Development and External Validation of a Machine Learning Model to Predict Pathological Complete Response After Neoadjuvant Chemotherapy in Breast Cancer / 한국유방암학회지

Purpose@#Several predictive models have been developed to predict the pathological complete response (pCR) after neoadjuvant chemotherapy (NAC); however, few are broadly applicable owing to radiologic complexity and institution-specific clinical variables, and none have been externally validated. This study aimed to develop and externally validate a machine learning model that predicts pCR after NAC in patients with breast cancer using routinely collected clinical and demographic variables. @*Methods@#The electronic medical records of patients with advanced breast cancer who underwent NAC before surgical resection between January 2017 and December 2020 were reviewed. Patient data from Seoul National University Bundang Hospital were divided into training and internal validation cohorts. Five machine learning techniques, including gradient boosting machine (GBM), support vector machine, random forest, decision tree, and neural network, were used to build predictive models, and the area under the receiver operating characteristic curve (AUC) was compared to select the best model. Finally, the model was validated using an independent cohort from Seoul National University Hospital. @*Results@#A total of 1,003 patients were included in the study: 287, 71, and 645 in the training, internal validation, and external validation cohorts, respectively. Overall, 36.3% of the patients achieved pCR. Among the five machine learning models, the GBM showed the highest AUC for pCR prediction (AUC, 0.903; 95% confidence interval [CI], 0.833–0.972).External validation confirmed an AUC of 0.833 (95% CI, 0.800–0.865). @*Conclusion@#Commonly available clinical and demographic variables were used to develop a machine learning model for predicting pCR following NAC. External validation of the model demonstrated good discrimination power, indicating that routinely collected variables were sufficient to build a good prediction model.

The Value of Adding Ductography to Ultrasonography for the Evaluation of Pathologic Nipple Discharge in Women with Negative Mammography

Objective@#The optimal imaging approach for evaluating pathological nipple discharge remains unclear. We investigated the value of adding ductography to ultrasound (US) for evaluating pathologic nipple discharge in patients with negative mammography findings. @*Materials and Methods@#From July 2003 to December 2018, 101 women (mean age, 46.3 ± 12.2 years; range, 23–75 years) with pathologic nipple discharge were evaluated using pre-ductography (initial) US, ductography, and post-ductography US. The imaging findings were reviewed retrospectively. The standard reference was surgery (70 patients) or > 2 years of followup with US (31 patients). The diagnostic performances of initial US, ductography, and post-ductography US for detecting malignancy were compared using the McNemar’s test or a generalized estimating equation. @*Results@#In total, 47 papillomas, 30 other benign lesions, seven high-risk lesions, and 17 malignant lesions were identified as underlying causes of pathologic nipple discharge. Only eight of the 17 malignancies were detected on the initial US, while the remaining nine malignancies were detected by ductography. Among the nine malignancies detected by ductography, eight were detected on post-ductography US and could be localized for US-guided intervention. The sensitivities of ductography (94.1% [16/17]) and post-ductography US (94.1% [16/17]) were significantly higher than those of initial US (47.1% [8/17]; p = 0.027 and 0.013, respectively). The negative predictive value of post-ductography US (96.9% [31/32]) was significantly higher than that of the initial US (83.3% [45/54]; p = 0.006). Specificity was significantly higher for initial US than for ductography and post-ductography US (p = 0.001 for all). @*Conclusion@#The combined use of ductography and US has a high sensitivity for detecting malignancy in patients with pathologic nipple discharge and negative mammography. Ductography findings enable lesion localization on second-look post-ductography US, thus facilitating the selection of optimal treatment plans.

Association between Bone Mineral Density and Coronary Atherosclerotic Plaque According to Plaque Composition: Registry for the Women Health Cohort for Bone, Breast, and Coronary Artery Disease Study

Background@#Although biological links are unclear, low bone density and atherosclerosis are inversely associated. This study evaluated the association between bone mineral density (BMD) and coronary computed tomographic angiography (CCTA) findings, including coronary artery calcification (CAC) score and the presence, extent, and composition of coronary atherosclerotic plaque (CAP) in asymptomatic women. @*Methods@#A symptomatic women aged ≥40 years (N=2, 100; median age, 52 years; range, 40-80 years) were selected from a retrospective observational cohort and stratified into normal, osteopenia, and osteoporosis groups according to BMD T-score grades. We evaluated CAC score and assessed the presence, extent, and stenosis severity of CAP on CCTA. Additionally, CAP was categorized as calcified, mixed, or non-calcified according to calcified component valiums (>130 Hounsfield units). @*Results@#Osteopenia and osteoporosis were found in 28.8% and 5.3% of participants, respectively. CAC score and CAC severity significantly increased with decreased BMD grades (from normal to osteoporosis). The presence of CAP (overall, 15.6%; normal, 12.6%; osteopenia, 20.2%; osteoporosis, 28.8%; P<0.001) and number of segments with CAP significantly increased with decreased BMD grades. Furthermore, the number of segments with calcified or mixed plaques, excluding non-calcified plaques, increased with decreased BMD grades. Although most associations were attenuated or disappeared after adjusting for age and other covariates, calcified plaques showed a strong and age-independent association with BMD grades. @*Conclusions@#The presence and severity of CAC and CAP were significantly associated with BMD severity in asymptomatic women, particularly for the presence of calcified plaques. Further studies are required to determine the association between vascular calcification and bone health status.

Diffusion-Weighted Magnetic Resonance Imaging for Breast Cancer Screening in High-Risk Women: Design and Imaging Protocol of a Prospective Multicenter Study in Korea / 한국유방암학회지

Purpose@#Interest in unenhanced magnetic resonance imaging (MRI) screening for breast cancer is growing due to concerns about gadolinium deposition in the brain and the high cost of contrast-enhanced MRI. The purpose of this report is to describe the protocol of the Diffusion-Weighted Magnetic Resonance Imaging Screening Trial (DWIST), which is a prospective, multicenter, intraindividual comparative cohort study designed to compare the performance of mammography, ultrasonography, dynamic contrast-enhanced (DCE) MRI, and diffusion-weighted (DW) MRI screening in women at high risk of developing breast cancer. @*Methods@#A total of 890 women with BRCA mutation or family history of breast cancer and lifetime risk ≥ 20% are enrolled. The participants undergo 2 annual breast screenings with digital mammography, ultrasonography, DCE MRI, and DW MRI at 3.0 T. Images are independently interpreted by trained radiologists. The reference standard is a combination of pathology and 12-month follow-up. Each image modality and their combination will be compared in terms of sensitivity, specificity, accuracy, positive predictive value, rate of invasive cancer detection, abnormal interpretation rate, and characteristics of detected cancers. The first participant was enrolled in April 2019. At the time of manuscript submission, 5 academic medical centers in South Korea are actively enrolling eligible women and a total of 235 women have undergone the first round of screening. Completion of enrollment is expected in 2022 and the results of the study are expected to be published in 2026.Discussion: DWIST is the first prospective multicenter study to compare the performance of DW MRI and conventional imaging modalities for breast cancer screening in high-risk women. DWIST is currently in the patient enrollment phase.

Diffusion-Weighted Magnetic Resonance Imaging for Breast Cancer Screening in High-Risk Women: Design and Imaging Protocol of a Prospective Multicenter Study in Korea / 한국유방암학회지

Purpose@#Interest in unenhanced magnetic resonance imaging (MRI) screening for breast cancer is growing due to concerns about gadolinium deposition in the brain and the high cost of contrast-enhanced MRI. The purpose of this report is to describe the protocol of the Diffusion-Weighted Magnetic Resonance Imaging Screening Trial (DWIST), which is a prospective, multicenter, intraindividual comparative cohort study designed to compare the performance of mammography, ultrasonography, dynamic contrast-enhanced (DCE) MRI, and diffusion-weighted (DW) MRI screening in women at high risk of developing breast cancer. @*Methods@#A total of 890 women with BRCA mutation or family history of breast cancer and lifetime risk ≥ 20% are enrolled. The participants undergo 2 annual breast screenings with digital mammography, ultrasonography, DCE MRI, and DW MRI at 3.0 T. Images are independently interpreted by trained radiologists. The reference standard is a combination of pathology and 12-month follow-up. Each image modality and their combination will be compared in terms of sensitivity, specificity, accuracy, positive predictive value, rate of invasive cancer detection, abnormal interpretation rate, and characteristics of detected cancers. The first participant was enrolled in April 2019. At the time of manuscript submission, 5 academic medical centers in South Korea are actively enrolling eligible women and a total of 235 women have undergone the first round of screening. Completion of enrollment is expected in 2022 and the results of the study are expected to be published in 2026.Discussion: DWIST is the first prospective multicenter study to compare the performance of DW MRI and conventional imaging modalities for breast cancer screening in high-risk women. DWIST is currently in the patient enrollment phase.

Ultrasonography and ultrasound-guided fine-needle aspiration biopsy can predict a heavy nodal metastatic burden in early-stage breast cancer

Purpose@#This study aimed to predict a heavy nodal burden (≥3 metastatic axillary lymph nodes [LNs]) using axillary ultrasonography (US) and US-guided fine-needle aspiration biopsy (FNAB) in patients with early-stage breast cancer. @*Methods@#We retrospectively reviewed the medical records of 403 women (404 cancers) who underwent US-guided FNAB for axillary LN staging from January 2006 to December 2015. US findings and US-guided FNAB results were reviewed and compared using pathology results as the reference. Diagnostic performance was analyzed, and clinicopathological and radiological findings were compared between patients with <3 metastatic LNs and ≥3 metastatic LNs. @*Results@#The final pathology results revealed that 20.5% of cancers had heavy nodal metastases. US-guided FNAB showed significantly higher sensitivity (79.0% vs. 63.0%, P=0.009) and specificity (84.8% vs. 79.3%, P=0.036) in predicting heavy nodal metastases than did US. The presence of a larger number of suspicious LNs (two or more) on axillary US and positive FNAB results were significantly correlated with a heavy nodal burden in the multivariate analysis. The odds ratios were 4.20 (95% confidence interval [CI], 1.90 to 9.39) for two suspicious LNs, 9.40 (95% CI, 2.99 to 29.54) for three or more suspicious LNs, and 14.22 (95% CI, 6.78 to 29.82) for positive FNAB results. @*Conclusion@#The number of suspicious LNs detected on axillary US and FNAB results can help predict a heavy axillary nodal burden in patients with early-stage breast cancer.

False-negative results on computer-aided detection software in preoperative automated breast ultrasonography of breast cancer patients

Purpose@#The purpose of this study was to measure the cancer detection rate of computer-aided detection (CAD) software in preoperative automated breast ultrasonography (ABUS) of breast cancer patients and to determine the characteristics associated with false-negative outcomes. @*Methods@#A total of 129 index lesions (median size, 1.7 cm; interquartile range, 1.2 to 2.4 cm) from 129 consecutive patients (mean age±standard deviation, 53.4±11.8 years) who underwent preoperative ABUS from December 2017 to February 2018 were assessed. An index lesion was defined as a breast cancer confirmed by ultrasonography (US)-guided core needle biopsy. The detection rate of the index lesions, positive predictive value (PPV), and false-positive rate (FPR) of the CAD software were measured. Subgroup analysis was performed to identify clinical and US findings associated with false-negative outcomes. @*Results@#The detection rate of the CAD software was 0.84 (109 of 129; 95% confidence interval, 0.77 to 0.90). The PPV and FPR were 0.41 (221 of 544; 95% CI, 0.36 to 0.45) and 0.45 (174 of 387; 95% CI, 0.40 to 0.50), respectively. False-negative outcomes were more frequent in asymptomatic patients (P<0.001) and were associated with the following US findings: smaller size (P=0.001), depth in the posterior third (P=0.002), angular or indistinct margin (P<0.001), and absence of architectural distortion (P<0.001). @*Conclusion@#The CAD software showed a promising detection rate of breast cancer. However, radiologists should judge whether CAD software-marked lesions are true- or false-positive lesions, considering its low PPV and high FPR. Moreover, it would be helpful for radiologists to consider the characteristics associated with false-negative outcomes when reading ABUS with CAD.

Comparison of One- and Two-Region of Interest Strain Elastography Measurements in the Differential Diagnosis of Breast Masses

OBJECTIVE: To compare the diagnostic performance and interobserver variability of strain ratio obtained from one or two regions of interest (ROI) on breast elastography.MATERIALS AND METHODS: From April to May 2016, 140 breast masses in 140 patients who underwent conventional ultrasonography (US) with strain elastography followed by US-guided biopsy were evaluated. Three experienced breast radiologists reviewed recorded US and elastography images, measured strain ratios, and categorized them according to the American College of Radiology breast imaging reporting and data system lexicon. Strain ratio was obtained using the 1-ROI method (one ROI drawn on the target mass), and the 2-ROI method (one ROI in the target mass and another in reference fat tissue). The diagnostic performance of the three radiologists among datasets and optimal cut-off values for strain ratios were evaluated. Interobserver variability of strain ratio for each ROI method was assessed using intraclass correlation coefficient values, Bland–Altman plots, and coefficients of variation.RESULTS: Compared to US alone, US combined with the strain ratio measured using either ROI method significantly improved specificity, positive predictive value, accuracy, and area under the receiver operating characteristic curve (AUC) (all p values < 0.05). Strain ratio obtained using the 1-ROI method showed higher interobserver agreement between the three radiologists without a significant difference in AUC for differentiating breast cancer when the optimal strain ratio cut-off value was used, compared with the 2-ROI method (AUC: 0.788 vs. 0.783, 0.693 vs. 0.715, and 0.691 vs. 0.686, respectively, all p values > 0.05).CONCLUSION: Strain ratios obtained using the 1-ROI method showed higher interobserver agreement without a significant difference in AUC, compared to those obtained using the 2-ROI method. Considering that the 1-ROI method can reduce performers' efforts, it could have an important role in improving the diagnostic performance of breast US by enabling consistent management of breast lesions.

Factors Affecting Breast Cancer Detectability on Digital Breast Tomosynthesis and Two-Dimensional Digital Mammography in Patients with Dense Breasts

OBJECTIVE: To compare digital breast tomosynthesis (DBT) and conventional full-field digital mammography (FFDM) in the detectability of breast cancers in patients with dense breast tissue, and to determine the influencing factors in the detection of breast cancers using the two techniques. MATERIALS AND METHODS: Three blinded radiologists independently graded cancer detectability of 300 breast cancers (288 women with dense breasts) on DBT and conventional FFDM images, retrospectively. Hormone status, histologic grade, T stage, and breast cancer subtype were recorded to identify factors affecting cancer detectability. The Wilcoxon signed-rank test was used to compare cancer detectability by DBT and conventional FFDM. Fisher's exact tests were used to determine differences in cancer characteristics between detectability groups. Kruskal-Wallis tests were used to determine whether the detectability score differed according to cancer characteristics. RESULTS: Forty breast cancers (13.3%) were detectable only with DBT; 191 (63.7%) breast cancers were detected with both FFDM and DBT, and 69 (23%) were not detected with either. Cancer detectability scores were significantly higher for DBT than for conventional FFDM (median score, 6; range, 0–6; p < 0.001). The DBT-only cancer group had more invasive lobular-type breast cancers (22.5%) than the other two groups (i.e., cancer detected on both types of image [both-detected group], 5.2%; cancer not detected on either type of image [both-non-detected group], 7.3%), and less detectability of ductal carcinoma in situ (5% vs. 16.8% [both-detected group] vs. 27.5% [both-non-detected group]). Low-grade cancers were more often detected in the DBT-only group than in the both-detected group (22.5% vs. 10%, p = 0.026). Human epidermal growth factor receptor-2 (HER-2)-negative cancers were more often detected in the DBT-only group than in the both-detected group (92.3% vs. 70.5%, p = 0.004). Cancers surrounded by mostly glandular tissue were detected less often in the DBT only group than in the both-non-detected group (10% vs. 31.9%, p = 0.016). DBT cancer detectability scores were significantly associated with cancer type (p = 0.012), histologic grade (p = 0.013), T and N stage (p = 0.001, p = 0.024), proportion of glandular tissue surrounding lesions (p = 0.013), and lesion type (p < 0.001). CONCLUSION: Invasive lobular, low-grade, or HER-2-negative cancer is more detectable with DBT than with conventional FFDM in patients with dense breasts, but cancers surrounded by mostly glandular tissue might be missed with both techniques.

A Survey on Current Trends of Breast Imaging Practices in Korea

PURPOSE@#This study aimed to analyze the current practices of breast imaging among Korean radiologists.@*MATERIALS AND METHODS@#We invited members of the Korean Society of Breast Imaging (KSBI) working as breast radiologists to participate in a survey on the current practices in breast imaging, and investigated how quality assurance (QA), medical audits, and imaging-histologic discordance were conducted.@*RESULTS@#The survey involved 312 members of the KSBI, and 116 (37%) responded to the 21 questions in the questionnaire. Most of the respondents were women (87%), aged below 50 years (82.7%), and working at university or tertiary hospitals (68.1%), who had varying levels of experience in breast imaging. Of the 116 respondents, 114 (96.6%) followed the Breast Imaging Reporting and Data System (BI-RADS) to interpret breast imaging. Out of 116, 72 (62.1%) interpreted 20 or more mammograms per day, 84 (72.4%) performed 10–30 breast ultrasound scans per day, and 65 (56%) interpreted fewer than 5 breast MRI scans per day. Among the respondents, 82% performed mammography QA, 76.9% evaluated imaging-histologic correlations, and only 38.9% performed medical audits.@*CONCLUSION@#The institutions and working patterns of breast radiologists were diverse. Although many respondents did not conduct medical audits, most of them followed BI-RADS when interpreting breast imaging, performing QA, and evaluating imaging-histologic correlations.

Clinical Applications of Automated Breast Ultrasound: Screening for Breast Cancer

Automated breast ultrasonography (ABUS) is a recently introduced technology. Similar to handheld ultrasound (HHUS), it is a supplementary screening test for breast cancer to be used along with mammography. It is particularly useful for detecting invasive breast cancers that may be overlooked by mammography in denser breast tissue. The use of ABUS is becoming more common because of the advantages of low operator dependency during image acquisition, high reproducibility, a wide field-of-view, and unavailability of better coronal imaging with HHUS. Consequently, there have been suggestions to extend ABUS use to diagnostic screening. Therefore, in this paper, we provide a review of the literature and discuss the usefulness and value of ABUS in breast cancer screening.

Reliability of automated versus handheld breast ultrasound examinations of suspicious breast masses

PURPOSE: The purpose of this study was to assess the reliability of automated breast ultrasound (ABUS) examinations of suspicious breast masses in comparison to handheld breast ultrasound (HHUS) with regard to Breast Imaging Reporting and Data System (BI-RADS) category assessment, and to investigate the factors affecting discrepancies in categorization. METHODS: A total of 135 masses that were assessed as BI-RADS categories 4 and 5 on ABUS that underwent ultrasound (US)-guided core needle biopsy from May 2017 to December 2017 were included in this study. The BI-RADS categories were re-assessed using HHUS. Agreement of the BI-RADS categories was evaluated using kappa statistics, and the positive predictive value of each examination was calculated. Logistic regression analysis was performed to identify the mammography and US findings associated with discrepancies in the BI-RADS categorization. RESULTS: The overall agreement between ABUS and HHUS in all cases was good (79.3%, kappa=0.61, P<0.001). Logistic regression analysis revealed that accompanying suspicious microcalcifications on mammography (odds ratio [OR], 4.63; 95% confidence interval [CI], 1.83 to 11.71; P=0.001) and an irregular shape on US (OR, 5.59; 95% CI, 1.43 to 21.83; P=0.013) were associated with discrepancies in the BI-RADS categorization. CONCLUSION: The agreement between ABUS and HHUS examinations in the BI-RADS categorization of suspicious breast masses was good. The presence of suspicious microcalcifications on mammography and an irregular shape on US were factors associated with ABUS yielding a lower level of suspicion than HHUS in terms of the BI-RADS category assessment.

Benign Intraductal Papilloma without Atypia on Core Needle Biopsy Has a Low Rate of Upgrading to Malignancy after Excision / 한국유방암학회지

PURPOSE: The management of benign intraductal papilloma (IDP) without atypia diagnosed on core needle biopsy (CNB) remains controversial. This study was performed to evaluate the rate of upgrading to malignancy or high-risk lesions after excision and to identify factors associated with upgrading using a large series of benign IDP cases without atypia. METHODS: We included patients who were diagnosed as having benign IDP without atypia on CNB and underwent surgical or vacuum-assisted excision between 2010 and 2015. We analyzed the clinical, radiologic, and histopathologic features of IDPs that were upgraded to malignancy or high-risk lesions after excision. RESULTS: A total of 511 benign IDPs without atypia diagnosed via CNB were identified, of which 398 cases were treated with excision. After reviewing these cases, four cases of high-risk lesions in adjacent tissue on CNB, two cases which were revealed as papilloma with atypia, and nine cases of malignancy in the same breast were excluded. In the remaining 383 cases, the rate of upgrading to malignancy and high-risk lesions after excision was 0.8% and 4.4%, respectively. The presence of concurrent contralateral breast cancer, the presence of symptoms, and multifocality were factors significantly associated with upgrading to malignancy on subsequent excision. Surgical excision rather than vacuum-assisted excision was significantly associated with upgrading to high-risk lesions or malignancy. CONCLUSION: The rate of upgrading to malignancy for benign IDP without atypia was very low, suggesting that close clinical and radiologic observation may be sufficient for patients with benign IDP without atypia on CNB under proper settings.

Ultrasonographic findings of Kikuchi cervical lymphadenopathy in children

PURPOSE: The purpose of this study was to analyze the ultrasonographic (USG) findings of Kikuchi cervical lymphadenopathy in pediatric patients. METHODS: Between April 2007 and September 2016, 84 children (42 male and 42 female; mean±standard deviation age, 12.9±3.2 years; range, 5 to 18 years) confirmed with Kikuchi disease were enrolled. Clinical findings and USG findings of Kikuchi cervical lymphadenopathy were retrospectively reviewed. Localized symptoms, systemic symptoms, and laboratory findings including the white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were analyzed. An analysis of the USG findings included evaluation of the location, size, and presence of intranodal abscess; intranodal calcification; perinodal fat swelling; localized fluid collection; and loss of nodal echogenic hilum. RESULTS: Among the patients, 49 (58%) showed localized tenderness at the cervical lymphadenopathy. Fever was present in 55 (66%), while 27 (32%) had prolonged fever. Of 74 with lab results, 54 (73%) had leukopenia but none had leukocytosis. Among the same 74, there was a high ESR (>50 mm/hr) in 10 (14%) and a high CRP level (>5 mg/dL) in seven (9%). The USG findings of most of the patients (n=72, 86%) showed unilateral neck involvement, especially in the left side neck (45 of 72, 63%). The most common site of Kikuchi lymphadenopathy involvement was the area at cervical lymph node level V, at the posterior triangle (n=77, 92%). Conglomerated nodal distribution (n=57, 68%), preserved central nodal echogenic hilum (n=84, 98%), and perinodal fat swelling (n=55, 65%) were common USG findings in the children with Kikuchi. In addition, multiple cervical lymph nodes showed a relatively even size distribution (n=73, 87%). CONCLUSION: The common USG findings of Kikuchi disease in the pediatric population of our study were multiple conglomerated unilateral cervical lymphadenopathy showing perinodal fat swelling and even size distribution.

Current Practices in Breast Magnetic Resonance Imaging: a Survey Involving the Korean Society of Breast Imaging

PURPOSE: To report on the current practices in breast magnetic resonance imaging (MRI) in Korea. MATERIALS AND METHODS: We invited the 68 members of the Korean Society of Breast Imaging who were working in hospitals with available breast MRI to participate in a survey on how they performed and interpreted breast MRI. We asked one member from each hospital to respond to the survey. A total of 22 surveys from 22 hospitals were analyzed. RESULTS: Out of 22 hospitals, 13 (59.1%) performed at least 300 breast MRI examinations per year, and 5 out of 22 (22.7%) performed > 1200 per year. Out of 31 machines, 14 (45.2%) machines were 1.5-T scanners and 17 (54.8%) were 3.0-T scanners. All hospitals did contrast-enhanced breast MRI. Full-time breast radiologists supervised the performance and interpreted breast MRI in 19 of 22 (86.4%) of hospitals. All hospitals used BI-RADS for MRI interpretation. For computer-aided detection (CAD), 13 (59.1%) hospitals sometimes or always use it and 9 (40.9%) hospitals did not use CAD. Two (9.1%) and twelve (54.5%) hospitals never and rarely interpreted breast MRI without correlating the mammography or ultrasound, respectively. The majority of respondents rarely (13/21, 61.9%) or never (5/21, 23.8%) interpreted breast MRI performed at an outside facility. Of the hospitals performing contrast-enhanced examinations, 15 of 22 (68.2%) did not perform MRI-guided interventional procedures. CONCLUSION: Breast MRI is extensively performed in Korea. The indication and practical patterns are diverse. The information from this survey would provide the basis for the development of Korean breast MRI practice guidelines.

Reproducibility of Apparent Diffusion Coefficient Measurements in Malignant Breast Masses

This study aimed to evaluate the reproducibility of apparent diffusion coefficient (ADC) measurements in malignant breast masses, and to determine the influence of mammographic parenchymal density on this reproducibility. Sixty-six patients with magnetic resonance findings of the mass were included. Two breast radiologists measured the ADC of the malignant breast mass and the same area on the contralateral normal breast in each patient twice. The effects of mammographic parenchymal density, histology, and lesion size on reproducibility were also assessed. There was no significant difference in the mean ADC between repeated measurements in malignant breast masses and normal breast tissue. The overall reproducibility of ADC measurements was good in both. The 95% limits of agreement for repeated ADCs were approximately 30.2%-33.4% of the mean. ADC measurements in malignant breast masses were highly reproducible irrespective of mass size, histologic subtype, or coexistence of microcalcifications; however, the measurements tended to be less reproducible in malignant breast masses with extremely dense parenchymal backgrounds. ADC measurements in malignant breast masses are highly reproducible; however, mammographic parenchymal density can potentially influence this reproducibility.

A New Full-Field Digital Mammography System with and without the Use of an Advanced Post-Processing Algorithm: Comparison of Image Quality and Diagnostic Performance

OBJECTIVE: To compare new full-field digital mammography (FFDM) with and without use of an advanced post-processing algorithm to improve image quality, lesion detection, diagnostic performance, and priority rank. MATERIALS AND METHODS: During a 22-month period, we prospectively enrolled 100 cases of specimen FFDM mammography (Brestige(R)), which was performed alone or in combination with a post-processing algorithm developed by the manufacturer: group A (SMA), specimen mammography without application of "Mammogram enhancement ver. 2.0"; group B (SMB), specimen mammography with application of "Mammogram enhancement ver. 2.0". Two sets of specimen mammographies were randomly reviewed by five experienced radiologists. Image quality, lesion detection, diagnostic performance, and priority rank with regard to image preference were evaluated. RESULTS: Three aspects of image quality (overall quality, contrast, and noise) of the SMB were significantly superior to those of SMA (p < 0.05). SMB was significantly superior to SMA for visualizing calcifications (p < 0.05). Diagnostic performance, as evaluated by cancer score, was similar between SMA and SMB. SMB was preferred to SMA by four of the five reviewers. CONCLUSION: The post-processing algorithm may improve image quality with better image preference in FFDM than without use of the software.

Intratumoral Heterogeneity of Breast Cancer Xenograft Models: Texture Analysis of Diffusion-Weighted MR Imaging

OBJECTIVE: To investigate whether there is a relationship between texture analysis parameters of apparent diffusion coefficient (ADC) maps and histopathologic features of MCF-7 and MDA-MB-231 xenograft models. MATERIALS AND METHODS: MCF-7 estradiol (+), MCF-7 estradiol (-), and MDA-MB-231 xenograft models were made with approval of the animal care committee. Twelve tumors of MCF-7 estradiol (+), 9 tumors of MCF-7 estradiol (-), and 6 tumors in MDA-MB-231 were included. Diffusion-weighted MR images were obtained on a 9.4-T system. An analysis of the first and second order texture analysis of ADC maps was performed. The texture analysis parameters and histopathologic features were compared among these groups by the analysis of variance test. Correlations between texture parameters and histopathologic features were analyzed. We also evaluated the intraobserver agreement in assessing the texture parameters. RESULTS: MCF-7 estradiol (+) showed a higher standard deviation, maximum, skewness, and kurtosis of ADC values than MCF-7 estradiol (-) and MDA-MB-231 (p < 0.01 for all). The contrast of the MCF-7 groups was higher than that of the MDA-MB-231 (p = 0.004). The correlation (COR) of the texture analysis of MCF-7 groups was lower than that of MDA-MB-231 (p < 0.001). The histopathologic analysis showed that Ki-67mean and Ki-67diff of MCF-7 estradiol (+) were higher than that of MCF-7 estradiol (-) or MDA-MB-231 (p < 0.05). The microvessel density (MVD)mean and MVDdiff of MDA-MB-231 were higher than those of MCF-7 groups (p < 0.001). A diffuse-multifocal necrosis was more frequently found in MDA-MB-231 (p < 0.001). The proportion of necrosis moderately correlated with the contrast (r = -0.438, p = 0.022) and strongly with COR (r = 0.540, p = 0.004). Standard deviation (r = 0.622, r = 0.437), skewness (r = 0.404, r = 0.484), and kurtosis (r = 0.408, r = 0.452) correlated with Ki-67mean and Ki-67diff (p < 0.05 for all). COR moderately correlated with Ki-67diff (r = -0.388, p = 0.045). Skewness (r = -0.643, r = -0.464), kurtosis (r = -0.581, r = -0.389), contrast (r = -0.473, r = -0.549) and COR (r = 0.588, r = 0.580) correlated with MVDmean and MVDdiff (p < 0.05 for all). CONCLUSION: The texture analysis of ADC maps may help to determine the intratumoral spatial heterogeneity of necrosis patterns, amount of cellular proliferation and the vascularity in MCF-7 and MDA-MB-231 xenograft breast cancer models.

Magnetic Resonance Imaging Factors Predicting Re-excision in Breast Cancer Patients Having Undergone Conserving Therapy

PURPOSE: The aim of this study was to determine the magnetic resonance imaging (MRI) features associated with re-excision due to the presence of a positive margin after breast conserving therapy (BCT) in breast cancer patients. MATERIALS AND METHODS: We reviewed the records of 286 consecutive breast cancer patients who received BCT between January 2006 and December 2007. Among 246 patients who had undergone BCT, 38 (15.4%) underwent immediate further surgery due to positive margin status. We analyzed the MRI findings using chi2 test, Fisher's exact test and t tests. Multivariate logistic regression was conducted for prediction of re-excision. RESULTS: Tumor size (p or = 5 cm) (odds ratio = 2.96), NMLE (odds ratio = 3.81), and multifocal lesions (odds ratio = 2.54) were positively associated with re-excision. In cases involving NMLE, segmental distribution was associated with a greater likelihood of immediate re-excision. CONCLUSION: Larger size, multiplicity, and NMLE on MRI are significantly associated with re-excision after BCT in breast cancer patients. For NMLE lesions, the segmental distribution pattern was predictive of re-excision.

Trastuzumab-Conjugated Liposome-Coated Fluorescent Magnetic Nanoparticles to Target Breast Cancer

OBJECTIVE: To synthesize mesoporous silica-core-shell magnetic nanoparticles (MNPs) encapsulated by liposomes (Lipo [MNP@m-SiO2]) in order to enhance their stability, allow them to be used in any buffer solution, and to produce trastuzumab-conjugated (Lipo[MNP@m-SiO2]-Her2Ab) nanoparticles to be utilized in vitro for the targeting of breast cancer. MATERIALS AND METHODS: The physiochemical characteristics of Lipo[MNP@m-SiO2] were assessed in terms of size, morphological features, and in vitro safety. The multimodal imaging properties of the organic dye incorporated into Lipo[MNP@m-SiO2] were assessed with both in vitro fluorescence and MR imaging. The specific targeting ability of trastuzumab (Her2/neu antibody, Herceptin(R))-conjugated Lipo[MNP@m-SiO2] for Her2/neu-positive breast cancer cells was also evaluated with fluorescence and MR imaging. RESULTS: We obtained uniformly-sized and evenly distributed Lipo[MNP@m-SiO2] that demonstrated biological stability, while not disrupting cell viability. Her2/neu-positive breast cancer cell targeting by trastuzumab-conjugated Lipo[MNP@m-SiO2] was observed by in vitro fluorescence and MR imaging. CONCLUSION: Trastuzumab-conjugated Lipo[MNP@m-SiO2] is a potential treatment tool for targeted drug delivery in Her2/neu-positive breast cancer.