Forget Me Not: Incidental Findings on Breast MRI

With the growing utilization and expanding role of breast MRI, breast imaging radiologists may encounter an increasing number of incidental findings beyond the breast and axilla. Breast MRI encompasses a large area of anatomic coverage extending from the lower neck to the upper abdomen. While most incidental findings on breast MRI are benign, identifying metastatic disease can have a substantial impact on staging, prognosis, and treatment. Breast imaging radiologists should be familiar with common sites, MRI features, and breast cancer subtypes associated with metastatic disease to assist in differentiating malignant from benign findings. Furthermore, detection of malignancies of nonbreast origin as well as nonmalignant, but clinically relevant, incidental findings can significantly impact clinical management and patient outcomes. Breast imaging radiologists should consistently follow a comprehensive search pattern and employ techniques to improve the detection of these important incidental findings.

Impact of Preoperative Extramammary Findings in Patients with Newly Diagnosed Breast Cancer

BACKGROUND

Breast MRI has been associated with significant rates of false positive findings. We aimed to determine the frequency of extramammary findings (EMFs) in newly diagnosed breast cancer patients on breast MRI with contrast and assess the significance of these findings and need for additional imaging and follow-up.

STUDY DESIGN

A retrospective review of patients diagnosed with breast cancer from October 2018 to October 2019 was performed. Clinicopathologic features were collected, including type of breast cancer, size, stage, and whether the patients had a breast MRI. Those who had MRI were included, and the MRI was reviewed to determine if EMFs were identified. Further imaging and follow-up were assessed and recorded.

RESULTS

Of the 480 patients included in this cohort, 353 (74%) had invasive cancer, and the remainder had ductal carcinoma in situ. Two hundred ninety patients (60%) underwent MRI, and 53 of 290 (18%) had EMFs on MRI. Of these, 28 of 53 (53%) underwent additional imaging to further evaluate findings. Two invasive procedures were performed (fine needle aspiration and thymectomy), and 1 malignancy was identified in the thymus. No metastatic breast cancer was identified in any patient.

CONCLUSIONS

MRIs are frequently obtained for newly diagnosed breast cancer patients, and additional findings, especially extramammary, can be stressful for patients, and potentially lead to treatment delay if further evaluation is warranted. Our results demonstrate that incidental EMFs discovered via breast MRI are common and often lead to additional imaging studies. However, no metastatic lesions were found, and only 1 separate malignancy was identified, which did not affect breast cancer management. In patients with early-stage breast cancer, EMFs yield a very low rate of malignancy, providing high levels of reassurance and supporting the option of proceeding with surgery or treatment without delay.

A Retrospective Analysis of Sternal Lesions Detected on Breast MRI in Patients Without History of Cancer

OBJECTIVE

To determine the imaging characteristics and stability over time of sternal lesions identified on breast MRI in patients without history of cancer.

METHODS

An IRB-approved retrospective analysis of all breast MRIs performed at our institution from September 1, 2017 to December 1, 2021 that included one of several key words related to the sternum. Studies with history of non-dermatologic malignancy including breast cancer, absence of a true sternal lesion, or presence of symptoms during the examination were excluded. Imaging was reviewed for size, distribution, signal characteristics, and presence of contrast enhancement, perilesional edema, periosteal edema, or intralesional fat. Available comparison imaging, clinical history, and follow-up recommendations were reviewed. Descriptive statistics were used to summarize lesion data.

RESULTS

Of 60 lesions included from 60 patients, 40 lesions with more than two years of comparison imaging were either stable or decreased in size and none demonstrated change in signal characteristics. The majority of these presumed benign lesions demonstrated hypointense signal on T1-weighted sequences (21/40, 52.5%), hyperintense signal on fluid-sensitive sequences (33/40, 82.5%), contrast enhancement (32/40, 80.0%), and absence of clear intralesional fat (29/40, 72.5%). One patient who did not have comparison imaging was diagnosed with malignancy (multiple myeloma) eight months following their MRI. This lesion demonstrated uniquely diffuse and heterogeneous enhancement but did not undergo biopsy.

CONCLUSION

Sternal lesions in women without history of non-dermatologic malignancy have a very low likelihood of malignancy. Common imaging characteristics of the presumed benign lesions can inform imaging recommendations when incidental sternal lesions are discovered.

Bone Lesions Detected on Breast MRI: Clinical Outcomes and Features Associated with Metastatic Breast Cancer

Objective

To determine prevalence and frequency of malignancy among bone lesions detected on breast MRI and to identify clinical and imaging features associated with bone metastases from breast cancer (BC), as bone lesions are suboptimally evaluated on breast imaging protocols and can present a diagnostic challenge.

Methods

This IRB-approved retrospective review of breast MRIs performed from June 2009 to June 2018 identified patients with bone lesions. Demographic, clinical, and MRI features were reviewed. Clinical outcome of bone lesions was determined based on pathology and/or additional diagnostic imaging. All benign lesions had ≥ 2 years of imaging follow-up. Statistics were computed with Fisher's exact and Wilcoxon rank sum tests.

Results

Among all patients with breast MRI, 1.2% (340/29 461) had bone lesions. Of these, 224 were confirmed benign or metastatic BC by pathology or imaging follow-up, with 70.1% (157/224) be- nign and 29.9% (67/224) metastatic. Bone metastases were associated with BC history (P < 0.001), with metastases occurring in 58.2% (53/91) of patients with current BC, 17.9% (14/78) patients with prior BC, and 0.0% (0/55) without BC. Bone metastases were associated with invasive and ad- vanced stage BC and, on MRI, with location in sternum, ribs, or clavicles, larger size, multiplicity, andT1 hypointensity (all P < 0.01 in tests of overall association).

Conclusion

Of clinically confirmed breast MRI-detected bone lesions, 30% were bone metastases; all were detected in patients with current or prior BC. Metastases were associated with advanced stage, invasive carcinoma, larger lesion size, multiplicity, low T1 signal, and non-spine location.

MRI Screening after Silicone Implant Breast Surgery: Patient Survey of Adherence to FDA Recommendations

BACKGROUND

The FDA recommends women with silicone breast implants undergo MRI surveillance to detect asymptomatic rupture. Screening is costly and often not covered by insurance. We assessed awareness of and adherence to FDA recommendations among patients with silicone breast implants.

METHODS

We searched electronic medical records for patients ≥18 years old with silicone breast implants placed between 2011 and 2016. Consenting patients were surveyed by telephone using a standardized script to assess awareness of FDA recommendations, whether they had undergone MRI screening, and barriers to testing. Patients who declined to participate or could not be contacted were excluded. Demographics and operative data were collected. Odds ratios were calculated with one-sample 95% confidence intervals and Fisher's exact tests of independence were conducted under assumptions of normality. Multivariable logistic regression analysis was performed to test for confounding.

RESULTS

Of 370 patients meeting inclusion criteria, 109 consented to participate. Adherence to FDA recommendations was 5.9% (95%CI [0.15%-28.7%]). There was no difference in adherence between patients undergoing cosmetic versus reconstructive surgery (p = 1.00, OR 0.80, 95% CI 1.17-2.93), having health insurance (p = 0.58) or residing in a county with median annual household income greater than that of the state of residence (p = 0.33).

CONCLUSIONS

A small proportion of respondents had undergone MRI in accordance with FDA recommendations. Low adherence highlights a potential limitation of current Federal surveillance recommendations. Additional research is needed to better characterize adherence to MRI surveillance recommendations, identify barriers to implementation, and determine whether this recommendation remains valid.

Incidental liver lesions on baseline breast MRI: Outcomes on subsequent abdominal imaging

PURPOSE

To examine outcomes of incidental liver lesions on baseline breast magnetic resonance imaging (MRI) that were further evaluated with dedicated abdominal imaging.

METHODS

Consecutive breast MRI reports from 2011 to 2016 were retrospectively reviewed to identify incidental liver lesions. Only patients without prior breast MRI, without prior abdominal imaging, and with subsequent abdominal imaging were included. Patient demographics, breast MRI indication, and final liver lesion diagnosis were recorded.

RESULTS

Of 131 women (mean age 53.8 years), 94/131 (71.8%) underwent breast MRI for extent of disease evaluation, 25/131 (19.1%) for high-risk screening, 11/131 (8.4%) for implant evaluation, and 1/131 (0.8%) for problem-solving. Of 131 liver lesions (6-80 mm), 117/131 (89.3%) were deemed benign on subsequent abdominal imaging; 10/131 (7.6%) probably benign; and 4/131 lesions (3.1%) were confirmed breast cancer metastases. Metastatic liver lesions identified on breast MRI were more likely for women with a current diagnosis of breast cancer than for women without a current diagnosis of breast cancer: 4.3% vs 0%. Similarly, metastatic liver lesions identified on breast MRI were more likely for those with a higher prognostic stage (2 or 3) vs a lower prognostic stage (0 or 1) or no current breast cancer: 11.1% vs 0%.

CONCLUSION

Baseline breast MRIs showing incidental liver lesions showed unsuspected liver metastases only in women with a current diagnosis of clinical stage 2 or 3 breast cancer. This suggests breast MRI indication and clinical staging of current breast cancer, if present, can help plan management and decisions to obtain follow-up of liver lesions.

Downstream Mammary and Extramammary Cascade Services and Spending Following Screening Breast Magnetic Resonance Imaging vs Mammography Among Commercially Insured Women

Importance

Increasing use of screening breast magnetic resonance imaging (MRI), including among women at low or average risk of breast cancer, raises concerns about resulting mammary and extramammary cascades (downstream services and new diagnoses) of uncertain value.

Objective

To estimate rates of cascade events (ie, laboratory tests, imaging tests, procedures, visits, hospitalizations, and new diagnoses) and associated spending following screening breast MRI vs mammography among commercially insured US women.

Design, Setting, and Participants

This cohort study used 2016 to 2018 data from the MarketScan research database (IBM Corporation), which includes claims and administrative data from large US employers and commercial payers. Participants included commercially insured women aged 40 to 64 years without prior breast cancer who received an index bilateral screening breast MRI or mammogram between January 1, 2017, and June 30, 2018. We used propensity scores based on sociodemographic, clinical, and utilization variables to match MRI recipients to mammogram recipients in each month of index service use. Data were analyzed from October 8, 2020, to October 28, 2021.

Exposures

Breast MRI vs mammography.

Main Outcomes and Measures

Mammary and extramammary cascade event rates and associated total and patient out-of-pocket spending in the 6 months following the index test.

Results

In this study, 9208 women receiving breast MRI were matched with 9208 women receiving mammography (mean [SD] age, 51.4 [6.7] years). Compared with mammogram recipients, breast MRI recipients had 39.0 additional mammary cascade events per 100 women (95% CI, 33.7-44.2), including 5.0 additional imaging tests (95% CI, 3.8-6.2), 17.3 additional procedures (95% CI, 15.5-19.0), 13.0 additional visits (95% CI, 9.4-17.2), 0.34 additional hospitalizations (95% CI, 0.18-0.50), and 3.0 additional new diagnoses (95% CI, 2.5-3.6). For extramammary cascades, breast MRI recipients had 19.6 additional events per 100 women (95% CI, 8.6-30.7) including 15.8 additional visits (95% CI, 10.2-21.4) and no statistically significant differences in other events. Breast MRI recipients had higher total spending for mammary events ($564 more per woman; 95% CI, $532-$596), extramammary events ($42 more per woman; 95% CI, $16-$69), and overall ($1404 more per woman; 95% CI, $1172-$1636). They also had higher overall out-of-pocket spending ($31 more per woman; 95% CI, $6-$55).

Conclusions and Relevance

In this cohort study of commercially insured women, breast MRI was associated with more mammary and extramammary cascade events and spending relative to mammography. These findings can inform cost-benefit assessments and coverage policies to ensure breast MRI is reserved for patients for whom benefits outweigh harms.

Comparing Breast and Abdominal Subspecialists' Follow-Up Recommendations for Incidental Liver Lesions on Breast MRI

Purpose:

The aim of this study was to compare breast imaging subspecialists’ follow-up recommendations for incidental liver lesions (ILLs) on breast MRI with abdominal subspecialty radiologists’ opinions informed by best-practice recommendations.

Methods:

In this retrospective study at an academic medical center, natural language processing identified reports with ILLs among 2,181 breast MRI studies completed in 2015. Electronic health record and radiology report reviews abstracted malignancy presence or absence, prior imaging, and breast subspecialists’ recommendations regarding ILLs for random sets of 30 patients: ILLs with follow-up recommendations, ILLs without recommendations, and without ILLs. Two abdominal radiologists evaluated MRI liver findings and offered follow-up recommendations in consensus. The primary outcome was agreement between breast and abdominal subspecialists in patients with ILL follow-up recommendations compared with those without (χ² analysis). Secondary outcomes were agreement between subspecialists when ILLs were reported and referring clinicians’ adherence to follow-up recommendations.

Results:

ILLs were identified in 11.3% of breast MRI reports (247 of 2,181); breast subspecialists made follow-up recommendations in 12% of them (30 of 247). Abdominal subspecialists agreed with breast subspecialists when ILLs required no follow-up (29 of 30 cases) but disagreed with 28 of 30 breast subspecialists’ follow-up recommendations (agreement proportion 29 of 30 versus 2 of 30, P < .0001). Subspecialists agreed in 93% of cases (28 of 30) when breast imagers reported no ILLs. Overall, 16 of 30 breast subspecialists’ follow-up recommendations were performed; ILLs were benign in 15.

Conclusions:

Abdominal subspecialists disagreed frequently with breast subspecialists regarding follow-up recommendations for ILLs on breast MRI. Abdominal subspecialty consultation or embedding liver imaging decision support in breast imaging reporting workflow may reduce unnecessary imaging and improve care. Improvement opportunities may exist in other cross-subspecialty interpretation workflows.

Characterization of Metastatic Sternal Lesions on Dynamic Contrast-Enhanced Breast MRI in Women with Invasive Breast Cancer

RATIONALE AND OBJECTIVES

Detecting sternal lesions is not the purpose of breast MRI, but diagnosing metastasis has major clinical implications. Our purpose was to determine the breast MRI features of sternal metastases detected on PET-CT and bone-scan.

MATERIALS AND METHODS

Between 01/2010-09/2018, 379 patients with breast cancer had sternal findings on PET-CT or bone-scan, 21 of which underwent breast MRI within 100 days. Sternal lesions were considered metastatic if (1) biopsy demonstrated metastasis, (2) the lesion had similar appearance to synchronous sites of biopsy-proven osseous metastases, or (3) there were numerous suspicious lesions in which widespread osseous metastasis was presumed. Four radiologists reviewed the MR images to determine if metastases were retrospectively detectable. MRI reports were reviewed to determine if lesions were prospectively described. MRI features of metastatic sternal lesions were compared to benign controls.

RESULTS

Fourteen sternal metastases met inclusion criteria. Lesions were retrospectively detectable on breast MRI by all radiologists in 86% (12/14) of cases, but prospectively reported in 57%. Of the 12 MRI-detectable metastases, mean maximum dimension was 33 mm, 7 had >1 lesion, all were T1-hypointense, 11 were T2-hyperintense, 11 were noncircumscribed, 6 extended beyond cortex, 11 enhanced heterogeneously, and 11 demonstrated washout. Heterogeneous enhancement (p = 0.002), noncircumscribed margins (p < 0.001), multiplicity (p = 0.005), and size >1 cm (p < 0.001) were more frequent with metastatic compared to benign sternal lesions.

CONCLUSION

Most sternal metastases (86%) were retrospectively detectable on breast MRI, but only 57% were prospectively reported, emphasizing the importance evaluating the sternum on breast MRI. Certain MRI features may raise suspicion for metastasis.

Prevalence and clinical significance of incidental extra-mammary findings in breast magnetic resonance imaging: A retrospective study of 1070 patients

PURPOSE

The purpose of this study was to analyze the prevalence of extra-mammary findings in magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Data from 1070 consecutive breast MRI studies was analyzed. MR-BI-RADS (Breast Imaging Reporting and Data System) was used to classify the risk category.

RESULTS

According to MR-BI-RADS, 915 (85.5%) of 1070 women were classified into MR-BI-RADS categories 1-3, and 155 (14.5%) into MR-BI-RADS categories 4-5. MR-BI-RADS categories 4-5 had a 10-times higher risk for major extra-mammary findings (odds ratio 10.1, P<0.01).

CONCLUSION

Extra-mammary findings are common and may have important clinical consequences.

Breast findings incidentally detected on body MRI

Objectives

To evaluate breast findings incidentally detected on body MRI.

Methods

A retrospective review of the institutional database identified 1752 body MRI performed between January 2015 and September 2015. MRI of women with breast tissue visible in the field-of-view were reviewed for breast findings. Breast findings were classified with the breast imaging reporting and data system (BI-RADS) lexicon. The standard statistic, costs of additional work-up, and the clinical relevance were used to describe breast findings, and we calculated 95 % exact confidence intervals (CIs).

Results

440 body MRI of 440 women (mean age: 57 ± 20 years) included breast tissue in the field-of-view. A total of 41 breast findings were identified in 41 patients. Breast findings were classified BI-RADS 2 N = 25, BI-RADS 3 N = 13, BI-RADS 4 N = 3. A total of 3.6 % [95 % CI 1.6 %, 5.6 %] women with breast tissue visible on MRI had a recommendation for further imaging work-up for a breast finding. The 18.7 % (3 of 16) of these patients had a clinically important finding (breast cancer). Further imaging evaluation increased costs of €108.3 per patient with a breast finding.

Conclusions

Clinically important breast findings could be detected on body MRI in up to 0.7 % (3 of 440) of women.

Frequency and Clinical Significance of Extramammary Findings on Breast Magnetic Resonance Imaging

BACKGROUND

Use of breast magnetic resonance imaging (MRI) for screening and local staging of breast cancer has increased. With this, questions have emerged regarding the management and effect of extramammary findings (EMFs) reported on breast MRI.

PATIENTS AND METHODS

Breast MRI studies performed between January 1, 2007 and December 31, 2012 at the University of Iowa were analyzed. Data were collected regarding number and location of EMFs, characteristics of the patients who had a breast MRI, and time to first treatment among the patients who had a breast MRI for stage I-III breast cancer.

RESULTS

During the study period, 1305 breast MRIs were obtained in 772 women. An EMF was found in 140 studies (10.7%) and 113 women (14.6%). EMFs were more likely in MRIs of older patients (50 vs. 54 years, P = .004) and postmenopausal women (P = .001). Anatomically, most EMFs were seen in the liver (89 of 140) or bone (21 of 140). Eight women (0.6%) had an EMF on breast MRI that led to upstaging to stage IV breast cancer. For patients with stage I-III breast cancer, the finding of an EMF on breast MRI did not affect time to initial cancer treatment (13 vs. 14 days; P = .586).

CONCLUSION

EMFs on breast MRI are seen with some frequency and occur more commonly in older, postmenopausal women. In our study, most EMFs were benign and did not affect patient outcome with regard to upstaging to stage IV disease or time to cancer treatment. A very small portion of studies revealed subclinical advanced breast cancer.