• Korean Journal of Optics and Photonics
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• v.25 no.2
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• pp.67-71
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• 2014

Intravascular optical coherence tomography (OCT) enables imaging of the three-dimensional (3D) microstructure of a blood vessel wall. While 3D vascular visualization provides detailed information of the vessel wall and intraluminal structures, a longitudinal imaging pitch that is several times bigger than the imaging resolution of the system has limited true high-resolution 3D imaging. In this paper we demonstrate high-speed intravascular OCT in vivo, acquiring images at a rate of 350 frames per second. A 47-mm-long rabbit aorta was imaged in 3.7 seconds, after a short flush with contrast agent. The longitudinal imaging pitch was 34 micrometers, comparable to the transverse imaging resolution of the system. Three-dimensional volume rendering showed greatly enhanced visualization of tissue microstructure and stent struts, relative to what is provided by conventional intravascular imaging speeds.

• Korean Journal of Radiology
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• v.24 no.1
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• pp.39-50
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• 2023

Objective: To assess the contrast-enhanced CT and ultrasonography (US) findings of intracholecystic papillary neoplasm (ICPN) and determine the imaging features predicting ICPN associated with invasive carcinoma (ICPN-IC). Materials and Methods: In this retrospective study, we enrolled 119 consecutive patients, including 60 male and 59 female, with a mean age ± standard deviation of 63.3 ± 12.1 years, who had pathologically confirmed ICPN (low-grade dysplasia [DP] = 34, high-grade DP = 35, IC = 50) and underwent preoperative CT or US. Two radiologists independently assessed the CT and US findings, focusing on wall and polypoid lesion characteristics. The likelihood of ICPN-IC was graded on a 5-point scale. Univariable and multivariable logistic regression analyses were performed to identify significant predictors of ICPN-IC separately for wall and polypoid lesion findings. The performances of CT and US in distinguishing ICPN-IC from ICPN with DP (ICPN-DP) was evaluated using the area under the receiver operating characteristic curve (AUC). Results: For wall characteristics, the maximum wall thickness (adjusted odds ratio [aOR] = 1.4; 95% confidence interval [CI]: 1.1-1.9) and mucosal discontinuity (aOR = 5.6; 95% CI: 1.3-23.4) on CT were independently associated with ICPN-IC. Among 119 ICPNs, 110 (92.4%) showed polypoid lesions. Regarding polypoid lesion findings, multiplicity (aOR = 4.0; 95% CI: 1.6-10.4), lesion base wall thickening (aOR = 6.0; 95% CI: 2.3-15.8) on CT, and polyp size (aOR = 1.1; 95% CI: 1.0-1.2) on US were independently associated with ICPN-IC. CT showed a higher diagnostic performance than US in predicting ICPN-IC (AUC = 0.793 vs. 0.676; p = 0.002). Conclusion: ICPN showed polypoid lesions and/or wall thickening on CT or US. A thick wall, multiplicity, presence of wall thickening in the polypoid lesion base, and large polyp size are imaging findings independently associated with invasive cancer and may be useful for differentiating ICPN-IC from ICPN-DP.

• Investigative Magnetic Resonance Imaging
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• v.19 no.4
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• pp.231-236
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• 2015

A 17-year-old girl presented with complaints of headache and decreasing vision of one month's duration, without any history of fever, weight loss, or any evidence of an immuno-compromised state. Her neurological examination was normal, except for papilledema. Laboratory investigations were within normal limits, except for a slightly increased Erythrocyte Sedimentation Rate (ESR). Non-contrast computerized tomography of her head revealed complex mass in left frontal lobe with a concentric, slightly hyperdense, thickened wall, and moderate perilesional edema with mass effect. Differential diagnoses considered in this case were pilocytic astrocytoma, metastasis and abscess. Magnetic resonance imaging (MRI) obtained in 3.0 Tesla (3.0T) scanner revealed a lobulated outline cystic mass in the left frontal lobe with two concentric layers of T2 hypointense wall, with T2 hyperintensity between the concentric ring. Moderate perilesional edema and mass effect were seen. Post gadolinium study showed a markedly enhancing irregular wall with some enhancing nodular solid component. No restricted diffusion was seen in this mass in diffusion weighted imaging (DWI). Magnetic resonance spectroscopy (MRS) showed increased lactate and lipid peaks in the central part of this mass, although some areas at the wall and perilesional T2 hyperintensity showed an increased choline peak without significant decrease in N-acetylaspartate (NAA) level. Arterial spin labelling (ASL) and dynamic susceptibility contrast (DSC) enhanced perfusion study showed decrease in relative cerebral blood volume at this region. These features in MRI were suggestive of brain abscess. The patient underwent craniotomy with excision of a grayish nodular lesion. Abundant acid fast bacilli (AFB) in acid fast staining, and epithelioid cell granulomas, caseation necrosis and Langhans giant cells in histopathology, were conclusive of tubercular abscess. Tubercular brain abscess is a rare manifestation that simulates malignancy and cause diagnostic dilemma. MRI along with MRS and magnetic resonance perfusion studies, are powerful tools to differentiate lesions in such equivocal cases.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.97-102
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• 2012

High-resolution carotid MRI allows visualization of carotid atherosclerotic plaque characteristics. MRI serves as a noninvasive option for the detection of active plaque inflammation and intraplaque hemorrhage. Significant gains in signal-tonoise ratio and contrast-to-noise ratio can be obtained for carotid atheroma imaging at 3T compared with 1.5T. Normalized wall index or wall area on MRI has shown its efficacy in monitoring the response after medical therapy. $T(2)^*$ quantification in carotid plaques before and after the administration of ultrasmall superparamagnetic iron oxide particles shows difference in response to treatment according to drug doses. In conclusion, high-resolution MRI is useful in the diagnosis and monitoring of carotid atherosclerotic plaques prone to transient ischemic attack and stroke.

• Korean Journal of Radiology
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• v.23 no.6
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• pp.581-597
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• 2022

Left ventricular (LV) wall thickening, or LV hypertrophy (LVH), is common and occurs in diverse conditions including hypertrophic cardiomyopathy (HCM), hypertensive heart disease, aortic valve stenosis, lysosomal storage disorders, cardiac amyloidosis, mitochondrial cardiomyopathy, sarcoidosis and athlete's heart. Cardiac magnetic resonance (CMR) imaging provides various tissue contrasts and characteristics that reflect histological changes in the myocardium, such as cellular hypertrophy, cardiomyocyte disarray, interstitial fibrosis, extracellular accumulation of insoluble proteins, intracellular accumulation of fat, and intracellular vacuolar changes. Therefore, CMR imaging may be beneficial in establishing a differential diagnosis of LVH. Although various diseases share LV wall thickening as a common feature, the histologic changes that underscore each disease are distinct. This review focuses on CMR multiparametric myocardial analysis, which may provide clues for the differentiation of thickened myocardium based on the histologic features of HCM and its phenocopies.

• Investigative Magnetic Resonance Imaging
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• v.24 no.2
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• pp.85-89
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• 2020

Amyloidosis is an all-inclusive disease of deposition of amyloid proteins in the extracellular spaces, which in localized or systemic form cause tissue damage and dysfunction. Herein, we report a case of small bowel involvement of systemic amyloidosis presenting with multiple polypoid wall thickening mimicking small bowel polyposis syndrome in an age 75 male. Interestingly, polypoid wall thickening and amyloidoma showed hypointensity on T2-weighted images. To our knowledge, there has been no literature describing MRI findings of poylpoid wall thickening and amyloidoma. Although the underlying mechanisms are unclear and need validation, hypointensity on T2-weighted images could be valuable in diagnosing small bowel involvement of amyloidosis in patients presenting with poylpoid wall thickening and amyloidoma.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.747-752
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• 2003

Many clinical studies have suggested that the blood flow in ideal geometry is involved in the development of atherosclerosis. This study simulated blood flow in the abdominal artery with real geometry to investigate MWSS(mean wall shear stress), AWSS(amplitude of wall shear stress) and OSI(oscillator shear index). The calculation grid for the real geometry was constructed by extracting the surface of arterial wall from CT(Computed Tomography) or MRI(Magnetic Resonance Imaging) sheets called as DICOM (Digital Imaging and Communications in Medicines). The calculated MWSS, AWSS and OSI are much different from those of ideal geometry calculation. The MWSS increased while the AWSS decreased. Many shear forces are related to shapes of gradient. This paper will give clinical datum where the MWSS, AWSS and OSI are strong or weak. The hemodynamic analysis based on real geometry can provide surgeons with more reliable information about the effect of blood flow.

• Investigative Magnetic Resonance Imaging
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• v.23 no.4
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• pp.374-380
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• 2019

Collision tumor is a synchronous neoplasm wherein two histologically distinct tumors co-exist within the same anastomosis site. Collision tumor can occur in any organ, but the incidence is markedly rare. Additionally, preoperative diagnosis can be challenging to the radiologist. Herein, we report an age 60 male with collision tumor of rectal adenocarcinoma and diffuse large B-cell lymphoma, presented as a semi-annular wall thickening and bulky exophytic mass on MR imaging.

• Journal of the Korean Society of Visualization
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• v.12 no.3
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• pp.9-14
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• 2014

Two-photon microscopy (TPM) has been used in plant research as a high-resolution high-depth 3D imaging modality. However, TPM is known to induce photo-damage to the plant in case of long time exposure, and optimal excitation wavelength for plant imaging has not been investigated. Longer excitation wavelength may be appropriate for in vivo two-photon imaging of Arabidopsis thaliana leaves, and effects of longer excitation wavelength were investigated in terms of imaging depth, emission spectrum. Changes of emission spectrum as a function of exposure time at longer excitation wavelength were measured for in vivo longitudinal imaging. Imaging depth was not changed much probably because photon scattering at the cell wall was a limiting factor. Chloroplast emission spectrum showed its intensity peak shift by 20 nm with transition of excitation wavelength from 849 nm or below to 850 nm or higher. Emission spectrum showed different change patterns with excitation wavelengths in longitudinal imaging. Longer excitation wavelengths appeared to interact with chloroplasts differently in comparison with 780 nm excitation wavelength, and may be good for in vivo imaging.

• Korean Journal of Veterinary Research
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• v.62 no.3
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• pp.23.1-23.5
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• 2022

A 5-year-old castrated male domestic shorthair cat was referred for further investigation of pulmonary nodules incidentally detected on thoracic radiographs. Thoracic radiographs identified ill-defined soft tissue opacity nodules with small faint mineral opacity. Thoracic computed tomography (CT) revealed that bronchial dilation and bronchial wall thickening in bilateral cranial and accessory lung lobes. Round to ellipsoid mineralized concretions were found embedded in the intrabronchial soft tissue attenuation material. Based on radiography, CT, and cytology, the patient was tentatively diagnosed as having broncholithiasis with chronic bronchitis. This report described the CT diagnosis of broncholithiasis, which has been rarely reported in a cat.