• Korean Journal of Radiology
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• 제22권8호
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• pp.1323-1331
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• 2021

Objective: To identify the association between renal tumor complexity and pathologic renal sinus invasion (RSI) and evaluate the usefulness of computed tomography tumor features for predicting RSI in patients with renal cell carcinoma (RCC). Materials and Methods: This retrospective study included 276 consecutive patients who underwent radical nephrectomy for RCC with a size of ≤ 7 cm between January 2014 and October 2017. Tumor complexity and anatomical renal sinus involvement were evaluated using two standardized scoring systems: the radius (R), exophytic or endophytic (E), nearness to collecting system or sinus (N), anterior or posterior (A), and location relative to polar lines (RENAL) nephrometry and preoperative aspects and dimensions used for anatomical classification (PADUA) system. CT-based tumor features, including shape, enhancement pattern, margin at the interface of the renal sinus (smooth vs. non-smooth), and finger-like projection of the mass, were also assessed by two independent radiologists. Univariable and multivariable logistic regression analyses were performed to identify significant predictors of RSI. The positive predictive value, negative predictive value (NPV), accuracy of anatomical renal sinus involvement, and tumor features were evaluated. Results: Eighty-one of 276 patients (29.3%) demonstrated RSI. Among highly complex tumors (RENAL or PADUA score ≥ 10), the frequencies of RSI were 42.4% (39/92) and 38.0% (71/187) using RENAL and PADUA scores, respectively. Multivariable analysis showed that a non-smooth margin and the presence of a finger-like projection were significant predictors of RSI. Anatomical renal sinus involvement showed high NPVs (91.7% and 95.2%) but low accuracy (40.2% and 43.1%) for RSI, whereas the presence of a non-smooth margin or finger-like projection demonstrated comparably high NPVs (90.0% and 91.3% for both readers) and improved accuracy (67.0% and 73.9%, respectively). Conclusion: A non-smooth margin or the presence of a finger-like projection can be used as a preoperative CT-based tumor feature for predicting RSI in patients with RCC.

• Korean Journal of Radiology
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• 제22권4호
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• pp.502-512
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• 2021

Objective: To objectively and subjectively assess and compare the characteristics of monoenergetic images [MEI (+)] and polyenergetic images (PEI) acquired by dual-energy CT (DECT) of patients with breast cancer. Materials and Methods: This retrospective study evaluated the images and data of 42 patients with breast cancer who had undergone dual-phase contrast-enhanced DECT from June to September 2019. One standard PEI, five MEI (+) in 10-kiloelectron volt (keV) intervals (range, 40-80 keV), iodine density (ID) maps, iodine overlay images, and Z effective (Z_eff) maps were reconstructed. The contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) were calculated. Multiple quantitative parameters of the malignant breast lesions were compared between the arterial and the venous phase images. Two readers independently assessed lesion conspicuity and performed a morphology analysis. Results: Low keV MEI (+) at 40-50 keV showed increased CNR and SNR_{breast lesion} compared with PEI, especially in the venous phase ([CNR: 40 keV, 20.10; 50 keV, 14.45; vs. PEI, 7.27; p < 0.001], [SNR_{breast lesion}: 40 keV, 21.01; 50 keV, 16.28; vs. PEI, 10.77; p < 0.001]). Multiple quantitative DECT parameters of malignant breast lesions were higher in the venous phase images than in the arterial phase images (p < 0.001). MEI (+) at 40 keV, ID, and Z_eff reconstructions yielded the highest Likert scores for lesion conspicuity. The conspicuity of the mass margin and the visual enhancement were significantly better in 40-keV MEI (+) than in the PEI (p = 0.022, p = 0.033, respectively). Conclusion: Compared with PEI, MEI (+) reconstructions at low keV in the venous phase acquired by DECT improved the objective and subjective assessment of lesion conspicuity in patients with malignant breast lesions. MEI (+) reconstruction acquired by DECT may be helpful for the preoperative evaluation of breast cancer.

• Korean Journal of Radiology
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• 제22권5호
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• pp.829-839
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• 2021

Objective: To compare the diagnostic performance of contrast-enhanced radial T1-weighted gradient-echo 3-tesla (3T) magnetic resonance imaging (MRI) and computed tomography (CT) for the detection of visceral pleural surface invasion (VPSI). Visceral pleural invasion by non-small-cell lung cancer (NSCLC) can be classified into two types: PL1 (without VPSI), invasion of the elastic layer of the visceral pleura without reaching the visceral pleural surface, and PL2 (with VPSI), full invasion of the visceral pleura. Materials and Methods: Thirty-three patients with pathologically confirmed VPSI by NSCLC were retrospectively reviewed. Multidetector CT and contrast-enhanced 3T MRI with a free-breathing radial three-dimensional fat-suppressed volumetric interpolated breath-hold examination (VIBE) pulse sequence were compared in terms of the length of contact, angle of mass margin, and arch distance-to-maximum tumor diameter ratio. Supplemental evaluation of the tumor-pleura interface (smooth versus irregular) could only be performed with MRI (not discernible on CT). Results: At the tumor-pleura interface, radial VIBE MRI revealed a smooth margin in 20 of 21 patients without VPSI and an irregular margin in 10 of 12 patients with VPSI, yielding an accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and F-score for VPSI detection of 91%, 83%, 95%, 91%, 91%, and 87%, respectively. The McNemar test and receiver operating characteristics curve analysis revealed no significant differences between the diagnostic accuracies of CT and MRI for evaluating the contact length, angle of mass margin, or arch distance-to-maximum tumor diameter ratio as predictors of VPSI. Conclusion: The diagnostic performance of contrast-enhanced radial T1-weighted gradient-echo 3T MRI and CT were equal in terms of the contact length, angle of mass margin, and arch distance-to-maximum tumor diameter ratio. The advantage of MRI is its clear depiction of the tumor-pleura interface margin, facilitating VPSI detection.

• Korean Journal of Radiology
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• 제22권3호
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• pp.344-353
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• 2021

Objective: The mitotic count of gastrointestinal stromal tumors (GIST) is closely associated with the risk of planting and metastasis. The purpose of this study was to develop a predictive model for the mitotic index of local primary GIST, based on deep learning algorithm. Materials and Methods: Abdominal contrast-enhanced CT images of 148 pathologically confirmed GIST cases were retrospectively collected for the development of a deep learning classification algorithm. The areas of GIST masses on the CT images were retrospectively labelled by an experienced radiologist. The postoperative pathological mitotic count was considered as the gold standard (high mitotic count, > 5/50 high-power fields [HPFs]; low mitotic count, ≤ 5/50 HPFs). A binary classification model was trained on the basis of the VGG16 convolutional neural network, using the CT images with the training set (n = 108), validation set (n = 20), and the test set (n = 20). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated at both, the image level and the patient level. The receiver operating characteristic curves were generated on the basis of the model prediction results and the area under curves (AUCs) were calculated. The risk categories of the tumors were predicted according to the Armed Forces Institute of Pathology criteria. Results: At the image level, the classification prediction results of the mitotic counts in the test cohort were as follows: sensitivity 85.7% (95% confidence interval [CI]: 0.834-0.877), specificity 67.5% (95% CI: 0.636-0.712), PPV 82.1% (95% CI: 0.797-0.843), NPV 73.0% (95% CI: 0.691-0.766), and AUC 0.771 (95% CI: 0.750-0.791). At the patient level, the classification prediction results in the test cohort were as follows: sensitivity 90.0% (95% CI: 0.541-0.995), specificity 70.0% (95% CI: 0.354-0.919), PPV 75.0% (95% CI: 0.428-0.933), NPV 87.5% (95% CI: 0.467-0.993), and AUC 0.800 (95% CI: 0.563-0.943). Conclusion: We developed and preliminarily verified the GIST mitotic count binary prediction model, based on the VGG convolutional neural network. The model displayed a good predictive performance.

• Korean Journal of Radiology
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• 제22권2호
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• pp.281-290
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• 2021

Objective: To assess the performance of content-based image retrieval (CBIR) of chest CT for diffuse interstitial lung disease (DILD). Materials and Methods: The database was comprised by 246 pairs of chest CTs (initial and follow-up CTs within two years) from 246 patients with usual interstitial pneumonia (UIP, n = 100), nonspecific interstitial pneumonia (NSIP, n = 101), and cryptogenic organic pneumonia (COP, n = 45). Sixty cases (30-UIP, 20-NSIP, and 10-COP) were selected as the queries. The CBIR retrieved five similar CTs as a query from the database by comparing six image patterns (honeycombing, reticular opacity, emphysema, ground-glass opacity, consolidation and normal lung) of DILD, which were automatically quantified and classified by a convolutional neural network. We assessed the rates of retrieving the same pairs of query CTs, and the number of CTs with the same disease class as query CTs in top 1-5 retrievals. Chest radiologists evaluated the similarity between retrieved CTs and queries using a 5-scale grading system (5-almost identical; 4-same disease; 3-likelihood of same disease is half; 2-likely different; and 1-different disease). Results: The rate of retrieving the same pairs of query CTs in top 1 retrieval was 61.7% (37/60) and in top 1-5 retrievals was 81.7% (49/60). The CBIR retrieved the same pairs of query CTs more in UIP compared to NSIP and COP (p = 0.008 and 0.002). On average, it retrieved 4.17 of five similar CTs from the same disease class. Radiologists rated 71.3% to 73.0% of the retrieved CTs with a similarity score of 4 or 5. Conclusion: The proposed CBIR system showed good performance for retrieving chest CTs showing similar patterns for DILD.

• Korean Journal of Radiology
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• 제22권2호
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• pp.213-224
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• 2021

Objective: Clinical outcomes of patients who undergo transarterial chemoembolization (TACE) for single small hepatocellular carcinoma (HCC) are not consistent, and may differ based on certain imaging findings. This retrospective study was aimed at determining the efficacy of pre-TACE CT or MR imaging findings in predicting survival outcomes in patients with small HCC upon being treated with TACE. Besides, the study proposed to build a risk prediction model for these patients. Materials and Methods: Altogether, 750 patients with functionally good hepatic reserve who received TACE as the first-line treatment for single small HCC between 2004 and 2014 were included in the study. These patients were randomly assigned into training (n = 525) and validation (n = 225) sets. Results: According to the results of a multivariable Cox analysis, three pre-TACE imaging findings (tumor margin, tumor location, enhancement pattern) and two clinical factors (age, serum albumin level) were selected and scored to create predictive models for overall, local tumor progression (LTP)-free, and progression-free survival in the training set. The median overall survival time in the validation set were 137.5 months, 76.1 months, and 44.0 months for low-, intermediate-, and high-risk groups, respectively (p < 0.001). Time-dependent receiver operating characteristic curves of the predictive models for overall, LTP-free, and progression-free survival applied to the validation cohort showed acceptable areas under the curve values (0.734, 0.802, and 0.775 for overall survival; 0.738, 0.789, and 0.791 for LTP-free survival; and 0.671, 0.733, and 0.694 for progression-free survival at 3, 5, and 10 years, respectively). Conclusion: Pre-TACE CT or MR imaging findings could predict survival outcomes in patients with small HCC upon treatment with TACE. Our predictive models including three imaging predictors could be helpful in prognostication, identification, and selection of suitable candidates for TACE in patients with single small HCC.

• Tuberculosis and Respiratory Diseases
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• 제47권5호
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• pp.642-649
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• 1999

연구배경: 비소세포폐암의 림프절의 병기 결정은 치료 및 예후 결정에 매우 중요하나 정확한 병기 결정에는 많은 어려움이 있다. 야에 저자들은 최근에 개발된 CoDe PET의 림프절 병기 결정에 대한 유용성을 알아보고자 하였다. 방 법: 1998년 2월부터 1999년 6월까지 아주대학교병원에 내원하여 원발성 비소세포폐암으로 진단되어 치료를 시행하였던 환자 21예를 대상으로 하였다. 수술적 술전 폐암의 병기 결정을 위하여 흉부 전산화단층촬영, 복부 초음파검사, 전신 골주사 촬영, CoDe PET를 시행하였다. 대상 환자들의 수술후 병리학적 병기를 기준으로 하여서 CoDe PET로 결정된 림프절 병기의 민감도, 특이도, 양성 예측도, 음성 예측도, 정확도를 분석하였다. 결 과: 21예의 비소세포폐암중 20예에서 원발 종괴에 $^{18}FDG$가 섭취되었으며 위음성이 1예가 있었다. 림프절 병기에 있어 전체 21예중 13예에서는 병리학적 병기와 일치하였다. 병리학적 N0는 14예이었으며 CoDe PET의 N0에 대한 특이도는 64.3%이었다. N1 림프절에 대한 민감도는 83.3%, 특이도는 73.3%, 양성 예측도는 55.6%, 음성 예측도는 91.7%, 정확도는 76.2%이였다. N2 림프절에 대한 민감도는 60.0%, 특이도는 87.5%, 양성 예측도는 60.0%, 음성 예측도는 87.5%, 정확도는 90.0%이었다. 병리학적으로 그 크기가 측정된 림프절 29개중 암세포의 침윤이 있었던 림프절은 6개이었으며 이중 3개의 림프절은 CoDe PET에 국소 섭취로 나타났다. 위음성으로 나타난 3개의 림프절은 그 크기가 모두 1cm 이하였으며, 양성으로 나타난 림프절의 크기는 각각 1.1cm, 1.0cm, 0.5cm이었다. 크기가 1cm 이상이나 암세포의 침윤이 없었던 12개의 림프절중 1예에서만 위양성으로 나타났다. 5예에서는 위양성 소견을 보였는데 이중 1예는 폐결핵에 의한 육이종을 관찰할 수 있었으며, 1예는 pneumoconiosis, 1예는 anthracosis이었다. 결 론: CoDe PET는 크기가 1.5cm 이상의 림프절에 대한 음성 예측도가 비교적 높기 때문에 N3 림프절의 확대가 있는 비소세포폐암에서 CoDe PET를 시행하여 국소 섭취가 없는 경우에는 수술적 치료를 고려해 볼 수 있으리라 생각된다. 또한 CoDe PET는 아직 개발 단계에 있어서 향후 보다 더 발전된 영상을 얻을 수 있을 것으로 기대된다.

• 대한방사선기술학회지:방사선기술과학
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• 제31권4호
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• pp.389-399
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• 2008

단일광자방출컴퓨터단층촬영(SPECT) 시 정확도의 개선을 위하여 산란과 감약의 보정, 분해능의 개선이 매우 중요하다. 특히 호흡이나 맥동에 대한 심장의 움직임은 보정 에러의 원인이 된다. 심장 팬텀이 보정방법에 대한 검증을 위해 사용되고 있으나, 현재 사용 중인 팬텀들은 실제 인체 데이터와 다른 점이 많이 나타나고 있다. 즉 팬텀을 사용한 결과는 임상데이터와 같게 취급할 수가 없다. 저자들은 흉곽의 인체 구조와 같은 신뢰성 있는 새로운 팬텀을 개발하였다. 새로운 팬텀은 폐와 심장의 전면, 측면 및 상부가 접하는 작은 종격구조를 가지고 있다. 용기는 아크릴로 만들었으며 종격은 물 등가물질을 사용하여 제조하였다. 폐는 에폭시레진의 고형 폴리우레탄 폼을 사용하였다. 5가지 크기의 심장은 게이트 심근관류 SPECT의 정량적 분석을 위하여 개발되었다. 심장팬텀들의 종격은 같은 포지션에 위치할 수 있도록 고안되었다. 완성된 팬텀은 간과 담낭에 부착되고 각각 높이 조절이 가능하다. 5개의 심실의 용적은 각각 150.0, 137.3, 83.1, 42.7과 38.6ml이다. 새로운 팬톰을 사용하여 SPECT 검사를 시행하고 보정법을 적용한 후에 영상의 차이를 검토하였다. 심장의 3차원 단층상이 효율적으로 재구성 되었으며 여러 가지 보정방법의 차이를 나타내기 위하여 주관적 평가도 시행하였다. 저자들은 SPECT영상과 QGS(Quantitative Gated SPECT) 결과로서 보정방법의 차이를 나타낼 수 있는 새로운 팬텀을 개발하여 보고하는 바이다.

• Journal of Chest Surgery
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• 제37권12호
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• pp.992-998
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• 2004

배경 및 목적: 식도암의 병기 결정은 병변의 절제 가능성 여부를 결정하고 환자의 예후를 예측하는 데 지대한 영향을 미친다. 흉부 전산화 단층 촬영(Computerized Tomography, CT)은 식도암의 병기 결정을 위해 현재까지 가장 널리 사용되고 있는 진단 방법 중의 하나이지만, 다양한 위양성 및 위음성 소견에 의해 제한점들이 보고되고 있다. 이에 본 저자는 수술 전 식도암의 병기 결정에 있어서 흉부 CT의 유용성에 대해 연구하고자 하였다. 대상 및 방법: 1999년 1월부터 2003년 6월까지 식도 편평 상피 세포 암으로 진단받고 수술을 시행한 환자 114예를 대상으로 수술 전 CT에 의한 병기와 수술 후 조직 소견에 의한 병기를 후향적으로 비교 분석하였다. CT 진단에 의한 주변 조직 침습, 림프절 침범, 그리고 원위부 전이 여부 등을 관찰하고, 이를 수술 후 조직 병리 소견과 비교함으로써, 이들의 진단에 대한 CT의 민감도(Sensitivity), 특이도(Specificity), 정확도(Accuracy) 및 일치도(Reproducibility)를 구하였다. 일치도는 Z-test를 시행하여 통계적 유의성을 평가하였다. 결과: 식도암의 CT에 의한 병기와 조직 병리 소견에 의한 병기의 일치도는 원발성 종양의 국소 침윤의 경우 0.32 (p<0.01), 림프절 전이에 대하여는 0.36 (p<0.01)이었으며, 원위부 장기에 대한 전이 여부에 대하여는 0.62 (p<0.01)이었다. 림프절 전이나 원거리 전이에 대한 CT와 조직 병리 소견의 일치도는 종양의 국소 침윤에 대한 일치도보다 우수하였다. 원발성 종양의 주변 장기 침습에 대한 CT의 정확도는 71군(78.9%)과 72군 (62.3%)에 비해 73군(65.8%)과 74군(98.2%)에서 우수하였다. 또한 식도암의 국소 종양 침윤에 대한 CT진단은 각 병기별로 민감도에 비해 특이도가 높았다. 결론: 식도암의 병기 결정에 있어 CT진단은 종양에 의한 식도 벽의 침습 정도를 파악하는 것보다 주위 조직이나 장기, 그리고 림프절의 전이를 파악하는데 더 유용함을 알 수 있었다.

• Radiation Oncology Journal
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• 제33권3호
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• pp.188-197
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• 2015

Purpose: To investigate the patterns of care for patients with nasopharyngeal carcinoma (NPC) in South Korea. Materials and Methods: A multi-institutional retrospective study was performed (Korean Radiation Oncology Group [KROG] 11-06) on a total of 1,445 patients from 15 institutions. Results: Of the 1,445 patients, more than half were stages III (39.9%) and IV (35.8%). In addition to patterns of care, we also investigated trends over time with the periods 1988-1993, 1994-2002, and 2003-2011. The frequencies of magnetic resonance imaging and positron emission tomography-computed tomography were markedly increased in the third period compared to previous 2 periods. Concurrent chemoradiation (CCRT) was performed on 894 patients (61.9%), neoadjuvant chemotherapy on 468 patients (32.4%), and adjuvant chemotherapy on 366 patients (25.3%). Of stage II-IV patients, CCRT performed on 78.8% in 2003-2011 compared to 15.0% in 1988-1993. For patients treated with CCRT, cisplatin was the most commonly used agent in 81.3% of patients. Over the periods of time, commonly used radiotherapy (RT) techniques were changed from 2-dimensional RT (1988-1993, 92.5%) to 3-dimensional RT (2003-2011, 35.5%) or intensity-modulated RT (IMRT; 2003-2011, 56.5%). Median RT doses given to primary tumors, high-risk lymphatics, and low-risk lymphatics were 70.0 Gy, 58.1 Gy, and 48.0 Gy, respectively. Adoption of IMRT increased the dose per fraction and escalated total radiation dose. Conclusion: Assessment of the patterns of care for NPC patients in South Korea demonstrated that management for NPC including diagnostic imaging, treatment regimen, RT techniques and dose schedule, advanced in accordance with the international guidelines.