• Journal of the Korean Society of Radiology
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• v.81 no.1
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• pp.147-156
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• 2020

Purpose The objective of this study was to evaluate the diagnostic value and threshold levels of cytokeratin fragment 21-1 (CYFRA 21-1) in fine-needle aspiration (FNA) washouts for detection of lymph node (LN) recurrence in postoperative breast cancer patients. Materials and Methods FNA cytological assessments and CYFRA 21-1 measurement in FNA washouts were performed for 64 axillary LNs suspicious for recurrence in 64 post-operative breast cancer patients. Final diagnosis was made on the basis of FNA cytology and follow-up data over at least 2 years. The concentration of CYFRA 21-1 was compared between recurrent LNs and benign LNs. Diagnostic performance and cut-off value were evaluated using a receiver operating characteristic curve. Results Regardless of the non-diagnostic results, the median concentration of CYFRA 21-1 in recurrent LNs was significantly higher than that in benign LNs (p < 0.001). The optimal diagnostic cut-off value was 1.6 ng/mL. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CYFRA 21-1 for LN recurrence were 90.9%, 100%, 100%, 98.1%, and 98.4%, respectively. Conclusion Measurement of CYFRA 21-1 concentration from ultrasound-guided FNA biopsy aspirates showed excellent diagnostic performance with a cut-off value of 1.6 ng/mL. These results indicate that measurement of CYFRA 21-1 concentration in FNA washouts is useful for the diagnosis of axillary LN recurrence in post-operative breast cancer patients.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.9-18
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• 2024

The importance of active sonar systems is emerging due to the quietness of underwater targets and the increase in ambient noise due to the increase in maritime traffic. However, the low signal-to-noise ratio of the echo signal due to multipath propagation of the signal, various clutter, ambient noise and reverberation makes it difficult to identify underwater targets using active sonar. Attempts have been made to apply data-based methods such as machine learning or deep learning to improve the performance of underwater target recognition systems, but it is difficult to collect enough data for training due to the nature of sonar datasets. Methods based on mathematical modeling have been mainly used to compensate for insufficient active sonar data. However, methodologies based on mathematical modeling have limitations in accurately simulating complex underwater phenomena. Therefore, in this paper, we propose a sonar signal synthesis method based on a deep neural network. In order to apply the neural network model to the field of sonar signal synthesis, the proposed method appropriately corrects the attention-based encoder and decoder to the sonar signal, which is the main module of the Tacotron model mainly used in the field of speech synthesis. It is possible to synthesize a signal more similar to the actual signal by training the proposed model using the dataset collected by arranging a simulated target in an actual marine environment. In order to verify the performance of the proposed method, Perceptual evaluation of audio quality test was conducted and within score difference -2.3 was shown compared to actual signal in a total of four different environments. These results prove that the active sonar signal generated by the proposed method approximates the actual signal.

• Journal of the Korean Society of Radiology
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• v.84 no.3
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• pp.638-652
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• 2023

Purpose To investigate the MRI markers for the prediction of amyloid β (Aβ)-positivity in mild cognitive impairment (MCI) and Alzheimer's disease (AD), and to evaluate the differences in MRI markers between Aβ-positive (Aβ [+]) and -negative groups using the machine learning (ML) method. Materials and Methods This study included 139 patients with MCI and AD who underwent amyloid PET-CT and brain MRI. Patients were divided into Aβ (+) (n = 84) and Aβ-negative (n = 55) groups. Visual analysis was performed with the Fazekas scale of white matter hyperintensity (WMH) and cerebral microbleeds (CMB) scores. The WMH volume and regional brain volume were quantitatively measured. The multivariable logistic regression and ML using support vector machine, and logistic regression were used to identify the best MRI predictors of Aβ-positivity. Results The Fazekas scale of WMH (p = 0.02) and CMB scores (p = 0.04) were higher in Aβ (+). The volumes of hippocampus, entorhinal cortex, and precuneus were smaller in Aβ (+) (p < 0.05). The third ventricle volume was larger in Aβ (+) (p = 0.002). The logistic regression of ML showed a good accuracy (81.1%) with mini-mental state examination (MMSE) and regional brain volumes. Conclusion The application of ML using the MMSE, third ventricle, and hippocampal volume is helpful in predicting Aβ-positivity with a good accuracy.

• The Korean Journal of Medicine
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• v.99 no.3
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• pp.149-157
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• 2024

Background/Aims: Carbapenems are recommended for treating bacteremia caused by extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae (ESBL-E). However, this has resulted in a significant rise in the utilization of carbapenems in cases of ESBL-E infection. We evaluated the clinical outcomes of patients with ESBL-E bacteremia treated with non-carbapenem antimicrobials. Methods: We conducted a retrospective case-control study of a cohort of patients with documented ESBL-E bacteremia from January 2021 to December 2021. The patients were divided into two groups according to whether they received non-carbapenem or carbapenem therapy. The rates of treatment failure, 30-day mortality and microbiologic failure, and the durations of hospitalization and of antimicrobial therapy were compared between the two groups. Antimicrobial susceptibility testing and phenotypic identification of ESBL-E were performed using the Vitek 2 system. Results: Of 118 patients with ESBL-E bacteremia, 54 received non-carbapenem drugs (non-carbapenem group [NCG]) and 64 received carbapenems (carbapenem group [CG]). Treatment failure at 30 days occurred in 16.7% of the patients in the NCG and in 18.8% in the CG (p = 0.65). The 30-day mortality rate was 14.8% in the NCG and 17.2% in the CG (p = 0.63). Extra-urinary tract infection and prior antimicrobial therapy within 30 days were risk factors for treatment failure in patients with ESBL-E bacteremia. The clinical outcomes did not differ significantly between the two groups, challenging the prevailing preference for carbapenems in the treatment of ESBL-E bacteremia. Conclusions: Non-carbapenem antimicrobials such as piperacillin/tazobactam are recommended for patients with mild ESBL-E bacteremia in South Korea.

• Tuberculosis and Respiratory Diseases
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• v.44 no.4
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• pp.853-860
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• 1997

Background : Chronic cough, defined as a cough persisting for three weeks or longer, is a common symptom for which outpatient care is sought. The most common etiologies of chronic cough are postnasal drip, asthma, and gastroesophageal reflux. Methacholine challenge is a useful diagnostic study in the evaulation of chronic cough, particularly useful in chronic cough patients with asthmatic symptom. Patients with chronic cough may have dysfunction of bronchial and extrathoracic airways. To evaluate if dysfunction of the bronchial and extrathoracic airways causes chronic cough, we assessed bronchial (BHR) and extrathoracic airway (EAHR) responsiveness to inhaled methacholine in patients with chronic cough. Method : 111 patients with chronic cough were enrolled in our study. Enrolled patients had no recorded diagnosis of asthma, bronchopulmonary disease, hypertension, heart disease or systemic disease and no current treatment with bronchodilator or corticosteroid. Enrolled patients consisted of 46 patients with cough alone, 24 patients with wheeze, 22 patients with dyspnea, 19 patients with wheeze and dyspnea. The inhaled methacholine concentrations causing a 20% fall in forced expiratory volume in 1s($PC_{20}FEV_1$) and 25% fall in maximal mid-inspiratory flow ($PC_{25}MIF_{50}$) were used as bronchial and extra thoracic hyperresponsiveness. Results : There were four response patterns to methacholine challenge study : BHR in 27 patients, EAHR in 16 patients, combined BHR and EAHR in 8 patients, and no hyperresponsiveness in 60 patients. In patients with cough alone, there were BHR in 3 patients, EAHR in 9 patients, and combined BHR and EAHR in 2 patients. In patients with wheeze and/or dyspnea, there were BHR in 24 patients, EAHR in 7 patients, and BHR and EAHR in 6 patients. Compared with patients with wheeze and/or dyspnea, patients with cough alone had more common EAHR than BHR. In patients with wheeze and/or dyspnea, BHR was more common than EAHR. Conclusion : These results show that among patients with hyperresponsiveness to methacholine, those with dyspnea and/or wheezing had mainly bronchial hyperresponsiveness, whereas those with chronic cough alone had mainly extrathoracic airway hyperresponsiveness.

• Tuberculosis and Respiratory Diseases
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• v.55 no.1
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• pp.69-87
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• 2003

Background : LB20304(gemifloxacin) is a new fluoroquinolone antibacterial agent with excellent activity against both Gram-negative and Gram-positive organisms. In vitro studies using clinical isolates have shown gemifloxacin to be highly active against penicillin-resistant strains of S. pneumoniae and in contrast to other reference quinolones, gemifloxacin retained good activity against clinical isolates of S. pneumoniae that were resistant to other members of the quinolone class. Therefore, gemifloxacin is thought to be effective in treating acute bacterial exacerbation of chronic bronchitis(AECB). The objective of this study was to evaluate the efficacy and safety of oral gemifloxacin at doses of 160mg or 320mg once daily for 7 days for the treatment of AECB in Korean adult population. Methods : This was a randomized, multicenter, double-blind, parallel group Phase II study to assess the clinical and antibacterial efficacy and safety of oral gemifloxacin for the treatment of AECB. Treatment Group A (67 patients) took oral gemifloxacin 160mg once daily for seven days and treatment Group B (70 patients) took oral gemifloxacin 320mg once daily for seven days. Results : The demographic profiles of the two treatment groups were similar. The clinical response at follow-up was 84.2% in the gemifloxacin 160-mg group, and 88.7% in the gemifloxacin-320 mg group, showing no statistically significant difference between two treatment groups(p=0.49). The clinical response at the end of therapy was 96.5% in the 160-mg group, and 96.4% in the 320-mg group. The bacteriological response at the end of therapy and follow-up were 81.8% and 78.9%, respectively, in the 160-mg group, and 86.4% and 84.2%, respectively, in the 320-mg group, showing no statistically significant difference between two treatment groups(p=0.68 and 0.68, respectively). S. pneumoniae(12 isolates) and H. influenzae(10 isolates) were the most prevalent pathogens. The MICs were lower for gemifloxacin than other quinolones against these key pathogens, and for S. pneumoniae, the MICs for gemifloxacin were considerably lower(${\leq}0.03$ ug/mL) than those for other quinolones, beta-lactams and macrolides. In the period on-therapy plus 30 days post-therapy, a total of 18 patients(26.9%) in the gemifloxacin 160mg group and 22 patients(31.4%) in the 320mg group reported at least one adverse event(AE). The most frequently reported AE was abdominal pain(3/67 patients, 4.5%) in the gemifloxacin 160mg group and increased level of hepatic enzyme(5/70 patients, 7.1%) in the 320mg group. The overall AE profiles for the two treatment groups were similar. Two out of 67 patients(3.0%) in the gemifloxacin 160mg group and 1/70 patients(1.4%) in the 320mg group reported at least one serious AE, however, none of which was considered by the investigator to be of suspected or probable relationship to study medication. Conclusion : The results of this study showed that gemifloxacin at doses of 160mg or 320mg once daily for 7 days in the treatment of acute exacerbations of chronic bronchitis(AECB) in adult Koreans was a very effective and safe treatment both clinically and bacteriologically.