US, Mammography, and Histopathologic Evaluation to Identify Low Nuclear Grade Ductal Carcinoma in Situ.

Background Low nuclear grade ductal carcinoma in situ (DCIS) identified at biopsy can be upgraded to intermediate to high nuclear grade DCIS at surgery. Methods that confirm low nuclear grade are needed to consider nonsurgical approaches for these patients. Purpose To develop a preoperative model to identify low nuclear grade DCIS and to evaluate factors associated with low nuclear grade DCIS at biopsy that was not upgraded to intermediate to high nuclear grade DCIS at surgery. Materials and Methods In this retrospective study, 470 women (median age, 50 years; interquartile range, 44-58 years) with 477 pure DCIS lesions at surgical histopathologic evaluation were included (January 2010 to December 2015). Patients were divided into the training set (n = 330) or validation set (n = 147) to develop a preoperative model to identify low nuclear grade DCIS. Features at US (mass, nonmass) and at mammography (morphologic characteristics, distribution of microcalcification) were reviewed. The upgrade rate of low nuclear grade DCIS was calculated, and multivariable regression was used to evaluate factors for associations with low nuclear grade DCIS that was not upgraded later. Results A preoperative model that included lesions manifesting as a mass at US without microcalcification and no comedonecrosis at biopsy was used to identify low nuclear grade DCIS, with a high area under the receiver operating characteristic curve of 0.97 (95% CI: 0.94, 1.00) in the validation set. The upgrade rate of low nuclear grade DCIS at biopsy was 38.8% (50 of 129). Ki-67 positivity (odds ratio, 0.04; 95% CI: 0.0003, 0.43; P = .005) was inversely associated with constant low nuclear grade DCIS. Conclusion The upgrade rate of low nuclear grade ductal carcinoma in situ (DCIS) at biopsy to intermediate to high nuclear grade DCIS at surgery occurred in more than a third of patients; low nuclear grade DCIS at final histopathologic evaluation could be identified if the mass was viewed at US without microcalcifications and had no comedonecrosis at histopathologic evaluation of biopsy. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Rahbar in this issue. An earlier incorrect version appeared online. This article was corrected on April 14, 2022.

AI-CAD for differentiating lesions presenting as calcifications only on mammography: outcome analysis incorporating the ACR BI-RADS descriptors for calcifications.

OBJECTIVES: To evaluate how AI-CAD triages calcifications and to compare its performance to an experienced breast radiologist. METHODS: Among routine mammography performed between June 2016 and May 2018, 535 lesions detected as calcifications only on mammography in 500 women (mean age, 48.8 years) that were additionally interpreted with additional magnification views were included in this study. One dedicated breast radiologist retrospectively reviewed the magnification mammograms to assess morphology, distribution, and final assessment category according to ACR BI-RADS. AI-CAD analyzed routine mammograms providing AI-CAD marks and corresponding AI-CAD scores (ranging from 0 to 100%), for which values ≥ 10% were considered positive. Ground truth in terms of malignancy or benignity was confirmed with a histopathologic diagnosis or at least 1 year of imaging follow - up. RESULTS: Of the 535 calcifications, 215 (40.2%) were malignant. Calcifications with positive AI-CAD scores showed significantly higher PPVs compared to calcifications with negative scores for all morphology (all p < 0.05). PPVs were significantly higher in calcifications with positive AI-CAD scores compared to those with negative scores for BI-RADS 3, 4a, or 4b assessments (all p < 0.05). AI-CAD and the experienced radiologist did not show significant difference in diagnostic performance; sensitivity 92.1% vs 95.4% (p = 0.125), specificity 71.9% vs 72.5% (p = 0.842), and accuracy 80.0% vs 81.7% (p = 0.413). CONCLUSION: Among calcifications with same morphology or BI-RADS assessment, those with positive AI-CAD scores had significantly higher PPVs. AI-CAD showed similar diagnostic performances to the experienced radiologist for calcifications detected on mammography. KEY POINTS: • Among calcifications with same morphology or BI-RADS assessment, those with positive AI-CAD scores had significantly higher PPVs. • AI-CAD showed similar diagnostic performance to an experienced radiologist in assessing lesions detected as calcifications only on mammography. • Among malignant calcifications, calcifications with positive AI-CAD scores showed higher rates of invasive cancers than calcifications with negative scores (all p > 0.05).

Ultrafast dynamic contrast-enhanced breast MRI: association with pathologic complete response in neoadjuvant treatment of breast cancer.

OBJECTIVES: The purpose of this study was to investigate whether pretreatment kinetic features from ultrafast DCE-MRI are associated with pathological complete response (pCR) in patients with invasive breast cancer and according to immunohistochemistry (IHC) subtype. METHODS: Between August 2018 and June 2019, 256 consecutive breast cancer patients (mean age, 50.2 years; range, 25-86 years) who underwent both ultrafast and conventional DCE-MRI and surgery following neoadjuvant chemotherapy were included. DCE-MRI kinetic features were obtained from pretreatment MRI data. Time-to-enhancement, maximal slope (MS), and volumes at U1 and U2 (U1, time point at which the lesion starts to enhance; U2, subsequent time point after U1) were derived from ultrafast MRI. Logistic regression analysis was performed to identify factors associated with pCR. RESULTS: Overall, 41.4% of all patients achieved pCR. None of the kinetic features was associated with pCR when including all cancers. Among ultrafast DCE-MRI kinetic features, a lower MS (OR, 0.982; p = 0.040) was associated with pCR at univariable analysis in hormone receptor (HR)-positive cancers. In triple-negative cancers, a higher volume ratio U1/U2 was associated with pCR at univariable (OR, 11.787; p = 0.006) and multivariable analysis (OR, 14.811; p = 0.005). Among conventional DCE-MRI kinetic features, a lower peak enhancement (OR, 0.993; p = 0.031) and a lower percentage of washout (OR, 0.904; p = 0.039) was associated with pCR only in HR-positive cancers at univariable analysis. CONCLUSIONS: A higher volume ratio of U1/U2 derived from ultrafast DCE-MRI was independently associated with pCR in triple-negative invasive breast cancer. KEY POINTS: • The ratio of tumor volumes obtained at the first (U1) and second time points (U2) of enhancement was independently associated with pCR in triple-negative invasive breast cancers. • Ultrafast MRI has the potential to improve accuracy in predicting treatment response and personalizing therapy.

Cancer yield and imaging features of probably benign calcifications at digital magnification view.

OBJECTIVES: To investigate the malignancy rate of probably benign calcifications assessed by digital magnification view and imaging and clinical features associated with malignancy. METHODS: This retrospective study included consecutive women with digital magnification views assessed as probably benign for calcifications without other associated mammographic findings from March 2009 to January 2014. Initial studies rendering a probably benign assessment were analyzed, with biopsy or 4-year imaging follow-up. Fisher's exact test and univariable logistic regression were performed. Cancer yields were calculated. RESULTS: A total of 458 lesions in 422 patients were finally included. The overall cancer yield was 2.2% (10 of 458, invasive cancer [n = 4] and DCIS [n = 6]). Calcification distribution (OR = 23.80, p = .041), calcification morphology (OR = 10.84, p = .005), increased calcifications (OR = 29.40, p = .001), and having a concurrent newly diagnosed breast cancer or high-risk lesion (OR = 10.24, p = .001) were associated with malignancy. Cancer yields did not significantly differ between grouped punctate calcifications vs. calcifications with other features (1.2% [2 of 162] vs. 2.7% [8 of 296], p = .506). The cancer yield was 1.6% (7 of 437) in women without newly diagnosed breast cancer or high-risk lesions. CONCLUSION: The cancer yield of probably benign calcifications assessed by digital magnification view was below the 2% threshold for grouped punctate calcifications and for women without newly diagnosed breast cancer or high-risk lesions. Calcification distribution, morphology, increase in calcifications, and the presence of newly diagnosed breast cancer/high-risk lesion were associated with malignancy. KEY POINTS: • Among 458 probably benign calcifications assessed by digital magnification view, the overall cancer yield was 2.2% (10 of 458). • The cancer yield was below the 2% threshold for grouped punctate calcifications (1.2%, 2 of 162) and in women without newly diagnosed breast cancer or high-risk lesions (1.6%, 7 of 437). • Calcification distribution, morphology, increase in calcifications, and the presence of newly diagnosed breast cancer/high-risk lesion were associated with malignancy (all p < .05).

Application of Artificial Intelligence Computer-Assisted Diagnosis Originally Developed for Thyroid Nodules to Breast Lesions on Ultrasound.

As thyroid and breast cancer have several US findings in common, we applied an artificial intelligence computer-assisted diagnosis (AI-CAD) software originally developed for thyroid nodules to breast lesions on ultrasound (US) and evaluated its diagnostic performance. From January 2017 to December 2017, 1042 breast lesions (mean size 20.2 ± 11.8 mm) of 1001 patients (mean age 45.9 ± 12.9 years) who underwent US-guided core-needle biopsy were included. An AI-CAD software that was previously trained and validated with thyroid nodules using the convolutional neural network was applied to breast nodules. There were 665 benign breast lesions (63.0%) and 391 breast cancers (37.0%). The area under the receiver operating characteristic curve (AUROC) of AI-CAD to differentiate breast lesions was 0.678 (95% confidence interval: 0.649, 0.707). After fine-tuning AI-CAD with 1084 separate breast lesions, the diagnostic performance of AI-CAD markedly improved (AUC 0.841). This was significantly higher than that of radiologists when the cutoff category was BI-RADS 4a (AUC 0.621, P < 0.001), but lower when the cutoff category was BI-RADS 4b (AUC 0.908, P < 0.001). When applied to breast lesions, the diagnostic performance of an AI-CAD software that had been developed for differentiating malignant and benign thyroid nodules was not bad. However, an organ-specific approach guarantees better diagnostic performance despite the similar US features of thyroid and breast malignancies.

Implications of US radiomics signature for predicting malignancy in thyroid nodules with indeterminate cytology.

OBJECTIVES: The purpose of this study was to evaluate the role of the radiomics score using US images to predict malignancy in AUS/FLUS and FN/SFN nodules. METHODS: One hundred fifty-five indeterminate thyroid nodules in 154 patients who received initial US-guided FNA for diagnostic purposes were included in this retrospective study. A representative US image of each tumor was acquired, and square ROIs covering the whole nodule were drawn using the Paint program of Windows 7. Texture features were extracted by in-house texture analysis algorithms implemented in MATLAB 2019b. The LASSO logistic regression model was used to choose the most useful predictive features, and ten-fold cross-validation was performed. Two prediction models were constructed using multivariable logistic regression analysis: one based on clinical variables, and the other based on clinical variables with the radiomics score. Predictability of the two models was assessed with the AUC of the ROC curves. RESULTS: Clinical characteristics did not significantly differ between malignant and benign nodules, except for mean nodule size. Among 730 candidate texture features generated from a single US image, 15 features were selected. Radiomics signatures were constructed with a radiomics score, using selected features. In multivariable logistic regression analysis, higher radiomics score was associated with malignancy (OR = 10.923; p < 0.001). The AUC of the malignancy prediction model composed of clinical variables with the radiomics score was significantly higher than the model composed of clinical variables alone (0.839 vs 0.583). CONCLUSIONS: Quantitative US radiomics features can help predict malignancy in thyroid nodules with indeterminate cytology.

Comparison of diagnostic performance of the ACR and Kwak TIRADS applying the ACR TIRADS' size thresholds for FNA.

OBJECTIVE: To investigate the diagnostic performances and unnecessary fine-needle aspiration (FNA) rates of two point-scale based TIRADS and compare them with a modified version using the ACR TIRADS' size thresholds. METHODS: Our Institutional Review Board approved this retrospective study and waived the requirement for informed consent. A total of 2106 thyroid nodules 10 mm or larger in size in 2084 patients with definitive cytopathologic findings were included. Ultrasonography categories were assigned according to each guideline. We applied the ACR TIRADS' size thresholds for FNA to the Kwak TIRADS and defined it as the modified Kwak TIRADS (mKwak TIRADS). Diagnostic performances and unnecessary FNA rates were evaluated for both the original and modified guidelines. RESULTS: Of the original guidelines, the ACR TIRADS had higher specificity, accuracy, and area under the receiver operating characteristic curve (AUC) (63.1%, 68.9%, and 0.748, respectively). When the size threshold of the ACR TIRADS was applied to the Kwak TIRADS, the resultant mKwak TIRADS had higher specificity, accuracy, and AUC (64.7%, 70.3%, and 0.765, respectively) than the ACR TIRADS. The mKwak TIRADS also had a lower unnecessary FNA rate than the ACR TIRADS (54.8% and 56.4%, respectively). The false-negative rate of the Kwak TIRADS was the lowest (1.9%) among all TIRADS. CONCLUSION: The modified Kwak TIRADS incorporating the size thresholds of the ACR TIRADS showed higher diagnostic performance and a lower unnecessary FNA rate than the original point-scale based TIRADS. KEY POINTS: • Of the original guidelines, the ACR TIRADS had the highest specificity, accuracy, and area under the receiver operating characteristic curve (AUC) (63.1%, 68.9%, and 0.748, respectively). • When the size threshold of the ACR TIRADS was applied to the Kwak TIRADS, the resultant modified version of Kwak TIRADS had higher specificity, accuracy, and AUC (64.7%, 70.3%, and 0.765, respectively) than the ACR TIRADS. • The false-negative rate of the Kwak TIRADS was the lowest (1.9%) among all TIRADS.

Factors Predicting Breast Cancer Development in Women During Surveillance After Surgery for Atypical Ductal Hyperplasia of the Breast: Analysis of Clinical, Radiologic, and Histopathologic Features.

BACKGROUND: This study aimed to evaluate the risk of breast cancer development for women under surveillance after surgery for atypical ductal hyperplasia (ADH), as well as the clinical and pathologic factors associated with breast cancer development. METHODS: From November 2003 to December 2014, the study included 205 women (mean age, 47.1 ± 11.2 years; range 18-73 years) with a pathologic diagnosis of ADH at surgical excision who had preoperative mammography and ultrasonography (US) images and pathology slides available for review. The patients were classified into three groups according to the detection method as follows: negative group (with ADH occult on imaging), mammography group (with ADH detected on mammography), and US group (with ADH detected on US only). Clinical, radiologic, and histopathologic factors associated with breast cancer development after ADH surgery were evaluated. RESULTS: Breast cancer developed in 15 patients (7.3%) during surveillance after ADH surgery (follow-up period, 63.9 ± 40.8 months). Palpable lesions had significantly higher rates of breast cancer development after ADH surgery (26.7% vs 6.8%; P = 0.045). Breast cancer development after ADH surgery did not differ according to the detection method (P = 0.654). Palpability was significantly associated with breast cancer development during surveillance after ADH surgery (hazard ratio, 3.579; 95% confidence interval 1.048-12.220; P = 0.042). CONCLUSION: The breast cancer development rate for women under surveillance after ADH surgery was 7.3%. Palpability at the time of ADH diagnosis was significantly associated with breast cancer development.

Pattern-based vs. score-based guidelines using ultrasound features have different strengths in risk stratification of thyroid nodules.

OBJECTIVE: To evaluate and compare the diagnostic performances between recently published pattern-based and score-based TIRADS according to the experience level of the performer. METHODS: From July 2013 to January 2019, 8657 thyroid nodules in 8364 patients that had been cytopathologically diagnosed as benign or malignant were included (mean size, 22.0 mm ± 12.1). Thyroid nodules were categorized into US-based final assessment categories and US-FNA indications of five recently published TIRADS. Radiologists performing the US examinations were divided into the experienced vs. inexperienced group. Diagnostic performances and unnecessary biopsy rates were calculated and compared between the five TIRADS, also the experienced vs. inexperienced group. RESULTS: Of the 8657 thyroid nodules, 6706 (77.5%) were benign and 1951 (22.5%) were malignant. Diagnostic performances for US-based final assessment categories showed higher sensitivity and NPV for EU-TIRADS (92.7% and 96.5%), while Kwak-TIRADS had higher specificity, PPV, accuracy, and AUC (89.6%, 68.0%, 86.5%, and 0.878; all p < 0.05, respectively). Diagnostic performances for US-FNA indications showed higher sensitivity and NPV for KTA/KSThR TIRADS (98.5% and 97.0%), while Kwak-TIRADS had higher specificity, PPV, accuracy, and AUC (70.3%, 46.6%, 74.5%, and 0.797; all p < 0.05, respectively). Unnecessary biopsy rates were the lowest in Kwak-TIRADS for both US categories and US-FNA indications (32.0% and 53.4%, p < 0.001). Similar trends were seen in both the experienced and inexperienced group. CONCLUSION: The currently published score-based guidelines for thyroid nodules have significantly higher specificity, PPV, accuracy, and AUC and lower unnecessary biopsy rates, whereas pattern-based guidelines have higher sensitivity and NPV, regardless of the level of experience of the performer. KEY POINTS: • For US-based final assessment categories, EU-TIRADS had higher sensitivity and NPV, while Kwak-TIRADS had higher specificity, PPV, accuracy, and AUC. • For US-FNA indications, KTA/KSThR TIRADS had higher sensitivity and NPV, while Kwak-TIRADS had higher specificity, PPV, accuracy, and AUC. • Similar trends were seen in diagnostic performances for both experienced and inexperienced groups.

Comparing recall rates following implementation of digital breast tomosynthesis to synthetic 2D images and digital mammography on women with breast-conserving surgery.

OBJECTIVES: To evaluate the recall rates of digital mammography (DM) and synthetic images after adding digital breast tomosynthesis (DBT) in patients with breast-conserving surgery. METHODS: From November 2015 to April 2017, 229 women with breast-conserving surgery due to breast cancer who underwent DBT after surgery were included (mean interval, 12.9 ± 1.4 months). All women underwent combo-mode DBT examinations including full-field DM, tomosynthesis, and reconstructed synthetic 2D images. Three board-certified breast radiologists reviewed the images sequentially: synthetic 2D+DBT and, 1 month later, DM and then DM+DBT. Recall rates and the abnormality type causing the recall were calculated and compared for each mammographic modality and breast density. RESULTS: Of the 229 patients included, 230 mammography images were reviewed. One patient (0.4%) developed locoregional recurrences during follow-up (mean duration, 25.8 ± 4.5 months). Recall rates for synthetic 2D+DBT were significantly lower than for DM alone (4.1% (2.6-6.2) vs. 11.6% (9.2-14.5), respectively; p < 0.001). Recall rates did not differ between synthetic 2D+DBT and DM+DBT (4.1% (2.6-6.2) vs. 2.9% (1.9-4.5), respectively; p = 0.234). Recall rates of synthetic 2D+DBT and DM+DBT were significantly lower than those of DM alone, regardless of mammographic breast density (all p < 0.05, respectively). CONCLUSION: Adding DBT to synthetic 2D images or DM shows significant reduction in recall rates compared with DM alone for women who undergo breast-conserving surgery for breast cancer, regardless of mammographic density. KEY POINTS: • Recall rates for synthetic 2D+DBT were significantly lower than those of DM alone (4.1% (2.6-6.2) vs. 11.6% (9.2-14.5), respectively; p < 0.001). • No significant differences were seen in recall rates between synthetic 2D+DBT and DM+DBT (4.1 (2.6-6.2) vs. 2.9 (1.9-4.5), respectively; p = 0.234). • Reader-averaged recall rates after adding DBT to synthetic 2D or DM were significantly lower than those of DM alone, regardless of mammographic breast density (all p < 0.05, respectively).

BI-RADS category 3, 4, and 5 lesions identified at preoperative breast MRI in patients with breast cancer: implications for management.

OBJECTIVES: To investigate outcomes and retrospectively evaluate characteristics of additional lesions initially assessed as BI-RADS category 3, 4, and 5 at preoperative MRI to determine appropriate follow-up management. METHODS: We retrospectively reviewed 429 lesions other than primary cancer initially assessed as BI-RADS category 3, 4, and 5 at preoperative MRI in 391 patients with breast cancer from March 2012 to December 2013. We investigated their malignancy rate and outcome according to BI-RADS category assessments. We also analyzed clinical and imaging characteristics of each lesion. Pathological results and imaging follow-up of at least 2 years were used as reference standards. RESULTS: Of 429 lesions in 391 patients (mean 48.1 years ± 9.4), the malignancy rate of BI-RADS 3, 4, and 5 lesions was 1.4% (3/213), 17.8% (38/214), and 50% (1/2), respectively. Of BI-RADS 3 lesions or BI-RADS 4 or 5 lesions that were followed up after benign-concordant biopsy (n = 114), two contralateral masses (2/306, 0.7%) were diagnosed as malignancy at 13.3 and 33.2 months after initial detection, within a median follow-up of 63.3 months. None of the NME or foci or lesions followed up after benign-concordant biopsy had a delayed diagnosis of malignancy. Of the 391 patients, 97.4% (381/391) received at least one type of adjuvant therapy. CONCLUSION: The incidence of delayed cancer diagnosis among additionally detected lesions other than primary cancer is very low and short-term follow-up is unnecessary. Contralateral masses which were not confirmed by biopsy may need annual follow-up. KEY POINTS: • 1.4% (3/213) of BI-RADS 3 lesions were malignant including 2 delayed diagnoses after 13.2 months and 33.2 months, and 17.8% (38/214) of BI-RADS 4 lesions and 50% (1/2) of BI-RADS 5 lesions were malignant. • The incidence of delayed diagnosis from additional MRI-detected lesions was very low (0.7%, 2/306) during follow-up, which were all T1N0 contralateral cancer. • Annual follow-up might be adequate for preoperative MRI-detected BI-RADS 3 lesions and BI-RADS 4 lesions followed up after benign-concordant biopsy.

Guideline Implementation on Fine-Needle Aspiration for Thyroid Nodules: Focusing on Micronodules.

OBJECTIVE: We investigated patients who were referred to our institution after fine-needle aspiration (FNA) was performed at outside clinics to evaluate how many nodules satisfied the FNA indications of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and compare that to the number of thyroid nodules that satisfy the FNA indications of the American College of Radiology (ACR)-TIRADS and American Thyroid Association (ATA) guidelines. METHODS: Between January 2018 and December 2018, 2,628 patients were included in our study. The included patients were those referred for thyroid surgery after having a suspicious thyroid nodule. We retrospectively applied the three guidelines to each thyroid nodule and determined whether each nodule satisfied the FNA indications. We compared the proportion of nodules satisfying the FNA indications of each guideline using a generalized linear model and generalized estimating equation. RESULTS: The median size of the 2,628 thyroid nodules was 0.9 cm (range, 0.2 to 9.5 cm). We found that FNA was not indicated for 54.1%, 47.7%, and 19.1% of nodules and 87.3%, 99.0%, and 97.8% among them were micronodules (<1 cm) according to the ACR-TIRADS, ATA guideline, and K-TIRADS, respectively. The proportion of micronodules which satisfied the FNA indications was significantly higher for the K-TIRADS (65.1%) compared to the ACR TIRADS (12.1%) and ATA guideline (12.1%) (P<.001). CONCLUSION: Among patients referred for thyroid surgery to our institutions, about 35% of the micronodules underwent FNA despite not being appropriate for indications by the K-TIRADS. Systematic training for physicians as well as modifications to increase the sensitivity of the guideline may be needed to reduce the overdiagnosis of thyroid cancers, especially for micronodules.

Role of elastography for downgrading BI-RADS category 4a breast lesions according to risk factors.

BACKGROUND: Elastography has been introduced as an additional diagnostic tool to ultrasonography (US) which helps clinicians decide whether or not to perform biopsy on US-detected lesions. PURPOSE: To evaluate the role of strain elastography in downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4a breast lesions according to personal risk factors for breast cancer in asymptomatic women. MATERIAL AND METHODS: Strain elastography features of a total of 255 asymptomatic category 4a lesions were classified as soft and not soft (intermediate and hard). Malignancy was confirmed by surgery or biopsy, and benignity was confirmed by surgery or biopsy with no change on US for at least six months. Malignancy rates of lesions with soft and not soft elastography were calculated according to the presence of risk factors. RESULTS: Of 255 lesions, 25 (9.8%) were malignant and 230 (90.2%) were benign. Of 195 lesions in average-risk women, the malignancy rate of lesions with soft elastography was 1.5% (1/68), which was significantly lower than the 14.2% (18/127) of lesions with not soft elastography ( P = 0.004). Of 60 lesions in increased-risk women, the malignancy rate of lesions with soft elastography was 15.0% (3/20), which was not significantly different from the 7.5% (3/40) of lesions with not soft elastography ( P = 0.390). CONCLUSION: In average-risk women, category 4a lesions with soft elastography could be followed up with US because of a low malignancy rate of 1.5%.

Breast magnetic resonance imaging for surveillance of women with a personal history of breast cancer: outcomes stratified by interval between definitive surgery and surveillance MR imaging.

BACKGROUND: Women with a personal history of breast cancer are at increased risk of future breast cancer events, and may benefit from supplemental screening methods that could enhance early detection of subclinical disease. However, current literature on breast magnetic resonance (MR) imaging surveillance is limited. We investigated outcomes of surveillance breast magnetic resonance (MR) imaging in women with a personal history of breast cancer. METHODS: We reviewed 1053 consecutive breast MR examinations that were performed for surveillance in 1044 women (median age, 53 years; range, 20-85 years) previously treated for breast cancer between August 2014 and February 2016. All patients had previously received supplemental surveillance with ultrasound. Cancer detection rate (CDR), abnormal interpretation rate and characteristics of MR-detected cancers were assessed, including extramammary cancers. We also calculated the PPV 1 , PPV 3 , sensitivity and specificity for MR-detected intramammary lesions. Performance statistics were stratified by interval following initial surgery. RESULTS: The CDR for MR-detected cancers was 6.7 per 1000 examinations (7 of 1053) and was 3.8 per 1000 examinations (4 of 1053) for intramammary cancers. The overall abnormal interpretation rate was 8.0%, and the abnormal interpretation rate for intramammary lesions was 7.2%. The PPV1, PPV3, sensitivity and specificity for intramammary lesions was 5.3% (4 of 76), 15.8% (3 of 19), 75.0% (3 of 4) and 98.3% (1031 of 1049), respectively. For MR examinations performed ≤36 months after surgery, the overall CDR was 1.4 per 1000 examinations. For MR examinations performed > 36 months after surgery, the overall CDR was 17.4 per 1000 examinations. CONCLUSIONS: Surveillance breast MR imaging may be considered in women with a history of breast cancer, considering the low abnormal interpretation rate and its high specificity. However, the cancer detection rate was low and implementation may be more effective after more than 3 years after surgery.

Role of dynamic contrast-enhanced MRI in evaluating the association between contralateral parenchymal enhancement and survival outcome in ER-positive, HER2-negative, node-negative invasive breast cancer.

BACKGROUND: Background parenchymal enhancement (BPE) on dynamic contrast-enhanced (DCE)-MRI has been associated with breast cancer risk, both based on qualitative and quantitative assessments. PURPOSE: To investigate whether BPE of the contralateral breast on preoperative DCE-MRI is associated with therapy outcome in ER-positive, HER2-negative, node-negative invasive breast cancer. STUDY TYPE: Retrospective. POPULATION: In all, 289 patients with unilateral ER-positive, HER2-negative, node-negative breast cancer larger than 5 mm. FIELD STRENGTH/SEQUENCE: 3T, T1 -weighted DCE sequence. ASSESSMENT: BPE of the contralateral breast was assessed qualitatively by two dedicated radiologists and quantitatively (using region-of-interest and automatic breast segmentation). STATISTICAL TESTS: Cox regression analysis was used to determine associations with recurrence-free survival (RFS) and distant metastasis-free survival (DFS). Interobserver variability for parenchymal enhancement was assessed using kappa statistics and intraclass correlation coefficient (ICC). RESULTS: The median follow-up time was 75.8 months. Multivariate analysis showed receipt of total mastectomy (hazard ratio [HR]: 5.497) and high Ki-67 expression level (HR: 5.956) were independent factors associated with worse RFS (P < 0.05). Only a high Ki-67 expression level was associated with worse DFS (HR: 3.571, P = 0.045). BPE assessments were not associated with outcome (RFS [qualitative BPE: P = 0.75, 0.92 for readers 1 and 2; quantitative BPE: P = 0.38-0.99], DFS, [qualitative BPE: P = 0.41, 0.16 for readers 1 and 2; quantitative BPE: P = 0.68-0.99]). For interobserver variability, there was good agreement between qualitative (κ = 0.700) and good to perfect agreement for most quantitative parameters of BPE. DATA CONCLUSION: Contralateral BPE showed no association with survival outcome in patients with ER-positive, HER2-negative, node-negative invasive breast cancer. A high Ki-67 expression level was associated with both worse recurrence-free and distant metastasis-free survival. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;48:1678-1689.

Thyroid Nodules With Nondiagnostic Cytologic Results: Follow-Up Management Using Ultrasound Patterns Based on the 2015 American Thyroid Association Guidelines.

OBJECTIVE: The purpose of this study was to evaluate the malignancy rate of nodules with nondiagnostic cytologic results based on the American Thyroid Association (ATA) ultrasound (US) patterns and to suggest management guidelines for these nodules. MATERIALS AND METHODS: From January 2013 to December 2014, 441 nodules (≥ 1 cm) were found in 437 patients with nondiagnostic results of ultrasound (US)-guided fine-needle aspiration biopsy (nondiagnostic nodules). A total of 191 nodules that were cytopathologically confirmed or were smaller (> 3 mm) at follow-up US were enrolled. The US findings of each nodule were reviewed. One radiologist classified the nodules into the following five categories according to the 2015 ATA guidelines: high, intermediate, low, and very low suspicion for malignancy and benign. The reference standard was histopathologic confirmation. Nodules that were smaller at follow-up US were considered benign. The malignancy rate of each category was calculated. RESULTS: Among a total 191 nodules, 20 (10.5%) were malignant. Solid composition, marked hypoechogenicity, microlobulated or irregular margins, microcalcifications, and taller-than-wide shape were more frequently seen in malignant nodules (all p < 0.001). The malignancy rate of nodules with very low suspicion of malignancy was 0% (0/58); low, 0% (0/45); intermediate, 10.3% (6/58); and high, 46.7% (14/30) (p < 0.001). CONCLUSION: When US findings of thyroid nodules are assessed according to the 2015 ATA guidelines, nondiagnostic thyroid nodules with very-low- or low-suspicion US patterns can be followed up with US. Nondiagnostic nodules with intermediate or highly suspicious US patterns should be evaluated with repeat US-guided fine-needle aspiration biopsy.

Intrinsic Subtypes of Breast Cancers Initially Assessed as Probably Benign or of Low Suspicion on Ultrasonography Differ According to Tumor Size.

OBJECTIVES: To investigate whether the intrinsic subtypes of breast cancers initially assessed as American College of Radiology Breast Imaging and Reporting System (BI-RADS) category 3 or 4a differ according to tumor size. METHODS: A total of 444 breast cancers in 439 patients initially assessed as BI-RADS 3 or 4a through ultrasound-guided core needle biopsy were included. Tumors were classified by the size criterion of 10 mm or smaller or larger than 10 mm and categorized as the luminal type (estrogen receptor [ER] positive and/or progesterone receptor [PR] positive and human epidermal growth factor receptor 2 [HER2] negative), HER2 type (HER2 positive regardless of ER or PR status), or triple-negative type (ER negative, PR negative, and HER2 negative). The relationships between tumor size and breast cancer intrinsic subtypes were analyzed. RESULTS: A total of 247 (55.6%) cancers were 10 mm or smaller, and 197 (44.4%) were larger than 10 mm. The luminal type was more frequently present in tumors of 10 mm or smaller (185 of 247 [74.9%]) than those larger than 10 mm (112 of 197 [56.9%]; P < .001). No significant difference was noted in the frequency of the HER2 type in tumors of 10 and mm smaller and those larger than 10 mm (27 of 247 [10.9%] versus 36 of 197 [18.3%]; P = .084). The triple-negative type was more frequently present in tumors larger than 10 mm than those of 10 mm or smaller (49 of /197 [24.9%] versus 35 of 247 [14.2%]; P = .012). CONCLUSIONS: Breast cancers assessed as BI-RADS category 3 or 4a had differing intrinsic subtypes according to tumor size, as the luminal type was more frequently present in tumors of 10 mm or smaller than those larger than 10 mm, whereas the triple-negative type was more frequently present in tumors larger than 10 mm.

Perfusion Parameters on Breast Dynamic Contrast-Enhanced MRI Are Associated With Disease-Specific Survival in Patients With Triple-Negative Breast Cancer.

OBJECTIVE: The aim of this study was to investigate the association between perfusion parameters on MRI performed before treatment and survival outcome (disease-free survival [DFS], disease-specific survival [DSS]) in patients with triple-negative breast cancer (TNBC). MATERIALS AND METHODS: Sixty-one patients (median age, 50 years; age range, 27-77 years) with TNBC (tumor size on MRI: median, 25.5 mm; range, 11.0-142.0 mm) were included. We analyzed clinical and pathologic variables and MRI parameters. Cox proportional hazards models were used to determine associations with survival outcome. RESULTS: The median follow-up time was 46.1 months (range, 13.9-58.4 months). Eleven of 61 (18.0%) patients had events (i.e., local, regional, or distant recurrence or contralateral breast cancer) and seven (11.5%) died of breast cancer. Among the pretreatment variables, a larger tumor size on MR images (hazard ratio [HR] = 1.024, p = 0.003) was associated with worse DFS at univariate analysis. In multivariate pretreatment models for DSS, a higher fractional volume of extravascular extracellular space per unit volume of tissue (ve) value (HR = 1.658, p = 0.038), higher peak enhancement (HR = 1.843, p = 0.018), and a larger tumor size on MR images (HR = 1.060, p = 0.001) were associated with worse DSS. In multivariate posttreatment models, a larger pathologic tumor size (HR for DFS, 1.074 [p = 0.005]; HR for DSS, 1.050 [p = 0.042]) and metastasis in surgically resected axillary lymph nodes (HR for DFS, 5.789 [p = 0.017]; HR for DSS, 23.717 [p = 0.005]) were associated with worse survival outcome. CONCLUSION: A higher ve value, higher peak enhancement, and larger tumor size of the primary tumor on pretreatment MRI were independent predictors of worse DSS in patients with TNBC.