Medico-Legal Cases in Breast Imaging in Canada: A Trend Analysis.

Purpose: Breast imaging accounts for a large proportion of medico-legal cases involving radiologists in several countries and may be a disincentive to breast imaging. As this has not been well studied in Canada, we evaluated the key medico-legal issues of breast imaging in Canada and their implications for health care providers and patient safety. Methods: In collaboration with Canadian Medical Protective Association (CMPA), we obtained information from the medico-legal repository, including civil-legal, medical regulatory authority (College) and hospital complaints occurring between 2002-2021. Canadian Classification of Health Interventions (CCI) codes were used for breast imaging and biopsy. Trend analysis was done comparing cases involving breast imaging/biopsy to all cases where a radiologist was named. Results: Radiologists were named in 3108 medico-legal cases, 188 (6%, 188/3108) of which were CCI coded for breast imaging or biopsy. Factors related to radiologists were most frequent (64%, 120/188), followed by team (23.4%, 44/188) and system (6.9%, 13/188). Equal representation of male and female radiologists was found (IRR = 1.22; 95% CI: .89, 1.56). In a 10-year test window from 2006 - 2015 we identified an increasing trend for all cases involving radiologists (P = 0,0128) but a decreasing trend for cases coded with breast imaging or biopsy (P = 0,0099). Conclusions: A significant decrease in cases involving breast imaging were found from 2006-2015, accounting for 6% of the medico-legal cases. The lower risk of breast imaging medico-legal issues may encourage more radiologists in breast imaging.

Canadian Radiology Gender Pay Gap-Reality or Myth?

Introduction: Prior studies on Canadian physicians' income have demonstrated a gender pay gap (GPG); however, there is a paucity of data in the Radiology specialty. A cross-sectional study was conducted to determine if practicing Canadian radiologists' self-reported income is related to gender, controlling for demographic and work variables. Methods: English and French online surveys were distributed by email and social media to radiologists and trainees (May-July 2021). The association between Gender (controlling for Ethnicity variables, Region, having Children, Full-/Part-Time work, and Academic position) and Self-Reported Income was examined using chi-square tests. Pearson correlations examined relationships between opinion variables. Analyses were conducted using SPSS V28.0. A priori significance was P < .05. Study had ethics approval. Results: Four hundred and fifty-four practicing Canadian radiologists responded. Majority were women (51.2%, n = 227), a non-visible Minority (71.7%, n = 317), and from Western Provinces (67.8%, n = 308). Significant relationship was established between Self-Reported Income and Gender (χ2 = 10.44, df = 2, P < .05). More men (70.6%, n = 120) than women (56.4%, n = 110), reported income "greater than $500 000"; fewer men (20.6%, n = 35) than women (35.9%, n = 70) reported "$300 000-$500 000"; a similar percent of men (8.8%, n = 15) and women (7.7%, n = 15) reported "less than $300 000." No relationship was found between self-reported income and gender for ethnicity variables, those without children, part-time, or non-academic radiologists. The opinion "Addressing the GPG is important" correlated to "Canadian Association of Radiologists should collect demographic data" (r = 0.63). Responses were low for ethnic minorities and non-western provinces. Conclusion: Our results suggest a GPG exists in Canadian radiology and is an important first step for future studies.

Case 285: Primary Breast Lymphoma.

History A 25-year-old woman was referred to our breast clinic for assessment of a palpable mass in her left breast that developed quickly in 2 weeks. She denied any associated fever, chills, redness, or pain. She had no relevant medical or surgical history; no evidence of recent pregnancy, abortion, or breastfeeding; and no family history of breast cancer. Clinical examination enabled confirmation of a firm mass occupying the retroareolar region and the outer quadrant of the left breast with no skin retraction, edema, or erythema. There was no evidence of enlarged axillary lymph nodes. US of the left breast, bilateral breast MRI, and fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT were performed.

How Well Are Radiology Residents Prepared for Practice After Training? A Survey of French-Speaking Quebec Recent Graduates and Department Chiefs.

OBJECTIVE: Radiology residents must fulfill a standardized curriculum to complete residency and pass a certification exam before they are granted a licence to practice. We sought to evaluate how well residency prepares trainees for practice as perceived by recent graduates and their department chiefs. Subjects and Methods: Radiologists who graduated from the 4 Quebec radiology residency programs between 2005 and 2016 (n = 237) and Quebec radiology department chiefs (n = 98) were anonymously surveyed. Two electronic surveys were created, for recent graduates (74 questions) and for department chiefs (11 questions), with multiple-choice questions and open questions covering all fields of radiology. Surveys were administered between April and June 2016 using the Association des radiologistes du Québec database. RESULTS: Response rate was 75 (31.6%) of 237 from recent graduates and 96% rated their training as excellent or good. Satisfaction with training in computed tomography and magnetic resonance imaging was high, with musculoskeletal (MSK) imaging, particularly MSK ultrasound (US), as well as pediatric, cardiac, and vascular imaging needing more training. Thirty-nine (39.8%) of 98 department chiefs answered the survey and highlighted weaknesses in the interpretation of conventional radiography, obstetrical US, and invasive procedures, as well as limited leadership and administrative skills. Recent graduates and department chiefs both reported difficulties in the ability to interpret daily volume of examinations as scheduled and invasive procedure competency. CONCLUSION: This survey highlights areas of the radiology curriculum which may benefit from more emphasis during training. Adjustments in the residency program would ensure graduates are successful both in their certification exams and clinical practice.

Case 285.

History A 25-year-old woman was referred to our breast clinic for assessment of a palpable mass in her left breast that developed quickly in 2 weeks. She denied any associated fever, chills, redness, or pain. She had no relevant medical or surgical history; no evidence of recent pregnancy, abortion, or breastfeeding; and no family history of breast cancer. Clinical examination enabled confirmation of a firm mass occupying the retroareolar region and the outer quadrant of the left breast with no skin retraction, edema, or erythema. There was no evidence of enlarged axillary lymph nodes. US of the left breast (Fig 1), bilateral breast MRI (Fig 2), and fluorine 18 fluorodeoxyglucose PET/CT (Fig 3) were performed.

Comparative Evaluation of Iodine-125 Radioactive Seed Localization and Wire Localization for Resection of Breast Lesions.

PURPOSE: Radioactive seed localization (RSL) uses a titanium seed labeled with iodine-125 energy for surgery of nonpalpable breast lesions. RSL facilitates radiology-surgery scheduling and allows for improved oncoplasty compared with wire localization (WL). The purpose of this work was to compare the 2 techniques. METHODS: We performed a retrospective study of all breast lesions operated with RSL between February 2013 and March 2015 at our university institution, and compared with an equivalent number of surgeries performed with a single WL. Imaging and pathology reports were reviewed for information on guidance mode, accuracy of targeting, nature of excised lesion, size and volume of surgical specimen, status of margins, and reinterventions. RESULTS: A total of 254 lesions (247 women) were excised with RSL and compared with 257 lesions (244 women) whose surgery was guided by WL. Both groups were comparable in lesion pathology, guidance mode for RSL or WL positioning, and accuracy of targeting (98% correct). Mean delay between biopsy and surgery was 84 days for RSL versus 103 after WL (P = .04). No differences were noted after RSL or WL for surgical specimen mean weight, largest diameter, and volume excised. For malignancies, the rate of positive margins was comparable (2.8%-3%), with 5 of 10 women in the RSL group who underwent a second surgery displaying residual malignancy compared with 3 of 9 women in the WL group. CONCLUSIONS: RSL is safe and accurate, and has comparable surgical endpoints to WL. Because RSL offers flexible scheduling and facilitated oncoplasty, RSL may replace WL for resection of nonpalpable single breast lesions.

Contribution of mammography to MRI screening in BRCA mutation carriers by BRCA status and age: individual patient data meta-analysis.

BACKGROUND: We investigated the additional contribution of mammography to screening accuracy in BRCA1/2 mutation carriers screened with MRI at different ages using individual patient data from six high-risk screening trials. METHODS: Sensitivity and specificity of MRI, mammography and the combination of these tests were compared stratified for BRCA mutation and age using generalised linear mixed models with random effect for studies. Number of screens needed (NSN) for additional mammography-only detected cancer was estimated. RESULTS: In BRCA1/2 mutation carriers of all ages (BRCA1 = 1,219 and BRCA2 = 732), adding mammography to MRI did not significantly increase screening sensitivity (increased by 3.9% in BRCA1 and 12.6% in BRCA2 mutation carriers, P > 0.05). However, in women with BRCA2 mutation younger than 40 years, one-third of breast cancers were detected by mammography only. Number of screens needed for mammography to detect one breast cancer not detected by MRI was much higher for BRCA1 compared with BRCA2 mutation carriers at initial and repeat screening. CONCLUSIONS: Additional screening sensitivity from mammography above that from MRI is limited in BRCA1 mutation carriers, whereas mammography contributes to screening sensitivity in BRCA2 mutation carriers, especially those ⩽ 40 years. The evidence from our work highlights that a differential screening schedule by BRCA status is worth considering.

Breast MR biopsy: Pathological and radiological correlation.

PURPOSE: To identify pathological features for sample analysis of magnetic resonance imaging-guided vaccum-assisted breast biopsy (MRIgVaBB) to optimize radio pathological correlation and identify discordant benign result. MATERIAL AND METHODS: Databases of two centres were queried to identify MRIgVaBB performed between January 2009 and February 2013. A cohort of 197 women (mean age: 54.5 years (24-77)) with 208 lesions was identified. We retrospectively analyzed all prebiopsy MRI examinations according to the new BI-RADS lexicon, and all biopsy samples to describe the lesion of interest, its interface with the surrounding breast tissue and other associated features. RESULTS: The malignancy rate was 26.0 % (54/208) with an underestimation rate of 15.67 % (5/32). A visible interface at pathology between a biopsied lesion and the surrounding breast tissue was more frequently identified in mass enhancement compared to NME or focus (p = 0.0003). Regional NME was correlated with a high degree of fibrosis (p = 0.001) and the presence of PASH (p = 0.0007). Linear or segmental NME was correlated with the presence of periductal mastitis (p = 0.0003). CONCLUSION: The description of a visible interface between the target lesion and the surrounding tissue is crucial to confirm the correct targeting of an MR mass or a NME. KEY POINTS: • Pathological interface correlated with magnetic resonance mass and focal non-mass enhancement (NME). • Linear or segmental NME correlated with mastitis or ductal carcinoma in situ. • Fibrosis and pseudoangiomatous stromal hyperplasia (PASH) are correlated with regional NME.

The Added Value of Statistical Modeling of Backscatter Properties in the Management of Breast Lesions at US.

PURPOSE: To develop a classification method based on the statistical backscatter properties of tissues that can be used as an ancillary tool to the usual Breast Imaging Reporting and Data System (BI-RADS) classification for solid breast lesions identified at ultrasonography (US). MATERIALS AND METHODS: This study received institutional review board approval, and all subjects provided informed consent. Eighty-nine women (mean age, 50 years; age range, 22-82 years) with 96 indeterminate solid breast lesions (BI-RADS category 4-5; mean size, 13.2 mm; range, 2.6-44.7 mm) were enrolled. Prior to biopsy, additional radiofrequency US images were obtained, and a 3-second cine sequence was used. The research data were analyzed at a later time and were not used to modify patient management decisions. The lesions were segmented manually, and parameters of the homodyned K distribution (α, k, and µn values) were extracted for three regions: the intratumoral zone, a 3-mm supratumoral zone, and a 5-mm infratumoral zone. The Mann-Whitney rank sum test was used to identify parameters with the best discriminating value, yielding intratumoral α, supratumoral k, and infratumoral µn values. RESULTS: The 96 lesions were classified as follows: 48 BI-RADS category 4A lesions, 16 BI-RADS category 4B lesions, seven BI-RADS category 4C lesions, and 25 BI-RADS category 5 lesions. There were 24 cancers (25%). The area under the receiver operating characteristic curve was 0.76 (95% confidence interval: 0.65, 0.86). Overall, 24% of biopsies (in 17 of 72 lesions) could have been spared. By limiting analysis to lesions with a lower likelihood of malignancy (BI-RADS category 4A-4B), this percentage increased to 26% (16 of 62 lesions). Among benign lesions, the model was used to correctly classify 10 of 38 fibroadenomas (26%) and three of seven stromal fibroses (43%). CONCLUSION: The statistical model performs well in the classification of solid breast lesions at US, with the potential of preventing one in four biopsies without missing any malignancy.

Case 201: glomus tumor of the breast.

History A 55-year-old woman presented to our breast clinic with 1-year history of lancinating pain in the right breast that was exacerbated by blunt pressure and cold temperature. She denied any family history of breast cancer or any personal history of trauma, infection, or surgery of the breast. On clinical examination, exquisite pain was generated by simple light pressure over the upper outer quadrant of the right breast. Mammography and ultrasounography (US) with Doppler analysis of the right breast were painful but were performed with the least pressure possible.

Molecular classification of infiltrating breast cancer: toward personalized therapy.

Breast cancer is a heterogeneous disease, which comprises several molecular and genetic subtypes, each with characteristic clinicobiologic behavior and imaging patterns. Traditional classification of breast cancer is based on the histopathologic features but offers limited prognostic value. Novel molecular characterization of breast cancer with cellular markers has allowed a new classification that offers prognostic value, with predictive categories of disease aggressiveness. These molecular signatures also open the door to personalized therapeutic options, with new receptor-targeted therapies. For example, invasive cancer subtypes such as the luminal A and B subtypes show better prognosis and response to hormone receptor-targeted therapies compared with the triple-negative subtypes; on the other hand, triple-negative tumors respond better than luminal tumors to chemotherapy. Tumors that display amplification of the oncogene ERBB2 (also known as the HER2/neu oncogene) respond to drugs directed against this oncogene, such as trastuzumab. The imaging aspects of tumors correlate with molecular subgroups, as well as other pathologic features such as nuclear grade. Smooth tumor margins at mammography may be suggestive of a triple-negative breast cancer, and a human epidermal growth factor receptor 2 (HER2)-positive tumor is characteristically a spiculated mass with calcifications. Low-grade ductal carcinoma in situ (DCIS) is better detected with mammography, although magnetic resonance (MR) imaging may allow better characterization of high-grade DCIS. MR imaging diffusion sequences show higher values for the apparent diffusion coefficient for triple-negative and HER2-positive subtypes, compared with luminal A and B tumors. MR imaging is also a useful tool in the prediction of tumor response after chemotherapy, especially for triple-negative and HER2-positive subtypes.

Breast MR imaging at 3 T with dual-source radiofrequency transmission offers superior B1 homogeneity: an intraindividual comparison with breast MR imaging at 1.5 T.

PURPOSE: To evaluate and compare B1 homogeneity for breast magnetic resonance (MR) imaging performed at 3 T with dual-source radiofrequency (RF) transmission to 1.5-T MR imaging and 3-T MR imaging with quadrature transmission. MATERIALS AND METHODS: This prospective study received institutional review board approval and patients provided informed consent. Women (n = 25; mean age, 53 years; range, 30-68 years) suspected of having breast lesions underwent breast MR imaging examinations on comparable 1.5-T and 3-T clinical systems between February and May 2012. B1 maps were obtained at 1.5 T and at 3 T with quadrature and dual-source RF transmission. Intrabreast differences and differences in mean B1 values between right and left breasts were investigated by using two-sided multivariate analysis of variance with interaction; t tests were used to compare the differences between measured whole-breast mean B1 values and requested B1 values. RESULTS: With quadrature transmission at 1.5 T and 3 T, the mean B1 values showed a statistically significant difference: left-breast measured B1 was -8.9% of requested B1 value at 1.5 T and -13.7% at 3 T (P < .001), whereas right-breast measured B1 was +5.4% of requested B1 value at 1.5 T (P < .001) and +2.7% at 3 T (P = .01). With dual-source RF transmission at 3 T, mean B1 values across the breasts were not statistically different, nor were the measured B1 values compared with requested B1 values (left breast, -0.6%; right breast, -0.7%). At 3 T with dual-source transmission, slight intrabreast local variations in B1 were recorded. CONCLUSION: MR imaging at 3 T with dual-source RF transmission offered an overall B1 homogeneity for breast imaging that was better than that obtained at 1.5 T and with quadrature transmission.

Breast reconstruction: review of surgical methods and spectrum of imaging findings.

Breast reconstruction after mastectomy is often requested by women with breast cancer who are ineligible for breast-conserving therapy and women with a high genetic risk for breast cancer. Current breast reconstruction techniques are diverse and may involve the use of an autologous tissue flap, a prosthetic implant, or both. Regardless of the technique used, cancer may recur in the reconstructed breast; in addition, in breasts reconstructed with autologous tissue flaps, benign complications such as fat necrosis may occur. To detect breast cancer recurrences at a smaller size than can be appreciated clinically and as early as possible without evidence of metastasis, radiologists must be familiar with the range of normal and abnormal imaging appearances of reconstructed breasts, including features of benign complications as well as those of malignant change. Images representing this spectrum of findings were selected from the clinical records of 119 women who underwent breast magnetic resonance (MR) imaging at the authors' institution between January 2009 and March 2011, after mastectomy and breast reconstruction. In 32 of 37 women with abnormal findings on MR images, only benign changes were found at further diagnostic workup; in the other five, recurrent breast cancer was found at biopsy. Four of the five had been treated initially for invasive carcinoma, and one, for multifocal ductal carcinoma; three of the five were carriers of a BRCA gene mutation. On the basis of these results, the authors suggest that systematic follow-up examinations with breast MR imaging may benefit women with a reconstructed breast and a high risk for breast cancer recurrence.

Education Research: Neuroradiology Curriculum and Competencies Among Canadian Adult Neurology Residency Programs: A Cross-Sectional Study.

Background and Objectives: While benefitting from neuroradiologists' reports, neurologists use their own image interpretation to guide clinical decisions, especially in acute care settings. This calls for robust neuroradiology training in neurology residency, informed by current educational gaps and practices. This study aims to (1) characterize the formal neuroradiology curriculum among Canadian neurology residency programs; (2) assess neurology residents' neuroimaging interpretation competencies; and (3) define neurology residents' and program directors' (PDs) attitudes toward the current curriculum and future directions. Methods: Anonymous surveys were sent to Canadian neurology residents and PDs, querying neuroradiology learning activities, imaging modalities covered, assessment modalities, perceived residents' competencies to interpret different modalities, and attitudes regarding neuroradiology training. Residents were asked to interpret 15 neuroimaging cases. Descriptive and inferential analyses were performed. Potential differences in residents' interpretation success rates by seniority, self-perceived proficiency, and perception of curriculum sufficiency were examined using 2-tailed Welch tests with a 95% CI and Holm-Bonferroni comparison adjustment. Statistics were computed using Excel. Results: Seventy-eight (32.6%) residents and 11 (68.8%) PDs participated. Ten of 11 PDs reported including a mandatory neuroradiology rotation, and 9/11 offered a formal neuroradiology curriculum covering head CT, head and neck CT angiography (CTA), spine MRI, and head MRI. Programs predominantly offered additional didactic lectures (9/11), teaching cases (8/11), and imaging websites (8/11). Most of the residents agreed with a minimum 1-month long rotation and desired regular didactics from neuroradiologists. Residents favored learning about head MRI (88.5%), head and neck CTA (76.9%), and spine MRI (69.2%). Senior residents' self-perceived competencies were highest for head CT, head MRI, and head and neck CTA, but lower than PDs' perception. Senior residents had greater interpretation scores than juniors (84.5% ± 13.2% vs 69.1% ± 19.9%; p < 0.0001). Most PDs (7/11, 63.6%) expressed satisfaction with current curricula vs 32.1% of residents. PDs identified time and educator shortages as main barriers to increased training. Discussion: Neuroradiology training varies among programs. Residents expressed strong interest in commonly taught modalities, for which they also expressed high self-perceived competencies. However, PDs expressed greater satisfaction than residents with the current training. Leveraging interactions with neuroradiologists and online case-based learning while emphasizing trainees' interests can enhance postgraduate neuroradiology training for this useful skill.

Canadian radiology workforce demographics: Results from a national survey.

Rationale and objective: Demographic data collected about Canadian radiologists and trainees has been limited primarily to binary gender and geographic location. The purpose of this study was to investigate: (1) demographic characteristics of Canadian radiologists and trainees; (2) types of diversity important to radiologists; (3) relationship of radiologist demographics to practice characteristics; and (4) relationship of radiologist demographics to years in practice, (YIP). Materials and methods: French and English surveys were distributed via email through radiology associations and social media. Frequency counts of demographic variables were calculated, and chi-square and Fisher's Exact tests were performed to explore the relationships between demographic characteristics and role. Results: 611 individuals responded to the survey. 573 respondents were included in the analysis. 454 (78.8%) were practicing radiologists and 119 (20.7%) were residents/fellows. Half identified as women (50.4%). English was the primary language for most respondents. There was an association between role and sexual orientation (p = 0.02), visible minority (χ2 = 4.79, p < 0.05), religion (χ2 = 4.11, p < 0.05), and having children (χ2 = 136.65, p < 0.05). For radiologists, being a visible minority (χ2 = 11.59, p < 0.05) and age (χ2 = 56.3, p < 0.05) were associated with academic rank while gender (χ2 = 3.83, p < 0.05) and age (χ2 = 13.74, p < 0.05) were related to part-/full-time status. Less women, visible minorities, and women with children had been in practice for long. Discussion: This study represents a comprehensive analysis of Canadian radiology demographics. Results suggest there is increasing diversity among trainees; however, significant demographic underrepresentation compared to the diversity of Canada exists.

A plea for the biopsy marker: how, why and why not clipping after breast biopsy?

In the last decade, percutaneous breast biopsies have become a standard for the management of breast diseases. Biopsy clips allow for precise lesion localization, thus minimizing the volume of breast to be resected at the time of surgery. With the development of many imaging techniques (including mammography, sonography, and breast magnetic resonance imaging), one of the challenges of the multidisciplinary became to synthesize all informations obtained from the various imaging procedures. The use of biopsy markers after percutaneous biopsy is one of the keys for optimal patient management, helping the radiologist to deal with multiple lesions, to insure correlation across different imaging modalities and to follow-up benign lesions, helping the oncologist by marking a tumor prior to neoadjuvant chemotherapy, helping the surgeon by facilitating preoperative needle localization, to precisely mark the margins of extensive disease and to guide intraoperative tumor resection, and helping the pathologist to insure the lesion of interest has been removed and to identify the region of interest in a mastectomy specimen. We believe biopsy clip markers should be deployed after all percutaneous interventions and present in this review the arguments to support this statement. Minimal indications for clip deployment will also be detailed.

Surgical outcome of biopsy-proven lobular neoplasia: is there any difference between lobular carcinoma in situ and atypical lobular hyperplasia?

OBJECTIVE: The aims of our study were to determine the frequency of malignancy after surgical excision of biopsy-proven lobular carcinoma in situ (LCIS) or atypical lobular hyperplasia (ALH) lesions, to assess any difference between pure LCIS and pure ALH lesions regarding their radiologic presentation and the malignancy upgrade rate after surgical excision, and to evaluate the outcome of lesions that were not excised surgically but were followed up. MATERIALS AND METHODS: Radiologic and pathologic records of 14,435 imaging-guided needle biopsies of the breast performed between 2004 and 2008 in three different institutions were retrospectively reviewed. A total of 126 patients (0.9%) had biopsy-proven LCIS or ALH, or both, as the highest-risk lesion. Among the 126 patients, 89 (71%) continued to surgery, and 14 were followed up for more than 24 months. The Mantel-Haensel chi-square test was used for statistical analysis. RESULTS: Cancer upgrade was documented in 17 of the 43 LCIS (40%), 11 of the 40 ALH (27%), and two of the six combined ALH and LCIS lesions (33%) surgically excised, for a total malignancy upgrade rate of 34% (30/89). Both LCIS and ALH lesions presented mammographically in most cases as microcalcifications (p = 0.078). None of the 14 patients followed up for a mean period of 51 months showed development of malignancy. CONCLUSION: No statistically significant difference was found between mammographic presentation and postsurgical outcome of LCIS versus ALH lesions. Surgical excision of these lesions is recommended as long as no evident criteria are provided to differentiate those that might be associated with an underlying malignancy.

Quality initiatives: guidelines for use of medical imaging during pregnancy and lactation.

The use of computed tomography (CT) and magnetic resonance (MR) imaging has increased tremendously in the past 2 decades. Hence, pregnant and breast-feeding women, although generally healthier than the population at large, are also more likely to require contrast material-enhanced imaging. When a contrast-enhanced CT or MR imaging study is being considered for a pregnant or lactating patient, the potential risks to the fetus related to exposure to radiation, high magnetic fields, or contrast agents must be considered and weighed carefully against the risks of potential misdiagnosis due to withholding contrast agents and imaging studies. Fetal radiation doses up to 1 mGy are considered acceptable; with larger doses, the risk of carcinogenesis approximately doubles, although it remains low in absolute terms. No damage to a developing human fetus caused by MR imaging exposure has been documented. However, caution is advised, and risks and benefits must always be considered before evaluating a pregnant patient with MR imaging. The use of iodinated contrast agents is generally safe during pregnancy; nevertheless, these agents should be used with caution due to the risk of fetal hypothyroidism and should be administered only when the clinical situation clearly requires doing so. The use of gadolinium-based contrast agents during pregnancy remains controversial due to lack of human clinical data and potential toxicity. Use of all contrast agents is considered safe during lactation. It is hoped that this knowledge will help radiologists develop a consensus with their clinical colleagues regarding case management of pregnant and lactating patients.