• Korean Journal of Radiology
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• v.23 no.12
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• pp.1241-1250
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• 2022

Objective: To conduct a simulation study to determine whether artificial intelligence (AI)-aided mammography reading can reduce unnecessary recalls while maintaining cancer detection ability in women recalled after mammography screening. Materials and Methods: A retrospective reader study was performed by screening mammographies of 793 women (mean age ± standard deviation, 50 ± 9 years) recalled to obtain supplemental mammographic views regarding screening mammography-detected abnormalities between January 2016 and December 2019 at two screening centers. Initial screening mammography examinations were interpreted by three dedicated breast radiologists sequentially, case by case, with and without AI aid, in a single session. The area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and recall rate for breast cancer diagnosis were obtained and compared between the two reading modes. Results: Fifty-four mammograms with cancer (35 invasive cancers and 19 ductal carcinomas in situ) and 739 mammograms with benign or negative findings were included. The reader-averaged AUC improved after AI aid, from 0.79 (95% confidence interval [CI], 0.74-0.85) to 0.89 (95% CI, 0.85-0.94) (p < 0.001). The reader-averaged specificities before and after AI aid were 41.9% (95% CI, 39.3%-44.5%) and 53.9% (95% CI, 50.9%-56.9%), respectively (p < 0.001). The reader-averaged sensitivity was not statistically different between AI-unaided and AI-aided readings: 89.5% (95% CI, 83.1%-95.9%) vs. 92.6% (95% CI, 86.2%-99.0%) (p = 0.053), although the sensitivities of the least experienced radiologists before and after AI aid were 79.6% (43 of 54 [95% CI, 66.5%-89.4%]) and 90.7% (49 of 54 [95% CI, 79.7%-96.9%]), respectively (p = 0.031). With AI aid, the reader-averaged recall rate decreased by from 60.4% (95% CI, 57.8%-62.9%) to 49.5% (95% CI, 46.5%-52.4%) (p < 0.001). Conclusion: AI-aided reading reduced the number of recalls and improved the diagnostic performance in our simulation using women initially recalled for supplemental mammographic views after mammography screening.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.759-772
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• 2019

Objective: To investigate the value of ultrasound (US) microflow assessment in distinguishing malignant from benign solid breast masses as well as the association between US parameters and histologic microvessel density (MVD). Materials and Methods: Ninety-eight breast masses (57 benign and 41 malignant) were examined using Superb Microvascular Imaging (SMI) and contrast-enhanced US (CEUS) before biopsy. Two radiologists evaluated the quantitative and qualitative vascular parameters on SMI (vascular index, morphology, distribution, and penetration) and CEUS (time-intensity curve analysis and enhancement characteristics). US parameters were compared between benign and malignant masses and the diagnostic performance was compared between SMI and CEUS. Subgroup analysis was performed according to lesion size. The effect of vascular parameters on downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4A masses was evaluated. The association between histologic MVD and US parameters was analyzed. Results: Malignant masses were associated with a higher vascular index (15.1 ± 7.3 vs. 5.9 ± 5.6), complex vessel morphology (82.9% vs. 42.1%), central vascularity (95.1% vs. 59.6%), penetrating vessels (80.5% vs. 31.6%) on SMI (all, p < 0.001), as well as higher peak intensity (37.1 ± 25.7 vs. 17.0 ± 15.8, p < 0.001), slope (10.6 ± 11.2 vs. 3.9 ± 4.2, p = 0.001), area (1035.7 ± 726.9 vs. 458.2 ± 410.2, p < 0.001), hyperenhancement (95.1% vs. 70.2%, p = 0.005), centripetal enhancement (70.7% vs. 45.6%, p = 0.023), penetrating vessels (65.9% vs. 22.8%, p < 0.001), and perfusion defects (31.7% vs. 3.5%, p < 0.001) on CEUS (p ≤ 0.023). The areas under the receiver operating characteristic curve (AUCs) of SMI and CEUS were 0.853 and 0.841, respectively (p = 0.803). In 19 masses measuring < 10 mm, central vascularity on SMI was associated with malignancy (100% vs. 38.5%, p = 0.018). Considering all benign SMI parameters on the BI-RADS assessment, unnecessary biopsies could be avoided in 12 category 4A masses with improved AUCs (0.500 vs. 0.605, p < 0.001). US vascular parameters associated with malignancy showed higher MVD (p ≤ 0.016). MVD was higher in malignant masses than in benign masses, and malignant masses negative for estrogen receptor or positive for Ki67 had higher MVD (p < 0.05). Conclusion: US microflow assessment using SMI and CEUS is valuable in distinguishing malignant from benign solid breast masses, and US vascular parameters are associated with histologic MVD.

• Journal of Veterinary Clinics
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• v.40 no.6
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• pp.399-407
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• 2023

Chronic kidney disease (CKD) occurs in more than 15% of the dogs over 10 years of age and causes irreversible renal function deterioration. Therefore, it is important to diagnose CKD early and treat the disease properly. The purpose of this study aimed to to evaluate the clinical utility of urine albumin/creatinine ratio (ACR) using POC (point-of-care) device as an early detection urinary biomarker in CKD dogs and to confirm the correlation between ACR and other known CKD biomarkers. Urine and serum samples were obtained from 50 healthy dogs and 50 dogs with CKD. Serum blood urea nitrogen (BUN), creatinine, and symmetric dimethylarginine (SDMA) concentrations, and urine protein creatinine ratio (UPC) were measured. Urine specific gravity (USG) was evaluated using refractometer, and ACR was measured using an i-SENS A1Care analyzer. The ACR values of dogs with CKD were significantly different from those of healthy dogs (p < 0.001), as with other renal biomarkers. ACR showed significant differences between healthy dogs and dogs with CKD at every IRIS stage (p < 0.005), whereas no significant differences were observed between dogs with CKD IRIS stage I and healthy dogs with UPC. There are significant positive correlation between ACR and BUN (r = 0.611, p < 0.001), creatinine (r = 0.788, p < 0.001), SDMA (r = 0.747, p < 0.001), and UPC (r = 0.784, p < 0.001), and significant negative correlation between ACR and USG (r = -0.700, p < 0.001). In receiver operator characteristic curve analysis, the area under the curve (AUC) was 0.982 (95% CI 0.963-1.000, p < 0.001), with an optimal cut-off value of 64.20 mg/g (94% sensitivity and 94% specificity). Thus, ACR is a useful urinary biomarker for the early diagnosis of proteinuria in CKD and combined use of ACR and other renal biomarkers may be helpful for early diagnosis and prevention of CKD in dogs.

• Tuberculosis and Respiratory Diseases
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• v.87 no.4
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• pp.524-531
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• 2024

Background: Endothelial activation and stress index (EASIX) reflects endothelial dysfunction or damage. Because endothelial dysfunction is one of the key mechanisms, a few studies have shown the clinical usefulness of original and age-adjusted EASIX (age-EASIX) in patients with coronavirus disease 2019 (COVID-19). We aimed to evaluate the clinical utility of age-EASIX in predicting intensive care unit (ICU) mortality in critically ill patients with COVID-19 in South Korea. Methods: Secondary analysis was performed using clinical data retrospectively collected from 22 nationwide hospitals in South Korea between January 1, 2020, and August 31, 2021. Patients were at least 19 years old and admitted to the ICU for severe COVID-19, demanding at least high-flow nasal cannula oxygen therapy. EASIX [lactate dehydrogenase (U/L)×creatinine (mg/dL)/platelet count (10⁹ cells/L)] and age-EASIX (EASIX×age) were calculated and log₂-transformed. Results: The mean age of 908 critically ill patients with COVID-19 was 67.4 years with 59.7% male sex. The mean log₂ age-EASIX was 7.38±1.45. Non-survivors (n=222, 24.4%) in the ICU had a significantly higher log₂ age-EASIX than of survivors (8.2±1.52 vs. 7.1±1.32, p<0.001). Log₂ age-EASIX was significantly associated with ICU mortality (odds ratio, 1.541; 95% confidence interval, 1.322 to 1.796; p<0.001) and had a better area under the receiver operating characteristic curve than of the sequential organ failure assessment (SOFA) score in predicting ICU mortality (0.730 vs. 0.660, p=0.001). Conclusion: Age-EASIX is significantly associated with ICU mortality and has better discriminatory ability than the SOFA score in predicting ICU mortality.

• Tuberculosis and Respiratory Diseases
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• v.56 no.6
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• pp.600-610
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• 2004

Background : The plasma B-type natriuretic peptide(BNP) concentration increases with the degree of pulmonary hypertension in patients with chronic respiratory disease. The aim of this study was to examine the prognostic role of BNP in the acute exacerbation of chronic obstructive lung disease (COPD). Method : We selected 67 patients who were admitted our hospital because of an acute exacerbation of COPD. Their BNP levels were checked on admission at the Emergency Department. Their medical records were analyzed retrospectively. The patients were divided into two groups according to their in-hospital mortality. The patients' medical history, comobidity, exacerbation type, blood gas analysis, pulmonary function, APACHE II severity score and plasma BNP level were compared. Results : Multiple logistic regression analysis identified three independent predictors of mortality: $FEV_1$, APACHE II score and plasma BNP level. The decedents group showed a lower $FEV_1$($28{\pm}7$ vs. $37{\pm}15%$, p=0.005), a higher APACHE II score($22.4{\pm}6.1$ vs. $15.8{\pm}4.7$, p=0.000) and a higher BNP level ($201{\pm}116$ vs. $77{\pm}80pg/mL$, p=0.000) than the sSurvivors group. When the BNP cut-off level was set to 88pg/mL using the receiver operating characteristic curve, the sensitivity was 90% and the specificity was 75% in differentiating between the survivors and decedents. On Fisher's exact test, the odds ratio for mortality was 21.2 (95% CI 2.49 to 180.4) in the patients with a BNP level > 88pg/mL. Conclusion : The plasma BNP level might be a predictor of mortality in an acute exacerbation of COPD as well as the $FEV_1$ and APACHE II score.

• Journal of agricultural medicine and community health
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• v.39 no.3
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• pp.137-145
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• 2014

Objectives: Colonoscopy is a popular tool for screening for colon cancer throughout the world. The incidence of polypectomy and follow-up colonoscopy are persistently increasing but the studies about follow-up test after polypectomy are still lack of its domestic sources. This study is designed to look into the recurrence rate of colon polyps and risk factors after polypectomy. Methods: This is a retrospective study by reviewing medical charts of 147 patients who underwent polypectomy and follow-up colonoscopy from Jan. 2000 to Mar. 2008. The Kudo classification was used to describe the polyps found in the colonoscopy. The follow-up period was defined as the term between polypectomy and the first colonoscopy follow up. Results: Seventy six point two percent of the enrolled patient were male and the mean age was $56.5{\pm}8.1$. Mean follow-up period was $24.9{\pm}13.7$ (6 - 65) months. The cumulative recurrence rate of 1 year was 11.6%. The rate of 2 years was 36.7% and that of 3 years was 55.8%. The number of polyps was the factor which statistically showed significant relation of its recurrence rate. The histological morphology characteristic of polyps could be one independent factor which may be associated to the recurrence of polyps. Conclusions: The importance of colonoscopy follow up after polypectomy was clearly emphasized through the cumulative recurrence rate of 55.8%. Therefore, there is a need for more domestic studies with a large number of patients about the recurrence of polyps after polypectomy.

• Neonatal Medicine
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• v.18 no.2
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• pp.248-256
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• 2011

Purpose: Intrauterine growth retardation (IUGR) is the term used to designate a fetus that has not reached its growth potential. However it is difficult to make a distinction between infants who are constitutionally small and growth restricted small. In the present study, we focused on the clinical characteristics and the hematologic value in small for gestational age (SGA) infants and discussed how to distinguish intrauterine growth restricted infants from constitutionally small infants. Methods: SGA infants that did not have any other risk factors for IUGR in the medical record except maternal hypertension (HTN) and diabetes mellitus (DM) and born at the Seoul St Mary's Hospital and Yeouido St Mary`s Hospital from January 2007 to July 2010 were included. The frequency of IUGR is higher in the pregnancy with medical problem, and in preterm infants. Therefore, the data was categorized by maternal disease and gestational age. We assessed the clinical data and the hematologic value. Results: The leukocyte count and the platelet count were lower in the SGA with maternal HTN group and the preterm SGA group. There was no difference in the clinical data and the prognosis resulted from maternal HTN and maternal DM. However, the hematologic difference was not found in the categorization of the preterm SGA group as maternal diasease. Conclusion: The results of this study showed that it is possible the low leukocyte count and the low platelet count are the characteristic hematologic features in growth restricted small for gestational age infants.

• Tuberculosis and Respiratory Diseases
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• v.53 no.5
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• pp.550-560
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• 2002

Background : Lung cancer is the leading cause of cancer-related mortality in both men and women. Although most cases of lung cancer occur in the sixty to eight decades of life, 5 to 10% are diagnosed at a young age. There are characteristic features in young patients with lung cancer that differ from those in older patients with lung cancer. The purpose of this study was to determine if the basal characteristics and survival in young patients with lung cancer differed from those of old patients. Methods : We retrospectively reviewed the medical records of 94 young patients who were under 45 years of age and compared them with 1,728 old patients (= 46 years of age) in 4 medical schools at Daegu, between August 1986 and July 1995. Results : Significantly more female patients and adenocarcinomas were found in the young patients group. when compared to the old patients. Cough and sputum were the most frequent presenting symptom in both age groups. This was followed by chest discomfort, dyspnea and hemoptysis. The rates of smoking was significantly lower in the young patients. There was no statistical difference in the severity of the disease in terms of staging between the two age groups. Young patients received treatment more frequently than the older patients. The location of the primary tumors was equally frequent in both the upper and lower lobe. However, the survival was bettrer in the young patients(median survival time, 67.3 weeks), when compared to the old patients (median survival time, 26.8 weeks) (p<0.05). Conclusion : Females and adenocarcinoma patients were predominant in young patients with lung cancer. The young patients appeared to have significantly better prognosis.

• Journal of Korean Medical classics
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• v.12 no.2
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• pp.92-109
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• 1999

They say Y$\breve{o}$k'ak(易學) is the root of Oriental studies. This means philosophy, astronamy, geography, medicine, music, numbers are all based on Yin-Yang, and Five phases theory of Y$\breve{o}$k'ak. Nowadays studies are very much specialized but as we go back to old times, we cannot dearly set these studies apart. All the studies can be comprehensively understood with Y$\breve{o}$k'ak(易學). The original purpose of Y$\breve{o}$k'ak is to predict future with highly symbolized signs, Sang-Su(象數). However you cannot fully understand Y$\breve{o}$k'ak without knowing the principle of change in Sang-Su itself. We have to keep thinking about how we should further study Y$\breve{o}$k'ak, treat diseases with Sang-Su, and how Sang-Su can be used in medicine. As a previous step to this process, I will consider relationship of Y$\breve{o}$k'ak and medicine in this paper. This study will help us to set the goal and method in studying medicine. Conclusions of this paper are following: 1. The purpose of understanding a subject is to understand the principle of the subject. The principle of every subject can be turned into principle of changes in the universe. This principle is not affected by time nor space. It is only seen through the changes of subjects. 2. The reason we cannot easily understand the principle is that we have biased mind. How we should overcome this is through developing virtue, and by keep inspecting things over and over. 3. We see the outcome of changes inside but we should not neglect the principle. Therefore we see the principle through Sang. Sang is in between Principle(理) and Things(物), thereby has characteristics of both. Which means it is much like Principle but specific Things is related and it is much like Things but it is not easily understood. 4. There are various kinds of Sang. Mind-Sang(心象) is an image that comes before expressing it with symbols or words. When it is expressed in symbols or words, it is no longer considered as same Sang. Sang in symbol are Kwaesang(卦象), Hyosang(爻象) and Sang in words is Kyesa(卦辭). The characteristic of all these Sang is that it cannot be explained through the logics. 5. If we call Sanghak as the study with Sang, the method is same as that of understanding the principle. The fundamental purpose of Sanghak is to understand the principle of things and then apply this principle to the practical world so that the world can be a better place. So I would say Sanghak is the study of a saint and a ruler. 6. Since the object of medicine is human being who are the mixture of Principle and Ki, we can use Sang which is also related to both Principle and Ki. Actually terms we use in Oriental medicine are not easily understood without the knowledge of Sanghak. 7. When we diagnose a patient, we are looking for Sang that comes from the body inside. When we do the treatment, we cannot neglect the original change that's happening in our body. Therefore studying Sang is a necessary step to do the full diagnosis and treatment. 8. The method of studying medicine is first to get rid of biased mind, taking right Sang from various classics and then apply those Sang to actual situations.

• Progress in Medical Physics
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• v.2 no.2
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• pp.109-120
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• 1991

Total body irradiation is operated to irradicate malignant cells of bone marrow of patients to be treated with bone marrow transplantation. Field size of a linear accelerator or cobalt teletherapy unit with normal geometry for routine technique is too small to cover whole body of a patient. So, any special method to cover patient whole body must be developed. Because such environments as room conditions and machine design are not universal, some characteristic method of TBI for each hospital could be developed. At Seoul National University Hospital, at present, only a cobalt unit is available for TBI because source head of the unit could be tilted. When the head is tilted outward by 90$^{\circ}$, beam direction is horizontal and perpendicular to opposite wall. Then, the distance from cobalt source to the wall was 319 cm. Provided that the distance from the wall to midsagittal plane of a patient is 40cm, nominal field size at the plane(SCD 279cm) is 122cm$\times$122cm but field size by measurement of exposure profile was 130cm$\times$129cm and vertical profile was not symmetric. That field size is large enough to cover total body of a patient when he rests on a couch in a squatting posture. Assuming that average lateral width of patients is 30cm, percent depth dose for SSD 264cm and nominal field size 115.5cm$\times$115.5cm was measured with a plane-parallel chamber in a polystyrene phantom and was linear over depth range 10～20cm. An anthropomorphic phantom of size 25cm wide and 30cm deep. Depth of dose maximum, surface dose and depth of 50% dose were 0.3cm, 82% and 16.9cm, respectively. A dose profile on beam axis for two opposing beams was uniform within 10% for mid-depth dose. Tissue phantom ratio with reference depth 15cm for maximum field size at SCD 279cm was measured in a small polystyrene phantom and was linear over depth range 10～20cm. An anthropomorphic phantom with TLD chips inserted in holes on the largest coronal plane was bilaterally irradiated by 15 minute in each direction by cobalt beam aixs in line with the cross line of the coronal plane and contact surface of sections No. 27 and 28. When doses were normalized with dose at mid-depth on beam axis, doses in head/neck, abdomen and lower lung region were close to reference dose within $\pm$ 10% but doses in upper lung, shoulder and pelvis region were lower than 10% from reference dose. Particulaly, doses in shoulder region were lower than 30%. On this result, the conclusion such that under a geometric condition for TBI with cobalt beam as SNUH radiotherapy departement, compensators for head/neck and lung shielding are not required but boost irradiation to shoulder is required could be induced.