• Korean Journal of Radiology
• /
• 제23권2호
• /
• pp.237-245
• /
• 2022

Objective: Viscoelasticity is an essential feature of nerves, although little is known about their viscous properties. The discovery of shear wave dispersion (SWD) imaging has presented a new approach for the non-invasive evaluation of tissue viscosity. The present study investigated the feasibility of using SWD imaging to evaluate diabetic neuropathy using the sciatic nerve in a diabetic rat model. Materials and Methods: This study included 11 diabetic rats in the diabetic group and 12 healthy rats in the control group. Bilateral sciatic nerves were evaluated 3 months after treatment with streptozotocin. We measured the nerve cross-sectional area (CSA), nerve stiffness using shear wave elastography (SWE), and nerve viscosity using SWD imaging. The motor nerve conduction velocity (MNCV) was also measured. These four indicators and the histology of the sciatic nerves were then compared between the two groups. The performance of CSA, SWE, and SWD imaging in distinguishing the two groups was assessed using receiver operating characteristic (ROC) analysis. Results: Nerve CSA, stiffness, and viscosity in the diabetic group was significantly higher than those in the control group (all p < 0.05). The results also revealed a significantly lower MNCV in the diabetic group (p = 0.005). Additionally, the density of myelinated fibers was significantly lower in the diabetic group (p = 0.004). The average thickness of the myelin sheath was also lower in the diabetic group (p = 0.012). The area under the ROC curve for distinguishing the diabetic neuropathy group from the control group was 0.876 for SWD imaging, which was significantly greater than 0.677 for CSA (p = 0.030) and 0.705 for SWE (p = 0.035). Conclusion: Sciatic nerve viscosity measured using SWD imaging was significantly higher in diabetic rats. The viscosity measured using SWD imaging performed well in distinguishing the diabetic neuropathy group from the control group. Therefore, SWD imaging may be a promising method for the evaluation of diabetic neuropathy.

• Korean Journal of Radiology
• /
• 제23권1호
• /
• pp.139-149
• /
• 2022

Objective: To compare the effects of bone suppression imaging using deep learning (BSp-DL) based on a generative adversarial network (GAN) and bone subtraction imaging using a dual energy technique (BSt-DE) on radiologists' performance for pulmonary nodule detection on chest radiographs (CXRs). Materials and Methods: A total of 111 adults, including 49 patients with 83 pulmonary nodules, who underwent both CXR using the dual energy technique and chest CT, were enrolled. Using CT as a reference, two independent radiologists evaluated CXR images for the presence or absence of pulmonary nodules in three reading sessions (standard CXR, BSt-DE CXR, and BSp-DL CXR). Person-wise and nodule-wise performances were assessed using receiver-operating characteristic (ROC) and alternative free-response ROC (AFROC) curve analyses, respectively. Subgroup analyses based on nodule size, location, and the presence of overlapping bones were performed. Results: BSt-DE with an area under the AFROC curve (AUAFROC) of 0.996 and 0.976 for readers 1 and 2, respectively, and BSp-DL with AUAFROC of 0.981 and 0.958, respectively, showed better nodule-wise performance than standard CXR (AUAFROC of 0.907 and 0.808, respectively; p ≤ 0.005). In the person-wise analysis, BSp-DL with an area under the ROC curve (AUROC) of 0.984 and 0.931 for readers 1 and 2, respectively, showed better performance than standard CXR (AUROC of 0.915 and 0.798, respectively; p ≤ 0.011) and comparable performance to BSt-DE (AUROC of 0.988 and 0.974; p ≥ 0.064). BSt-DE and BSp-DL were superior to standard CXR for detecting nodules overlapping with bones (p < 0.017) or in the upper/middle lung zone (p < 0.017). BSt-DE was superior (p < 0.017) to BSp-DL in detecting peripheral and sub-centimeter nodules. Conclusion: BSp-DL (GAN-based bone suppression) showed comparable performance to BSt-DE and can improve radiologists' performance in detecting pulmonary nodules on CXRs. Nevertheless, for better delineation of small and peripheral nodules, further technical improvements are required.

• Korean Journal of Radiology
• /
• 제24권7호
• /
• pp.668-680
• /
• 2023

Objective: To compare multiparametric magnetic resonance imaging (MRI) features of intraductal carcinoma of the prostate (IDC-P) with those of prostatic acinar adenocarcinoma (PAC) and develop prediction models to distinguish IDC-P from PAC and IDC-P with a high proportion (IDC ≥ 10%, hpIDC-P) from IDC-P with a low proportion (IDC < 10%, lpIDC-P) and PAC. Materials and Methods: One hundred and six patients with hpIDC-P, 105 with lpIDC-P and 168 with PAC, who underwent pretreatment multiparametric MRI between January 2015 and December 2020 were included in this study. Imaging parameters, including invasiveness and metastasis, were evaluated and compared between the PAC and IDC-P groups as well as between the hpIDC-P and lpIDC-P subgroups. Nomograms for distinguishing IDC-P from PAC, and hpIDC-P from lpIDC-P and PAC, were made using multivariable logistic regression analysis. The discrimination performance of the models was assessed using the receiver operating characteristic area under the curve (ROC-AUC) in the sample, where the models were derived from without an independent validation sample. Results: The tumor diameter was larger and invasive and metastatic features were more common in the IDC-P than in the PAC group (P < 0.001). The distribution of extraprostatic extension (EPE) and pelvic lymphadenopathy was even greater, and the apparent diffusion coefficient (ADC) ratio was lower in the hpIDC-P than in the lpIDC-P group (P < 0.05). The ROC-AUCs of the stepwise models based solely on imaging features for distinguishing IDC-P from PAC and hpIDC-P from lpIDC-P and PAC were 0.797 (95% confidence interval, 0.750-0.843) and 0.777 (0.727-0.827), respectively. Conclusion: IDC-P was more likely to be larger, more invasive, and more metastatic, with obviously restricted diffusion. EPE, pelvic lymphadenopathy, and a lower ADC ratio were more likely to occur in hpIDC-P, and were also the most useful variables in both nomograms for predicting IDC-P and hpIDC-P.

• Korean Journal of Radiology
• /
• 제23권8호
• /
• pp.821-827
• /
• 2022

Objective: To determine the anatomical characteristics of the petrous ridge and trigeminal nerve in trigeminal neuralgia (TN) without neurovascular compression (NVC). Materials and Methods: From May 2017 to March 2021, 66 patients (49 female and 17 male; mean age ± standard deviation [SD], 56.8 ± 13.3 years) with TN without NVC and 57 controls (46 female and 11 male; 52.0 ± 15.6 years) were enrolled. The angle of the petrous ridge (APR) and angle of the trigeminal nerve (ATN) were measured using magnetic resonance imaging with a high-resolution three-dimensional T2 sequence. Data on the symptomatic side were compared with those on the asymptomatic side in patients and with the mean measurements of the bilateral sides in controls. Receiver operating characteristic (ROC) analysis was conducted to evaluate the performance of APR and ATN in distinguishing TN patients from controls. Results: In TN patients without NVC, the mean ± standard deviation (SD) of APR on the symptomatic side (98.40° ± 19.75°) was significantly smaller than that of the asymptomatic side (105.59° ± 22.45°, p = 0.019) and controls (108.44° ± 15.98°, p = 0.003). The mean ATN ± SD on the symptomatic side (144.41° ± 8.92°) was significantly smaller than that of the asymptomatic side (149.67° ± 8.09°, p = 0.003) and controls (150.45° ± 8.48°, p = 0.001). The area under the ROC curve for distinguishing TN patients from controls was 0.673 (95% confidence interval [CI]: 0.579-0.758) for APR and 0.700 (CI: 0.607-0.782) for ATN. The sensitivity and specificity using the diagnostic cutoff yielding the highest Youden index were 81.8% (54/66) and 49.1% (28/57), respectively, for APR (with a cutoff score of 94.30°) and 65.2% (43/66) and 66.7% (38/57), respectively, for ATN (cutoff score, 148.25°). Conclusion: In patients with TN without NVC, APR and ATN were smaller than those in controls, which may explain the potential cause of TN and provide additional information for diagnosis.

• Journal of Yeungnam Medical Science
• /
• 제23권2호
• /
• pp.205-212
• /
• 2006

연구 배경: 고립성 폐결절의 30%~40%는 악성결절의 가능성이 높다. 따라서 고립성 폐결절의 악성감별이 무엇보다 중요하다. 최근 PET/CT가 악성 감별에 널리 사용되며, 또한 그 중요성이 커지고 있다. 이 연구의 목적은 integrated PET/CT의 여러 인자들을 비교하여 고립성 폐결절의 악성 여부를 구별하는데 유용한 지표를 찾기 위한 것이다. 재료 및 방법: 2005년 12월부터 2006년 4월까지 3 cm 미만의 고립성 폐결절로 내원한 환자 19명을 대상으로 하였다. 환자는 integrated PET/CT의 최대 SUV는 FDG 주입 후 1 시간, 2 시간에 측정하였다. 또한 대상 환자 모두 경피세침술로 조직검사를 하였다. Levene's test를 이용하여 integrated PET/CT에서, 조직검사로 확인된 양성결절과 악성결절의 SUV1, SUV2, 보존지수(retention index)의 차이를 비교하였다. 성적: 조직검사 결과 12명이 악성결절로 확인되었고, 7명은 양성결절로 진단되었다. SUV1(p=0.006)과 SUV2(p=0.022)는 양성결절보다 악성결절에서 높았으며 이들 값은 통계적으로 유의하였으나 보존지수는 유의한 차이가 없었다(p=0.526). ROC 곡선을 이용한 양성결절과 악성결절을 구분하는 기준값은 SUV1은 5.40, SUV2는 7.45였다. 이때 SUV1의 민감도는 66.7%, 특이도는 71.4%였으며, SUV2의 민감도는 75%, 특이도는 71.4%였다. 결론: 이상의 결과로 integrated PET/CT에서 일반적으로 널리 사용하고 있는 SUV1은 양성결절과 악성결절을 구별하는데 있어 유용하다는 것을 확인할 수 있었고, 아직 많이 연구되지 않은 SUV2 또한 통계학적으로 의미 있는 차이를 보임을 알 수 있었다. 양성결절과 악성결절을 구분하는 기준값은 각각 5.40, 7.45였다. 연구결과 고립성 폐결절의 악성여부를 구별하는데 SUV1, SUV2 모두 유용하게 사용될 수 있으나 SUV2가 SUV1에 비교하여 특이도는 같으나 더 높은 민감도를 나타내었다.

• 한국콘텐츠학회논문지
• /
• 제13권12호
• /
• pp.829-839
• /
• 2013

본 연구는 로지스틱 회귀분석과 의사결정나무 분석을 활용하여 일 대도시 주민의 우울에 영향을 주는 요인을 예측하고 비교하고자 시도된 서술적 조사연구이다. 연구대상은 20세에서 65세 미만의 일 대도시 주민 462명이었다. 자료 수집은 2011년 10월 7일부터 10월 21일까지이었으며, 자료 분석은 SPSS 18.0 프로그램을 이용하여 빈도, 백분율, 평균과 표준편차 및 ${\chi}^2$-test, t-test, 로지스틱 회귀분석, roc curve, 의사결정나무 분석으로 분석하였다. 본 연구 결과, 로지스틱 회귀분석과 의사결정나무 분석에서 공통적으로 나타난 우울 예측요인은 사회부적응, 주관적 신체증상 및 가족 지지이었다. 로지스틱 회귀분석에서 특이도 93.8%, 민감도 42.5%이었고, 본 연구의 모형 적합도를 roc curve 검증 한 결과 AUC=.84으로 본 연구 모형은 적합(p=<.001)하다고 할 수 있다. 우울예측에 대한 의사결정나무 분석은 분류에 대한 예측 정확도에서 특이도 98.3%, 민감도 20.8%이었고, 전체 분류 정확도는 로지스틱 회귀분석은 82.0%, 의사결정나무 분석은 80.5% 이었다. 본 연구 결과 민감성과 분류 정확도와 더 높게 나타난 로지스틱 회귀분석 방법이 지역 주민의 우울 예측 모형을 구축하는데 더 유용한 자료로 사용될 수 있으리라 사료된다.

• Tuberculosis and Respiratory Diseases
• /
• 제64권4호
• /
• pp.266-271
• /
• 2008

연구배경: 급성 폐색전증의 발생을 예측하는 Wells 및 Geneva 예측 모형은 서구에서 잘 확립되어 있다. 폐색전증의 역학이 서구와 다를 것으로 보이는 국내에서의 예측모형의 유용성에 대해서 평가 하고자 한다. 방법: 단일 의료기관에서 폐색전증 의심 하에 multi-detector computed tomography (MDCT)를 시행한 환자 210명을 대상으로 후향적으로 조사하였다. 성별 구성은 남자 90명(42.9%), 여자 120명(57.1%)이었고, 평균 연령은 $63.3{\pm}15.9$세였다. 의무기록을 바탕으로 Wells 및 개정된 Geneva 예측 모형으로 폐색전증의 가능성에 대해 저위험군, 중등도 위험군, 고위험군으로 분류하였다. 결과: 폐색전증으로 진단된 환자는 210명 중 41명(19.5%)이었다. Wells 예측 모형을 적용한 폐색전증 발병 가능성 평가에서는, 2명(1%)이 저위험군, 137명(62.5%)이 중등도 위험군, 71명(3.8%)이 고위험군으로 분류되었고, 각 군에서 폐색전증의 발생률은 10%, 18.2%, 19.7%였다. 개정된 Geneva 예측 모형을 적용할 경우 44명(21%)이 저위험군, 160명(76.2%)이 중등도 위험군, 6명(2.8%)이 고위험군으로 분류되었고, 각 군에서 폐색전증의 발생률은 4.5%, 2.5%, 50%로 나타났다. Receiver operating characteristic (ROC) 곡선 분석에서 개정된 Geneva 예측 모형이 Wells 예측 모형에 비해 정확도가 높았다. 두 예측 모형 사이의 일치율은 불량했다($\kappa$ coefficient=0.06). 결론: 본 연구에서는 폐색전증이 의심되는 환자에서 개정된 Geneva 예측모형과 Wells 예측 모형으로 평가하여 두 모형 사이에 일치율이 불량하였으며, 개정된 Geneva 모형이 Wells 모형에 비해 폐색전증 진단 예측이 더 정확하였다.

• Korean Journal of Radiology
• /
• 제19권6호
• /
• pp.1110-1118
• /
• 2018

Objective: To perform a meta-analysis to quantitatively assess functional magnetic resonance imaging (MRI) in the diagnosis of locally recurrent prostate cancer. Materials and Methods: A comprehensive search of the PubMed, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews was conducted from January 1, 1995 to December 31, 2016. Diagnostic accuracy was quantitatively pooled for all studies by using hierarchical logistic regression modeling, including bivariate modeling and hierarchical summary receiver operating characteristic (HSROC) curves (AUCs). The Z test was used to determine whether adding functional MRI to T2-weighted imaging (T2WI) results in significantly increased diagnostic sensitivity and specificity. Results: Meta-analysis of 13 studies involving 826 patients who underwent radical prostatectomy showed a pooled sensitivity and specificity of 91%, and the AUC was 0.96. Meta-analysis of 7 studies involving 329 patients who underwent radiotherapy showed a pooled sensitivity of 80% and specificity of 81%, and the AUC was 0.88. Meta-analysis of 11 studies reporting 1669 sextant biopsies from patients who underwent radiotherapy showed a pooled sensitivity of 54% and specificity of 91%, and the AUC was 0.85. Sensitivity after radiotherapy was significantly higher when diffusion-weighted MRI data were combined with T2WI than when only T2WI results were used. This was true when meta-analysis was performed on a per-patient basis (p = 0.027) or per sextant biopsy (p = 0.046). A similar result was found when $^1H$-magnetic resonance spectroscopy ($^1H$-MRS) data were combined with T2WI and sextant biopsy was the unit of analysis (p = 0.036). Conclusion: Functional MRI data may not strengthen the ability of T2WI to detect locally recurrent prostate cancer in patients who have undergone radical prostatectomy. By contrast, diffusion-weight MRI and $^1H$-MRS data may improve the sensitivity of T2WI for patients who have undergone radiotherapy.

• 유통과학연구
• /
• 제12권11호
• /
• pp.77-83
• /
• 2014

Purpose - The National Agricultural Cooperative Federation of Korea and National Fisheries Cooperative Federation of Korea have prosecuted both financial and retail businesses. As cooperatives are public institutions and receive government support, their sound management is required by the Financial Supervisory Service in Korea. This is mainly managed by CAEL, which is changed by CAMEL. However, NFFC's business section, managing the finance and retail businesses, is unified and evaluated; the CAEL model has an insufficient classification to evaluate the retail industry. First, there is discrimination power as regards CAEL. Although the retail business sector union can receive a higher rating on a CAEL model, defaults have often been reported. Therefore, a default prediction model is needed to support a CAEL model. As we have the default prediction model using a subdivision of indexes and statistical methods, it can be useful to have a prevention function through the estimation of the retail sector's default probability. Second, separating the difference between the finance and retail business sectors is necessary. Their businesses have different characteristics. Based on various management indexes that have been systematically managed by the National Fisheries Cooperative Federation of Korea, our model predicts retail default, and is better than the CAEL model in its failure prediction because it has various discriminative financial ratios reflecting the retail industry situation. Research design, data, and methodology - The model to predict retail default was presented using logistic analysis. To develop the predictive model, we use the retail financial statements of the NFCF. We consider 93 unions each year from 2006 to 2012 to select confident management indexes. We also adapted the statistical power analysis that is a t-test, logit analysis, AR (accuracy ratio), and AUROC (Area Under Receiver Operating Characteristic) analysis. Finally, through the multivariate logistic model, we show that it is excellent in its discrimination power and higher in its hit ratio for default prediction. We also evaluate its usefulness. Results - The statistical power analysis using the AR (AUROC) method on the short term model shows that the logistic model has excellent discrimination power, with 84.6%. Further, it is higher in its hit ratio for failure (prediction) of total model, at 94%, indicating that it is temporally stable and useful for evaluating the management status of retail institutions. Conclusions - This model is useful for evaluating the management status of retail union institutions. First, subdividing CAEL evaluation is required. The existing CAEL evaluation is underdeveloped, and discrimination power falls. Second, efforts to develop a varied and rational management index are continuously required. An index reflecting retail industry characteristics needs to be developed. However, extending this study will need the following. First, it will require a complementary default model reflecting size differences. Second, in the case of small and medium retail, it will need non-financial information. Therefore, it will be a hybrid default model reflecting financial and non-financial information.

• Investigative Magnetic Resonance Imaging
• /
• 제26권2호
• /
• pp.104-116
• /
• 2022

The purpose of this study is to systematically determine an optimal percentile cut-off in histogram analysis for calculating the mean parameters obtained from a non-Gaussian continuous-time random-walk (CTRW) diffusion model for differentiating individual glioma grades. This retrospective study included 90 patients with histopathologically proven gliomas (42 grade II, 19 grade III, and 29 grade IV). We performed diffusion-weighted imaging using 17 b-values (0-4000 s/mm²) at 3T, and analyzed the images with the CTRW model to produce an anomalous diffusion coefficient (D_m) along with temporal (𝛼) and spatial (𝛽) diffusion heterogeneity parameters. Given the tumor ROIs, we created a histogram of each parameter; computed the P-values (using a Student's t-test) for the statistical differences in the mean D_m, 𝛼, or 𝛽 for differentiating grade II vs. grade III gliomas and grade III vs. grade IV gliomas at different percentiles (1% to 100%); and selected the highest percentile with P < 0.05 as the optimal percentile. We used the mean parameter values calculated from the optimal percentile cut-offs to do a receiver operating characteristic (ROC) analysis based on individual parameters or their combinations. We compared the results with those obtained by averaging data over the entire region of interest (i.e., 100th percentile). We found the optimal percentiles for D_m, 𝛼, and 𝛽 to be 68%, 75%, and 100% for differentiating grade II vs. III and 58%, 19%, and 100% for differentiating grade III vs. IV gliomas, respectively. The optimal percentile cut-offs outperformed the entire-ROI-based analysis in sensitivity (0.761 vs. 0.690), specificity (0.578 vs. 0.526), accuracy (0.704 vs. 0.639), and AUC (0.671 vs. 0.599) for grade II vs. III differentiations and in sensitivity (0.789 vs. 0.578) and AUC (0.637 vs. 0.620) for grade III vs. IV differentiations, respectively. Percentile-based histogram analysis, coupled with the multi-parametric approach enabled by the CTRW diffusion model using high b-values, can improve glioma grading.