을 평가하였고, 관상동맥 칼슘 측정 CT를 이용하여 판막의 칼슘 정도를 정량화하였다. 대동맥 판막은 융합형과 2-대동맥동형 아형으로 분류하였다. 심장 CT와 경흉부 심초음파의 진단정확도는 수술 소견을 대비표준으로 하여 계산하였다. 결과 CT는 이첨 대동맥 판막을 진단함에 있어서 경흉부 심초음파보다 민감도, 음성 예측도, 정확도에서 통계적으로 유의하게 높은 값을 보여주었다(각각 p < 0.001, p < 0.001, p = 0.003). 경흉부 심초음파는 판막의 석회화가 증가할수록 민감도가 감소하는 경향을 보였다. CT와 경흉부 심초음파 간의 진단 오류율은 2-대동맥동형 아형에서 10.9%, 융합형 아형에서 28.3%였다(p = 0.044). 결론 심장 CT는 이첨 대동맥 판막을 진단함에 있어 경흉부 심초음파보다 높은 진단능을 보여주며, 특히 판막 석회화가 심하거나 융합형의 아형인 환자에서 이첨 대동맥 판막을 진단하는데 도움을 줄 수 있다.

• Korean Journal of Radiology
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• 제22권12호
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• pp.1964-1973
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• 2021

Objective: To investigate the diagnostic performance of CT fractional flow reserve (CT-FFR) for myocardial bridging-related ischemia using dynamic CT myocardial perfusion imaging (CT-MPI) as a reference standard. Materials and Methods: Dynamic CT-MPI and coronary CT angiography (CCTA) data obtained from 498 symptomatic patients were retrospectively reviewed. Seventy-five patients (mean age ± standard deviation, 62.7 ± 13.2 years; 48 males) who showed myocardial bridging in the left anterior descending artery without concomitant obstructive stenosis on the imaging were included. The change in CT-FFR across myocardial bridging (ΔCT-FFR, defined as the difference in CT-FFR values between the proximal and distal ends of the myocardial bridging) in different cardiac phases, as well as other anatomical parameters, were measured to evaluate their performance for diagnosing myocardial bridging-related myocardial ischemia using dynamic CT-MPI as the reference standard (myocardial blood flow < 100 mL/100 mL/min or myocardial blood flow ratio ≤ 0.8). Results: ΔCT-FFR_systolic (ΔCT-FFR calculated in the best systolic phase) was higher in patients with vs. without myocardial bridging-related myocardial ischemia (median [interquartile range], 0.12 [0.08-0.17] vs. 0.04 [0.01-0.07], p < 0.001), while CT-FFR_systolic (CT-FFR distal to the myocardial bridging calculated in the best systolic phase) was lower (0.85 [0.81-0.89] vs. 0.91 [0.88-0.96], p = 0.043). In contrast, ΔCT-FFR_diastolic (ΔCT-FFR calculated in the best diastolic phase) and CT-FFR_diastolic (CT-FFR distal to the myocardial bridging calculated in the best diastolic phase) did not differ significantly. Receiver operating characteristic curve analysis showed that ΔCT-FFR_systolic had largest area under the curve (0.822; 95% confidence interval, 0.717-0.901) for identifying myocardial bridging-related ischemia. ΔCT-FFR_systolic had the highest sensitivity (91.7%) and negative predictive value (NPV) (97.8%). ΔCT-FFR_diastolic had the highest specificity (85.7%) for diagnosing myocardial bridging-related ischemia. The positive predictive values of all CT-related parameters were low. Conclusion: ΔCT-FFR_systolic reliably excluded myocardial bridging-related ischemia with high sensitivity and NPV. Myocardial bridging showing positive CT-FFR results requires further evaluation.