• Korean Journal of Radiology
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• v.2 no.1
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• pp.14-20
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• 2001

Objective: To compare the usefulness of unenhanced spiral CT (UCT) with that of excretory urography (EU) in patients with acute flank pain. Materials and Methods: Thirty patients presenting with acute flank pain underwent both UCT and EU. Both techniques were used to determine the presence, size, and location of urinary stone, and the presence or absence of secondary signs was also evaluated. The existence of ureteral stone was confirmed by its removal or spontaneous passage during follow-up. The absence of a stone was determined on the basis of the clinical and radiological evidence. Results: Twenty-one of the 30 patients had one or more ureteral stones and nine had no stone. CT depicted 22 of 23 calculi in the 21 patients with a stone, and no calculus in all nine without a stone. The sensitivity and specificity of UCT were 96% and 100%, respectively. EU disclosed 14 calculi in the 21 patients with a stone and no calculus in eight of the nine without a stone. UCT and EU demonstrated secondary signs of ureterolithiasis in 15 and 17 patients, respectively. Conclusion: For the evaluation of patients with acute flank pain, UCT is an excellent modality with high sensitivity and specificity. In near future it may replace EU.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.255-258
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• 2008

For rapidly increasing amount of medical images, it is difficult for radiologist to interpretate the medical images fastly and for sufficient time. We investigated whether liver CT image has good features to be analyzed by computer algorithm, We examed the CT images of liver tumors (Hepetocellular carcinomas; HCCs) and searched any potential morphologic characteristics to be analyzed by computer algorithms. On unenhanced CT, HCCs appeared hypodense After enhancement, most HCCs were hyperdense, and then. as a consequence of rapid washout, HCCS became hypodense compared with the liver parenchyma. Most CT images of HCCs showed synchronous phase-specific.morphologic features. We applied various edge detection filters to these images and some filters showed favorable performance in the detection of tile edge of liver and HCC. Therefore, theses features seems to be analyzed by computer algorithms effectively.Further studies may be warranted.

• Journal of Veterinary Science
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• v.21 no.4
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• pp.55.1-55.11
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• 2020

Background: Computed tomography urography (CTU), based on the excretion of contrast medium after its injection, allows visualization of the renal parenchyma and the renal collecting system. Objectives: To determine the optimal contrast medium dose allocation ratio to apply in split-bolus CTU in dogs. Methods: This prospective, experimental, exploratory study used 8 beagles. In 3-phase CTU, unenhanced-, nephrographic-, and excretory-phase images were obtained with a single injection of 600 mg iodine/kg iohexol. In split-bolus CTU, two different contrast medium allocation ratios (30% and 70% for split CTU 1; 50% and 50% for split CTU 2) were used. Unenhanced phase image and a synchronous nephrographic-excretory phase image were acquired. Results: Although the attenuation of the renal parenchyma was significantly lower when using both split CTUs than the 3-phase CTU, based on qualitative evaluation, the visualization score of the renal parenchyma of split CTU 1 was as high as that of the 3-phase CTU, whereas the split CTU 2 score was significantly lower than those of the two others. Artifacts were not apparent, regardless of CTU protocol. The diameter and opacification of the ureter in both split CTUs were not significantly different from those using 3-phase CTU. Conclusions: Split-bolus CTU with a contrast medium allocation ratio of 30% and 70% is feasible for evaluating the urinary system and allows sufficient enhancement of the renal parenchyma and appropriate distention and opacification of the ureter, with similar image quality to 3-phase CTU in healthy dogs. Split-bolus CTU has the advantages of reducing radiation exposure and the number of CT images needed for interpretation.

• Investigative Magnetic Resonance Imaging
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• v.5 no.2
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• pp.149-154
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• 2001

Purpose : Our aim was to evaluate the usefulness of fluid-attenuated inversion recovery (FLAIR) MR imaging for detection of acute subarachnoid hemorrhage (SAH) compared with unenhanced CT. Materials and methods ; We compared FLAIR MR images with unenhanced CT scans in 28 patients with acute SAH. Findings of SAH on CT and MR images were graded as 0 (absence), 1 (suspicious), 2 (definite) in the cerebral sulci, sylvian fissure, basal cistern, and cisterns of the posterior fossa. We also compared FLAIR MR images of 28 patients with those of 35 normal subjects, and then the sensitivity, specificity, and diagnostic accuracy of FLAIR MR image for detection of acute SAH were calculated. Results : FLAIR MR image was superior to CT in detecting SAH in the posterior fossa ($1.41{\pm}0.74{\;}vs{\;}0.78{\pm}0.80$; p<0.05) and cortical sulci ($1.11{\pm}0.80{\;}vs{\;}0.70{\pm}0.83$; p<0.05). There was no significant difference between FLAIR MR image and CT in detecting SAH in the basal cistern and sylvian fissure. The sensitivity, specificity, and diagnostic accuracy of FLAIR MR image for detection of SAH were 100% in all. Conclusion : FLAIR MR image is useful in detecting acute SAH, especially in patients with small amount of SAH or SAH in the posterior fossa.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2521-2526
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• 2015

Objective: The purpose of this study was to evaluate computed tomography (CT) virtual non-contrast (VNC) spectral imaging for gastric carcinoma. Materials and Methods: Fifty-two patients with histologically proven gastric carcinomas underwent gemstone spectral imaging (GSI) including non-contrast and contrast-enhanced hepatic arterial, portal venous, and equilibrium phase acquisitions prior to surgery. VNC arterial phase (VNCa), VNC venous phase (VNCv), and VNC equilibrium phase (VNCe) images were obtained by subtracting iodine from iodine/water images. Images were analyzed with respect to image quality, gastric carcinoma-intragastric water contrast-to-noise ratio (CNR), gastric carcinoma-perigastric fat CNR, serosal invasion, and enlarged lymph nodes around the lesions. Results: Carcinoma-water CNR values were significantly higher in VNCa, VNCv, and VNCe images than in normal CT images (2.72, 2.60, 2.61, respectively, vs 2.35, $p{\leq}0.008$). Carcinoma-perigastric fat CNR values were significantly lower in VNCa, VNCv, and VNCe images than in normal CT images (7.63, 7.49, 7.32, respectively, vs 8.48, p< 0.001). There were no significant differences of carcinoma-water CNR and carcinoma-perigastric fat CNR among VNCa, VNCv, and VNCe images. There was no difference in the determination of invasion or enlarged lymph nodes between normal CT and VNCa images. Conclusions: VNC arterial phase images may be a surrogate for conventional non-contrast CT images in gastric carcinoma evaluation.

• Journal of Veterinary Clinics
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• v.35 no.2
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• pp.53-56
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• 2018

Computed tomography (CT) findings of hepatic adenoma in veterinary medicine are variable and unlike in human medicine, not defined clearly. A 12-year-old neutered male Shih Tzu presented after a seizure, with weight loss, salivation, and cachexia. An abdominal mass was identified on radiography, and ultrasonographic images showed a mixed echo pattern with marked vascularity. CT showed that the mass originated from caudate lobe, was heterogeneously hypoattenuated compared with the hepatic parenchyma, and had irregular margins. Contrast enhanced CT showed that the mass enhanced like the surrounding liver parenchyma. However, it contained unenhanced areas and enhanced vessels were observed in the arterial phase at the periphery of the mass. The margins of mass were more enhanced in the venous phase than the arterial phase and the hypoattenuating regions within the mass were not enhanced. Greater enhancing in the venous phase is seen with adenomas; however, the heterogeneous enhancement pattern, especially the marginal vascular enhancement and internal hypoattenuating regions, is seen with malignancy. Although this is a single case of hepatic adenoma, the atypical enhanced pattern of this case can provide useful information to predict the malignancy of primary liver tumor.

• Korean Journal of Radiology
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• v.21 no.7
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• pp.838-850
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• 2020

Computed tomography (CT) is an important imaging modality in evaluating thoracic malignancies. The clinical utility of dual-energy spectral computed tomography (DESCT) has recently been realized. DESCT allows for virtual monoenergetic or monochromatic imaging, virtual non-contrast or unenhanced imaging, iodine concentration measurement, and effective atomic number (Z_eff map). The application of information gained using this technique in the field of thoracic oncology is important, and therefore many studies have been conducted to explore the use of DESCT in the evaluation and management of thoracic malignancies. Here we summarize and review recent DESCT studies on clinical applications related to thoracic oncology.

• Korean Journal of Radiology
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• v.1 no.2
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• pp.104-109
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• 2000

Objective: Multilocular cystic renal cell carcinoma (MCRCC) is a recently described variety of renal cell carcinoma with characteristic pathologic and clinical features. The purpose of this study was to analyze the imaging findings of MCRCCs. Materials and Methods: Ten adult patients with pathologically proven unilateral MCRCC who underwent renal US and CT were included in this study. The radiologic findings were retrospectively evaluated for cystic content, wall, septum, nodularity, calcification and solid portion by three radiologists who established a consensus. Imaging and postnephrectomy pathologic findings were compared. Results: All patients were adults (six males and four females) and their ages ranged from 33 to 68 years (mean, 46). On US and CT images, all tumors appeared as well-defined multilocular cystic masses composed of serous or complicated fluid. In all patients, unenhanced CT scans revealed hypodense cystic portions, and in four tumors, due to the presence of hemorrhage or gelatinous fluid, some hyperdense areas were also noted. In no tumor was an expansile solid nodule seen in the thin septa, and in only one was there dystrophic calcification in a septum. Small areas of solid portion constituting less than 10% of the entire lesion were found in six of the ten tumors, and these areas were slightly enhanced on enhanced CT scans. In all patients, imaging and pathologic findings correlated closely. Conclusion: On US and CT images, MCRCC appeared as a well-defined multilocular cystic mass with serous, proteinaceous or hemorrhagic fluid, with no expansile solid nodules in the thin septa, and sometimes with small slightly enhanced solid areas. Where radiologic examinations demonstrate a cystic renal mass of this kind in adult males, MCRCC should be included in the differential diagnosis.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.102-107
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• 2008

Background : Malignant pulmonary nodules account for 30 to 40 percent of all solitary pulmonary nodules (SPNs). Therefore, characterization of SPNs is very important for treatment. Recently, dynamic CT has been widely used for tissue characterization and formation of differential diagnoses. The purpose of this study was to evaluate the ability of dynamic CT to formulate the differential diagnosis of SPNs. Materials and Methods : Nineteen patients with SPNs underwent dynamic CT (unenhanced scans, followed by a series of images at 20, 40, 60, 80, 100, 120, 140, 160, and 180 sec after intravenous injection of contrast medium). Diagnosis of SPN was performed based on pathologic findings in needle biopsy samples. Peak enhancement, net enhancement, slope of enhancement, and maximum relative enhancement ratio of the SPN were measured on dynamic CT, and Levene's test was performed to assess benignancy and malignancy. Results : Twelve SPNs were confirmed to have malignant pathology. There were no significant differences between benign and malignant nodules with respect to peak enhancement (p=0.787), net enhancement (p=0.135), or slope of enhancement (p=0.698). The maximal enhancement ratio was increased in malignancy compared to benignancy, but the difference was not statistically significant (p=0.094). Conclusion : In our study, the hemodynamic characteristics of dynamic CT were not significantly different between benign and malignant nodules. Therefore, long-term studies of larger patient samples are required to confirm our findings.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.735-741
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• 2021

Objective: To evaluate circularity as a quantitative shape factor of small renal tumor on computed tomography (CT) in differentiating fat-poor angiomyolipoma (AML) from renal cell carcinoma (RCC). Materials and Methods: In 257 consecutive patients, 257 pathologically confirmed renal tumors (either AML or RCC less than 4 cm), which did not include visible fat on unenhanced CT, were retrospectively evaluated. A radiologist drew the tumor margin to measure the perimeter and area in all the contrast-enhanced axial CT images. In each image, a quantitative shape factor, circularity, was calculated using the following equation: 4 x π x (area ÷ perimeter²). The median circularity (circularity index) was adopted as a representative value in each tumor. The circularity index was compared between fat-poor AML and RCC, and the receiver operating characteristic (ROC) curve analysis was performed. Univariable and multivariable binary logistic regression analysis was performed to determine the independent predictor of fat-poor AML. Results: Of the 257 tumors, 26 were AMLs and 231 were RCCs (184 clear cell RCCs, 25 papillary RCCs, and 22 chromophobe RCCs). The mean circularity index of AML was significantly lower than that of RCC (0.86 ± 0.04 vs. 0.93 ± 0.02, p < 0.001). The mean circularity index was not different between the subtypes of RCCs (0.93 ± 0.02, 0.92 ± 0.02, and 0.92 ± 0.02 for clear cell, papillary, and chromophobe RCCs, respectively, p = 0.210). The area under the ROC curve of circularity index was 0.924 for differentiating fat-poor AML from RCC. The sensitivity and specificity were 88.5% and 90.9%, respectively (cut-off, 0.90). Lower circularity index (≤ 0.9) was an independent predictor (odds ratio, 41.0; p < 0.001) for predicting fat-poor AML on multivariable logistic regression analysis. Conclusion: Circularity is a useful quantitative shape factor of small renal tumor for differentiating fat-poor AML from RCC.