• Journal of the Korean Society of Radiology
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• v.84 no.5
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• pp.1047-1065
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• 2023

Multi-detector CT (MDCT) is a highly accurate diagnostic tool that is commonly used to evaluate appendicitis and its complications. The diagnosis of appendicitis based on MDCT findings can be difficult and challenging when the observed findings are inconsistent with the typical features. Atypical appendicitis includes a wide spectrum of features, such as variable positions of the appendix and cecum, complications, and unusual pathological findings of secondary appendicitis that mimic or induce appendicitis. Our pictorial essay describes the diverse spectrum of atypical appendicitis and appendicitis-like conditions in terms of location abnormalities, complications, and uncommon pathologies, including related tumors, reactive appendicitis, appendiceal diverticulitis, and IgG4-related disease. Through this essay, the readers can become more familiar with MDCT findings of atypical appendicitis.

• Journal of the Korean Society of Radiology
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• v.85 no.1
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• pp.235-239
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• 2024

An ilio-iliac arteriovenous fistula (AVF) is rare. Common factors leading to ilio-iliac AVF include congenital malformations, iatrogeny, and trauma. There is limited documentation in the literature of cases involving ilio-iliac AVF with May-Thurner syndrome. Here, we present a case of an ilio-iliac AVF with May-Thurner syndrome in an 80-year-old male. CT and angiography confirmed extensive ilio-iliac AVF. Successful endovascular procedures for ilio-iliac AVF were performed using several variable-sized coils and 1400-2000 ㎛ gelatin particles. After embolization, follow-up abdominopelvic CT revealed an improvement in edema in the left leg.

• Journal of Veterinary Clinics
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• v.28 no.5
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• pp.510-515
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• 2011

This study was performed to quantitatively assess the normal lung volume and density according to the position by multi-detector computed tomography (MDCT) in dogs. Helical CT of the thorax was performed on 4 different positions with dorsal, left lateral, right lateral and ventral recumbency in 6 Pekingese and 6 Maltese dogs. During CT scanning, dogs were kept hyperventilated. Through the 3-dimensional reconstruction of CT images, the lung parameters were measured as the volume and density of the left, right including accessory lobe, and total lung. 3D images represented the different lung shape between Pekingese and Maltese dogs. Their difference of total lung volume and total lung density was not significant on the each position in both breeds. Right lung volume was significantly higher than left. The difference of left and right volume was $66.91{\pm}25.1$ ml. Linear relationship was shown between body weight and lung volume of ventral recumbency position. The dependent lung had higher density and lower volume than nondependent lung in both breed dogs. The volume of nondependent lung was not changed compared with the volume on ventral or dorsal recumbency. The total lung volume measured with MDCT is correlated with the lung density, and the lung density is useful to predict the normal total lung volume.

• Journal of the Korea Computer Graphics Society
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• v.7 no.1
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• pp.37-49
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• 2001

We propose an optimization of mutual information for multiresolution image registration to represent useful information as integrated form obtaining from complementary information of multi modality images. The method applies mutual information as cost function to measure the statistical dependency or information redundancy between the image intensities of corresponding pixels in both images, which is assumed to be maximal if the images are geometrically aligned. As experimental results we validate visual inspection for accuracy, changning initial condition and addictive noise for robustness. Since our method uses the native image rather than prior feature extraction, few user interaction is required to perform the registration. In addition it leads to robust density estimation and convergence as applying non-parametric density estimation and stochastic multiresolution optimization.

• Journal of radiological science and technology
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• v.40 no.1
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• pp.79-85
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• 2017

The purpose of this study was to measure contrast to noise ratio (CNR) and signal to noise ratio (SNR) according to change of reconstruction from region of interest (ROI) in breast positron emission tomography-computed tomography (PET-CT), and to analyze the CNR and SNR statically. We examined images of breast PET-CT of 100 patients in a University-affiliated hospital, Seoul, Korea. Each patient's image of breast PET-CT were calculated by using ImageJ. Differences of CNR and SNR among four reconstruction algorithms were tested by SPSS Statistics21 ANOVA test for there was statistical significance (p<0.05). We have analysis socio-demographical variables, CNR and SNR according to reconstruction images, 95% confidence according to CNR and SNR of reconstruction and difference in a mean of CNR and SNR. SNR results, with the quality of distributions in the order of PSF_TOF, Iterative and Iterative-TOF, FBP-TOF. CNR, with the quality of distributions in the order of PSF_TOF, Iterative and Iterative-TOF, FBP-TOF. CNR and SNR of PET-CT reconstruction methods of the breast would be useful to evaluate breast diseases.

• Journal of the Korean Society of Radiology
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• v.83 no.1
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• pp.218-223
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• 2022

Although the typical CT findings of Pneumocystis jiroveci pneumonia (PJP) include diffuse or multifocal areas of ground-glass opacities in both lungs, it can also rarely manifest as multiple pulmonary nodules. We report a rare case of atypical PJP in an immunocompromised patient with multiple myeloma, presenting as widespread ground-glass opacities and multiple necrotic subpleural nodules in both lungs on CT, which proved to be granulomatous PJP on percutaneous transthoracic needle biopsy.

• Journal of Veterinary Clinics
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• v.25 no.2
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• pp.96-101
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• 2008

This study was performed to quantify the pleural effusion in radiography, ultrasonography and computed tomography(CT) and to evaluate and compare the usefulness of these methods. Normal saline of 10 ml/kg was infused into the pleural space until a final loading volume of 60 ml/kg body weight was reached in six Beagle dogs. The radiographic examination was performed for the detection and quantification of pleural effusion. On the ultrasonographic study, the maximum perpendicular distance was measured between the surface of the lung and the thoracic wall to evaluate pleural effusion. On the CT image, pleural effusion was evaluated as the perpendicular distance to the thoracic surface in the maximum pleural effusion volume on any transverse images with soft tissue window. Statistical analysis was performed using linear regression test. The volume of pleural effusion and measurements of radiography and ultrasonography had no statistical relationship. However, a significant correlation was identified between the volume of pleural effusion and the depth at right ($r^2=0.715$), left ($r^2=0.745$), and mean right and left depth ($r^2=0.844$) on the CT images. All of the thoracic radiographs, ultrasonography, and CT are useful in recognition of pleural effusion. In quantification of pleural effusion, the CT measurement method is superior to radiographic and ultrasonographic measurements.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.5
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• pp.23-32
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• 2001

Electrical impedance tomography (EIT) is a relatively new imaging modality in which the resistivity (conductivity) distribution of the unknown object is estimated based on the known sets of injected currents and measured voltages on the surface of the object. In this paper, we propose a dynamical EIT reconstruction algorithm based on the regularized extended Kalman filter(EKF). The EIT inverse problem is formulated as dynamic equation which consists of the slate equation and the observation equation, and the unknown state(resistivity) is estimated recursively with the aid of the EKF. In doing so, the generalized Tikhonov regularization technique is employed in the cost functional to mitigate the ill-posedness characteristics of the inverse problem. Computer simulations for the 16-channel synthetic data are provided to illustrate the reconstruction performance of the proposed algorithm.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.275-278
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• 2001

영상 분할은 임상에서의 진단과 분석 및 3차원 가시화하는데 있어 선행되어야 할 필수적인 과정이다. 본 논문에서는 심혈관계 영상의 분할을 위한 Wave-front SRG방법을 제안한다. 제안된 방법은 2차원 슬라이스 영상에서 사용자에 의한 씨앗점(seed front)을 입력으로 받아 그 이웃한 슬라이스들에 wave-front를 만들어 영역 성장법에 의해 3차원 volume을 확장시킨다. 이때 다음으로 성장할 wave-front voxel의 mean gradient 값을 사용하여 밝기값의 변화가 심한 심혈관계 영상을 분할하였으며, Wave-front voxel의 size를 계산하여 혈관분할 시 발생할 수 있는 작은 채널에서의 새나감을 방지하였다. 제안된 방법을 컴퓨터 단층촬영으로 얻은 심혈 관계 영상의 분할에 적용한 결과, 밝기값의 변화가 심한 심혈관계 영상을 성공적으로 분할했으며, 작의 채널의 새나감이 없이 분할을 수행하였다.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.717-723
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• 2023

Liver disease is highly associated with death, and other abdominal diseases are also important causes affecting a person's lifespan, and a CT scan is essential when treating abdominal diseases. High radiation exposure is essential to create images that are good for reading, but managing the patient's radiation exposure is also essential. In this study, a post-processing wavelet algorithm was proposed to improve the image quality of abdominal CT images. Wavelets have the disadvantage of having to set a threshold value depending on the type of input image. Therefore, we experimentally proposed the threshold value of the wavelet and evaluated whether the image quality was effective. As a result of the experiment, the optimal threshold value for abdominal CT images was calculated to be 50. In the case of image 1, noise was improved by 49% and in the case of image 2, by 29%, and the contrast also increased. if the results of this study are applied for post-processing after abdominal CT, image quality can be improved and it will be helpful in disease diagnosis.