• Korean Journal of Radiology
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• v.22 no.11
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• pp.1875-1885
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• 2021

Objective: Central nervous system involvement in coronavirus disease 2019 (COVID-19) has been increasingly reported. We performed a systematic review and meta-analysis to evaluate the incidence of radiologically demonstrated neurologic complications and detailed neuroimaging findings associated with COVID-19. Materials and Methods: A systematic literature search of MEDLINE/PubMed and EMBASE databases was performed up to September 17, 2020, and studies evaluating neuroimaging findings of COVID-19 using brain CT or MRI were included. Several cohort-based outcomes, including the proportion of patients with abnormal neuroimaging findings related to COVID-19 were evaluated. The proportion of patients showing specific neuroimaging findings was also assessed. Subgroup analyses were also conducted focusing on critically ill COVID-19 patients and results from studies that used MRI as the only imaging modality. Results: A total of 1394 COVID-19 patients who underwent neuroimaging from 17 studies were included; among them, 3.4% of the patients demonstrated COVID-19-related neuroimaging findings. Olfactory bulb abnormalities were the most commonly observed (23.1%). The predominant cerebral neuroimaging finding was white matter abnormality (17.6%), followed by acute/subacute ischemic infarction (16.0%), and encephalopathy (13.0%). Significantly more critically ill patients had COVID-19-related neuroimaging findings than other patients (9.1% vs. 1.6%; p = 0.029). The type of imaging modality used did not significantly affect the proportion of COVID-19-related neuroimaging findings. Conclusion: Abnormal neuroimaging findings were occasionally observed in COVID-19 patients. Olfactory bulb abnormalities were the most commonly observed finding. Critically ill patients showed abnormal neuroimaging findings more frequently than the other patient groups. White matter abnormalities, ischemic infarctions, and encephalopathies were the common cerebral neuroimaging findings.

• Korean Journal of Radiology
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• v.23 no.7
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• pp.742-751
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• 2022

Objective: To assess focal mineral deposition in the globus pallidus (GP) by CT and quantitative susceptibility mapping (QSM) of MRI scans and evaluate its clinical significance, particularly cerebrovascular degeneration. Materials and Methods: This study included 105 patients (66.1 ± 13.7 years; 40 male and 65 female) who underwent both CT and MRI with available QSM data between January 2017 and December 2019. The presence of focal mineral deposition in the GP on QSM (GP_QSM) and CT (GP_CT) was assessed visually using a three-point scale. Cerebrovascular risk factors and small vessel disease (SVD) imaging markers were also assessed. The clinical and radiological findings were compared between the different grades of GP_QSM and GP_CT. The relationship between GP grades and cerebrovascular risk factors and SVD imaging markers was assessed using univariable and multivariable linear regression analyses. Results: GP_CT and GP_QSM were significantly associated (p < 0.001) but were not identical. Higher GP_CT and GP_QSM grades showed smaller gray matter (p = 0.030 and p = 0.025, respectively) and white matter (p = 0.013 and p = 0.019, respectively) volumes, as well as larger GP volumes (p < 0.001 for both). Among SVD markers, white matter hyperintensity was significantly associated with GP_CT (p = 0.006) and brain atrophy was significantly associated with GP_QSM (p = 0.032) in at univariable analysis. In multivariable analysis, the normalized volume of the GP was independently positively associated with GP_CT (p < 0.001) and GP_QSM (p = 0.002), while the normalized volume of the GM was independently negatively associated with GP_CT (p = 0.040) and GP_QSM (p = 0.035). Conclusion: Focal mineral deposition in the GP on CT and QSM might be a potential imaging marker of cerebral vascular degeneration. Both were associated with increased GP volume.

• Korean Journal of Radiology
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• v.21 no.7
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• pp.812-828
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• 2020

Objective: To provide an evidence-based guide for the MRI interpretation of complete tumor response after neoadjuvant chemoradiation therapy (CRT) for rectal cancer using visual assessment on T2-weighted imaging (T2) and diffusion-weighted imaging (DWI). Materials and Methods: PubMed MEDLINE, EMBASE, and Cochrane Library were searched on November 28, 2019 to identify articles on the following issues: 1) sensitivity and specificity of T2 or DWI for diagnosing pathologic complete response (pCR) and the criteria for MRI diagnosis; 2) MRI alone vs. MRI combined with other test(s) in sensitivity and specificity for pCR; and 3) tests to select patients for the watch-and-wait management. Eligible articles were selected according to meticulous criteria and were synthesized. Results: Of 1615 article candidates, 55 eligible articles (for all three issues combined) were identified. Combined T2 and DWI performed better than T2 alone, with a meta-analytic summary sensitivity of 0.62 (95% confidence interval [CI], 0.43-0.77; I² = 80.60) and summary specificity of 0.89 (95% CI, 0.80-0.94; I² = 92.61) for diagnosing pCR. The criteria for the complete response on T2 in most studies had the commonality of remarkable tumor decrease to the absence of mass-like or nodular intermediate signal, although somewhat varied, as follows: (near) normalization of the wall; regular, thin, hypointense scar in the luminal side with (near) normal-appearance or homogeneous intermediate signal in the underlying wall; and hypointense thickening of the wall. The criteria on DWI were the absence of a hyperintense signal at high b-value (≥ 800 sec/mm²) in most studies. The specific algorithm to combine T2 and DWI was obscure in half of the studies. MRI combined with endoscopy was the most utilized means to select patients for the watch-and-wait management despite a lack of strong evidence to guide and support a multi-test approach. Conclusion: This systematic review and meta-analysis provide an evidence-based practical guide for MRI assessment of complete tumor response after CRT for rectal cancer.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.14 no.2
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• pp.130-136
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• 2011

Plain X-ray radiographs are the first line of investigation taken in the diagnosis of abdominal pathology and are considered an important diagnostic tool to provide guidelines for further imaging studies and comprehensive therapeutic management. Although most abdominal pathology demonstrates non-specific radiologic findings, the plain abdominal radiography is very useful in specific diseases, including certain gastrointestinal anomalies. This review provides image findings of normal plain abdominal radiography and some common abdominal pathology in infants and children.

• Journal of Korean Neurosurgical Society
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• v.40 no.4
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• pp.289-292
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• 2006

Thoracic spinal actinomycosis causing epidural abscess and significant spinal cord compression is very rare. A case is presented of a 56-year-old woman with rapid progressive upper back pain and weakness in both legs without evidence of systemic infection. Magnetic resonance imaging revealed a thoracic epidural enhancing lesion at the T1-T5 level. After decompression by laminectomy, precise diagnosis was accomplished using specific histopathological studies of the surgical specimens. A histopathologic findings showing typical Actinomyces sulfur granules surrounded by acute inflammatory cells. The clinical radiological findings of spinal actinomycosis closely resemble metastatic tumors and other infectious processes. Delay in diagnosis and treatment can significantly worsen the condition of patient.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.153-156
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• 2008

Sarcoma originated in bone or soft tissue is relatively rare disease. $^{18}F-FDG$ PET have been used in sarcoma for grading and predicting prognosis. In addition, FDG PET is expected to be useful in sarcoma for staging, detecting recurrence and monitoring therapy response in recent studies.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.35-41
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• 2003

Rock mass characterization is an integral part of rock engineering design. Much of the information for rock mass characterization comes from field fracture mapping and data collecting. This paper describes two technologies that can be used to assist with the field mapping and data collecting activities associated with rock mass characterization: digital image processing and 3D laserscanning. The basis for these techniques is described, as well as the results of field case studies and an analysis of the error in estimating fracture orientation.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.64-64
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• 1991

The interaction of high-intensity, focused, nanosecond laser light with matter results in the production of high-temperature plasma, which in turn emits an intense pulse of x rays. The x-ray spectrum consists of strong line components of several keV photon energy and broad continuum. Such an x-ray source provides many advantages over conventional ones for many applications. Pulse nature of the x-ray emission is well-suited for studying transient phenomena and for imaging living biological specimen. Recent experiments have also shown that the laser plasma x ray may be used for x ray lithography. These studies and other applications will be discussed in detail.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.155-156
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• 2009

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.684-689
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• 1987

Digital Subtraction Angiography(DSA) technique has been widely used to detect vascular diseases and hemodynamic parameters noninvasively. However, there are few quantitative studies on the factors in fluencing the resultant DSA image quality. In this paper, several important factors are suggested to improved the DSA image quality based on mathematical analysis. Experimental DSA images for different filters are shown and also discussed the difference between original and processed image quality.