Preoperative breast MRI positively impacts surgical outcomes of needle biopsy-diagnosed pure DCIS: a patient-matched analysis from the MIPA study.

OBJECTIVES: To investigate the influence of preoperative breast MRI on mastectomy and reoperation rates in patients with pure ductal carcinoma in situ (DCIS). METHODS: The MIPA observational study database (7245 patients) was searched for patients aged 18-80 years with pure unilateral DCIS diagnosed at core needle or vacuum-assisted biopsy (CNB/VAB) and planned for primary surgery. Patients who underwent preoperative MRI (MRI group) were matched (1:1) to those who did not receive MRI (noMRI group) according to 8 confounding covariates that drive referral to MRI (age; hormonal status; familial risk; posterior-to-nipple diameter; BI-RADS category; lesion diameter; lesion presentation; surgical planning at conventional imaging). Surgical outcomes were compared between the matched groups with nonparametric statistics after calculating odds ratios (ORs). RESULTS: Of 1005 women with pure unilateral DCIS at CNB/VAB (507 MRI group, 498 noMRI group), 309 remained in each group after matching. First-line mastectomy rate in the MRI group was 20.1% (62/309 patients, OR 2.03) compared to 11.0% in the noMRI group (34/309 patients, p = 0.003). The reoperation rate was 10.0% in the MRI group (31/309, OR for reoperation 0.40) and 22.0% in the noMRI group (68/309, p < 0.001), with a 2.53 OR of avoiding reoperation in the MRI group. The overall mastectomy rate was 23.3% in the MRI group (72/309, OR 1.40) and 17.8% in the noMRI group (55/309, p = 0.111). CONCLUSIONS: Compared to those going directly to surgery, patients with pure DCIS at CNB/VAB who underwent preoperative MRI had a higher OR for first-line mastectomy but a substantially lower OR for reoperation. CLINICAL RELEVANCE STATEMENT: When confounding factors behind MRI referral are accounted for in the comparison of patients with CNB/VAB-diagnosed pure unilateral DCIS, preoperative MRI yields a reduction of reoperations that is more than twice as high as the increase in overall mastectomies. KEY POINTS: • Confounding factors cause imbalance when investigating the influence of preoperative MRI on surgical outcomes of pure DCIS. • When patient matching is applied to women with pure unilateral DCIS, reoperation rates are significantly reduced in women who underwent preoperative MRI. • The reduction of reoperations brought about by preoperative MRI is more than double the increase in overall mastectomies.

Malignancy mimic: Suspicious mammographic and sonographic findings post-vacuum-assisted excision biopsy.

Vacuum-assisted excision biopsy (VAEB) provides a safe alternative to surgical excision for selected (low-risk) B3 breast lesions. We report a case of imaging findings that mimicked malignancy in a patient one year post-VAEB. Awareness of this entity is important to prevent misdiagnosis and unnecessary surgical excision.

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.

Interpreting contrast imaging to plan breast surgery.

BACKGROUND: Contrast enhanced mammography (CEM) and magnetic resonance imaging (MRI) are more accurate than conventional imaging (CI) for breast cancer staging. How adding CEM and MRI to CI might change the surgical plan is understudied. METHODS: Surgical plans (breast conserving surgery (BCS), wider BCS, BCS with diagnostic excision (>1BCS), mastectomy) were devised by mock-MDT (radiologist, surgeon and pathology reports) according to disease extent on CI, CI + CEM and CI + MRI. Differences in the mock-MDT's surgical plans following the addition of CEM or MRI were investigated. Using pre-defined criteria, the appropriateness of the modified plans was assessed by comparing estimated disease extent on imaging with final pathology. Surgery performed was recorded from patient records. RESULTS: Contrast imaging modified mock-MDT plans for 20 of 61(32.8%) breasts. The addition of CEM changed the plan in 16/20 (80%) and MRI in 17/20 breasts (85%). Identical changes were proposed by both CEM and MRI in 13/20 (65%) breasts. The modified surgical plan based on CI + CEM was possibly appropriate for 6/16 (37.5%), and CI + MRI in 9/17, (52.9%) breasts. The surgery performed was concordant with the mock-MDT plan for all 10 patients where the plans could be compared (BCS 1, >1 BCS 2 and mastectomy 7). CONCLUSION: Adding CEM or MRI to CI changed mock-MDT plans in up to one third of women, but not all were appropriate. Changing surgical plans following addition of contrast imaging to CI without biopsy confirmation could lead to over or under-treatment.

Localisation accuracy with iodine-125 seed versus wire guidance for breast cancer surgery.

INTRODUCTION: Impalpable breast lesions generally require image-guided localisation for breast-conserving surgery. A standard technique is to place a hook wire (HW) within the lesion. Radioguided occult lesion localisation using iodine seeds (ROLLIS) involves inserting a 4.5 mm iodine-125 seed (seed) into the lesion. We hypothesised that a seed could be more precisely positioned in relation to the lesion than a HW and that this may be associated with a lower re-excision rate. METHODS: Retrospective review of consecutive participant data from three ROLLIS RCT (ACTRN12613000655741) sites. Participants underwent preoperative lesion localisation (PLL) with seed or HW between September 2013 and December 2017. Lesion and procedural characteristics were recorded. Distances between (1) any part of the seed or thickened segment of the HW ('TSHW') and the lesion/clip ('distance to device' DTD) and (2) centre of the TSHW/seed and centre of the lesion/clip (device centre to target centre 'DCTC') were measured on immediate postinsertion mammograms. Pathological margin involvement and re-excision rates were compared. RESULTS: A total of 390 lesions (190 ROLLIS and 200 HWL) were analysed. Lesion characteristics and guidance modality used were similar between groups. Ultrasound-guided DTD and DCTC for seed were smaller than for HW (77.1% and 60.6%, respectively, P-value < 0.001). Stereotactic-guided DCTC for seeds was 41.6% smaller than for HW (P-value = 0.001). No statistically significant difference in the re-excision rates was found. CONCLUSION: Iodine-125 seeds can be more precisely positioned for preoperative lesion localisation than HW, however, no statistically significant difference in re-excision rates was detected.

Screening and diagnostic breast MRI: how do they impact surgical treatment? Insights from the MIPA study.

OBJECTIVES: To report mastectomy and reoperation rates in women who had breast MRI for screening (S-MRI subgroup) or diagnostic (D-MRI subgroup) purposes, using multivariable analysis for investigating the role of MRI referral/nonreferral and other covariates in driving surgical outcomes. METHODS: The MIPA observational study enrolled women aged 18-80 years with newly diagnosed breast cancer destined to have surgery as the primary treatment, in 27 centres worldwide. Mastectomy and reoperation rates were compared using non-parametric tests and multivariable analysis. RESULTS: A total of 5828 patients entered analysis, 2763 (47.4%) did not undergo MRI (noMRI subgroup) and 3065 underwent MRI (52.6%); of the latter, 2441/3065 (79.7%) underwent MRI with preoperative intent (P-MRI subgroup), 510/3065 (16.6%) D-MRI, and 114/3065 S-MRI (3.7%). The reoperation rate was 10.5% for S-MRI, 8.2% for D-MRI, and 8.5% for P-MRI, while it was 11.7% for noMRI (p ≤ 0.023 for comparisons with D-MRI and P-MRI). The overall mastectomy rate (first-line mastectomy plus conversions from conserving surgery to mastectomy) was 39.5% for S-MRI, 36.2% for P-MRI, 24.1% for D-MRI, and 18.0% for noMRI. At multivariable analysis, using noMRI as reference, the odds ratios for overall mastectomy were 2.4 (p < 0.001) for S-MRI, 1.0 (p = 0.957) for D-MRI, and 1.9 (p < 0.001) for P-MRI. CONCLUSIONS: Patients from the D-MRI subgroup had the lowest overall mastectomy rate (24.1%) among MRI subgroups and the lowest reoperation rate (8.2%) together with P-MRI (8.5%). This analysis offers an insight into how the initial indication for MRI affects the subsequent surgical treatment of breast cancer. KEY POINTS: • Of 3065 breast MRI examinations, 79.7% were performed with preoperative intent (P-MRI), 16.6% were diagnostic (D-MRI), and 3.7% were screening (S-MRI) examinations. • The D-MRI subgroup had the lowest mastectomy rate (24.1%) among MRI subgroups and the lowest reoperation rate (8.2%) together with P-MRI (8.5%). • The S-MRI subgroup had the highest mastectomy rate (39.5%) which aligns with higher-than-average risk in this subgroup, with a reoperation rate (10.5%) not significantly different to that of all other subgroups.

Iodine-125 seed versus hook-wire guided breast conserving surgery: do post operative complication rates differ?

BACKGROUND: Radio-guided occult lesion localisation using iodine 125 seeds (ROLLIS) is used to localize impalpable breast cancers for breast conserving surgery (BCS). Previous studies have suggested improved efficiency and patient outcomes with ROLLIS compared with hook-wire localisation (HWL). The aim of this report is to compare the post-operative complication rates and safety profiles of ROLLIS versus hook-wire guided surgery. METHODS: Between September 2013 and March 2018, 690 women with non-palpable breast cancer eligible for breast-conserving surgery were randomly assigned to either pre-operative localisation with 125 I seed or hook-wire as part of the ROLLIS clinical trial. Medical record review of 170 women (30% of the total participants) from three tertiary hospitals in Western Australia was performed. Post-operative complications were classified using the Common Terminology Criteria for Adverse Events(CTCAE) grade I to V. RESULTS: Total of 170 surgeries were performed: 82 by ROLLIS and 88 by hook-wire. The overall complication rate in the ROLLIS group was 19.5%, with 15.9% being grade II and 3.66% grade III. In the HWL group, the complication rate was 22.7% with 20.5% being grade II and 2.27% grade III. There was no statistically significant difference in complication grades between the 2 groups. No grade IV or grade V complications were reported. Complications observed included drainable seroma, drainable haematoma and surgical site infection. CONCLUSION: ROLLIS is a safe method of localisation for surgical resection with similar complication rates as hookwires. We encourage its use as an alternative localisation technique as it has demonstrable superiority and efficacy.

Contrast-enhanced mammography (CEM) versus MRI for breast cancer staging: detection of additional malignant lesions not seen on conventional imaging.

BACKGROUND: Contrast-enhanced mammography (CEM) is more available than MRI for breast cancer staging but may not be as sensitive in assessing disease extent. We compared CEM and MRI in this setting. METHODS: Fifty-nine women with invasive breast cancer underwent preoperative CEM and MRI. Independent pairs of radiologists read CEM studies (after reviewing a 9-case set prior to study commencement) and MRI studies (with between 5 and 25 years of experience in breast imaging). Additional lesions were assigned National Breast Cancer Centre (NBCC) scores. Positive lesions (graded NBCC ≥ 3) likely to influence surgical management underwent ultrasound and/or needle biopsy. True-positive lesions were positive on imaging and pathology (invasive or in situ). False-positive lesions were positive on imaging but negative on pathology (high-risk or benign) or follow-up. False-negative lesions were negative on imaging (NBCC < 3 or not identified) but positive on pathology. RESULTS: The 59 women had 68 biopsy-proven malignant lesions detected on mammography/ultrasound, of which MRI demonstrated 66 (97%) and CEM 67 (99%) (p = 1.000). Forty-one additional lesions were detected in 29 patients: six of 41 (15%) on CEM only, 23/41 (56%) on MRI only, 12/41 (29%) on both; CEM detected 1/6 and MRI 6/6 malignant additional lesions (p = 0.063), with a positive predictive value (PPV) of 1/13 (8%) and 6/26 (23%) (p = 0.276). CONCLUSIONS: While MRI and CEM were both highly sensitive for lesions detected at mammography/ultrasound, CEM may not be as sensitive as MRI in detecting additional otherwise occult foci of malignancy. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry: ACTRN 12613000684729.

Accuracy and precision of contrast enhanced mammography versus MRI for predicting breast cancer size: how "good" are they really?

OBJECTIVE: To evaluate and compare the accuracy and precision of contrast-enhanced mammography (CEM) vs MRI to predict the size of biopsy-proven invasive breast cancer. METHODS: Prospective study, 59 women with invasive breast cancer on needle biopsy underwent CEM and breast MRI. Two breast radiologists read each patient's study, with access limited to one modality. CEM lesion size was measured using low-energy and recombined images and on MRI, the first post-contrast series. Extent of abnormality per quadrant was measured for multifocal lesions. Reference standards were size of largest invasive malignant lesion, invasive (PathInvasive) and whole (PathTotal). Pre-defined clinical concordance ±10 mm. RESULTS: Mean patient age 56 years, 42 (71%) asymptomatic. Lesions were invasive ductal carcinoma 40 (68%) with ductal carcinoma in situ (31/40) in 78%, multifocal in 12 (20%). Median lesion size was 17 mm (invasive) and 27 mm (total), range (5-125 mm). Lin's concordance correlation coefficients for PathTotal 0.75 (95% CI 0.6, 0.84) and 0.71 (95% CI 0.56, 0.82) for MRI and contrast-enhanced spectral mammography (CESM) respectively. Mean difference for total size, 3% underestimated and 4% overestimated, and for invasive 41% and 50% overestimate on MRI and CESM respectively. LOAs for PathTotal varied from 60% under to a 2.4 or almost threefold over estimation. MRI was concordant with PathTotal in 36 (64%) cases compared with 32 (57%) for CESM. Both modalities concordant in 26 (46%) cases respectively. CONCLUSION: Neither CEM nor MRI have sufficient accuracy to direct changes in planned treatment without needle biopsy confirmation. ADVANCES IN KNOWLEDGE: Despite small mean differences in lesion size estimates using CEM or MRI, the 95% limits of agreement do not meet clinically acceptable levels.

Vacuum-assisted excision biopsy for definitive diagnosis of breast lesions of uncertain malignant potential (B3 lesions) on core biopsy - A single centre Western Australian experience.

INTRODUCTION: In Australia, the usual approach to breast lesions where core biopsy returns an uncertain result ("B3" breast lesion) is to perform surgical diagnostic open biopsy (DOB). This is associated with patient time off work, costs of hospital admission, risks of general anaesthesia and surgical complications. The majority of B3 lesions return benign results following surgery. Vacuum assisted excision biopsy (VAEB) is a less invasive, lower cost alternative, and is standard of care for selected B3 lesions in the United Kingdom. Similar use of VAEB in Australia, could save many women unnecessary surgery. The aim of this study was to document our experience during the introduction of VAEB as an alternative to DOB for diagnosis of selected B3 lesions. METHODS: The multidisciplinary team developed an agreed VAEB pathway for selected B3 lesions. Technically accessible papillary lesions, mucocele-like lesions and radial scars without atypia measuring ≤ 15mm were selected. RESULTS: Over a 7 month period, 18 women with 20 B3 lesions were offered VAEB. 16 women (18 lesions) chose VAEB over DOB. Papillomas were the commonest lesion type. All lesions were successfully sampled: 17/18 were benign. One lesion (6%) was upgraded to malignancy (ductal carcinoma in situ on VAEB, invasive ductal carcinoma at surgery). No major complications occurred. Patient satisfaction was high: 15/16 respondents would again choose VAEB over surgery. CONCLUSION: VAEB is a patient-preferred, safe, well-tolerated, lower-cost alternative to DOB for definitive diagnosis of selected B3 breast lesions.

Does breast biopsy marker cost and availability influence utilisation in radiology practice?

INTRODUCTION: Breast Screen Australia and Breast Screen Aotearoa guidelines recommend breast biopsy marker (BBM) use in indicated patients. This study aims to evaluate whether BBM cost and availability impacts BBM utilisation. METHODS: An online survey was disseminated to radiologists who identified 'breast imaging' as their area of practice in the Royal Australian and New Zealand College of Radiologists (RANZCR) customer relationship management system. Survey questions addressed participant demographics and factors relating to BBM use. RESULTS: Most (92%, 245/266) participants report that BBMs are routinely available at their place of practice. Those employed in private practice were more likely to report that BBMs are not routinely available. 22% (58/266) of radiologists report that BBM cost influences choice of biopsy type (core biopsy vs fine needle aspirate), this finding was more frequent in those employed in private practice. 47% of respondents report that the cost of BBMs is passed on to the patient, with all these respondents employed in a private or mixed private/public setting. Half the respondents (133/266) reported that their decision to use BBMs would be influenced by the availability of insurance coverage to cover BBM costs. CONCLUSIONS: Results suggest that BBM cost and availability influences both choice of biopsy type (core biopsy vs FNA) and choice to use a BBM. Radiologists working in private practice or mixed private/public practice report that BBMs are less likely to be available for use, and that BBM cost is more likely passed to the patient; possibly disadvantaging patients who present to private radiology providers with imaging findings or conditions that would indicate BBM insertion under current national guidelines.

Interviewing in virtual environments: Towards understanding the impact of rapport-building behaviours and retrieval context on eyewitness memory.

Given the complexities of episodic memory and necessarily social nature of in-person face-to-face interviews, theoretical and evidence-based techniques for collecting episodic information from witnesses, victims, and survivors champion rapport-building. Rapport is believed to reduce some of the social demands of recalling an experienced event in an interview context, potentially increasing cognitive capacity for remembering. Cognitive and social benefits have also emerged in remote interview contexts with reduced anxiety and social pressure contributing to improved performance. Here, we investigated episodic memory in mock-eyewitness interviews conducted in virtual environments (VE) and in-person face-to-face (FtF), where rapport-building behaviours were either present or absent. Main effects revealed when rapport was present and where interviews were conducted in a VE participants recalled more correct event information, made fewer errors and were more accurate. Moreover, participants in the VE plus rapport-building present condition outperformed participants in all other conditions. Feedback indicated both rapport and environment were important for reducing the social demands of a recall interview, towards supporting effortful remembering. Our results add to the emerging literature on the utility of virtual environments as interview spaces and lend further support to the importance of prosocial behaviours in applied contexts.

Evaluating breast biopsy practice and breast biopsy marker utilisation in the clinical setting.

INTRODUCTION: Breast Screen Australia and Breast Screen Aotearoa guidelines recommend breast biopsy marker (BBM) use in indicated patients. This study aims to evaluate breast biopsy practice and BBM utilisation by modality. METHODS: An online survey was disseminated to radiologists who identified 'breast imaging' as their area of practice in the Royal Australian and New Zealand College of Radiologists (RANZCR) customer relationship management system. Survey questions addressed participant demographics and factors relating to BBM use. RESULTS: Most respondents (72%) place between 1 and 4 BBMs per week. Almost all (99%) respondents perform ultrasound-guided biopsy of the breast or axillary nodes, with 85% performing stereotactic or tomosynthesis-guided breast biopsy and 27% performing MRI-guided breast biopsy. BBM utilisation differs by modality, with 97% respondents always placing a BBM post-MRI-guided breast biopsy, 50% always placing a BBM post-stereotactic-guided biopsy and 3% always placing a BBM post-ultrasound-guided breast biopsy. CONCLUSIONS: Almost all radiologists perform breast biopsy using ultrasound, stereotactic/tomosynthesis or MRI guidance. BBM utilisation varies by modality, with 72% of respondents placing between 1 and 4 clips per week. Reasons for placing or not placing BBM aligned with prior studies. This is the first study to evaluate the number of breast biopsies performed by radiologists on a weekly or monthly basis, providing a useful platform for comparison in the local setting.

ROLLIS roll-out: Pitfalls, errors, lessons learned and recommendations from Australian and New Zealand experience during the randomised controlled trial, implementing a novel localisation method for impalpable malignant breast lesions, radio-guided occult lesion localisation with iodine-125 (125 I) seed (ROLLIS).

INTRODUCTION: Breast cancer surgery aims to excise lesions with clear margins and provide optimal cosmesis with a low re-excision rates. These aims are aided by accurate lesion localisation and a surgical choice of incision site with minimal removal of healthy tissue. Problems associated with hookwires have led to adoption of non-wire methods including radioguided occult lesion localisation using iodine-125 (ROLLIS). This paper outlines the problems encountered and lessons learnt during the largest RCT involving 659 participants, conducted at eight sites (seven Australian, one New Zealand centres) between September 2013 and April 2018.* METHODS: Data, along with substantive comments, regarding each ROLLIS procedure, documenting each step from the seed insertion, ease of operative retrieval, to return of the seed to medical physics, from a shared on-line secure database and a separate site email survey, were synthesised and categorised. RESULTS: The Australian and New Zealand ROLLIS RCT experience highlights several important issues. Lessons learned were related to licencing the seed and tracking protocols. A Designated Team Lead, who is a good communicator, ensuring the Tracking Protocols were accurately followed and updated, subspecialty leads and a Co-ordinator, responsible for training, logbook maintenance and seed ordering, enhanced the success and acceptance of the programme. Addressing radiation issues, fears, education of staff and seed loss was imperative. CONCLUSION: The Australian and New Zealand ROLLIS RCT experience highlights the need for adherence to local licencing laws and protocols, appointing a dedicated ROLLIS Designated Team Lead with good communication and a ROLLIS Co-ordinator. These facilitate the adoption of a successful ROLLIS programme.

"No One Manages It; We Just Sign Them Up and Do It": A Whole System Analysis of Access to Healthcare in One Remote Australian Community.

OBJECTIVE: To assess the accessibility, availability and utilisation of a comprehensive range of community-based healthcare services for Aboriginal people and describe contributing factors to providing effective healthcare services from the provider perspective. SETTING: A remote community in New South Wales, Australia. PARTICIPANTS: Aboriginal and non-Aboriginal health and education professionals performing various roles in healthcare provision in the community. DESIGN: Case study. METHODOLOGY: The study was co-designed with the community. A mixed-methods methodology was utilised. Data were gathered through structured interviews. Descriptive statistics were used to analyse the availability of 40 health services in the community, whilst quotations from the qualitative research were used to provide context for the quantitative findings. RESULTS: Service availability was mapped for 40 primary, specialised, and allied health services. Three key themes emerged from the analysis: (1) there are instances of both underservicing and overservicing which give insight into systemic barriers to interagency cooperation; (2) nurses, community health workers, Aboriginal health workers, teachers, and administration staff have an invaluable role in healthcare and improving patient access to health services and could be better supported through further funding and opportunities for specialised training; and (3) visiting and telehealth services are critical components of the system that must be linked to existing community-led primary care services. CONCLUSION: The study identified factors influencing service availability, accessibility and interagency cooperation in remote healthcare services and systems that can be used to guide future service and system planning and resourcing.

Implant deformity on screening mammography, an unusual presentation of breast implant associated lymphoma.

Breast implant associated anaplastic large cell lymphoma (BIA-ALCL) is a rare condition related to textured breast implants. Recognition of characteristic imaging and pathological features are important, given the absence of symptoms can delay diagnosis, as illustrated by this case. Late-onset peri-implant effusion is commonly encountered whilst an associated mass or lymphadenopathy are rare. Clinical and radiological suspicion enables dedicated pathology work-up for diagnosis. Ultrasound is vital for initial work-up whilst MRI and PET-CT assist in staging. Surgical explantation is followed by adjuvant chemo-radiotherapy according to disease extent.

Magnetic resonance imaging before breast cancer surgery: results of an observational multicenter international prospective analysis (MIPA).

OBJECTIVES: Preoperative breast magnetic resonance imaging (MRI) can inform surgical planning but might cause overtreatment by increasing the mastectomy rate. The Multicenter International Prospective Analysis (MIPA) study investigated this controversial issue. METHODS: This observational study enrolled women aged 18-80 years with biopsy-proven breast cancer, who underwent MRI in addition to conventional imaging (mammography and/or breast ultrasonography) or conventional imaging alone before surgery as routine practice at 27 centers. Exclusion criteria included planned neoadjuvant therapy, pregnancy, personal history of any cancer, and distant metastases. RESULTS: Of 5896 analyzed patients, 2763 (46.9%) had conventional imaging only (noMRI group), and 3133 (53.1%) underwent MRI that was performed for diagnosis, screening, or unknown purposes in 692/3133 women (22.1%), with preoperative intent in 2441/3133 women (77.9%, MRI group). Patients in the MRI group were younger, had denser breasts, more cancers ≥ 20 mm, and a higher rate of invasive lobular histology than patients who underwent conventional imaging alone (p < 0.001 for all comparisons). Mastectomy was planned based on conventional imaging in 22.4% (MRI group) versus 14.4% (noMRI group) (p < 0.001). The additional planned mastectomy rate in the MRI group was 11.3%. The overall performed first- plus second-line mastectomy rate was 36.3% (MRI group) versus 18.0% (noMRI group) (p < 0.001). In women receiving conserving surgery, MRI group had a significantly lower reoperation rate (8.5% versus 11.7%, p < 0.001). CONCLUSIONS: Clinicians requested breast MRI for women with a higher a priori probability of receiving mastectomy. MRI was associated with 11.3% more mastectomies, and with 3.2% fewer reoperations in the breast conservation subgroup. KEY POINTS: • In 19% of patients of the MIPA study, breast MRI was performed for screening or diagnostic purposes. • The current patient selection to preoperative breast MRI implies an 11% increase in mastectomies, counterbalanced by a 3% reduction of the reoperation rate. • Data from the MIPA study can support discussion in tumor boards when preoperative MRI is under consideration and should be shared with patients to achieve informed decision-making.