• Progress in Medical Physics
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• v.23 no.4
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• pp.261-268
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• 2012

Breast cancer is the second leading cause of women cancer death in Korea. The key for reducing disease mortality is early detection. Although digital mammography (DM) has been credited as one of the major reasons for the early detection to decrease in breast cancer mortality observed in the last 20 years, DM is far from perfect for several limitations. Digital breast tomosynthesis (DBT) is expected to overcome some inherent limitations of conventional mammography caused by overlapping of normal tissue and pathological tissue during the standard 2D projections for the improved lesion margin visibility and early breast cancer detection. In this study, we compared a DM system and DBT system acquired with different thickness of breast phantom. We acquired breast phantom data with same average glandular dose (AGD) from 1 mGy to 4 mGy under same experimental condition. The contrast, micro-calcification measurement accuracy and observer study were conducted with breast phantom images. As a result, the higher accuracy of lesion detection with DBT system compared to DM system was demonstrated in this study. Furthermore, the pain of patients caused by severe compression can be reduced with DBT system. In conclusion, the results indicated that DBT system play an important role in breast cancer detection.

• Progress in Medical Physics
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• v.21 no.3
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• pp.239-245
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• 2010

The purpose of this study is to comprehensively compare and evaluate the characteristics of image quality for digital mammography systems which use a direct and indirect conversion detector. Three key metrics of image quality were evaluated for the direct and indirect conversion detector, the modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE), which describe the resolution, noise, and signal to noise performance, respectively. DQE was calculated by using a edge phantom for MTF determination according to IEC 62220-1-2 regulation. The contrast to noise ratio (CNR) was evaluated according to guidelines offered by the Korean Institute for Accreditation of Medical Image (KIAMI). As a result, the higher MTF and DQE was measured with direct conversion detector compared to indirect conversion detector all over spatial frequency. When the average glandular dose (AGD) was the same, direct conversion detector showed higher CNR value. The direct conversion detector which has higher DQE value all over spatial frequency would provide the potential benefits for both improved image quality and lower patient dose in digital mammography system.

• Korean Journal of Radiology
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• v.24 no.4
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• pp.274-283
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• 2023

Objective: To compare the outcomes of digital breast tomosynthesis (DBT) screening combined with ultrasound (US) with those of digital mammography (DM) combined with US in women with dense breasts. Materials and Methods: A retrospective database search identified consecutive asymptomatic women with dense breasts who underwent breast cancer screening with DBT or DM and whole-breast US simultaneously between June 2016 and July 2019. Women who underwent DBT + US (DBT cohort) and DM + US (DM cohort) were matched using 1:2 ratio according to mammographic density, age, menopausal status, hormone replacement therapy, and a family history of breast cancer. The cancer detection rate (CDR) per 1000 screening examinations, abnormal interpretation rate (AIR), sensitivity, and specificity were compared. Results: A total of 863 women in the DBT cohort were matched with 1726 women in the DM cohort (median age, 53 years; interquartile range, 40-78 years) and 26 breast cancers (9 in the DBT cohort and 17 in the DM cohort) were identified. The DBT and DM cohorts showed comparable CDR (10.4 [9 of 863; 95% confidence interval {CI}: 4.8-19.7] vs. 9.8 [17 of 1726; 95% CI: 5.7-15.7] per 1000 examinations, respectively; P = 0.889). DBT cohort showed a higher AIR than the DM cohort (31.6% [273 of 863; 95% CI: 28.5%-34.9%] vs. 22.4% [387 of 1726; 95% CI: 20.5%-24.5%]; P < 0.001). The sensitivity for both cohorts was 100%. In women with negative findings on DBT or DM, supplemental US yielded similar CDRs in both DBT and DM cohorts (4.0 vs. 3.3 per 1000 examinations, respectively; P = 0.803) and higher AIR in the DBT cohort (24.8% [188 of 758; 95% CI: 21.8%-28.0%] vs. 16.9% [257 of 1516; 95% CI: 15.1%-18.9%; P < 0.001). Conclusion: DBT screening combined with US showed comparable CDR but lower specificity than DM screening combined with US in women with dense breasts.

• Korean Journal of Radiology
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• v.22 no.6
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• pp.867-879
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• 2021

Objective: To compare the screening performance of diffusion-weighted (DW) MRI and combined mammography and ultrasound (US) in detecting clinically occult contralateral breast cancer in women with newly diagnosed breast cancer. Materials and Methods: Between January 2017 and July 2018, 1148 women (mean age ± standard deviation, 53.2 ± 10.8 years) with unilateral breast cancer and no clinical abnormalities in the contralateral breast underwent 3T MRI, digital mammography, and radiologist-performed whole-breast US. In this retrospective study, three radiologists independently and blindly reviewed all DW MR images (b = 1000 s/mm² and apparent diffusion coefficient map) of the contralateral breast and assigned a Breast Imaging Reporting and Data System category. For combined mammography and US evaluation, prospectively assessed results were used. Using histopathology or 1-year follow-up as the reference standard, cancer detection rate and the patient percentage with cancers detected among all women recommended for tissue diagnosis (positive predictive value; PPV2) were compared. Results: Of the 30 cases of clinically occult contralateral cancers (13 invasive and 17 ductal carcinoma in situ [DCIS]), DW MRI detected 23 (76.7%) cases (11 invasive and 12 DCIS), whereas combined mammography and US detected 12 (40.0%, five invasive and seven DCIS) cases. All cancers detected by combined mammography and US, except two DCIS cases, were detected by DW MRI. The cancer detection rate of DW MRI (2.0%; 95% confidence interval [CI]: 1.3%, 3.0%) was higher than that of combined mammography and US (1.0%; 95% CI: 0.5%, 1.8%; p = 0.009). DW MRI showed higher PPV2 (42.1%; 95% CI: 26.3%, 59.2%) than combined mammography and US (18.5%; 95% CI: 9.9%, 30.0%; p = 0.001). Conclusion: In women with newly diagnosed breast cancer, DW MRI detected significantly more contralateral breast cancers with fewer biopsy recommendations than combined mammography and US.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.1
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• pp.33-41
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• 2010

National Cancer Screening Project and Korean Society of Breast Imaging recommend that breast cancer screening should be performed on those aged 40 and above. Nevertheless, this recommendation is usually ignored by a number of medical institutions. The purpose of this study is to emphasize the necessity of an age limitation in screening mammography. Ten institutions were randomly selected and telephone inquiries about patients' age limitation and internal guidelines were set up. The 3,214 women, who underwent screening mammography through 'GE Senography 2000D' in each hospital, were classified into five groups according to age(from 20s to 40s, at intervals of 5). And then, collected data was analyzed by a radiologist in accordance with ACR-BIRADS(American College of Radiology Breast Imaging Reporting and Data System), through which breast parenchymal density and the results of analysis were categorized in order to predict the sensitivity of mammography. Information about craniocaudal-view mammograms was automatically produced by use of GE Senography 2000D, and the average glandular dose was retrospectively analyzed through the program 'Excel 2007.' Two institutions did not set the age limitation. Other seven institutions internally allowed those who wanted to receive mammography regardless of age. Approximately 99% of those aged 20 to 29 were judged as having the dense breast. In those aged 35 to 39, breast parenchymal density tended to be lower, but the fatty breast to increase. In the case of 'category-zero' that does not need additional tests, the rate of 'heterogeneously dense' and 'extremely dense' reached to 83.1% and 15.1% respectively. Regarding dense breasts, there was no sufficient information for image reading. The glandular dose, applied to 3,214, was 1.47mGy on the average. In those aged 20 to 24 who are sensitive to radiation, the average glandular dose indicated 1.59mGy. Those aged 35 and above showed the lowest value, 1.43mGy. In those aged 35 to 39, the breast tended to change from denseness to fattiness. The average glandular dose was lowest in those aged 35 and above, which suggests that screening mammography should be periodically performed on those aged 35 and above in order that breast cancer may be early detected. On the other hand, in those aged less than 35, it is difficult to analyze mammograms due to the high density of breast parenchyma, and also retakes become frequent. In particular, subjects may be exposed to excessive doses. Accordingly, it should be substituted by breast self-examination or clinical breast examination. In case of need, it is advisable to perform ultrasonography.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.247-254
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• 2014

For the purpose of early diagnosis of the breast cancer, the attention on the screening mammography has been increasing-with supply of digital mammography day by day. Image quality is decided by target materials and filter combinations. Optimized selection by a glandular density and a thickness is needed, because these combinations change x-ray spectrum and effect to image quality. The purpose of this study is to find out optimized target and filter combinations through the evaluation of quantitative image quality and to suggest means which minimize patient dose through MCNPX. In results, spatial frequency resolution evaluation which is quantitative image quality evaluation method, MTF, NPS, DQE shows that we have to select Mo/Mo combinations or Mo/Rh combinations when compressed breast is thin. but in case of that when compressed breast is thick, we have to select Rh/Rh combinations or W /Rh combinations. In a comprehensive evaluation, W!Rh combinations which are not used in thin breasts in practice was superior to all image quality evaluation. This result is somewhat different-with clinical examination results. Secondary end point was organ dose evaluation, radiation dose of opposite breast was approximately 47 ~73% effectiveness when selecting standard breast. In conculsion, the most important point is that we have to select the optimal combinations-with considering dose evaluation and various thickness.

• Journal of Biomedical Engineering Research
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• v.26 no.5
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• pp.283-294
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• 2005

The Center for Imaging Human Structures (CIH) was established in December 2002 to develop new diagnostic imaging techniques and to make them available to the greater community of biomedical and clinical researchers at Sungkyunkwan University. CIH has been involved in 5 specific activities to provide solutions for early diagnosis and improved treatment of human diseases. The five area goals include: 1) development of a digital mammography system with computer aided diagnosis (CAD); 2) development of digital radiological imaging techniques; 3) development of unified medical solutions using 3D image fusion; 4) development of multi-purpose digital endoscopy; and, 5) evaluation of new imaging systems for clinical application

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1090-1103
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• 2022

Purpose To evaluate the diagnostic performance of digital breast tomosynthesis (DBT) with the two-dimensional synthesized mammogram (2DSM), compared to full-field digital mammography (FFDM), for suspicious microcalcifications in the breast ahead of stereotactic biopsy and to assess the diagnostic image visibility of the images. Materials and Methods This retrospective study involved 189 patients with microcalcifications, which were histopathologically verified by stereotactic breast biopsy, who underwent DBT with 2DSM and FFDM between January 8, 2015, and January 20, 2020. Two radiologists assessed all cases of microcalcifications based on Breast Imaging Reporting and Data System (BI-RADS) independently. They were blinded to the histopathologic outcome and additionally evaluated lesion visibility using a fivepoint scoring scale. Results Overall, the inter-observer agreement was excellent (0.9559). Under the setting of category 4A as negative due to the low possibility of malignancy and to avoid the dilution of malignancy criteria in our study, McNemar tests confirmed no significant difference between the performances of the two modalities in detecting microcalcifications with a high potential for malignancy (4B, 4C, or 5; p = 0.1573); however, the tests showed a significant difference between their performances in detecting microcalcifications with a high potential for benignancy (4A; p = 0.0009). DBT with 2DSM demonstrated superior visibility and diagnostic performance than FFDM in dense breasts. Conclusion DBT with 2DSM is superior to FFDM in terms of total diagnostic accuracy and lesion visibility for benign microcalcifications in dense breasts. This study suggests a promising role for DBT with 2DSM as an accommodating tool for stereotactic biopsy in female with dense breasts and suspicious breast microcalcifications.

• Journal of Biomedical Engineering Research
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• v.27 no.5
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• pp.291-299
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• 2006

A Computer-Aided Diagnosis system has been examined to reduce the effort of radiologist. In this paper, we propose the algorithm using Support Vector Machine(SVM) classifier to discriminate whether microcalcifications are malignant or benign tumors. The proposed method to detect microcalcifications is composed of two detection steps each of which uses SVM classifier. The coarse detection step finds out pixels considered high contrasts comparing with neighboring pixels. Then, Region of Interest(ROI) is generated based on microcalcification characteristics. The fine detection step determines whether the found ROIs are microcalcifications or not by merging potential regions using obtained ROIs and SVM classifier. The proposed method is specified on Korean mammogram database. The experimental result of the proposed algorithm presents robustness in detecting microcalcifications than the previous method using Artificial Neural Network as classifier even when using small training data.

• Journal of Biomedical Engineering Research
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• v.30 no.2
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• pp.153-161
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• 2009

Mammogram is one of the important techniques for mass detection, which is the early diagnosis stage of a breast cancer. Especially, the CAD(Computer Aided Diagnosis) using mammogram improves the working performance of radiologists as it offers an effective mass detection. There are two types of CAD systems using mammogram; automatic and semi-automatic CAD systems. However, the automatic segmentation is limited in performance due to the difficulty of obtaining an accurate segmentation since mass occurs in the dense areas of the breast tissue and has smoother boundaries. Semi-automatic CAD systems overcome these limitations, however, they also have problems including high FP (False Positive) rate and a large amount of training data required for training a classifier. The proposed system which overcomes the aforementioned problems to detect mass is composed of the suspected area selection, the level set segmentation and SVM (Support Vector Machine) classification. To assess the efficacy of the system, 60 test images from the FFDM (Full-Field Digital Mammography) are analyzed and compared with the previous semi-automatic system, which uses the ANN classifier. The experimental results of the proposed system indicate higher accuracy of detecting mass in comparison to the previous systems.