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.

MRI of the Lactating Breast.

The breasts undergo marked physiologic changes during lactation that can make conventional imaging evaluation with mammography and US challenging. MRI can be a valuable diagnostic aid to differentiate physiologic and benign processes from malignancy in patients who are lactating. In addition, MRI may allow more accurate delineation of disease involvement than does conventional imaging and assists in locoregional staging, screening of the contralateral breast, assessment of response to neoadjuvant chemotherapy, and surgical planning. Although the American College of Radiology recommends against patients undergoing contrast-enhanced MRI during pregnancy because of fetal safety concerns, contrast-enhanced MRI is safe during lactation. As more women delay childbearing, the incidence of pregnancy-associated breast cancer (PABC) and breast cancer in lactating women beyond the 1st year after pregnancy is increasing. Thus, MRI is increasingly being performed in lactating women for diagnostic evaluation and screening of patients at high risk. PABC is associated with a worse prognosis than that of non-PABCs, with delays in diagnosis contributing to an increased likelihood of advanced-stage disease at diagnosis. Familiarity with the MRI features of the lactating breast and the appearance of various pathologic conditions is essential to avoid diagnostic pitfalls and prevent delays in cancer diagnosis and treatment. The authors review clinical indications for breast MRI during lactation, describe characteristic features of the lactating breast at MRI, and compare MRI features of a spectrum of benign and malignant breast abnormalities. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Chikarmane in this issue.

Prevalent vs Incident Screen: Why Does It Matter?

There are important differences in the performance and outcomes of breast cancer screening in the prevalent compared to the incident screening rounds. The prevalent screen is the first screening examination using a particular imaging technique and identifies pre-existing, undiagnosed cancers in the population. The incident screen is any subsequent screening examination using that technique. It is expected to identify fewer cancers than the prevalent screen because it captures only those cancers that have become detectable since the prior screening examination. The higher cancer detection rate at prevalent relative to incident screening should be taken into account when analyzing the medical audit and effectiveness of new screening technologies.

The role of digital mammographic surveillance for detection of asymptomatic recurrence in autologous flap reconstructions.

OBJECTIVE: To evaluate the utility of digital mammography in detecting asymptomatic malignancy in autologous flap reconstructions after mastectomy. METHODS: A retrospective database review identified all mammograms performed on asymptomatic patients with flap reconstructions over a 9-year period (1/1/2009 to 12/31/2017). A negative examination was defined as BI-RADS 1 or 2 and a positive examination was defined as BI-RADS 0, 4, or 5 assigned to the mastectomy side. Malignant outcomes were determined by pathology results. Interval cancers, or false negatives, were defined as locoregional malignant diagnosis within one year of a negative mammogram. Sensitivity, specificity, predictive values, abnormal interpretation rate, and cancer detection rate were calculated. RESULTS: 626 mammograms of asymptomatic flap reconstructions were performed in 183 patients. The most common flap type was TRAM (83.5 %, 523/626) and DIEP (13.4 %, 84/626). Most exams (98.2 %, 615/626) were negative, assessed as BI-RADS 1 or 2, with no interval cancers at follow-up. Eleven exams (1.8 %, 11/626) were positive, assessed as BI-RADS 0, 4, or 5. After diagnostic work-up of all BI-RADS 0 exams, 9 cases had a final recommendation for biopsy of which 3 were malignant. Mammography yielded a cancer detection rate of 0.5 % (3/626), abnormal interpretation rate of 1.8 % (11/626), NPV of 100 % (615/615), overall PPV of 27.3 % (3/11), PPV2 (positive predictive value of a biopsy recommendation) of 33.3 % (3/9), sensitivity of 100 % (3/3), and specificity of 98.7 % (615/623). CONCLUSION: Digital mammography of asymptomatic autologous flap reconstructions after mastectomy demonstrated high sensitivity and low abnormal interpretation rate. Cancer detection rate was comparable to current national benchmarks for mammographic screening in the general U.S. population without mastectomy.

Radiation safety in an era of diagnostic radiology growth in Africa: Lessons learned from Tanzania.

PURPOSE: As radiology continues to grow in low- and middle-income countries (LMICs), radiation exposure and risk to patients and staff will concurrently increase. This study aims to assess the knowledge of radiation safety among medical staff in Tanzania. METHODS: A survey was distributed to 350 staff members at a national referral hospital in Tanzania over a 7-month period (February-August 2021). This consisted of a structured questionnaire evaluating participants' knowledge and awareness ionizing radiation and radiation safety. Chi-square and Fisher's exact tests were used to determine the association between independent and dependent categorical variables. RESULTS: A total of 300 surveys were completed (86% response rate). Mean age was 31 and 53% of participants were female. The majority (89%) were clinical staff employed in direct patient care. Most reported having heard of radiation protection (85%) but only 61% reported receiving training in radiation protection. Regarding radiation knowledge, 73% correctly answered how to protect oneself from radiation and 74% knew which medical staff were at greater risk of radiation exposure. However, only 32% correctly answered which imaging tests emit more radiation and only 53% correctly answered which age group was at greatest risk of radiation effects. Non-clinical staff had a significantly lower radiation awareness than clinical staff, with 69.7% reporting having heard about radiation protection, compared to 88.3% of clinical staff (p = 0.004). Female participants were more knowledgeable of radiation risks in pregnancy (p = 0.002). More early career staff reported receiving radiation protection training (64.5%) compared to those with >5 years work experience (53.9%), though this difference was not statistically significant (p = 0.09). When stratifying radiation knowledge by high (score of 80-100%), moderate (60-79.9%) and low (<60%), 20% of participants scored high, 47% moderate, and 33% low. CONCLUSION: Most staff had low to moderate knowledge on radiation safety. Our findings highlight the importance of education on ionizing radiation as medical imaging continues to rise in Africa.

Deep Learning to Simulate Contrast-enhanced Breast MRI of Invasive Breast Cancer.

Background There is increasing interest in noncontrast breast MRI alternatives for tumor visualization to increase the accessibility of breast MRI. Purpose To evaluate the feasibility and accuracy of generating simulated contrast-enhanced T1-weighted breast MRI scans from precontrast MRI sequences in biopsy-proven invasive breast cancer with use of deep learning. Materials and Methods Women with invasive breast cancer and a contrast-enhanced breast MRI examination that was performed for initial evaluation of the extent of disease between January 2015 and December 2019 at a single academic institution were retrospectively identified. A three-dimensional, fully convolutional deep neural network simulated contrast-enhanced T1-weighted breast MRI scans from five precontrast sequences (T1-weighted non-fat-suppressed [FS], T1-weighted FS, T2-weighted FS, apparent diffusion coefficient, and diffusion-weighted imaging). For qualitative assessment, four breast radiologists (with 3-15 years of experience) blinded to whether the method of contrast was real or simulated assessed image quality (excellent, acceptable, good, poor, or unacceptable), presence of tumor enhancement, and maximum index mass size by using 22 pairs of real and simulated contrast-enhanced MRI scans. Quantitative comparison was performed using whole-breast similarity and error metrics and Dice coefficient analysis of enhancing tumor overlap. Results Ninety-six MRI examinations in 96 women (mean age, 52 years ± 12 [SD]) were evaluated. The readers assessed all simulated MRI scans as having the appearance of a real MRI scan with tumor enhancement. Index mass sizes on real and simulated MRI scans demonstrated good to excellent agreement (intraclass correlation coefficient, 0.73-0.86; P < .001) without significant differences (mean differences, -0.8 to 0.8 mm; P = .36-.80). Almost all simulated MRI scans (84 of 88 [95%]) were considered of diagnostic quality (ratings of excellent, acceptable, or good). Quantitative analysis demonstrated strong similarity (structural similarity index, 0.88 ± 0.05), low voxel-wise error (symmetric mean absolute percent error, 3.26%), and Dice coefficient of enhancing tumor overlap of 0.75 ± 0.25. Conclusion It is feasible to generate simulated contrast-enhanced breast MRI scans with use of deep learning. Simulated and real contrast-enhanced MRI scans demonstrated comparable tumor sizes, areas of tumor enhancement, and image quality without significant qualitative or quantitative differences. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Slanetz in this issue. An earlier incorrect version appeared online. This article was corrected on January 17, 2023.

Delayed diagnostic evaluation of symptomatic breast cancer in sub-Saharan Africa: A qualitative study of Tanzanian women.

BACKGROUND: Women with breast cancer in sub-Saharan Africa are commonly diagnosed at advanced stages. In Tanzania, more than 80% of women are diagnosed with stage III or IV disease, and mortality rates are high. This study explored factors contributing to delayed diagnostic evaluation among women with breast cancer in Tanzania. METHODS: A qualitative study was performed at Muhimbili National Hospital in Dar es Salaam, Tanzania. Twelve women with symptomatic pathologically proven breast cancer were recruited. In-depth, semi-structured interviews were conducted in Swahili. Interviews explored the women's journey from symptom recognition to diagnosis, including the influence of breast cancer knowledge and pre-conceptions, health seeking behaviors, psychosocial factors, preference for alternative treatments, and the contribution of culture and norms. Audio-recorded interviews were transcribed and translated into English. Thematic analysis was facilitated by a cloud-based qualitative analysis software. RESULTS: All women reported that their first breast symptom was a self-identified lump or swelling. Major themes for factors contributing to delayed diagnostic presentation of breast cancer included lack of basic knowledge and awareness of breast cancer and misconceptions about the disease. Participants faced barriers with their local primary healthcare providers, including symptom mismanagement and delayed referrals for diagnostic evaluation. Other barriers included financial hardships, fear and stigma of cancer, and use of traditional medicine. The advice and influence of family members and friends played key roles in healthcare-seeking behaviors, serving as both facilitators and barriers. CONCLUSION: Lack of basic knowledge and awareness of breast cancer, stigma, financial barriers, and local healthcare system barriers were common factors contributing to delayed diagnostic presentation of breast cancer. The influence of friends and family also played key roles as both facilitators and barriers. This information will inform the development of educational intervention strategies to address these barriers and improve earlier diagnosis of symptomatic breast cancer in Tanzania.

Utility and Outcomes of Preoperative Screening Breast MRI for Planned Bilateral Prophylactic Mastectomy in High-Risk Patients.

BACKGROUND. There is a paucity of data and consensus guidelines on the utility of preoperative MRI for planned bilateral prophylactic mastectomy. OBJECTIVE. The purpose of this study was to evaluate the utility of breast MRI performed in high-risk patients for the indication of planned bilateral prophylactic mastectomy, with attention given to the diagnostic performance for breast cancer detection. A secondary aim was to assess the potential impact of breast MRI findings on the decision to perform sentinel lymph node biopsy at the time of prophylactic mastectomy. METHODS. A retrospective database review identified MRI examinations performed at an academic medical center from August 2003 to January 2020 for the indication of planned bilateral prophylactic mastectomy. Patient demographics, imaging findings, operative details, and pathology were recorded. BI-RADS category 1 and 2 assessments were considered negative examinations, and BI-RADS category 3, 4, and 5 assessments were considered positive examinations. Descriptive statistics and performance metrics were calculated. RESULTS. The final cohort included 53 patients (mean age, 45 years). Most (35/53; 66.0%) studies were baseline examinations. Of the 53 patients, 31 (58.5%) had negative MRI examinations and 22 (41.5%) had positive MRI examinations. MRI detected two malignancies (one invasive lobular carcinoma and one high-grade ductal carcinoma in situ), both of which were assessed as BI-RADS category 4. The patient with invasive lobular cancer underwent sentinel lymph node biopsy at the time of mastectomy, which showed metastasis. Breast MRI had sensitivity of 100.0% and specificity of 60.8% for overall breast cancer detection and sensitivity of 100.0% and specificity of 59.6% for invasive cancer detection. CONCLUSION. Preoperative MRI for planned bilateral prophylactic mastectomy detected all cancers, indicating a potential role for MRI in impacting surgical decision making. CLINICAL IMPACT. Given the high NPV for cancer, our results suggest that lymph node biopsy may be safely avoided in patients with a negative MRI examination. This is clinically relevant because sentinel nodes cannot be identified after mastectomy.

Outcomes of screening mammography performed prior to fertility treatment in women ages 40-49.

OBJECTIVE: There are currently various conflicting recommendations for breast cancer screening with mammography in women between ages 40-49. There are no specific guidelines for breast cancer screening in women of this age group prior to assisted reproductive technology (ART) for the treatment of infertility. The purpose of our study was to evaluate outcomes of screening mammography, specifically ordered for the purpose of pre-fertility treatment clearance in women aged 40-49 years old. MATERIALS AND METHODS: This was an IRB approved retrospective study of women aged 40-49 presenting for screening mammography prior to ART between January 2010 and October 2018. Clinical history, imaging, and pathology results were gathered from the electronic medical record. Descriptive statistics were performed. RESULTS: Our study cohort consisted of 118 women with a mean age of 42 years (range 40-49). Sixteen of 118 (14%) women were recalled from screening for additional diagnostic work-up. Five of the 16 (31%) were recommended for biopsy (BI-RADS 4 or 5). One of 5 biopsies yielded a malignant result (PPV 20%). Overall cancer detection rate was 0.85% or 8.5 women per 1000 women screened. The single cancer in this cohort was an ER+ PR+ HER2- invasive ductal carcinoma. CONCLUSION: Screening mammography in women 40-49 performed prior to initiation of ART may identify asymptomatic breast malignancy. In accordance with ACR and SBI guidelines to screen women of this age group, women of this age group should undergo screening mammography prior to ART.

Frequency and Outcomes of New Suspicious Lesions on Breast MRI in the Setting of Neoadjuvant Therapy.

OBJECTIVE. The purpose of this article was to determine the frequency and outcomes of new suspicious findings on breast MRI after initiation of neoadjuvant therapy. MATERIALS AND METHODS. A retrospective database review identified all breast MRI examinations performed to assess response to neoadjuvant therapy between 2010 and 2018. Cases with new suspicious lesions assessed as BI-RADS 4 or 5 and found after the initiation of neoadjuvant treatment were included. Cases with no pretreatment MRI, cases in which the suspicious lesion was present on the baseline MRI but remained suspicious, and cases with insufficient follow-up were excluded. Radiologic, pathologic, and surgical reports were reviewed. Malignant outcomes were determined by pathologic examination. Benignity was established by pathologic examination, follow-up imaging, or both. A total of 419 breast MRI examinations in 297 women were performed to assess response to neoadjuvant therapy. After exclusions, 23 MRI examinations (5.5%) with new suspicious findings, all assessed as BI-RADS 4, comprised the final cohort. RESULTS. Of the 23 lesions, 13 new suspicious findings (56.5%) were contralateral to the known malignancy, nine (39.1%) were ipsilateral, and one (4.3%) involved the bilateral breasts. Lesion types included mass (16, 69.6%), nonmass enhancement (5, 21.7%) and focus (2, 8.7%). None of the new suspicious findings were malignant. CONCLUSION. New suspicious findings occurred in 5.5% of breast MRI examinations performed to monitor response to neoadjuvant therapy, and none of these new lesions were malignant. Our findings suggest that new lesions that arise in the setting of neoadjuvant therapy are highly unlikely to represent a new site of malignancy, particularly if the index malignancy shows treatment response. Larger studies are needed to confirm whether biopsy may be safely averted in this scenario.

Intermediary clip placement to assist accurate axillary lymph node localization.

Localization of metastatic axillary lymph nodes in breast cancer patients is an increasingly common procedure performed by radiologists. In 2014, the National Comprehensive Cancer Network guidelines stated that "clinically positive axillary lymph node (s) should be sampled by FNA or core biopsy and clipped with image-detectable marker; clipped lymph nodes must be removed if FNA or core biopsy was positive prior to neoadjuvant therapy". Since then, multiple studies have further supported targeted axillary surgery after neoadjuvant chemotherapy (NAC), with excision of the clipped metastatic axillary node in addition to the sentinel node (s). Requests for image guided localization of clipped axillary nodes will continue to increase and likely become the standard of care. However, when lymph nodes have decreased in size after NAC, or when small deep lymph nodes are sampled, the clipped node can be difficult to identify under ultrasound at the time of localization. When the target node is questionable, we have found it valuable to place an intermediary clip, and use an axillary mammographic view to confirm this intermediary clip co-localizes with the intended target. With this confirmation, safe, accurate localization can then be performed. We describe 3 cases of intermediary clip placement facilitating successful localization of previously clipped axillary lymph nodes.

The Value of Targeted Ultrasound for the Primary Evaluation of Breast Symptoms in Pregnant Women of All Ages.

OBJECTIVE: Data on breast imaging in symptomatic pregnant women are limited. Our aim was to assess the value of targeted breast US for the primary evaluation of breast symptoms in pregnant women of all ages. METHODS: This IRB-approved retrospective study included all pregnant patients who underwent targeted US for focal breast symptoms at an academic imaging facility over an 18-year period (2000-2018). Clinical, imaging, and pathology results were reviewed. Malignant outcomes were determined by histology. Benign outcomes were confirmed by pathology or ≥2 years of follow-up. Descriptive statistics and 2 × 2 contingency table analyses were performed at the presentation level. RESULTS: The study cohort comprised 178 presentations in 175 pregnant women. Mean age was 34.7 years (standard deviation, 5.2). The majority (153/178, 86.0%) were more than 30 years old. At presentation, 42.1% (75/178) were in the first trimester of pregnancy, 27.0% (48/178) in the second, and 29.8% (53/178) in the third. The most common presenting symptom was a palpable lump (162/178, 91.0%), followed by focal pain (7/178, 3.9%). The vast majority (174/178, 97.8%) of cases were non-malignant. However, targeted US detected all 4 malignancies (cancer detection rate, 22/1000; negative predictive value 136/136, 100%). Sensitivity and specificity were 100% (4/4) and 78.2% (136/174), respectively. CONCLUSION: Benign causes of symptoms in pregnant women were far more common; malignancy was rare, accounting for only 2.2% (4/178) of cases. Targeted breast US detected all malignancies, supporting US as the primary imaging modality for evaluating symptomatic pregnant women, regardless of age.

US as the Primary Imaging Modality in the Evaluation of Palpable Breast Masses in Breastfeeding Women, Including Those of Advanced Maternal Age.

Background Women are increasingly delaying childbearing, and thus lactation, into their 30s and 40s, when mammography would typically be the initial imaging modality to evaluate palpable masses in the general population. Current guidelines recommend US as the first-line imaging modality for palpable masses in pregnant and lactating women, but data regarding breastfeeding women age 30 years and older are near nonexistent. Purpose To evaluate the diagnostic performance of targeted US as the primary imaging modality for the evaluation of palpable masses in lactating women, including those of advanced maternal age. Materials and Methods Lactating women with palpable breast masses evaluated at targeted US over a 17-year period (January 2000 to July 2017) were retrospectively identified. All US evaluations were performed at diagnostic evaluation, and mammography was performed at the discretion of the interpreting radiologist. Breast Imaging Reporting and Data System assessments, imaging, and pathology results were collected. Descriptive statistics and 2 × 2 contingency tables were assessed at the patient level. Results There were 167 women (mean age, 35 years ± 5 [standard deviation]), 101 of whom (60%) were of advanced maternal age (≥35 years). All women underwent targeted US, and 98 (59%) underwent mammography in addition to US. The frequency of malignancy was five of 167 (3.0%). Targeted US demonstrated a sensitivity and specificity of five of five (100%; 95% confidence interval [CI]: 48%, 100%) and 114 of 162 (70%; 95% CI: 63%, 77%), respectively. Negative predictive value, positive predictive value of an abnormal examination, and positive predictive value of biopsy were 114 of 114 (100%; 95% CI: 97%, 100%), five of 53 (9.4%; 95% CI: 3%, 21%), and five of 50 (10%; 95% CI: 3%, 22%), respectively. In the subset of 98 women who underwent mammography in addition to US, mammography depicted seven incidental suspicious findings, which lowered the specificity from 62 of 93 (67%; 95% CI: 56%, 76%) to 57 of 93 (61%; 95% CI: 51%, 71%) (P = .02). Conclusion Targeted US depicted all malignancies in lactating women with palpable masses. Adding mammography increased false-positive findings without any additional cancer diagnoses. © RSNA, 2020 See also the editorial by Newell in this issue.