Heather I. Greenwood

Ductal Carcinoma in Situ of the Breasts: Review of MR Imaging Features

The incidence of ductal carcinoma in situ (DCIS) has increased over the past few decades and now accounts for over 20% of newly diagnosed cases of breast cancer. Although the detection of DCIS has increased with the advent of widespread mammography screening, it is essential to have a more accurate assessment of the extent of DCIS for successful breast conservation therapy. Recent studies evaluating the detection of DCIS with magnetic resonance (MR) imaging have used high spatial resolution techniques and have increasingly been performed to screen a high-risk population as well as to evaluate the extent of disease. This work has shown that MR imaging is the most sensitive modality currently available for identifying DCIS and is more accurate than mammography in evaluating the extent of DCIS. MR imaging is particularly sensitive for identifying high-grade and intermediate-grade DCIS. DCIS may have variable morphologic features on MR images, with non-mass enhancement morphology being the most common manifestation. Less commonly, DCIS may also manifest as a mass on MR images, in which case it is most likely to be irregular. The kinetics of DCIS are also variable, with fast uptake and a plateau curve reported as the most common kinetic pattern. Additional MR imaging tools such as diffusion-weighted imaging and quantitative kinetic analysis combined with the benefit of high field strength, such as 3 T, may increase the sensitivity and specificity of breast MR imaging in the detection of DCIS.

Outcome of High-Risk Lesions at MRI-Guided 9-Gauge Vacuum- Assisted Breast Biopsy

OBJECTIVE The purposes of this study were to determine the frequency of underestimation of high-risk lesions at MRI-guided 9-gauge vacuum-assisted breast biopsy and to determine the imaging and demographic characteristics predictive of lesion upgrade after surgery. MATERIALS AND METHODS We retrospectively reviewed consecutively detected lesions that were found only at MRI and biopsied under MRI guidance from May 2007 to April 2012. Imaging indications, imaging features, and histologic findings were reviewed. The Fisher exact test was used to assess the association between characteristics and lesion upgrade. Patients lost to follow-up or who underwent mastectomy were excluded, making the final study cohort 140 women with 151 high-risk lesions, 147 of which were excised. RESULTS A database search yielded the records of 1145 lesions in 1003 women. Biopsy yielded 252 (22.0%) malignant tumors, 184 (16.1%) high-risk lesions, and 709 (61.9%) benign lesions. Thirty of the 147 (20.4%) excised high-risk lesions were upgraded to malignancy. The upgrade rate was highest for atypical ductal hyperplasia, lobular carcinoma in situ, and radial scar. No imaging features were predictive of upgrade. However, there was a significantly higher risk that a high-risk lesion would be upgraded to malignancy if the current MRI-detected high-risk lesion was in the same breast as a malignant tumor previously identified in the remote history, a recently diagnosed malignant tumor, or a high-risk lesion previously identified in the remote history (p = 0.0001). The upgrade rate was significantly higher for women with a personal cancer history than for other indications combined (p = 0.0114). CONCLUSION The rate of underestimation of malignancy in our series was 20%. No specific imaging features were seen in upgraded cases. Surgical excision is recommended for high-risk lesions found at MRI biopsy and may be particularly warranted for women with a personal history of breast cancer.

Clinical Breast Magnetic Resonance Imaging: Technique, Indications, and Future Applications

Breast magnetic resonance imaging (MRI) is the most sensitive imaging modality for the detection of breast cancer, and it is indicated for breast cancer screening in patients at high-risk of developing breast cancer. It is limited to this group given the high cost. In addition, breast MRI is also indicated for evaluating the extent of disease in patients with new breast cancer diagnoses, monitoring the response to neoadjuvant treatment, and evaluating implant integrity. New promising innovations in breast MRI include fast abbreviated MRI, and functional techniques including diffusion-weighted imaging and magnetic resonance spectroscopy are promising particularly as regards to treatment response.

Effect of Background Parenchymal Enhancement on Breast MR Imaging Interpretive Performance in Community-based Practices

Purpose To evaluate the effect of background parenchymal enhancement (BPE) on breast magnetic resonance (MR) imaging interpretive performance in a large multi-institutional cohort with independent analysis of screening and diagnostic MR studies. Materials and Methods Analysis of 3770 breast MR studies was conducted. Examinations were performed in 2958 women at six participating facilities in the San Francisco Bay Area from January 2010 to October 2012. Findings were recorded prospectively in the San Francisco Mammography Registry. Performance measures were compared between studies with low BPE (mild or minimal) and those with high BPE (moderate or marked) by using binomial tests of proportions. Results Of 1726 MR imaging studies in the screening group, 1301 were classified as having low BPE and 425 were classified as having high BPE (75% vs 25%, respectively; P < .001). Of 2044 MR imaging studies in the diagnostic group, 1443 were classified as having low BPE and 601 were classified as having high BPE (71% vs 29%, respectively; P < .001). For low versus high BPE groups at screening, abnormal interpretation rate was 157 of 1301 versus 111 of 424 (12% vs 26%, P < .001); biopsy recommendation rate was 85 of 1301 versus 54 of 424 (7% vs 13%, P < .001); and specificity was 89% (95% confidence interval [CI]: 87, 91) versus 75% (95% CI: 71, 80) (P = .01). For the low versus high BPE groups at diagnostic MR imaging, biopsy recommendation rate was 325 of 1443 versus 195 of 601 (23% vs 32%, P < .001); and specificity was 86% (95% CI: 84, 88) versus 75% (95% CI: 74, 82) (P < .001). There were no significant differences between studies with low versus high BPE in sensitivity for screening (76% [95% CI: 55, 91] vs 83% [95% CI: 52, 98]; P = .94) or diagnostic (93% [95% CI: 87, 97] vs 96% [95% CI: 87, 99]; P = .69) MR imaging, nor were there significant differences in cancer detection rate per 1000 patients between the low BPE versus high BPE groups for screening (15 per 1000 vs 24 per 1000, P = .30) or diagnostic (78 per 1000 vs 85 per 1000, P = .64) MR imaging. Conclusion Relative to MR studies with minimal or mild BPE, those with moderate or marked BPE were associated with higher abnormal interpretation and biopsy rates and lower specificity, with no difference in cancer detection rate.

Clustered Microcysts on Breast Ultrasound: What Is an Appropriate Management Recommendation?

OBJECTIVE The objective of our study was to determine outcomes of lesions identified as clustered microcysts on breast ultrasound to augment the existing literature and help guide appropriate management recommendations. MATERIALS AND METHODS We retrospectively identified cases at our institution, from January 2003 through December 2013, of all lesions classified as clustered microcysts at breast ultrasound. Breast ultrasound examinations were performed by the interpreting physician. If ultrasound-guided sampling was performed, results were obtained from the pathology or cytology reports. If sampling was not performed, only lesions with at least 24 months of imaging follow-up or any imaging follow-up with interval resolution or decrease in size were included in the study. Outcomes and frequency of malignancy were determined by reviewing the electronic medical records and our PACS. RESULTS Of 144 patients with 148 lesions classified as clustered microcysts on ultrasound, 93 patients with 95 lesions had adequate follow-up and were included in our study population. The mean patient age was 50 years (range, 32-72 years). Of the 16 lesions that underwent percutaneous sampling, none (0% [95% CI, 0-21%]) yielded malignancy. Fourteen (88%) sampled lesions were benign, and two (12%) of the sampled lesions revealed atypical ductal hyperplasia at percutaneous sampling but no atypia or upgrade at subsequent surgical excision. In total, 0 of 95 lesions (0% [95% CI, 0-3.8%]) showed malignancy at sampling or imaging follow-up. CONCLUSION Our results support that lesions sonographically characterized as clustered microcysts carry an extremely low risk of malignancy, and biopsy should be avoided.

Abbreviated protocol breast MRI: The past, present, and future

Breast MRI has been shown to be the most sensitive examination in the detection of breast cancer. However, given the high associated costs, its use in the screening setting has traditionally been limited to those who are at high-risk for breast cancer. Abbreviated protocol breast MRI is capable of reducing the traditional costs associated with breast MRI, while maintaining diagnostic accuracy and cancer detection, and therefore a potential future screening tool for breast cancer in a broader population of women than just those at high-risk. New techniques, such as Ultrafast breast MRI, are able to not only shorten the traditional breast MRI acquisition and interpretation time, but also provide kinetic information.

Impact of Advancing Technology on Diagnosis and Treatment of Breast Cancer

New emerging breast imaging techniques have shown great promise in breast cancer screening, evaluation of extent of disease, and response to neoadjuvant therapy. Tomosynthesis, allows 3-dimensional imaging of the breast, and increases breast cancer detection. Fast abbreviated MRI has reduced time and costs associated with traditional breast MRI while maintaining cancer detection. Diffusion-weighted imaging is a functional MRI technique that does not require contrast and has shown potential in screening, lesion characterization and also evaluation of treatment response. New image-guided preoperative localizations are available that have increased patient satisfaction and decreased operating room delays.

Sonographic-MRI Correlation After Percutaneous Sampling of Targeted Breast Ultrasound Lesions: Initial Experiences With Limited-Sequence Unenhanced MRI for Postprocedural Clip Localization

OBJECTIVE The purpose of this study is to determine the frequency of correlation of sonographic and MRI findings after percutaneous sampling of presumed ultrasound correlates to suspicious lesions detected on breast MRI and to describe our initial experiences with limited-sequence MRI for postprocedural clip verification. MATERIALS AND METHODS Between January 1, 2014, and March 31, 2016, a total of 1947 contrast-enhanced breast MRI examinations were performed, and 245 targeted ultrasound examinations were conducted to identify correlates to suspicious MRI findings. We retrospectively identified all lesions that underwent ultrasound-guided sampling of a presumed sonographic correlate and for which a subsequent postprocedural limited-sequence unenhanced MR image for clip localization was available. This consisted of a T1-weighted non-fat-saturated and a T2-weighted fat-saturated sequence. Frequencies of sonographic-MRI correlation were quantified. RESULTS The study cohort consisted of 35 patients with 38 presumed correlates that underwent ultrasound-guided sampling with postprocedural MRI for clip verification. The mean time from percutaneous sampling to postprocedural MRI examination was 1 day. Ten presumed sonographic correlates (26%) were found to localize to a site distinct from the lesion originally identified on MRI. One of these discordant cases revealed malignancy on subsequent MRI-guided biopsy, whereas the presumed sonographic correlate was found to be benign. No patient or lesion characteristics were associated with significantly different frequencies of correlation. CONCLUSION In our initial experiences with MRI performed for postprocedural clip verification, 26% of presumed correlates to suspicious lesions detected on MRI were not the actual correlate, and 10% of these discordant cases ultimately revealed malignancy. Radiologists should take caution presuming that lesions identified on ultrasound actually represent the suspicious lesions detected on MRI. MRI for clip verification may be useful if ultrasound-guided sampling is pursued.

Deep learning methods aid in predicting risk of interval cancer.

Purpose: The purpose of this study was to apply a neural net to a dataset of women who later experienced either screening detected or interval cancers and determine if it aids in classifying risk of interval cancer compared to using BI-RADS density. Materials and Methods: Full-field digital screening mammograms acquired in our clinics were reviewed from 2006-2015. Interval cancers were matched to screening-detected cancers based on age, race, exam date, and time since last imaging examination. A deep learning architecture (ResNet50) was trained on this dataset with the goal to classify between interval and screen detected cancers. Network weights were initialized from ImageNet training and the final fully connected layers were retrained. Prediction loss, prediction accuracy, and ROC curves were calculated using this deep learning architecture and compared to predictions from conditional logistic regression using BI-RADS density. Results: 182 interval and 173 screening-detected cancers were found in our study group. The prediction accuracy improved from 63% using only BI-RADS density to 78% after including predictions from the deep learning model. The area under the ROC curve improved from 0.65 using only BI-RADS density to 0.84 after including the deep learning network as a predictor. Conclusions: We conclude that deep learning methods may be useful in identifying individuals at risk of interval cancer and that these methods can provide additional risk information not contained in breast density alone.

In Situ Disease on Breast MRI

Ductal Carcinoma in Situ is a non-invasive form of breast cancer, in which malignant ductal epithelial cells proliferate, but do not invade through the basement membrane. It is a heterogeneous disease, and is a non-obligate precursor to invasive carcinoma. With the advent of screening mammography the incidence of DCIS has greatly increased. MRI is the most sensitive examination for detecting DCIS. The most common presenting morphology of DCIS is nonmass enhancement, with a clumped internal enhancement pattern and with a segmental distribution pattern. There is great variety in the kinetic patterns of DCIS, and therefore assessment must be based on morphology. Additional tools, such as diffusion weighted imaging have been shown to be promising in helping detect clinically relevant DCIS.