• Progress in Medical Physics
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• v.32 no.1
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• pp.1-17
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• 2021

The evolution of X-ray computed tomography (CT) has been based on the discovery of X-rays, the inception of the Radon transform, and the development of X-ray digital data acquisition systems and computer technology. Unlike conventional X-ray imaging (general radiography), CT reconstructs cross-sectional anatomical images of the internal structures according to X-ray attenuation coefficients (approximate tissue density) for almost every region in the body. This article reviews the essential physical principles and technical aspects of the CT scanner, including several notable evolutions in CT technology that resulted in the emergence of helical, multidetector, cone beam, portable, dual-energy, and phase-contrast CT, in integrated imaging modalities, such as positron-emission-tomography-CT and single-photon-emission-computed-tomography-CT, and in clinical applications, including image acquisition parameters, CT angiography, image adjustment, versatile image visualizations, volumetric/surface rendering on a computer workstation, radiation treatment planning, and target localization in radiotherapy. The understanding of CT characteristics will provide more effective and accurate patient care in the fields of diagnostics and radiotherapy, and can lead to the improvement of image quality and the optimization of exposure doses.

• Journal of Korean Neurosurgical Society
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• v.61 no.1
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• pp.28-34
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• 2018

Objective : Duplication of the vertebral artery (VA) is a rare vascular variant. This paper describes the anatomy and embryological development of duplicated VAs and reviews the clinical significance. Methods : Computed tomography (CT) angiography was performed in 3386 patients (1880 females, 1506 males) between March 2014 and November 2015. We defined duplication of the VA as a condition in which the VA has two origins that fused at different levels of the neck. Results : Ten of the 3386 patients (0.295%) who received CT angiography had a dual origin of the VA; three on the left side, and seven on the right side. In all seven with right dual origin of the VA, both limbs of the VA origin originated from the right subclavian artery. In all three patients with left dual origin of the VA, both limbs of the VA originated from the left subclavian artery and aortic arch. In all 10 patients, the medial limb of the duplicated VA was located posteriorly and medially to the common carotid artery (CCA) and anteriorly and laterally to the vertebral transverse foramen. In two patients, the medial limb of the duplicated VA was located in close proximity to the CCA. In another two patients, the medial limb of the duplicated VA was located in close proximity to the CCA, carotid bifurcation, and proximal internal carotid artery. Conclusion : Although duplication of the VA is asymptomatic in most patients, clinicians should consider this anomaly during diagnosis and treatment.

• Korean Journal of Veterinary Research
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• v.47 no.2
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• pp.247-254
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• 2007

This study was performed to identify the normal anatomic orientation of pulmonary arteries and to obtain the normal baseline parameters and the optimal contrast material delivery methods of computed tomographic pulmonary angiography (CTPA) on normal beagle dogs. Based on the contrast injection flow rate, the contrast volume, and the administration methods, the experimental groups were divided into 4 groups such as group 1 : 2 ml/s, 3 ml/kg, and monophasic administration; group 2 : 5 ml/s, 3 ml/kg, and monophasic administration; group 3 : 5 ml/s, 4 ml/kg, and monophasic administration; group 4 : 5 ml/s and 2 ml/kg in first phase, 0.3 ml/s and 2 ml/kg in second phase, as biphasic administration. Normal anatomic orientation of pulmonary arteries in CTPA was evaluated through reformatted and 3D images after retro-reconstruction. Normal parameters for great arteries and peripheral pulmonary arteries were obtained on the factor of basement hounsfield unit (HU) values, contrast enhanced HU values, delay time, and peak time. And the optimal contrast delivery methods were evaluated on the factor of contrast enhanced HU values, image quality, and artifact. The monophasic administration with 5 ml/s contrast injection flow rate and 3 ml/kg contrast volume was optimal in canine CTPA.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1472-1477
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• 2020

Dural arteriovenous fistula is an acquired vascular anomaly that can cause various symptoms. Here, we report a rare case of Borden type I sigmoid sinus dural arteriovenous fistula presenting as subarachnoid hemorrhage. Bleeding occurred from a side-wall aneurysm in the lateral pontomedullary segment of the anterior inferior cerebellar artery, which was a minor pial feeder. Features on imaging modalities, including brain CT, CT angiography, MR imaging/angiography and digital subtraction angiography, are described with a literature review.

• Korean Journal of Radiology
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• v.21 no.9
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• pp.1095-1103
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• 2020

Objective: The present study aimed to investigate whether quantitative dual-energy computed tomography (DECT) parameters offer an incremental risk stratification benefit over the CT ventricular diameter ratio in patients with acute pulmonary embolism (PE) by using propensity score analysis. Materials and Methods: This study was conducted on 480 patients with acute PE who underwent CT pulmonary angiography (CTPA) or DECT pulmonary angiography (DE CT-PA). This propensity-matched study population included 240 patients with acute PE each in the CTPA and DECT groups. Altogether, 260 (54.1%) patients were men, and the mean age was 64.9 years (64.9 ± 13.5 years). The primary endpoint was all-cause death within 30 days. The Cox proportional hazards regression model was used to identify associations between CT parameters and outcomes and to identify potential predictors. Concordance (C) statistics were used to compare the prognoses between the two groups. Results: In both CTPA and DECT groups, right to left ventricle diameter ratio ≥ 1 was associated with an increased risk of all-cause death within 30 days (hazard ratio: 3.707, p < 0.001 and 5.573, p < 0.001, respectively). However, C-statistics showed no statistically significant difference between the CTPA and DECT groups for predicting death within 30 days (C-statistics: 0.759 vs. 0.819, p = 0.117). Conclusion: Quantitative measurement of lung perfusion defect volume by DECT had no added benefit over CT ventricular diameter ratio for predicting all-cause death within 30 days.

• Journal of the Korean Society of Radiology
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• v.83 no.2
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• pp.400-405
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• 2022

Gastrointestinal stromal tumors (GISTs) are not uncommon and often cause gastrointestinal bleeding. GISTs occurring in the small intestine are occasionally difficult to identify by endoscopy and CT. In this case, the patient underwent CT three times before surgery, and the lesion was found to be located in a different area of the abdominal cavity on each CT scan. Moreover, the lesion was missed in the first two CT images because it was difficult to distinguish it from the nearby collapsed small intestine. The lesion was eventually detected through angiography; however, the correct diagnosis and treatment were delayed for 3 years because it was mistaken for a vascular malformation, which is the most common cause of obscure GI bleeding in elderly patients. This report emphasizes the need for interventional radiologists to be updated and vigilant of the angiographic features of GISTs to make an accurate diagnosis and establish a management strategy.

• Korean Journal of Radiology
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• v.21 no.12
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• pp.1285-1293
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• 2020

Objective: To evaluate the effects of vasodilators on contrast enhancement and transluminal attenuation gradient (TAG) of coronary arteries at coronary computed tomography angiography (CCTA). Materials and Methods: We retrospectively reviewed CCTA scans of patients who underwent double-acquisition CCTA; CCTA without a vasodilator, and CCTA during a intravenous (IV) infusion of nitrate. Among them, we enrolled 19 patients who had no significant atherosclerotic lesions or coronary spasms. In the control group, 28 patients were enrolled who showed normal coronary arteries on CCTA, which was acquired by a conventional method (sublingual vasodilator). We measured the TAG and Hounsfield units for each of the three major epicardial coronary arteries (reported as 'ProxHU') and then compared the results between the nitrate administration methods (CT without vasodilator [CT_pre], CT with IV vasodilator [CT_iv], and CT with sublingual vasodilator [CT_sub]). Results: The mean TAG showed a significant difference between the coronary arteries (right coronary artery [RCA] > left anterior descending artery [LAD] > left circumflex artery [LCX], p < 0.05), while there was no difference in ProxHU of each coronary artery in all three types of nitrate administration methods (p > 0.05). The TAG of CT_pre group showed steeper slope than those of vasodilator groups (CT_iv and CT_sub) on LAD and LCX ([LAD: CT_pre = -22.1 ± 6.66, CT_iv = -16.76 ± 5.78, and CT_sub = -16.47 ± 5.78, p = 0.005], [LCX: CT_pre = -31.26 ± 17.43, CT_iv = -23.74 ± 14.06, and CT_sub = -20.94 ± 12.15, p = 0.051]), while that of RCA showed no significant differences (p = 0.600). When comparing proxHU, CT_iv showed higher proxHU than that of CT_pre or CT_sub, especially on LCX (CT_pre = 426.7 ± 68.3, CT_iv = 467.9 ± 84.9, and CT_sub = 404.9 ± 63.3, p = 0.013). ProxHU showed a negative correlation with TAG on all three of methods (r = -0.280, p < 0.001). Conclusion: TAG in CCTA was significantly affected by vasodilator administration. Both TAG and ProxHU of coronary arteries tend to increase with vasodilator administration on CCTA.

• Journal of Korean Neurosurgical Society
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• v.42 no.1
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• pp.49-52
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• 2007

The authors report a unique case of unilateral Moyamoya disease with a rare combination of arteriovenous malformation (AVM) who presented with intracerebral hemorrhage (ICH). A 50-year-old man suffered from sudden onset of mental deterioration and right hemiparesis. Brain computed tomography (CT) showed intracerebral hemorrhage on left thalamus. Brain CT angiography and cerebral digital subtraction angiography (DSA) revealed AVM combined with unilateral moyamoya disease involving left middle cerebral artery (MCA) and choroid plexus in left lateral ventricle. Intraventricular hemorrhage and hydrocephalus were managed conservatively. A rare case of unilateral Moyamoya disease accompanied by a cerebral arteriovenous malformation is described and discussed with review of pertinent literature.

• Journal of Veterinary Clinics
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• v.34 no.5
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• pp.359-365
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• 2017

Two spaniel dogs were presented with a history of lethargy, weakness, refractory hypoglycemia, and episodic seizure. A pancreatic mass on the distal end of the left limb was identified through screening tests including dualphase CT angiography in each patient. Canine insulinoma was suspected with low blood glucose, low fructosamine, and normal to high serum insulin levels. Exploratory laparotomies were performed, and partial pancreatectomy using an ultrasonic-activated scalpel was achieved without enzyme leakage or fistula formation after surgery. The lesions were definitively diagnosed as insulinoma via histopathologic examination. One dog has been doing well until POD 870 with medication; in the other dog, diffuse hepatic nodules noted during surgery were confirmed as a liver metastasis. This dog died at POD 45. This case report addresses the utility of the ultrasonic scalpel in partial pancreatectomy for the treatment of canine insulinoma and differences in prognosis according to disease stage.

• Knee surgery & related research
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• v.30 no.4
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• pp.364-368
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• 2018

We report a case of 53-year-old woman with an injured popliteal artery due to excessive drilling with a drill bit during medial opening wedge high tibial osteotomy (MOWHTO). Pseudoaneurysm was diagnosed three days after surgery and confirmed by urgent computed tomography (CT) angiography. Open vascular surgery with resection of the perivascular hematoma and end-to-end anastomosis using ipsilateral saphenous vein interposition graft was performed. CT angiography at 8 months postoperatively showed that blood flow was maintained without obstruction of the graft site and active dorsiflexion of the foot was possible. To reduce neurovascular injury during MOWHTO, it is important not to drill the far cortex at the proximal part of the osteotomy site when using a drill bit, and the metal should be positioned posteromedially as much as possible.