Radial Scars of the Breast Encountered at Core Biopsy: Review of Histologic, Imaging, and Management Considerations

A Nomogram Based on Conventional Ultrasound Radiomics for Differentiating Between Radial Scar and Invasive Ductal Carcinoma of the Breast

ABSTRACT

We aimed to develop and validate a nomogram based on conventional ultrasound (CUS) radiomics model to differentiate radial scar (RS) from invasive ductal carcinoma (IDC) of the breast. In total, 208 patients with histopathologically diagnosed RS or IDC of the breast were enrolled. They were randomly divided in a 7:3 ratio into a training cohort (n = 145) and a validation cohort (n = 63). Overall, 1316 radiomics features were extracted from CUS images. Then a radiomics score was constructed by filtering unstable features and using the maximum relevance minimum redundancy algorithm and the least absolute shrinkage and selection operator logistic regression algorithm. Two models were developed using data from the training cohort: one using clinical and CUS characteristics (Clin + CUS model) and one using clinical information, CUS characteristics, and the radiomics score (radiomics model). The usefulness of nomogram was assessed based on their differentiating ability and clinical utility. Nine features from CUS images were used to build the radiomics score. The radiomics nomogram showed a favorable predictive value for differentiating RS from IDC, with areas under the curve of 0.953 and 0.922 for the training and validation cohorts, respectively. Decision curve analysis indicated that this model outperformed the Clin + CUS model and the radiomics score in terms of clinical usefulness. The results of this study may provide a novel method for noninvasively distinguish RS from IDC.

The conundrum of breast cancer mimics

The BIRADS lexicon ensures a standard reporting terminology in breast imaging and serves as a means of smooth communication between the radiologist and the referring physician. BIRADS assessment categories 4 and 5 warrant a biopsy to rule out underlying malignancy. However, a substantial number of cases in these categories sometimes turn out to be benign on biopsy. These benign mimics encompass inflammatory, sclerosing, neoplastic and a few other miscellaneous conditions. Awareness of these various mimics of breast cancer can equip the radiologist to handle these apparent cases of radiologic-pathological (rad-path) discordance better, guide overall patient management, avoiding inadvertent excisional biopsies and help alleviate patient anxiety and confusion.

Updates in the Surgical Management of Benign and High-Risk Breast Lesions

Benign breast disease (BBD) is a heterogenous group of lesions often classified as nonproliferative or proliferative, with the latter group further categorized based on the presence of atypia. Although nonproliferative lesions are more common, the risk of breast cancer is elevated in women with proliferative lesions. Historically, the majority of proliferative lesions were excised due to concern for future and/or concomitant breast cancer at the site of the index lesion. However, contemporary data suggest that the risk of cancer associated with various proliferative lesions may be lower than previously thought, and management of BBD has become more nuanced. In this review, we will focus on recent updates in the management of a select group of benign and high-risk lesions.

Radial Scars on Screening Digital Breast Tomosynthesis: Upstaging Rates and Management Strategies

BACKGROUND. Radial scars are more commonly identified on digital breast tomosynthesis (DBT) than on digital mammography (DM). Nonetheless, universal guidelines for radial scar management in the current era of DBT are lacking. OBJECTIVE. The purpose of this study was to determine the upstaging rates of screening DBT-detected radial scars with and without atypia and to identify features related to upstaging risk. METHODS. This retrospective study included patients who underwent core needle biopsy (CNB) showing a radial scar after screening DBT and DM from January 1, 2013, to December 31, 2020. Patients without surgical excision or at least 2 years of imaging follow-up after CNB were excluded. Rates of upstaging to breast cancer (ductal carcinoma in situ [DCIS] or invasive disease) were compared between radial scars with and without atypia at CNB. Associations of upstaging with patient, imaging, and pathologic variables were explored using standard statistical tests. RESULTS. Of 165 women with 171 radial scars, the final study sample included 153 women (mean age, 56 years; range, 33-83 years) with 159 radial scars that underwent surgical excision (80.5%, 128/159) or at least 2 years of imaging follow-up (19.5%, 31/159). Seven radial scars were upstaged to DCIS and one to invasive disease. Therefore, the up-staging rate of radial scars to cancer was 5.0% (8/159). The upstaging rate of radial scars without atypia at CNB was 1.6% (2/129) and that of radial scars with atypia was 20.0% (6/30) (p < .001). On multivariable analysis, features associated with higher upstaging risk included a prior breast cancer diagnosis (62.5% vs 4.8%; p = .01) and the presence of atypia at CNB (75.0% vs 15.9%; p = .02). The upstaging rate according to mammographic finding type was 7.1% (1/14) for asymmetries, 12.5% (2/16) for masses, 5.3% (5/95) for architectural distortion, and 0.0% (0/34) for calcifications. CONCLUSION. Screening-detected radial scars without atypia at CNB have a low upstaging rate to breast cancer of 1.6%. CLINICAL IMPACT. Imaging surveillance rather than surgery is a reasonable approach for radial scars without atypia, particularly for those presenting as calcifications.

Meta-analysis: Radial Scar and Breast MRI

BACKGROUND

The implementation of digital breast tomosynthesis has increased the detection of radial scar (RS). Managing this finding may be experienced as a clinical dilemma in daily practice. Breast Contrast-Enhanced MRI (CE-BMR) is a known modality in case of problem-solving tool for mammographic abnormalities. However, the data about AD and CE-BMR are scant.

OBJECTIVE

The purpose was to estimate the benefit of CE-BMR in the setting of RS detected mammographically through a systematic review and meta-analysis of the literature.

METHODS

A search of MEDLINE and EMBASE databases were conducted in 2022. Based on the PRISMA guidelines, an analysis was performed. The primary endpoint was the correlation between CE-BMR findings and definite outcome for RS (pure RS versus RS associated with atypia or malignancy).

RESULTS

Three studies were available. The negative predictive value (NPV) was 100% for each.

CONCLUSION

The high NPV could allow for deferral of a biopsy in favor of a short-interval imaging follow-up in the setting of a negative CE-BMR.

Retained Biopsy Site Markers After Breast Lesion Surgical Resection: Associations With Residual Malignancy

BACKGROUND. Biopsy site markers (BSMs) placed during image-guided core needle biopsy (CNB) are typically targeted for surgical excision, along with the breast imaging abnormality. Retained BSMs raise concern of incomplete resection of the breast abnormality. OBJECTIVE. The purpose of our study was to assess the frequency of residual malignancy in patients with retained BSMs identified on the initial mammography performed after breast lesion surgical excision. METHODS. This retrospective study included 30 patients (median age, 59 years) who underwent surgical resection between August 2015 and April 2022 of a borderline, high-risk, or malignant breast lesion after CNB and technically adequate preoperative image-guided localization, in whom the initial postoperative mammography report described a retained nonmigrated BSM. EMR data were extracted. The index pathology from CNB and initial surgical resection was classified as malignant or nonmalignant. The presence of residual malignancy after initial surgical resection required pathologic confirmation from subsequent tissue sampling; the absence of residual malignancy required 2 years of benign imaging follow-up. RESULTS. Thirteen specimen radiographs were interpreted intraoperatively by a surgeon with later radiologist interpretation, and 17 underwent real-time radiologist interpretation. Eighteen patients had malignant index pathology from the initially resected lesion. The frequency of residual malignancy on subsequent follow-up after initial surgical resection was higher in patients with malignant than nonmalignant index pathology (39% [7/18] vs 0% [0/12], respectively; p = .02). Among patients with malignant index pathology, the frequency of residual malignancy was higher in those without, than with, malignancy in the initial surgical specimen (80% [4/5] vs 23% [3/13]; p = .047). Also in these patients, the frequency of a positive interpretation of the initial postoperative mammography (BI-RADS category 4 or 6) was not significantly different between those with and without residual malignancy (57% [4/7] vs 55% [6/11]; p > .99). CONCLUSION. Patients with retained BSMs associated with malignant index lesions are at substantial risk of having residual malignancy. Initial postoperative mammography is not sufficient for excluding residual malignancy. CLINICAL IMPACT. Retained BSMs associated with index malignancy should be considered suspicious for residual malignancy. In this scenario, timely additional tissue sampling targeting the retained BSM is warranted, given the greater-than-2% chance of malignancy. Active surveillance is a reasonable management strategy in patients with retained BSMs from nonmalignant index lesions.

European guidelines for the diagnosis, treatment and follow-up of breast lesions with uncertain malignant potential (B3 lesions) developed jointly by EUSOMA, EUSOBI, ESP (BWG) and ESSO

INTRODUCTION

Breast lesions of uncertain malignant potential (B3) include atypical ductal and lobular hyperplasias, lobular carcinoma in situ, flat epithelial atypia, papillary lesions, radial scars and fibroepithelial lesions as well as other rare miscellaneous lesions. They are challenging to categorise histologically, requiring specialist training and multidisciplinary input. They may coexist with in situ or invasive breast cancer (BC) and increase the risk of subsequent BC development. Management should focus on adequate classification and management whilst avoiding overtreatment. The aim of these guidelines is to provide updated information regarding the diagnosis and management of B3 lesions, according to updated literature review evidence.

METHODS

These guidelines provide practical recommendations which can be applied in clinical practice which include recommendation grade and level of evidence. All sections were written according to an updated literature review and discussed at a consensus meeting. Critical appraisal by the expert writing committee adhered to the 23 items in the international Appraisal of Guidelines, Research and Evaluation (AGREE) tool.

RESULTS

Recommendations for further management after core-needle biopsy (CNB) or vacuum-assisted biopsy (VAB) diagnosis of a B3 lesion reported in this guideline, vary depending on the presence of atypia, size of lesion, sampling size, and patient preferences. After CNB or VAB, the option of vacuum-assisted excision or surgical excision should be evaluated by a multidisciplinary team and shared decision-making with the patient is crucial for personalizing further treatment. De-escalation of surgical intervention for B3 breast lesions is ongoing, and the inclusion of vacuum-assisted excision (VAE) will decrease the need for surgical intervention in further approaches. Communication with patients may be different according to histological diagnosis, presence or absence of atypia, or risk of upgrade due to discordant imaging. Written information resources to help patients understand these issues alongside with verbal communication is recommended. Lifestyle interventions have a significant impact on BC incidence so lifestyle interventions need to be suggested to women at increased BC risk as a result of a diagnosis of a B3 lesion.

CONCLUSIONS

These guidelines provide a state-of-the-art overview of the diagnosis, management and prognosis of B3 lesions in modern multidisciplinary breast practice.

Upgrade risk of image-targeted radial scar and complex sclerosing lesions diagnosed at needle-guided biopsy: a retrospective study

OBJECTIVES

To determine the upgrade rate of radial scar (RS) and complex sclerosing lesions (CSL) diagnosed with percutaneous biopsy. The secondary objectives were to determine the new atypia rate after surgery and to assess the diagnosis of subsequent malignancy on follow-up.

METHODS

This single-institution retrospective study had IRB approval. All image-targeted RS and CSL diagnosed with percutaneous biopsy between 2007 and 2020 were reviewed. Patient demographics, imaging presentation, biopsy characteristics, histological report, and follow-up data were collected.

RESULTS

During the study period, 120 RS/CSL were diagnosed in 106 women (median age, 43.5 years; range, 23-74), and 101 lesions were analyzed. At biopsy, 91 (90.1%) lesions were not associated with another atypia or malignancy and 10 (9.9%) were associated with another atypia. Out of the 91 lesions that were not associated with malignancy or atypia, 75 (82.4%) underwent surgical excision, and one upgrade to low-grade CDIS was detected (1.3%). Among the 10 lesions initially associated with another atypia, 9 were surgically excised and no malignancy was detected. After a median follow-up of 47 months (range: 12-143 months), two (1.98%) developed malignancy in a different quadrant; in both cases, another atypia was present at biopsy.

CONCLUSION

We found a low upgrade rate on image-detected RS/CSL, with or without another atypia associated. Associated atypia was underdiagnosed at biopsy in almost one-third of cases. Subsequent cancer risk could not be established because the only two cases were associated with another high-risk lesion (HRL), which might have increased the patient's risk of developing malignancy.

CLINICAL RELEVANCE STATEMENT

Our upgrade rates of RS/CSL with or without atypia diagnosed with core needle biopsy are almost as low as the ones reported with larger sampling methods. This result has particular importance in places with limited accessibility to US-guided vacuum-assisted biopsy.

KEY POINTS

•New evidence is showing lower upgrade rates of RS and CSL after surgery, leading to a more conservative management with extensive sampling using VAB or VAE. •Our study showed only one upgrade to a low-grade DCIS after surgery, yielding an upgrade rate of 1.33%. •During follow-up, no new malignancy was detected in the same quadrant where RS/CSL was diagnosed, including patients without surgery.

Imaging and Management of Radial Scars and Complex Sclerosing Lesions

Radial scars and complex sclerosing lesions, often collectively referred to as radial sclerosing lesions (RSLs), are breast lesions characterized by sclerotic stroma with entrapped epithelial elements. RSLs have imaging features that overlap with those of breast malignancy and often become the target of imaging-guided biopsy given their suspicious imaging appearance. These can be identified in isolation or can also be associated with atypia or other high-risk lesions that have intrinsic malignant potential, increasing the risk of carcinoma and affecting prognosis and management of RSLs. Because of this, management of these lesions remains controversial. Traditional management has been surgical excisional biopsy. However, as more RSLs are identified (because digital breast tomosynthesis allows identification of more architectural distortions), optimal management is evolving. Physicians in some practices are using a multidisciplinary approach to the management of RSLs when deciding on surgical excision of these lesions versus imaging follow-up. These discussions also incorporate individual patient risk factors and greater patient informed medical decision making. Reported upgrade rates of RSLs at core needle biopsy vary and can depend on the sampling method, number of samples, gauge of the needle, target being sampled, and radiologic-pathologic concordance or discordance. A precise sampling technique also allows greater accuracy of diagnosis and lower upgrade rates for these lesions, with radiologic-pathologic correlation as an integral component for further management decisions. The authors review the overall histopathologic, clinical, and imaging features of RSLs and discuss appropriate management based on currently available data regarding upgrade rates. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Demystifying Breast Disease Markers

Breast imaging radiologists regularly perform image-guided biopsies of suspicious breast lesions based on features that are associated with a likelihood of malignancy ranging from 2% to greater than 95% (Breast Imaging Reporting and Data System categories 4 and 5). As diagnostic partners, pathologists perform histopathologic assessment of these tissue samples to confirm a diagnosis. Correlating the imaging findings with the histopathologic results is an integral aspect of multidisciplinary breast care. Assessment of radiologic-pathologic concordance is vital in guiding appropriate management, as it enables identification of discordant results, minimizing the chance of misdiagnosis. Undersampling can lead to false-negative results, with the frequencies of false-negative diagnoses varying on the basis of multiple factors, including biopsy type (eg, core needle, vacuum-assisted needle), needle gauge, and type of lesion sampled at biopsy (ie, mass, calcifications, asymmetry, architectural distortion). Improving a radiologist's knowledge of macroscopic and microscopic breast anatomy and more common breast diseases and their expected imaging findings ensures more accurate radiologic-pathologic correlation and management recommendations. The histopathologic and molecular characteristics of biopsy-sampled breast lesions aid in making an accurate diagnosis. Hematoxylin-eosin staining provides critical morphologic details, whereas immunohistochemical staining enables molecular characterization of many benign and malignant lesions, which is critical for tailored treatment. The authors review commonly encountered benign and malignant breast diseases, their corresponding histopathologic phenotypes, and the histopathologic markers that are essential to clinching the diagnosis of these entities. As part of a multidisciplinary team that provides optimal patient care, radiologists should be knowledgeable of the foundations of histopathologic diagnosis and the implications for patient management to ensure appropriate radiologic-pathologic concordance. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Diagnostic Pitfalls in Breast Cancer Pathology With an Emphasis on Core Needle Biopsy Specimens

CONTEXT.—

Breast pathology has many mimics and diagnostic pitfalls. Evaluation of malignant breast lesions, particularly in the biopsy setting, can be especially challenging, with diagnostic errors having significant management implications.

OBJECTIVE.—

To discuss the pitfalls encountered when evaluating ductal carcinoma in situ and invasive breast carcinomas, providing histologic clues and guidance for appropriate use and interpretation of immunohistochemistry to aid in the correct diagnosis.

DATA SOURCES.—

Data were obtained from review of pertinent literature of ductal carcinoma in situ and invasive breast carcinomas and from the experience of the authors as practicing breast pathologists.

CONCLUSIONS.—

Awareness of the pitfalls in diagnosing breast cancers is important when creating a differential diagnosis for each breast lesion evaluated. This review will cover some of these scenarios to aid in the diagnostic process.

Radial scar appearances on contrast-enhanced mammography

With modern technological advances in imaging, radial scars are more frequently encountered in clinical practice. The management of radial scars remains challenging due to associated upgrade to malignancy at excision. Contrast-enhanced mammography (CEM) has a similar sensitivity compared to MRI in addition to lower cost, better availability and fewer contra-indications. CEM is reported to have an overall excellent negative predictive value for malignancy. In this study, imaging of 55 patients with a core biopsy diagnosis of radial scar since the introduction of CEM into local practice was reviewed. Nine patients underwent CEM as part of their diagnostic work-up and these appearances are presented as a pictorial essay to demonstrate enhancement patterns of radial scars on CEM in this cohort and consider how this knowledge may influence management.

Third International Consensus Conference on lesions of uncertain malignant potential in the breast (B3 lesions)

The heterogeneous group of B3 lesions in the breast harbors lesions with different malignant potential and progression risk. As several studies about B3 lesions have been published since the last Consensus in 2018, the 3rd International Consensus Conference discussed the six most relevant B3 lesions (atypical ductal hyperplasia (ADH), flat epithelial atypia (FEA), classical lobular neoplasia (LN), radial scar (RS), papillary lesions (PL) without atypia, and phyllodes tumors (PT)) and made recommendations for diagnostic and therapeutic approaches. Following a presentation of current data of each B3 lesion, the international and interdisciplinary panel of 33 specialists and key opinion leaders voted on the recommendations for further management after core-needle biopsy (CNB) and vacuum-assisted biopsy (VAB). In case of B3 lesion diagnosis on CNB, OE was recommended in ADH and PT, whereas in the other B3 lesions, vacuum-assisted excision was considered an equivalent alternative to OE. In ADH, most panelists (76%) recommended an open excision (OE) after diagnosis on VAB, whereas observation after a complete VAB-removal on imaging was accepted by 34%. In LN, the majority of the panel (90%) preferred observation following complete VAB-removal. Results were similar in RS (82%), PL (100%), and FEA (100%). In benign PT, a slim majority (55%) also recommended an observation after a complete VAB-removal. VAB with subsequent active surveillance can replace an open surgical intervention for most B3 lesions (RS, FEA, PL, PT, and LN). Compared to previous recommendations, there is an increasing trend to a de-escalating strategy in classical LN. Due to the higher risk of upgrade into malignancy, OE remains the preferred approach after the diagnosis of ADH.

Prevalence, Impact, and Diagnostic Challenges of Benign Breast Disease: A Narrative Review

Benign breast diseases, which are commonly seen in clinical practice, have various clinical presentations and implications, as well as management strategies. This article describes common benign breast lesions, presentations of these lesions, and typical radiographic and histologic findings. Also included in this review are the most recent data and guideline-based recommendations for the management of benign breast diseases at diagnosis, including surgical referral, medical management, and ongoing surveillance.

Pathologic Outcomes in Single Versus Multiple Areas of Architectural Distortion on Digital Breast Tomosynthesis

BACKGROUND. Digital breast tomosynthesis (DBT) has led to increased detection of architectural distortion (AD). Management of patients with multiple areas of AD is not established. OBJECTIVE. The purpose of this article is to compare pathologic outcomes between single and multiple areas of AD identified on DBT. METHODS. This retrospective study included 402 patients (mean age, 56 years) who underwent image-guided core needle biopsy of AD visualized on DBT between April 7, 2017, and April 16, 2019. Patients were classified as having a single or multiple areas of AD according to the presence of distinct areas of AD described in the clinical radiology reports. The pathologic diagnosis for each AD was on the basis of the most aggressive pathology identified on either biopsy or surgical excision, if performed. Patients with single and multiple areas of AD were compared. RESULTS. The sample included 372 patients with a single AD (145 benign, 121 high risk, 105 malignant, one other) and 30 patients with multiple visualized ADs, including 66 biopsied ADs (10 benign, 35 high risk, 21 malignant). At pathologic assessment on a per-lesion basis, multiple compared with single ADs showed higher frequency of high-risk pathology (53.0% vs 32.5%, p = .002) but no difference in frequency of malignancy (31.8% vs 28.2%, p = .56). In multivariable analysis of a range of patient-related characteristics, the presence of single versus multiple areas of AD was not independently associated with malignancy (p = .51). In patients with multiple areas of AD, the most aggressive pathology (benign, high risk, or malignant) across all ADs was not associated with the number of ADs (p = .73). In 8 of 24 patients with at least two ipsilateral biopsied ADs, the ipsilateral areas varied in terms of most aggressive pathology; in 5 of 10 patients with contralateral biopsied ADs, the contralateral areas varied in most aggressive pathology. CONCLUSION. The presence of multiple areas of AD, compared with a single AD, was significantly more likely to yield high-risk pathology but was not significantly different in yield of malignancy. In patients with multiple ADs, multiple ipsilateral or contralateral ADs commonly varied in pathologic classification (benign, high risk, or malignant). CLINICAL IMPACT. These findings may help guide management of AD visualized by DBT, including multiple ADs. For patients with multiple areas of AD, biopsy of all areas may be warranted given variation in pathologic diagnoses.

Rethinking Routine Surgical Excision for all Radial Sclerosing Lesions of the Breast

INTRODUCTION

The need for routine surgical excision of a radial sclerosing lesions (RSL) of the breast identified on percutaneous biopsy remains controversial, as contemporary upgrade rates are lower than historically cited.

MATERIALS AND METHODS

A prospectively-maintained database of high-risk breast biopsies undergoing multidisciplinary review at a single institution was queried to identify cases of RSL from 2/2015 to 11/2020. Demographic, radiologic, and pathologic variables were summarized using frequencies and analyzed in association with RSL excision status using mixed-effects logistic regression or Fisher's exact tests.

RESULTS

217 RSL were identified, diagnosed at a mean age of 57 y. The median imaging size was 1.3 cm and the majority had estimated >50% of the target removed by core needle biopsy. 32.3% underwent surgical excision of the RSL biopsy site and 2/70 (2.9%) upgraded to ductal carcinoma in situ (DCIS) on final surgical pathology. Upgrade was significantly higher for atypical RSL (P = 0.02). None of the RSL (n = 60) without atypia who had undergone excision were upgraded. For those omitting surgical excision, there was no subsequent breast cancer diagnosis at the RSL site over a mean follow-up of 23 mo.

CONCLUSIONS

Surgical excision may be omitted for RSL without atypia as this group has 0% risk of upgrade after multidisciplinary review.

Meta-analysis: Architectural distortion and breast MRI

BACKGROUND

The implementation of digital breast tomosynthesis has increased the detection of architectural distortion (AD). Managing this finding may be experienced as a clinical dilemma in daily practice. Breast Contrast-Enhanced MRI (CE-BMR) is a known modality in case of problem-solving tool for mammographic abnormalities. However, the data about AR and CE-BMR are scant.

OBJECTIVE

The purpose was to estimate the benefit of CE-BMR in the setting of architectural distortion detected mammographically through a systematic review and meta-analysis of the literature.

METHODS

A search of MEDLINE and EMBASE databases were conducted in 2020. Based on the PRISMA guidelines, an analysis was performed using the chi-square test of independence to determine if there was a significant association between the result of the test (positive or negative) and the participant condition (malignant or non-malignant).

RESULTS

Four studies were available. The negative predictive value (NPV) was 98.3% to 100%. The result of the chi-square indicated that there was significant association between the participant test result and the participant condition for the included publications (X(1,175)2= 84.051, p = 0.0001).

CONCLUSIONS

The high NPV could allow for deferral of a biopsy in favor of a short-interval imaging follow-up in the setting of a negative CE-BMR.

Pathological outcome of sonographically occult architectural distortions (AD) visible only on digital breast tomosynthesis, and comparison with AD visible also on 2D mammography

PURPOSE

To evaluate the rates of malignant and of high-risk lesions among sonographically occult architectural distortions (AD) visible only on digital breast tomosynthesis (DBT) and compare them with AD visible on 2D mammography (2D) and DBT.

METHOD

The records of 1104 DBT-vacuum assisted biopsies (DBT-VAB) were retrospectively reviewed and 218 cases of AD were identified. Complete radiologic examinations and pathologic results were available for 113 sonographically occult AD (1 clinically-detected, 112 clinically-occult). 2D and DBT images were reviewed and AD were divided into a "DBT-detected" group (visible on only DBT) and a "2D-detected" group (visible both in 2D and DBT). The rates of malignant and of high-risk lesions in the "DBT-detected" AD group were calculated and compared to those of the "2D-detected" AD group.

RESULTS

Thirty-five (31%) of 113 AD were assessed as "DBT-detected", while 78 (69%) as "2D-detected". DBT-VAB results were benign lesions in 63 (56%) AD, high-risk lesions in 32 (28%) AD and malignant lesions in 18 (16%) AD. Four (12.5%) high-risk lesions were upgraded to malignancy at surgery. Based on final pathology, the malignancy rate was significantly higher in the "DBT-detected" group than the "2D-detected" group (34% [12/35 cases] vs 13% [10/78]; p < 0.05). The high-risk lesion rates were 32% (11/35 cases) in the "DBT-detected" group and 22% (17/78 cases) in the "2D-detected" group (p > 0.05).

CONCLUSIONS

AD visible on only DBT proved to be malignant in about one third of cases, which exceeded the malignancy rate of AD visible on also 2D. A similar proportion of DBT-only AD was represented by high-risk lesions.

Malignancy Upgrade Rates of Radial Sclerosing Lesions at Breast Cancer Screening

Purpose To determine the upgrade rate for biopsy-proven radial scars and radial sclerosing lesions (RS). Materials and Methods In this retrospective study, radiology and pathology databases from two tertiary breast centers were searched to identify patients with biopsy-confirmed RS between March 1, 2012, and December 31, 2017, during which all mammography was performed with digital breast tomosynthesis (DBT). Adjunct modalities such as MRI or US are performed at our centers to better characterize lesions identified at DBT. Patient demographics, imaging, needle and excisional biopsies, and follow-up data were collected at the patient level. Clopper-Pearson interval estimate for upgrade was calculated for 95% confidence using PropCIs package with R version 4.1.0 (R Foundation for Statistical Computing) (1). Results During the study period, a total of 155 885 DBT examinations were performed. From these examinations, 146 biopsy-proven RS were identified in 142 women (median age, 58 years; age range, 26-87 years). A total of 80.1% (117 of 146) of all RS did not have associated atypia or malignancy, and 19.9% (29 of 146) had associated atypia at initial biopsy. A total of 66.7% (78 of 117) of RS without atypia or malignancy were surgically excised, 25.6% (30 of 117) were followed (median, 3 years; range, 1-7 years) with benign findings on imaging, and 7.7% (nine of 117) were lost to follow-up. The rate of malignancy upgrade was 0.9% (one of 117 [95% CI: 0.02, 4.7]); one RS without concurrent atypia or malignancy demonstrated invasive carcinoma at surgical excision. Conclusion RS without atypia had a low upgrade rate. Keywords: Mammography, Breast © RSNA, 2021.

Pure Radial Scars Do Not Require Surgical Excision When Concordant and Benign at Image-guided Breast Biopsy

OBJECTIVE

To determine the best management option (surgical excision versus imaging surveillance) following the diagnosis of pure radial scars (RSs) and RSs with associated additional high-risk lesions (HRLs) encountered on percutaneous core-needle breast biopsy.

METHODS

An IRB-approved retrospective review of the breast imaging reporting system database was performed to identify all cases of pure RS alone or RS plus an additional HRL (papilloma, atypia, lobular neoplasia) diagnosed on core-needle biopsy, from 2007 to 2016, at four breast centers in our institution. Cases with associated malignancy, discordant radiologic-pathologic results, or those lost to follow-up were excluded. The remaining cases were evaluated to determine results of either subsequent surgical excision or long-term follow-up imaging (minimum of two years). Additional data recorded included clinical presentation, breast density, personal and family history of breast cancer, lesion imaging characteristics, and biopsy method.

RESULTS

The study cohort included 111 patients with 111 lesions: 56.8% (63/111) with RS alone (pure) and 43.2% (48/111) with RS plus additional HRL(s). Out of the 63 radiologic-pathologic concordant pure RSs, there were no upgrades to malignancy in 51 subsequent surgical excisions or 12 long-term surveillance cases (0/63, 0%). Out of the 48 RSs plus additional HRL(s), there were 2 upgrades to malignancy (2/48, 4.2%).

CONCLUSION

Cases of radiologic-pathologic concordant pure RS diagnosed at core-needle biopsy do not require surgical excision. On the other hand, surgical excision should be considered for RS plus additional HRLs diagnosed at core-needle biopsy.

High-risk lesions of the breast: concurrent diagnostic tools and management recommendations

Breast lesions with uncertain malignant behavior, also known as high-risk or B3 lesions, are composed of a variety of pathologies with differing risks of associated malignancy. While open excision was previously preferred to manage all high-risk lesions, tailored management has been increasingly favored to reduce overtreatment and spare patients from unnecessary anxiety or high healthcare costs associated with surgical excision. The purpose of this work is to provide the reader with an accurate overview focused on the main high-risk lesions of the breast: atypical intraductal epithelial proliferation (atypical ductal hyperplasia), lobular neoplasia (including the subcategories lobular carcinoma in situ and atypical lobular hyperplasia), flat epithelial atypia, radial scar and papillary lesions, and phyllodes tumor. Beyond merely presenting the radiological aspects of these lesions and the recent literature, information about their potential upgrade rates is discussed in order to provide a useful guide for appropriate clinical management while avoiding the risks of unnecessary surgical intervention (overtreatment).

Radial Scar: a management dilemma

Radial scar (RS) or complex sclerosing lesions (CSL) if > 10 mm is a benign lesion with an increasing incidence of diagnosis (ranging from 0.6 to 3.7%) and represents a challenge both for radiologists and for pathologists. The digital mammography and digital breast tomosynthesis appearances of RS are well documented, according to the literature. On ultrasound, variable aspects can be detected. Magnetic resonance imaging contribution to differential diagnosis with carcinoma is growing. As for the management, a vacuum-assisted biopsy (VAB) with large core is recommended after a percutaneous diagnosis of RS due to potential sampling error. According to the recent International Consensus Conference, a RS/CSL lesion, which is visible on imaging, should undergo therapeutic excision with VAB. Thereafter, surveillance is justified. The aim of this review is to provide a practical guide for the recognition of RS on imaging, illustrating radiological findings according to the most recent literature, and to delineate the management strategies that follow.

Upstage rate of radial scar/complex sclerosing lesion identified on core needle biopsy

BACKGROUND

We assessed the cancer upstage rate of Radial Scars (RS), and Complex Sclerosing Lesions (CSL), and risk-stratified lesions based on radiological and pathological features.

METHODS

Characteristics of RS/CSL treated from 2013 to 2018 were examined for features associated with cancer.

RESULTS

78 RS/CSL were found on core needle biopsy (CNB) and surgically excised. 9 (11.5%) lesions were upstaged. Upstaged patients were older (66 vs 51, p = 0.033). More upstaged lesions were accompanied by a mass on both mammography (87.5% vs. 30.0%, p = 0.005) and ultrasound (100.0% vs. 62.8%, p = 0.043). 20.5% of lesions biopsied under ultrasound guidance with small needles (14-18G) were upstaged, but no lesions biopsied under stereotactic guidance with large needles (9-12 G) with vacuum assistance were upstaged (p = 0.009).

CONCLUSIONS

Excision of RS/CSL seen on CNB is warranted, especially if the patient is older, the CNB is performed under ultrasound guidance with small needles, or if a mass is present on imaging.

High-Risk Lesions Detected by MRI-Guided Core Biopsy: Upgrade Rates at Surgical Excision and Implications for Management

OBJECTIVE. The purpose of our study was to evaluate the upgrade rates of high-risk lesions (HRLs) diagnosed by MRI-guided core biopsy and to assess which clinical and imaging characteristics are predictive of upgrade to malignancy. MATERIALS AND METHODS. A retrospective review was performed of all women who presented to an academic breast radiology center for MRI-guided biopsy between January 1, 2015, and November 30, 2018. Histopathologic results from each biopsy were extracted. HRLs-that is, atypical ductal hyperplasia (ADH), lobular carcinoma in situ (LCIS), atypical lobular hyperplasia (ALH), radial scar, papilloma, flat epithelial atypia (FEA), benign vascular lesion (BVL), and mucocelelike lesion-were included for analysis. Clinical history, imaging characteristics, surgical outcome, and follow-up data were recorded. Radiologic-pathologic correlation was performed. RESULTS. Of 810 MRI-guided biopsies, 189 cases (23.3%) met the inclusion criteria for HRLs. Of the 189 HRLs, 30 cases were excluded for the following reasons: 15 cases were lost to follow-up, six cases were in patients who received neoadjuvant chemotherapy after biopsy, two lesions that were not excised had less than 2 years of imaging follow-up, and seven lesions had radiologic-pathologic discordance at retrospective review. Of the 159 HRLs in our study cohort, 13 (8.2%) were upgraded to carcinoma. Surgical upgrade rates were high for ADH (22.5%, 9/40) and FEA (33.3%, 1/3); moderate for LCIS (6.3%, 3/48); and low for ALH (0.0%, 0/11), radial scar (0.0%, 0/28), papilloma (0.0%, 0/26), and BVL (0.0%, 0/3). Of the upgraded lesions, 69.2% (9/13) were upgraded to ductal carcinoma in situ (DCIS) or well-differentiated carcinoma. ADH lesions were significantly more likely to be upgraded than non-ADH lesions (p = .005). CONCLUSION. ADH diagnosed by MRI-guided core biopsy warrants surgical excision. The other HRLs, however, may be candidates for imaging follow-up rather than excision, especially after meticulous radiologic-pathologic correlation.

Management of High-Risk Breast Lesions

High-risk breast lesions (HRLs) are a group of heterogeneous lesions that can be associated with a synchronous or adjacent breast cancer and that confer an elevated lifetime risk of breast cancer. Management of HRLs after core needle biopsy may include close imaging and clinical follow-up or excisional biopsy to evaluate for cancer. This article reviews histologic features and clinical presentation of each of the HRLs, current evidence with regard to management, and guidelines from the American Society of Breast Surgeons and National Comprehensive Cancer Network. In addition, imaging surveillance and risk-reduction strategies for women with HRLs are discussed.

Malignant Outcomes of Architectural Distortion on Tomosynthesis: A Systematic Review and Meta-Analysis

BACKGROUND. The literature has reported varying rates of malignancy for architectural distortion (AD) on digital breast tomosynthesis (DBT). OBJECTIVE. The purpose of this study was to evaluate the PPV for malignancy of AD on DBT without a known cause and to assess the presence of an ultrasound (US) correlate for malignant AD through systematic review and meta-analysis of the literature. EVIDENCE ACQUISITION. This meta-analysis included all studies published in Em-base, MEDLINE, and Evidence-Based Medicine Reviews databases through July 15, 2020, that assessed the rate of malignancy in patients with AD on DBT without a known cause that was deemed BI-RADS category 4 or 5. Rates of benign or high-risk lesions and the presence of a US correlate for malignant AD were assessed. Core needle biopsy or surgical pathology was used as the reference standard for lesion diagnosis. The pooled PPV and 95% CI were estimated using a random-effects model. EVIDENCE SYNTHESIS. Thirteen retrospective, observational studies were included, yielding 857 ADs seen on DBT. Of the 857 ADs, 339 were breast malignancies, yielding a pooled PPV for malignancy of 34.6% (95% CI, 24.5-46.3%). The pooled PPV for invasive malignancy was 34% (95% CI, 25-45%) and for ductal carcinoma in situ was 5% (95% CI, 4-7%). Of the 857 ADs, 235 (27.4%) were benign lesions, 282 (32.9%) were high-risk lesions, and 1 (0.1%) was a nonbreast metastatic lesion. From the studies that assessed for US correlates, 217 of 277 malignant ADs (78.3%) had a US correlate. CONCLUSION. The pooled PPV for malignancy of AD on DBT without a known cause is high at 34.6%, warranting tissue sampling. CLINICAL IMPACT. A needle biopsy should be performed for ADs on DBT without a known cause. Because most malignant distortions have a corresponding finding on US, a US examination should be performed to look for a correlate, but the absence of a correlate does not obviate a biopsy.

Radial scars and complex sclerosing lesions on core needle biopsy of the breast: upgrade rates and long-term outcomes

PURPOSE

Radial scars and complex sclerosing lesions of the breast are part of a group of "indeterminate" breast lesions, which are excised due to risk of coexistent carcinoma. The aim of this study was to assess rate of upgrade of these lesions to invasive and in situ carcinoma and to quantify the risk of development of subsequent cancer in women diagnosed with these lesions.

METHODS

A retrospective review of a prospectively maintained breast screening database was performed. All patients with radial scar identified at either core biopsy or final excision biopsy between January 2006 and July 2012 were identified. Full pathological reports for both core biopsy and final excision biopsy were reviewed. Patient outcomes were followed for a mean of 117.1 months.

RESULTS

Of 451 B3 biopsies performed at our screening unit, 95 (22%) were found to have a radial scar or complex sclerosing lesion (CSL) on core needle biopsy. Within this group, 77 had no atypia on CNB, with 7 (9%) upgraded to invasive/in situ carcinoma on final excision. Of nine with definite atypia on CNB, 3 (33%) were upgraded. In those patients without atypia or malignancy on final excision, 7.5% developed cancer during 10-year follow-up.

CONCLUSION

Patients with radial scar with atypia have a higher risk of upgrade to malignancy. Further research is needed to identify which patients may safely avoid excision of radial scar. Patients with a diagnosis of radial scar on CNB are at increased subsequent risk of breast cancer and may benefit from additional screening.

Benign Breast Disease in Women

BACKGROUND

Most clinical breast changes in women are benign; in only 3% to 6% of cases are they due to breast cancer. How- ever, there is a lack of up-to-date, evidence-based treatment recommendations for the various benign differential diagnoses.

METHODS

Selective literature search of PubMed from 1985 to May 2019, including current national (AWMF, Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften [Association of Scientific Medical Societies in Germany]) and inter- national guidelines.

RESULTS

Mastalgia and fibrocystic changes are common (around 50% of all women over the age of 30). Fibroadenomas occur in 25% of women; they are the most common benign tumors of the breast and do not require treatment. With most benign breast changes the risk of dedifferentiation is very low. However, it is important in the differential diagnosis to distinguish between such benign changes and breast cancer or changes that carry a risk of malignancy. Complex cysts, for example, carry a risk of malig- nancy of 23% to 31%, papillary lesions 16% , and radial scars 7%. Where there is doubt, histological confirmation should be sought by means of percutaneous biopsy.

CONCLUSION

Benign breast changes can be definitively distinguished from malignant lesions through the selective use of avail- able diagnostic investigations and interdisciplinary collaboration. When lesions of uncertain malignant potential are found (B3 in the biopsy classification), complete excision is indicated. Prospective studies on the early diagnosis of breast cancer in lesions carrying a risk of malignancy are desirable.

Breast MRI Does Not Help Differentiating Radial Scar With and Without Associated Atypia or Malignancy

PURPOSE

To review breast magnetic resonance imaging (MRI) features of radial scar (RS) with and without associated atypia/malignancy.

METHODS

Twenty-eight (mean age 56.8) patients diagnosed with 30 biopsy-proven RS (n = 25, ultrasound-guided 14-gauge, n = 5, stereotactically guided 9-gauge) subsequently underwent breast MRI followed by surgery. Magnetic resonance imaging protocol included axial T1, axial fat sat T2, and postgadolinium in axial and sagittal planes. Two radiologists reviewed the mammographic and MRI findings in consensus according to the Breast Imaging Reporting and Data System lexicon.

RESULTS

Of the 30 RSs excised surgically, 14 (14/30, 47.7%) were not associated with atypia/malignancy while atypia/malignancy was found in 16 (16/30, 53.3%) RSs. Three (3/30, 10%) RS lesions did not enhance on dynamic MR. Mean lesion size on MRI was 1.4 cm (range, 0.5-5 cm). Seventeen (17/30, 56.7%) lesions presented as nonmass enhancement and 9 (9/30, 30%) as masses. Nonmass lesions showed focal distribution (13/17, 76.5%) and heterogeneous enhancement (15/17, 88.2%). Masses showed irregular shape and margins (6/9, 67%) and heterogeneous enhancement (8/9, 89%). Multivariate analysis did not show any significant difference in MRI presentation between RS only and RS associated with atypia/malignancy.

CONCLUSION

Breast MRI does not help differentiate between RS with or without associated atypia/malignancy.

Imaging Follow-up Versus Surgical Excision for Radial Scars Identified on Tomosynthesis-Guided Core Needle Biopsy

RATIONALE AND OBJECTIVES

We investigated if imaging or pathology features could determine when imaging follow-up is appropriate after diagnosis of radial scar on digital breast tomosynthesis (DBT)-guided core needle biopsy (CNB).

MATERIALS AND METHODS

We conducted a retrospective review of all patients diagnosed with radial scars on DBT-guided CNB at our institution between November 2014 and December 2016. Cases were excluded if DCIS or invasive malignancy was present in the same core specimens. Patient age; needle size; number of cores; visibility on full-field digital mammography versus DBT; lesion size; presence of architectural distortion, mass, or calcifications; imaging stability; presence or absence of atypia; length of imaging follow-up, and excisional pathology were collected.

RESULTS

Of 45 eligible biopsies, 6 cases had radial scars with associated atypia and 39 cases had no associated atypia. Twenty-four patients underwent surgical excision, including all patients with atypia on CNB. One case (4%) was upstaged to DCIS on surgical excision after CNB revealed a radial scar with associated ADH. There was also a case without atypia on CNB, but excisional pathology revealed associated ADH. In cases with radial scars and associated atypia on CNB, the upstage rate was 17%. In cases without atypia on CNB that underwent surgical excision, the upstage rate was 0%. Imaging follow-up was available in 13 patients who did not undergo surgical excision, with stability in all 13 with a median follow-up of 18 months.

CONCLUSION

Annual imaging follow-up appears reasonable in selected patients with radial scars but no atypia on DBT-guided CNB.

Reducing indications for radial scar surgical excision in Slovenian breast cancer screening program

PURPOSE

Management of the radial scar (RS)/complex sclerosing lesion (CSL) diagnosed by core needle biopsy (CNB) in breast cancer screening population (BCSP) is controversial due to its intrinsic malignant potential. We aimed to determine (i) the rate of upgrade of the RS/CSL to malignant lesions and (ii) radiological characteristics and CNB histopathological findings of the lesions related to the upgrade of the RS/CSL to malignant lesions after surgical excision in our BCSP.

PATIENTS AND METHODS

Database of Slovenian National Breast Cancer Screening Program was checked for terms RS/CSL in all patients who underwent CNB in the period 2008-2018. The ratios of upgrade from CNB RS/SCL to malignant lesions after surgical excision were calculated with specific interest to the radiological characteristics and the CNB patohistologically findings of the lesions.

RESULTS

Of 162 patients with diagnosis of RS/CSL on the CNB, 121/156 (78%) cases underwent surgical excision. 6 of 121 (5%) cases were upgraded to a malignant diagnosis in surgical specimen, 3 cases of invasive carcinoma and 3 cases of DCIS, respectively. Five of the upgraded cases (5/6, 83.3%) showed atypical epithelial proliferative lesions (AEPL) on CNB. In one upgraded case without AEPL the lesion presented as 33 mm architectural distortion with microcalcifications on the mammogram.

CONCLUSIONS

In BCSP setting RS/CSL without AEPL/papilloma and those measuring less than 2 cm in the largest diameter can be followed radiologically. Increasing the number of cores and adequate sampling of the periphery and the centre of the RS/CSL improves the pick-up rate of associated atypia/malignancy.

Computer-Aided Diagnosis of Solid Breast Lesions With Ultrasound: Factors Associated With False-negative and False-positive Results

OBJECTIVES

To investigate factors that may lead to false-positive or false-negative results in a computer-aided diagnostic system (S-Detect; Samsung Medison Co, Ltd, Seoul, Korea) for ultrasound (US) examinations of solid breast lesions.

METHODS

This prospective study was approved by the Institutional Review Board of Sun Yat-sen Memorial Hospital. All patients signed and provided written informed consent before biopsy or surgery. From September 2017 to May 2018, 269 consecutive women with 338 solid breast lesions were included. All lesions were examined with US and S-Detect before biopsy or surgical excision. The final US assessments made by radiologists and S-Detect were matched to the pathologic results. Patient and lesion factors in the "true" and "false" S-Detect groups were compared, and multivariate logistic regression analyses were used to identify the factors associated with false S-Detect results.

RESULTS

The mean age of the patients ± SD was 42.6 ± 12.9 years (range, 18-77 years). Of the 338 lesions, 209 (61.8%) were benign, and 129 (38.2%) were malignant. Larger lesions, the presence of lesion calcifications detected by B-mode US, and grades of 2 and 3 according to Adler et al (Ultrasound Med Biol 1990; 16:553-559) were significantly associated with false-positive S-Detect results (odds ratio [OR], 1.071; P = .006; OR, 5.851; P = .001; OR, 1.726; P = .009, respectively). Smaller lesions and the absence of calcifications detected by B-mode US in malignant solid breast lesions were significantly associated with false-negative S-Detect results (OR, 1.141; P = .015; OR, 7.434; P = .016).

CONCLUSIONS

Larger benign lesions, the presence of lesion calcifications, and high degrees of vascularity are likely to show false-positive S-Detect results. Smaller malignant lesions and the absence of calcifications are likely to show false-negative S-Detect results.

Positive Predictive Value of Tomosynthesis-guided Biopsies of Architectural Distortions Seen on Digital Breast Tomosynthesis and without an Ultrasound Correlate

Objective

The objective of the study was to determine the positive predictive value (PPV) of architectural distortions (AD) observed on digital breast tomosynthesis (DBT) and without an ultrasound (US) correlate.

Materials and Methods

In this single-institution, retrospective study, patients who underwent DBT-guided biopsies of AD without any associated findings on digital mammography (DM) or DBT, and without a correlate on targeted US exam, over a 14-month period were included in this study. All patients had DM and DBT and targeted US exams. The PPV was computed along with the exact 95% confidence limits (CL) using simple binomial proportions, with histopathology as the reference standard.

Results

A total of 45 ADs in 45 patients met the inclusion criteria. Histopathology indicated 6/45 (PPV: 13.3%, CL: 5.1-26.8%), ADs were malignant, including one high-risk lesion that was upgraded at surgery. ADs were appreciated only on DBT in 12/45 (26.7%) patients, and on both DBT and DM in 33/45 (73.3%) patients, and the corresponding PPV was 25% (3/12, CL: 5.5-57.2%) and 9.1% (3/33, CL: 1.9-24.3%), respectively. In all analyses, the observed PPV significantly exceeded the 2% probability of malignancy for Breast Imaging Reporting and Data System-3 diagnostic categories (P < 0.004).

Conclusions

The PPV of malignancy in DBT detected AD without an US correlate in our series of 45 cases was 6/45 (13.3%). In the absence of an US correlate, the PPV of AD is lower than that mentioned in prior literature but exceeds the 2% threshold to justify DBT-guided biopsy.

Excision or Observation: The Dilemma of Managing High-Risk Breast Lesions

There is an enduring dilemma on the appropriate management of high-risk breast lesions; is surgical excision always warranted or can conservative management be utilized? We present cases of high-risk breast lesions diagnosed at core needle biopsy at our institution along with relevant factors to consider for appropriate management. We conclude that a nuanced approach is warranted over the broad stroke approach of surgical excision of all high-risk breast lesions.

Radial scars/complex sclerosing lesions of the breast: radiologic and clinicopathologic correlation

Background

We investigated the radiologic and clinical findings of radial scar and complex sclerosing lesions, and evaluated the rate of pathologic upgrade and predicting factors.

Methods

From review of our institution’s database from January 2006 to December 2012, we enrolled 82 radial scars/complex sclerosing lesions in 80 women; 51 by ultrasound guided core needle biopsy, 1 by mammography-guided stereotactic biopsy, and 38 by surgical excision. The initial biopsy pathology revealed that 53 lesions were without high risk lesions and 29 were with high risk lesions. Radiologic, clinical and pathological results were analyzed statistically and upgrade rates were calculated.

Results

Of the 82 lesions, 64 (78.0%) were surgically excised. After surgical excision, two were upgraded to DCIS and two were upgraded to lesions with high risk lesions. The rate of radial scar with high risk lesions was significantly higher in the surgical excision group (11.1% vs. 42.2%, p = 0.015), which also demonstrated larger lesion size (10.7 ± 6.5 vs. 7.1 ± 2.6 mm, p = 0.001). The diagnoses with high risk lesions on final pathological results showed older age (52.9 ± 6.0 years vs. 48.4 ± 6.7 years, p = 0.018).

Conclusions

Radial scars with and without high risk lesions showed no statistically significant differences in imaging, and gave relatively low cancer upgrade rates.

Electronic supplementary material

The online version of this article (10.1186/s12880-018-0279-z) contains supplementary material, which is available to authorized users.