Magnetic resonance imaging in the preoperative assessment of patients with primary breast cancer: systematic review of diagnostic accuracy and meta-analysis

Can a low b-value diffusion-weighted imaging sequence replace the standard T2-weighted fluid-sensitive sequence in breast MRI? A single-center prospective study

OBJECTIVES

To determine whether a low b-value (b0) diffusion-weighted imaging (DWI) sequence of a similar acquisition time can fulfill the role of a T2-weighted/fluid-sensitive short tau inversion recovery (STIR) sequence.

MATERIALS AND METHODS

In this prospective, single-institutional study, participants underwent 3-T or 1.5-T breast MRI, which included a standard T2-weighted/fluid-sensitive short TI inversion recovery (STIR) sequence and an investigational DWI sequence (comprising readout segmented echo planar imaging (rs-EPI) and simultaneous multi-slice (SMS) imaging). Five radiologists independently scored 121 lesions on imaging by answering three questions assessing lesion conspicuity, lesion signal characteristics, and artifact grading. Statistical analysis included one-sample tests of proportions and Nelson's model kappa.

RESULTS

From 605 assessments in 72 patients (mean age, 48.3 ± 12.5 years [standard deviation]; 72 women), 537 (88.8%, p < 0.001) received assessments that lesion conspicuity on DWI was not inferior to STIR, 586 (96.9%, p < 0.001) received assessments that DWI followed the lesion signal characteristics on STIR, and 595 (98.3%, p < 0.001) received assessments that there were no or mild artifacts on DWI. Inter-reader agreement was substantial for similar lesion conspicuity (89.9%, к = 0.790, 95% CI: 0.76-0.82) and similar lesion signal characteristics (95.7%, к = 0.733, CI 0.69-0.77) on DWI and STIR, and moderate for whether there was mild/no artifact vs. moderate/substantial artifact on DWI (97.2%, к = 0.515, CI: 0.29-0.75).

CONCLUSION

Low b-value DWI provides similar diagnostic capabilities as T2-weighted/fluid-sensitive STIR, with comparable lesion conspicuity and lesion signal characteristics and without significant artifacts.

KEY POINTS

Question Can diffusion-weighted imaging (DWI) be incorporated into clinical 1.5-T and 3-T breast MRI protocols without adding acquisition time? Findings The signal characteristics and conspicuity of breast lesions on low b-value (b0) DWI were not inferior compared with that on standard T2-weighted/fluid-sensitive imaging. Clinical relevance The incorporation of low b-value DWI can translate to improved cost-effectiveness and patient experience of breast MRI by reducing false-positives and reducing overall scan time.

Association of preoperative MRI with breast cancer treatment and survival: A single institution observational study

PURPOSE

To evaluate the association between preoperative breast MRI with surgery type, contralateral cancer, recurrence-free (RFS) and overall survival (OS) in women with early-stage breast cancer.

MATERIALS AND METHODS

In this dual-affiliated single institution, retrospective study, we identified women with Stage I-III breast cancer diagnosed between 03/01/2013-03/31/2016 with available follow-up. Patient and tumor characteristics were recorded. Two cohorts were created based on the use of preoperative MRI(PMRI) versus no preoperative MRI(no-MRI) with Wilcoxon signed-rank and χ2 tests utilized for cross-group comparisons. Kaplan-Meier, log-rank and cox proportional hazards model analysis were used to compare RFS and OS in women with and without MRI.

RESULTS

593 eligible patients were included [322(54.3 %) with PMRI, 271(45.7 %) no-MRI]. Mean patient age was younger (53.8 ± 11.8vs59.3 ± 12.6 years, p < 0.001) and dense breasts more common (51.6 %vs22.5 %, p < 0.001) in PMRI group. Seventeen bilateral cancers (5.3 %) were in PMRI [14/17(82.4 %) detected only on MRI] vs 10 (3.7 %) in no-MRI (p = 0.34). Molecular subtype distribution(luminal A:27.2 % vs 31.1 %; luminal B:51.8 %vs44.2 %; HER2:5.4 %vs4.2 %; triple negative:15.6 %vs20.5 %, p = 0.28) were similar in PMRI vs no-MRI groups. PMRI group had higher rates of cT2-4(45.0 %vs28.8 %, p < 0.001), cN+(27.3 % vs 18.1 %, p < 0.01), and neoadjuvant therapy (NAC, 41.3 % vs 18.8 %, p < 0.001). Total mastectomy(57.8 %vs51.3 %, p = 0.12), margin positivity(6.2 %vs7.4 %, p = 0.63), recurrence(10.2 %vs7.0 %, p = 0.20) and death rates(8.1 %vs7.7 %, p = 0.88) were similar in PMRI vs no-MRI. Mastectomy rates remained comparable after adjusting for age and breast density (p = 0.28). At median follow-up of 70 months(IQR, 64-70), time to recurrence was [PMRI:30(IQR, 19-47)vs no-MRI:23(IQR, 9-31) months, p = 0.04]. Contralateral cancers were identified sooner and more frequently in the no-MRI group [4(2.1 %)vs2(0.9 %) cancers, p = 0.32, 21 ± 20vs48 ± 13 months, p = 0.27]. There was no significant difference in 5-year RFS[hazard ratio(HR) 1.05, 95 %CI 0.67-1.67, p = 0.84] and OS[HR 0.94, 95 %CI: 0.51-1.74, p = 0.85] between PMRI and no-MRI groups even after adjusting for age, cancer type, breast density, cN stage, and NAC. which were different between two groups (RFS, HR 0.87, 95 %CI: 0.53-1.43, p = 0.57; OS, HR 0.78, 95 %CI: 0.40-1.52, p = 0.46). NHW patients had higher RFS compared to Black patients in PMRI group (HR 0.45, 95 % CI: 0.21-0.96, p = 0.04) in adjusted analysis.

CONCLUSIONS

Preoperative MRI utilization is not associated with improved surgical margin, 5-year RFS or OS in our cohort. This effect persisted after adjusting for patient age, tumor stage, cancer type, breast density and NAC. At post therapy surveillance, contralateral cancers are identified earlier and more frequently in the no-MRI group.

The Value of Second-look Ultrasound and Mammography for Assessment and Biopsy of MRI-detected Breast Lesions

RATIONALE AND OBJECTIVES

Suspicious lesions detected in multiparametric breast MRI can be further analyzed with second-look ultrasound (SLUS) and/or mammography. This study aims to assess the value of second-look imaging in selecting the appropriate biopsy method for different lesion characteristics.

MATERIALS AND METHODS

Between January 2021 and December 2023, 212 women underwent contrast-enhanced multiparametric breast MRI at 3 Tesla. A total of 241 suspicious lesions (108 malignancies, 44.8%) were further assessed with SLUS and second-look mammography. Subsequent image-guided biopsy of each lesion was performed using the most suitable modality. Size-dependent lesion detection rates in SLUS and mammography were compared by means of the McNemar test.

RESULTS

Lesions referred to MRI-guided biopsy were predominantly ≤ 10 mm in size (52.8%). SLUS allowed for higher detection rates than mammography in mass lesions (55.6% [95% confidence interval 46.4-64.4%] versus 16.7% [10.6-24.3%]; p < 0.001) with a particularly high sensitivity for malignant mass lesions > 10 mm (88.5% [69.9-97.6%]). In contrast, the detection rate for malignant non-mass lesions was lower in SLUS than in second-look mammography (22.0% [11.5-36.0%] versus 38.0% [24.7-52.8%]; p < 0.001). The malignancy rates in ultrasound-, mammography-, and MRI-guided biopsies were 53.7%, 55.2%, and 35.0%, respectively.

CONCLUSION

SLUS is an excellent tool for further assessment and biopsy of suspicious mass lesions > 10 mm without associated calcifications. In contrast, supplemental ultrasound is of limited value in the evaluation and biopsy guidance of suspicious non-mass lesions compared to second-look mammography.

Breast cancer staging with contrast-enhanced imaging. The benefits and drawbacks of MRI, CEM, and dedicated breast CT

Pretherapeutic breast cancer staging is pivotal for patient-centered disease management, guiding treatment stratification and assessing prognostic outcomes. Breast imaging plays a key role in both anatomic and prognostic staging by providing comprehensive insights into disease extent, localization, and tumor aggressiveness characteristics. To date, clinical image-based staging relies on conventional modalities such as digital mammography (DM), digital breast tomosynthesis (DBT), and ultrasound. Considering the phenotypic disparities of breast cancer and their relation to treatment response, other imaging techniques based on contrast-enhanced mechanisms, which highlight areas of increased neovascularity, appear indispensable in breast cancer staging. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) offers a comprehensive 3-dimensional assessment of extent of disease and characterization of lesions, capturing both morphological and functional aspects which are crucial for treatment and monitoring of the disease. Based on this established approach, contrast-enhanced x-ray-based techniques, with high spatial resolution, such as contrast-enhanced mammography (CEM) and dedicated contrast-enhanced breast computed tomography (dCEBCT), have emerged. This review outlines the current status, limitations, and ongoing challenges associated with each one contrast-enhanced imaging modality, while emphasis is given to key breast cancer manifestations and the optimal interpretation of their imaging phenotypes, in the current era of image-based (anatomic and prognostic) breast cancer staging.

Evaluation of contrast-enhanced mammography (CEM) in the preoperative staging of breast cancer: large-scale single center experience, update to 1005 cases

PURPOSE

The purpose of this study was to assess the diagnostic performance of CEM in the preoperative staging of breast cancer in a large cohort of patients.

MATERIALS AND METHODS

A retrospective review of preoperative staging CEM exams was conducted at our centre between June 2016 and June 2021. We evaluated cases where CEM influenced the type of surgery, necessitated additional biopsies or imaging, and identified additional lesions. The sensitivity, specificity, positive and negative predictive values (PPV and NPV), and accuracy of CEM for the entire sample and each subgroup setting were calculated. A receiver operating characteristic (ROC) curve and multivariate analysis were performed.

RESULTS

991 women, mean age 61.3 years old [35-93], with 1005 malignant lesions were included. CEM led to additional imaging in 36.7% (364/991) women and to additional biopsies in 18.5% (183/991) women. CEM altered the initial surgical plan based on conventional imaging in 226 out of 991 patients (22.8%). CEM had a sensitivity in the whole population of 91.5% (204/223), specificity of 96.8% (757/782), PPV of 89.1% (204/229), NPV of 97.5% (757/776) and an accuracy of 95.6% (961/1005); the AUC of the ROC curve was 0.941. We found CEM better performed in patients with a low BPE level compared with a high BPE level (ρ = 0.028861). We see that the presence of additional lesions at CEM was the only significant predictor in the model.

CONCLUSION

This study reaffirms the high diagnostic accuracy of CEM for preoperative breast cancer staging in a large patient cohort.

Preoperative breast MRI in HER2-positive/hormone receptor-negative breast cancer: surgical outcomes using propensity score matching

OBJECTIVES

To examine the association between preoperative magnetic resonance imaging (MRI) and surgical outcomes in human epidermal growth factor receptor 2 (HER2)-positive/hormone receptor (HR)-negative breast cancer through a propensity score (PS)-matched analysis.

MATERIALS AND METHODS

Patients with HER2-positive/HR-negative invasive ductal carcinoma between 2007 and 2014 were retrospectively assessed and compared according to whether they underwent preoperative MRI. Inverse probability weighting (IPW) analysis and PS matching were used to adjust 17 covariates to control between the MRI and no-MRI groups. Surgical outcomes were compared between two groups and clinicopathologic variables were evaluated to determine who benefited from MRI.

RESULTS

Among 965 women (mean age ± standard deviation, 52 years ± 10), 423 (44%) underwent preoperative MRI and 542 (56%) did not. In the MRI group, a change in surgical management occurred in 48 patients (11%), and the change was appropriate in 31 of those patients (65%). The MRI group had a lower odds of initial mastectomy (odds ratio [OR], 0.63; 95% confidence interval [CI]: 0.47, 0.84; p = 0.002 and OR, 0.67; 95% CI: 0.48, 0.92; p = 0.01 for IPW and PS matching, respectively) and overall mastectomy (OR, 0.60; 95% [CI]: 0.45, 0.80; p = 0.001 and OR, 0.68; 95% CI: 0.49, 0.93; p = 0.02 for IPW and PS matching, respectively). In the subgroup analysis, asymptomatic patients or those with multifocal or multicentric lesions benefited more from MRI (61% vs 36%, p = 0.006 and 52% vs 31%, p = 0.02, respectively).

CONCLUSION

Patients with HER2-positive/HR-negative breast cancer who received preoperative MRI had a lower likelihood of undergoing mastectomy.

KEY POINTS

Question The role of preoperative MRI in predicting surgical outcomes in patients with HER2-positive/HR-negative breast cancer remains uncertain. Findings Preoperative MRI in HER2-positive/HR-negative breast cancer reduces mastectomy rates without increasing the positive resection margin or reoperation rate. Clinical relevance Preoperative MRI is beneficial in reducing mastectomy rates in women with HER2-positive/HR-negative breast cancer.

Additional breast lesions on MRI in patients with small early stage luminal type breast cancer: Important consequences for future thermal ablation treatment

In this study, data from 50 postmenopausal women with unilateral cT1N0 breast cancer, who underwent MRI as part of the THERMAC trial for a thermal ablation protocol, were analyzed. Additional MRI findings were classified as benign or malignant based on histopathology. Results showed that 30 % of patients had additional MRI findings, with 40 % of those being malignant, which led to exclusion from the trial and altered surgical management. Malignant lesions included lobular carcinoma, NST tumors, and multifocal/multicentric disease, while benign findings were predominantly fibroadenomas, cysts, and mastopathy. Malignant lesions required changes in the treatment approach, including exclusion from the ablation protocol, wider excisions, and in some cases, mastectomy. The study highlights the significant role of MRI in patient selection and treatment planning, emphasizing the need for further investigation into the long-term oncological outcomes in early-stage breast cancer patients.

Utility of chest CT in the diagnosis of additional suspicious lesions on MRI in women with breast cancer

BACKGROUND

Dedicated breast computed tomography (CT) is an emerging modality, but no study has compared breast lesions additionally detected on magnetic resonance imaging (MRI) with correlated CT lesions. Although there are differences between chest CT and dedicated breast CT, a preliminary evaluation would be valuable.

PURPOSE

To evaluate the usefulness of contrast-enhanced chest CT in evaluating additional suspicious lesions preoperatively detected on MRI in patients with breast cancer.

MATERIAL AND METHODS

Between January 2020 and December 2021, 245 patients with breast cancer who underwent preoperative breast MRI and contrast-enhanced chest CT were included. Enhancing lesions detected on CT showing correlation with additional suspicious lesions detected on MRI were recorded as CT-correlated enhancements. The pathological findings were confirmed by subsequent percutaneous biopsy or lesion excision. The clinical and MRI features of additional suspicious lesions were compared according to the standard reference or the presence of CT-correlated enhancement.

RESULTS

There were 96 (39.2%) additional suspicious lesions detected on preoperative breast MRI and a malignancy rate of 39.6%. Of 96 lesions, chest CT revealed correlated enhancement in 64 (66.7%) lesions, including 33 malignant lesions. Among the 32 lesions that showed no correlation enhancement on chest CT, 5 (15.6%) were malignant. Malignancy, diffusion-weighted image restriction, and fast/washout kinetics were more frequently observed in lesions with CT-correlated enhancement than in those without correlated enhancement (P < 0.001, P = 0.001, and P = 0.020, respectively).

CONCLUSION

When evaluating MRI-detected additional suspicious lesions in patients with breast cancer, lesions with CT-correlated enhancement were significantly more likely to be malignant than those without CT-correlated enhancement.

Pre-Treatment Breast MRI: Clinical Indications, Outcomes, and Future Directions

Breast MRI is the most sensitive modality for assessing the extent of disease in patients with newly-diagnosed breast cancer because it identifies clinically- and mammographically-occult breast cancers. Though highly sensitive, breast MRI has lower specificity that may result in false positive findings and potential overestimation of disease if additional MRI findings are not biopsied prior to surgery. It had been anticipated that the superior cancer detection rate of pre-treatment MRI would translate to improved immediate (surgical re-excision) and long-term patient outcomes such as breast cancer recurrence and survival rates, but studies have not necessarily supported this assumption. In this review, current recommendations and utilization of breast MRI for pre-treatment local staging of breast cancer will be presented, with an emphasis on specific clinical scenarios for patient selection and its impact on short- and long-term patient clinical outcomes. We will also present new evidence that pre-treatment MRI may support de-escalation of treatment and discuss emerging advanced MRI techniques that may improve diagnostic performance.

Ultrafast sequence-based prediction model and nomogram to differentiate additional suspicious lesions on preoperative breast MRI

OBJECTIVES

To investigate whether ultrafast sequence improves the diagnostic performance of conventional dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in differentiating additional suspicious lesions (ASLs) on preoperative breast MRI.

MATERIALS AND METHODS

A retrospective database search identified 668 consecutive patients who underwent preoperative breast DCE-MRI with ultrafast sequence between June 2020 and July 2021. Among these, 107 ASLs from 98 patients with breast cancer (36 multifocal, 42 multicentric, and 29 contralateral) were identified. Clinical, pathological, conventional MRI findings, and ultrafast sequence-derived parameters were collected. A prediction model that adds ultrafast sequence-derived parameters to clinical, pathological, and conventional MRI findings was developed and validated internally. Decision curve analysis and net reclassification index statistics were performed. A nomogram was constructed.

RESULTS

The ultrafast model adding time to peak enhancement, time to enhancement, and maximum slope showed a significantly increased area under the receiver operating characteristic curve compared with the conventional model which includes age, human epidermal growth factor receptor 2 expression of index cancer, size of index cancer, lesion type of index cancer, location of ASL, and size of ASL (0.92 vs. 0.82; p = 0.002). The decision curve analysis showed that the ultrafast model had a higher overall net benefit than the conventional model. The net reclassification index of ultrafast model was 23.3% (p = 0.001).

CONCLUSION

A combination of ultrafast sequence-derived parameters with clinical, pathological, and conventional MRI findings can aid in the differentiation of ASL on preoperative breast MRI.

CLINICAL RELEVANCE STATEMENT

Our prediction model and nomogram that was based on ultrafast sequence-derived parameters could help radiologists differentiate ASLs on preoperative breast MRI.

KEY POINTS

Ultrafast MRI can diminish background parenchymal enhancement and possibly improve diagnostic accuracy for additional suspicious lesions (ASLs). Location of ASL, larger size of ASL, and higher maximum slope were associated with malignant ASL. The ultrafast model and nomogram can help preoperatively differentiate additional malignancies.

Positive predictive value of malignancy for additional calcifications found during evaluation of a synchronous breast cancer

PURPOSE

To evaluate the positive predictive value and factors predictive of malignancy of additional calcifications in the pre-therapeutic work-up of a synchronous breast cancer.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective study and informed consent was waved. Consecutive patients referred to our center between January 1st 2018 and December 31st 2022 for a breast cancer and who presented additional calcifications detected during the pretreatment work-up were eligible for inclusion in this study. Morphology, distribution and BI-RADS category of the calcifications were assessed in consensus by 3 radiologists specialized in breast imaging. Side and distance from the cancer were collected. The predictive value of malignancy of the calcifications was calculated for each BI-RADS category. Factors associated with malignancy were evaluated by logistic non-conditional regression on univariate and multivariate analysis.

RESULTS

One hundred and thirteen clusters of calcifications in 103 patients were included. Among the groups of calcifications 41 % were malignant, 31 % benign and 28 % were atypia on biopsy. After exclusion of the non-operated atypia, 50.5 % of additional calcifications were ultimately malignant and 49.5 % were benign. The predictive value of malignancy was 20.7 %; 40.7 %; 63 %; 85.7 % and 100 % for category BI-RADS 3, 4a, 4B, 4c and 5 respectively. On multivariate analysis, multifocality or centricity of the index tumour (P = 0.01), BI-RADS classifications (P = 0.0001) and location ipsilateral less than 35 mm to the index cancer (P = 0.008) of the additional calcifications were found to be independent predictors of malignancy. Sixty percent of calcifications were not described on the initial out-center diagnostic work-up.

CONCLUSION

Additional calcifications detected during the pretreatment work-up of a breast cancer are associated with a higher probability of malignancy than in a screening population and require biopsy even when demonstrating probably benign (BI-RADS 3) features.

Contrast-Enhanced Mammography in Local Staging of Screen-Detected Breast Cancer

BACKGROUND

BreastScreen Australia, the population mammographic screening program for breast cancer, uses two-view digital screening mammography ± ultrasound followed by percutaneous biopsy to detect breast cancer. Secondary breast imaging for further local staging, not performed at BreastScreen, may identify additional clinically significant breast lesions. Staging options include further mammography, bilateral ultrasound, and/or contrast-based imaging (CBI) [magnetic resonance imaging (MRI) or contrast-enhanced mammography (CEM)]. CBI for local staging of screen-detected cancer was introduced at an academic hospital breast service in Melbourne, VIC, Australia. We report findings for otherwise occult disease and resulting treatment changes.

MATERIAL AND METHODS

Patients staged using CEM between November 2018 and April 2022 were identified from hospital records. Data were extracted from radiology, pathology, and breast unit databases. CEM-detected abnormalities were documented as true positive (TP) for invasive cancer or ductal carcinoma in situ (DCIS), or otherwise false positive (FP). The impact on surgical decisions was assessed.

RESULTS

Of 202 patients aged 44-84 years, 60 (30%) had 74 additional findings [34 (46%) TP, 40 (54%) FP]. These were malignant in 29/202 (14%) patients (79% invasive cancers, 21% DCIS). CEM resulted in surgical changes in 43/202 (21%) patients: wider resection (24/43), conversion to mastectomy (6/43), contralateral breast surgery (6/43), additional ipsilateral excision (5/43), and bracketing (2/43). Additional findings were more common for patients with larger index lesions and for invasive cancer, but there was no significant variation by age, breast density, or index lesion grade.

CONCLUSIONS

CEM for local staging of screen-detected breast cancers identified occult malignancy in 14% of patients. CEM improves local staging and may facilitate appropriate management of screen-detected breast cancers.

Multimodal ultrasound assessment of mass and non-mass enhancements by MRI: Diagnostic accuracy in idiopathic granulomatous mastitis and breast cancer

PURPOSE

Idiopathic granulomatous mastitis (IGM) poses diagnostic challenges due to its diverse clinical and radiological presentations, often mimicking malignancies. This study aimed to assess the diagnostic efficacy of multimodal ultrasound for mass and non-mass enhancements in Dynamic Contrast-Enhanced MRI (DCE-MRI) of IGM and breast cancer.

METHODS

A retrospective analysis involved patients confirmed histopathologically with IGM and BC. All patients underwent conventional ultrasound (C-US), ultrasound elastography (UE), contrast-enhanced ultrasound (CEUS), and DCE-MRI examinations. Blinded experienced radiologists assessed imaging findings. Diagnostic accuracy, sensitivity, and specificity were calculated for mass and non-mass enhancements.

RESULTS

For mass enhancements (ME), multimodal ultrasound demonstrated strong efficacy (AUC = 0.8651, 95 % CI: 0.7431 to 0.9871), exhibiting high sensitivity (83.3 %) and specificity (92.4 %) in differentiating IGM from breast cancer. However, for non-mass enhancements (NME), multimodal ultrasound showed limited accuracy (AUC = 0.6306) with lower sensitivity (65.6 %) and specificity (81.2 %) in distinguishing between IGM and breast cancer.

CONCLUSION

Multimodal ultrasound displayed good diagnostic efficacy for mass enhancements in DCE-MRI for IGM and breast cancer, while for non-mass enhancement patterns, DCE-MRI remains the most valuable radiological modality for comprehensively assessing this condition's complexities.

The impact of preoperative breast MRI on the therapeutic management of breast cancer patients

BACKGROUND

The role of preoperative breast MRI to evaluate the extent of disease in breast cancer patients is considered controversial. We aimed at assessing the effect of breast MRI on the management of newly diagnosed breast cancer.

MATERIALS

A retrospective review of 202 consecutively seen patients who were newly diagnosed with breast cancer and who underwent preoperative breast MRIs at Assuta Ashdod between June 1, 2017, and June 1, 2020. Data included discovering suspicious lesions by conventional imaging, MRI findings, and surgical pathology results. This was analyzed to determine whether the MRI changed the management and whether it had a justified or unjustified effect on the treatment.

RESULTS

The mean age was 54.51 (standard deviation, 11.34 years). Breast MRI revealed additional findings in 56 % of patients and modified therapeutic management in 32 % of the cases evaluated, having a justified effect in 87.6 %. Patients with changed management had a statistically significantly higher mastectomy rate (36 %) than those who did not (14 %). No statistically significant association was found between independent variables such as breast density, tumor location on the breast, type of tumor, patient's demographic information, etc. And whether MRI findings changed the initial treatment plan.

CONCLUSIONS

MRI played an essential role in the preoperative staging of breast cancer in our study, modifying therapeutic planning in approximately one-third of the cases and having a justified effect on most of them. We, therefore, support preoperative breast MRI in newly diagnosed breast cancer patients.

A Systematic Review and Meta-analysis of the Role of Preoperative MRI in In-breast Tumor Recurrence After Breast-Conserving Surgery

BACKGROUND

It is unknown whether the identification of additional tumors in the breast using preoperative magnetic resonance imaging (pMRI) results in a lower risk of in-breast tumor recurrence (IBTR) after breast-conserving surgery (BCS).

METHODS

A systematic review and meta-analysis of relevant studies were performed. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

From 768 citations, 20 studies met the inclusion criteria for the systematic review. The 20 studies consisted of 14 retrospective reviews, 3 matched cohorts, and 3 randomized controlled trials. Whereas 2 studies reported a statistically significant lower rate of IBTR with pMRI, 18 studies showed no difference, and no studies reported a higher rate. Of the 18 studies showing no significant difference, 12 demonstrated a trend toward a lower IBTR rate in the pMRI group. The criteria for meta-analysis were met by 16 studies. A meta-analysis of 11 studies that reported hazard ratios (HR) for IBTR showed a trend toward a lower rate of IBTR for patients who received preoperative MRI (hazard ratio (HR), 0.89; 95% confidence interval (CI), 0.74-1.05). A meta-analysis of five studies that reported event rates and had similar follow-up duration for both groups demonstrated a lower relative risk (RR) of IBTR (RR, 0.45; 95% CI 0.25-0.81).

CONCLUSIONS

Although some evidence supports the hypothesis that identification of additional tumors in the breast using pMRI results in lower rates of IBTR after BCS, the main meta-analysis in this study did not confirm this hypothesis.

Multiparametric MRI-based radiomic nomogram for predicting HER-2 2+ status of breast cancer

Objective

To explore the application of multiparametric MRI-based radiomic nomogram for assessing HER-2 2+ status of breast cancer (BC).

Methods

Patients with pathology-proven HER-2 2+ invasive BC, who underwent preoperative MRI were divided into training (72 patients, 21 HER-2-positive and 51 HER-2-negative) and validation (32 patients, 9 HER-2-positive and 23 HER-2-negative) sets by randomization. All were classified as HER-2 2+ FISH-positive (HER-2-positive) or -negative (HER-2-negative) according to IHC and FISH. The 3D VOI was drawn on MR images by two radiologists. ADC, T2WI, and DCE images were analyzed separately to extract features (n = 1906). L1 regularization, F-test, and other methods were used to reduce dimensionality. Binary radiomics prediction models using features from single or combined imaging sequences were constructed using logistic regression (LR) classifier then and validated on a validation dataset. To build a radiomics nomogram, multivariate LR analysis was conducted to identify independent indicators. An evaluation of the model's predictive efficacy was made using AUC.

Results

On the basis of combined ADC, T2WI, and DCE images, ten radiomic features were extracted following feature dimensionality reduction. There was superior diagnostic efficiency of radiomic signature using all three sequences compared to either one or two sequences (AUC for training group: 0.883; AUC for validation group: 0.816). Based on multivariate LR analysis, radiomic signature and peritumoral edema were independent predictors for identifying HER-2 2 +. In both training and validation datasets, nomograms combining peritumoral edema and radiomics signature demonstrated an effective discrimination (AUCs were respectively 0.966 and 0. 884).

Conclusion

The nomogram that incorporated peritumoral edema and multiparametric MRI-based radiomic signature can be used to effectively predict the HER-2 2+ status of BC.

Discriminative Factors of Malignancy of Ipsilateral Nonmass Enhancement in Women With Newly Diagnosed Breast Cancer on Initial Staging Breast MRI

BACKGROUND

Nonmass enhancement (NME) on breast MRI impacts surgical planning.

PURPOSE

To evaluate positive predictive values (PPVs) and identify malignancy discriminators of NME ipsilateral to breast cancer on initial staging MRI.

STUDY TYPE

Retrospective.

SUBJECTS

Eighty-six women (median age, 48 years; range, 26-75 years) with 101 NME lesions (BI-RADS 4 and 5) ipsilateral to known cancers and confirmed histopathology.

FIELD STRENGTH/SEQUENCE

1.5 T and 3.0 T dynamic contrast-enhanced fat-suppressed T1-weighted fast spoiled gradient-echo.

ASSESSMENT

Three radiologists blinded to pathology independently reviewed MRI features (distribution, internal enhancement pattern, and enhancement kinetics) of NME, locations relative to index cancers (contiguous, non-contiguous, and different quadrants), associated mammographic calcifications, lymphovascular invasion (LVI), axillary node metastasis, and radiology-pathology correlations. Clinical factors, NME features, and cancer characteristics were analyzed for associations with NME malignancy.

STATISTICAL TESTS

Fisher's exact, Chi-square, Wilcoxon rank sum tests, and mixed-effect multivariable logistic regression were used. Significance threshold was set at P < 0.05.

RESULTS

Overall NME malignancy rate was 48.5% (49/101). Contiguous NME had a significantly higher malignancy rate (86.7%) than non-contiguous NME (25.0%) and NME in different quadrants (10.7%), but no significant difference was observed by distance from cancer for non-contiguous NME, P = 0.68. All calcified NME lesions contiguous to the calcified index cancer were malignant. NME was significantly more likely malignant when index cancers were masses compared to NME (52.9% vs. 21.4%), had mammographic calcifications (63.2% vs. 39.7%), LVI (81.8% vs. 44.4%), and axillary node metastasis (70.8% vs. 41.6%). NME features with highest PPVs were segmental distribution (85.7%), clumped enhancement (66.7%), and nonpersistent kinetics (77.1%). On multivariable analysis, contiguous NME, segmental distribution, and nonpersistent kinetics were associated with malignancy.

DATA CONCLUSION

Malignancy discriminators of ipsilateral NME on staging MRI included contiguous location to index cancers, segmental distribution, and nonpersistent kinetics.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Radiologic-Pathologic Correlation of Nonmass Enhancement Contiguous with Malignant Index Breast Cancer Masses at Preoperative Breast MRI

Purpose To determine the pathologic features of nonmass enhancement (NME) directly adjacent to biopsy-proven malignant masses (index masses) at preoperative MRI and determine imaging characteristics that are associated with a malignant pathologic condition. Materials and Methods This retrospective study involved the review of breast MRI and mammography examinations performed for evaluating disease extent in patients newly diagnosed with breast cancer from July 1, 2016, to September 30, 2019. Inclusion criteria were limited to patients with an index mass and the presence of NME extending directly from the mass margins. Wilcoxon rank sum test, Fisher exact test, and χ2 test were used to analyze cancer, patient, and imaging characteristics associated with the NME diagnosis. Results Fifty-eight patients (mean age, 58 years ± 12 [SD]; all women) were included. Malignant pathologic findings for mass-associated NME occurred in 64% (37 of 58) of patients, 43% (16 of 37) with ductal carcinoma in situ and 57% (21 of 37) with invasive carcinoma. NME was more likely to be malignant when associated with an index cancer that had a low Ki-67 index (<20%) (P = .04). The presence of calcifications at mammography correlating with mass-associated NME was not significantly associated with malignant pathologic conditions (P = .19). The span of suspicious enhancement measured at MRI overestimated the true span of disease at histologic evaluation (P < .001), while there was no evidence of a difference between span of calcifications at mammography and true span of disease at histologic evaluation (P = .27). Conclusion Mass-associated NME at preoperative MRI was malignant in most patients with newly diagnosed breast cancer. The span of suspicious enhancement measured at MRI overestimated the true span of disease found at histologic evaluation. Keywords: Breast, Mammography © RSNA, 2024 See also the commentary by Newell in this issue.

Artificial Intelligence-Enhanced Breast MRI: Applications in Breast Cancer Primary Treatment Response Assessment and Prediction

ABSTRACT

Primary systemic therapy (PST) is the treatment of choice in patients with locally advanced breast cancer and is nowadays also often used in patients with early-stage breast cancer. Although imaging remains pivotal to assess response to PST accurately, the use of imaging to predict response to PST has the potential to not only better prognostication but also allow the de-escalation or omission of potentially toxic treatment with undesirable adverse effects, the accelerated implementation of new targeted therapies, and the mitigation of surgical delays in selected patients. In response to the limited ability of radiologists to predict response to PST via qualitative, subjective assessments of tumors on magnetic resonance imaging (MRI), artificial intelligence-enhanced MRI with classical machine learning, and in more recent times, deep learning, have been used with promising results to predict response, both before the start of PST and in the early stages of treatment. This review provides an overview of the current applications of artificial intelligence to MRI in assessing and predicting response to PST, and discusses the challenges and limitations of their clinical implementation.

Staging of breast cancer in the breast and regional lymph nodes using contrast-enhanced photon-counting detector CT: accuracy and potential impact on patient management

OBJECTIVES

To describe the feasibility and evaluate the performance of multiphasic photon-counting detector (PCD) CT for detecting breast cancer and nodal metastases with correlative dynamic breast MRI and digital mammography as the reference standard.

METHODS

Adult females with biopsy-proven breast cancer undergoing staging breast MRI were prospectively recruited to undergo a multiphasic PCD-CT using a 3-phase protocol: a non-contrast ultra-high-resolution (UHR) scan and 2 intravenous contrast-enhanced scans with 50 and 180 s delay. Three breast radiologists compared CT characteristics of the index malignancy, regional lymphadenopathy, and extramammary findings to MRI.

RESULTS

Thirteen patients underwent both an MRI and PCD-CT (mean age: 53 years, range: 36-75 years). Eleven of thirteen cases demonstrated suspicious mass or non-mass enhancement on PCD-CT when compared to MRI. All cases with metastatic lymphadenopathy (3/3 cases) demonstrated early avid enhancement similar to the index malignancy. All cases with multifocal or multicentric disease on MRI were also identified on PCD-CT (3/3 cases), including a 4 mm suspicious satellite lesion. Four of five patients with residual suspicious post-biopsy calcifications on mammograms were detected on the UHR PCD-CT scan. Owing to increased field-of-view at PCD-CT, a 5 mm thoracic vertebral metastasis was identified at PCD-CT and not with the breast MRI.

CONCLUSIONS

A 3-phase PCD-CT scan protocol shows initial promising results in characterizing breast cancer and regional lymphadenopathy similar to MRI and detects microcalcifications in 80% of cases.

ADVANCES IN KNOWLEDGE

UHR and spectral capabilities of PCD-CT may allow for comprehensive characterization of breast cancer and may represent an alternative to breast MRI in select cases.

Cryoablation Therapy for Early-Stage Breast Cancer: Evidence and Rationale

Recent advances in breast cancer research and treatment propel a paradigm shift toward less aggressive and less invasive treatment for some early-stage breast cancer. Select patients with small, low-risk tumors may benefit from a less aggressive approach with de-escalated local therapy. Cryoablation of breast cancer is an emerging nonsurgical treatment alternative to breast-conserving surgery. Advantages of cryoablation over surgery include the use of local anesthesia, faster recovery, improved cosmesis, and cost savings. Proper patient selection and meticulous technique are keys to achieving successful clinical outcomes. The best candidates for cryoablation have unifocal invasive ductal carcinoma tumors that are low grade, hormone receptor positive, and ≤1.5 cm in size. In this review, we outline the current evidence, patient selection criteria, procedural technique, pre- and postablation imaging, and the advantages and limitations of cryoablation therapy.

Triple-negative breast cancer: predictive model of early recurrence based on MRI features

AIM

To develop an integrated model based on preoperative magnetic resonance imaging (MRI) features for predicting early recurrence in patients with triple-negative breast cancer (TNBC).

MATERIALS AND METHODS

Women with TNBC who underwent breast MRI and surgery between 2009 and 2019 were evaluated retrospectively. Two breast radiologists reviewed MRI images independently based on the Breast Imaging Reporting and Data System Lexicon (BI-RADS), and classified the breast oedema scores on T2-weighted imaging (WI) as no oedema, peritumoural oedema, prepectoral oedema, or subcutaneous oedema. The relationship between disease-free survival (DFS) and MRI features was analysed by Cox regression, and a nomogram model was generated based on the results.

RESULTS

150 patients with TNBC were included and divided into a training cohort (n=78) and validation cohort (n=72). MRI features including subcutaneous oedema and rim enhancement showed a tendency to worsen DFS in univariate analysis. Multivariate analysis showed that subcutaneous oedema (p=0.049, HR [95% confidence interval {CI} = 8.24 [1.01-67.52]) and rim enhancement (p=0.016, HR [95% CI] = 4.38 [1.32-14.54]) were independent predictors for DFS. In the nomogram, the areas under the curves (AUCs) of the training cohort was 0.808, and that of the validation cohort was 0.875.

CONCLUSION

The presence of subcutaneous oedema or rim enhancement on preoperative breast MRI was shown to be a good predictor of poor survival outcomes in patients with TNBC.

Molecular Breast Imaging and Positron Emission Mammography

There is growing interest in application of functional imaging modalities for adjunct breast imaging due to their unique ability to evaluate molecular/pathophysiologic changes, not visible by standard anatomic breast imaging. This has led to increased use of nuclear medicine dedicated breast-specific single photon and coincidence imaging systems for multiple indications, such as supplemental screening, staging of newly diagnosed breast cancer, evaluation of response to neoadjuvant treatment, diagnosis of local disease recurrence in the breast, and problem solving. Studies show that these systems maybe especially useful for specific subsets of patients, not well served by available anatomic breast imaging modalities.

Does Preoperative MRI Reduce Positive Margins after Breast-Conserving Surgery?

BACKGROUND

Breast-conserving surgery (BCS) is a mainstay for breast cancer management, and obtaining negative margins is critical. Some have advocated for the use of preoperative magnetic resonance imaging (MRI) in reducing positive margins after BCS. We sought to determine whether preoperative MRI was associated with reduced positive margins.

PATIENTS AND METHODS

The SHAVE/SHAVE2 trials were multicenter trials in ten US centers with patients with stage 0-3 breast cancer undergoing BCS. Use of preoperative MRI was at the discretion of the surgeon. We evaluated whether or not preoperative MRI was associated with margin status prior to randomization regarding resection of cavity with shave margins.

RESULTS

A total of 631 patients participated. Median age was 64 (range 29-94) years, with a median tumor size of 1.3 cm (range 0.1-9.3 cm). Patient factors included 26.1% of patients (165) had palpable tumors, and 6.5% (41) received neoadjuvant chemotherapy. Tumor factors were notable for invasive lobular histology in 7.0% (44) and extensive intraductal component (EIC) in 32.8% (207). A preoperative MRI was performed in 193 (30.6%) patients. Those who underwent preoperative MRI were less likely to have a positive margin (31.1% versus 38.8%), although this difference was not statistically significant (p = 0.073). On multivariate analysis, controlling for patient and tumor factors, utilization of preoperative MRI was not a significant factor in predicting margin status (p = 0.110). Rather, age (p = 0.032) and tumor size (p = 0.040) were the only factors associated with margin status.

CONCLUSION

These data suggest that preoperative MRI is not associated margin status; rather, patient age and tumor size are the associated factors.

Imaging of breast cancer-beyond the basics

Imaging of breast cancer is the backbone of breast cancer screening, diagnosis, preoperative/treatment assessment and follow-up. The main modalities are mammography, ultrasound and magnetic resonance imaging, each with its own advantages and disadvantages. New emerging technologies have also enabled each modality to improve on their weaknesses. Imaging-guided biopsies have allowed for accurate diagnosis of breast cancer, with low complication rates. The purpose of this article is to review the common modalities for breast cancer imaging in current practice with emphasis on the strengths and potential weaknesses, discuss the selection of the best imaging modality for the specific clinical question or patient population, and explore new technologies / future directions of breast cancer imaging.

Preoperative Breast MRI: Current Evidence and Patient Selection

Breast MRI is the most sensitive imaging modality for the assessment of newly diagnosed breast cancer extent and can detect additional mammographically and clinically occult breast cancers in the ipsilateral and contralateral breasts. Nonetheless, appropriate use of breast MRI in the setting of newly diagnosed breast cancer remains debated. Though highly sensitive, MRI is less specific and may result in false positives and overestimation of disease when MRI findings are not biopsied prior to surgical excision. Furthermore, improved anatomic depiction of breast cancer on MRI has not consistently translated to improved clinical outcomes, such as lower rates of re-excision or breast cancer recurrence, though there is a paucity of well-designed studies examining these issues. In addition, current treatment paradigms have been developed in the absence of this more accurate depiction of disease span, which likely has limited the value of MRI. These issues have led to inconsistent and variable utilization of preoperative MRI across practice settings and providers. In this review, we discuss the history of breast MRI and its current use and recommendations with a focus on the preoperative setting. We review the evidence surrounding the use of preoperative MRI in the evaluation of breast malignancies and discuss the data on breast MRI in the setting of specific patient factors often used to determine breast MRI eligibility, such as age, index tumor phenotype, and breast density. Finally, we review the impact of breast MRI on surgical outcomes (re-excision and mastectomy rates) and long-term breast recurrence and survival outcomes.

Prospective study: Impact of breast magnetic resonance imaging on oncoplastic surgery and on indications of mastectomy in patients who were previously candidates to breast conserving surgery

Background

Routine use of magnetic resonance imaging (MRI) in the staging of patients with early breast cancer is still controversial. Oncoplastic surgery (OP) allows for wider resections without compromising the aesthetic results. This study aimed to assess the impact of preoperative MRI on surgical planning and on indications of mastectomy.

Methods

Prospective study including T1-T2 breast cancer patients treated between January 2019 and December 2020 in the Breast Unit of the Hospital Nossa Senhora das Graças in Curitiba, Brazil. All patients had indication for breast conserving surgery (BCS) with OP and did a breast MRI after conventional imaging.

Results

131 patients were selected. Indication for BCS was based on clinical examination and conventional imaging (mammography and ultrasound) findings. After undergoing breast MRI, 110 patients (84.0%) underwent BCS with OP and 21 (16.0%) had their surgical procedure changed to mastectomy. Breast MRI revealed additional findings in 52 of 131 patients (38%). Of these additional findings, 47 (90.4%) were confirmed as invasive carcinoma. Of the 21 patients who underwent mastectomies, the mean tumor size was 2.9 cm (± 1,7cm), with all having additional findings on breast MRI (100% of the mastectomies group vs 28.2% of the OP, p&lt;0.01). Of the 110 patients submitted to OP, the mean tumor size was 1,6cm (± 0,8cm), with only 6 (5.4%) presenting positive margins at the final pathology assessment.

Conclusion

Preoperative breast MRI has an impact on the OP scenario, bringing additional information that may help surgical planning. It allowed selecting the group with additional tumor foci or greater extension to convert to mastectomy, with a consequent low reoperation rate of 5.4% in the BCS group. This is the first study to assess the impact of breast MRI in the preoperative planning of patients undergoing OP for the treatment of breast cancer.

Costing analysis to introduce a contrast-enhanced mammography service to replace an existing breast MRI service for local staging of breast cancer

AIM

To assess the cost impact of switching from contrast-enhanced magnetic resonance imaging (CE-MRI) to contrast-enhanced spectral mammography (CESM) for loco-regional staging of breast cancer from a public healthcare perspective.

MATERIALS AND METHODS

The CE-MRI cost was obtained from the NHS reference cost. The CESM cost was calculated using a bottom-up approach including use of the machine, pump injector, contrast medium, image storage, and time allocation for staff reporting and cannulation. The cost of upgrading existing machines to CESM or purchasing new mammographic machines was obtained via national procurement. Other costs were obtained from local pharmacy, published unit cost data, or estimated based on surveys.

RESULTS

For large health boards in Scotland (≥500 cancers diagnosed per annum), the cost savings of switching from CE-MRI to CESM range from £64,069 to £81,570. For small health boards (<500 cancers diagnosed per annum), the cost savings of switching from CE-MRI to CESM range from £6,453 to £23,953. The cost savings are most sensitive to the number of tests conducted per year, and whether the existing mammography machine can be upgraded to CESM or not.

CONCLUSION

Switching from CE-MRI to CESM for loco-regional staging of breast cancer is likely to be cost saving for both large and small health boards in Scotland. Further research is urgently needed to confirm the non-inferiority of CESM to CE-MRI as a locoregional staging technique. The input data of this analysis can be updated when such results become available.

Clinical impact of MRI-detected additional lesions in breast cancer patients with neoadjuvant systemic therapy at the Netherlands cancer institute

BACKGROUND

In breast cancer patients treated with neoadjuvant systemic therapy (NST), MRI is used pre- and post-NST for response monitoring. The relevance of additional MRI-detected lesions in these patients is unclear. Therefore, we aimed to assess the impact of pre-NST MRI-detected additional lesions on surgical treatment and outcome.

METHODS

We retrospectively selected all early-stage breast cancer patients with MRI pre-NST at our institute from January 2010-2015. MRI-detected lesions were defined as separated from the index tumor and occult at conventional mammography and ultrasound. Outcomes were change in surgical treatment and five-year recurrence-free and overall survival.

RESULTS

Overall, MRI detected additional lesions in 206 (31%) of 656 patients: in 160 patients in the ipsilateral breast and in 78 contralateral breasts, including 32 bilateral cases. Ipsilateral lesions were mostly categorized BI-RADS 5 (54 %) and contralateral lesions BI-RADS 3 (64%). Targeted ultrasound was performed in 115 (56%) patients: in 70 ipsilateral and in 64 contralateral cases. Biopsy was obtained in 44 (28% of 160) ipsilateral and 50 (64% of 78) contralateral breasts, containing tumor foci in 20 (13% of 160) and 11 (14% of 78) cases, respectively. Surgical treatment changed in 54 (26% of 206) patients: 19 (9%) had mastectomy, 24 (12%) had wider local excision and 11 (5%) underwent contralateral surgery. Five-year recurrence-free and overall survival did not differ for patients with local excision or mastectomy.

CONCLUSION

Pre-NST MRI-detected additional lesions in 31% of patients, resulting in more extensive surgery in 26% of these patients, including 5% contralateral surgeries.

Advanced Magnetic Resonance Imaging Modalities for Breast Cancer Diagnosis: An Overview of Recent Findings and Perspectives

Breast cancer is the most prevalent cancer among women and the leading cause of death. Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are advanced magnetic resonance imaging (MRI) procedures that are widely used in the diagnostic and treatment evaluation of breast cancer. This review article describes the characteristics of new MRI methods and reviews recent findings on breast cancer diagnosis. This review study was performed on the literature sourced from scientific citation websites such as Google Scholar, PubMed, and Web of Science until July 2021. All relevant works published on the mentioned scientific citation websites were investigated. Because of the propensity of malignancies to limit diffusion, DWI can improve MRI diagnostic specificity. Diffusion tensor imaging gives additional information about diffusion directionality and anisotropy over traditional DWI. Recent findings showed that DWI and DTI and their characteristics may facilitate earlier and more accurate diagnosis, followed by better treatment. Overall, with the development of instruments and novel MRI modalities, it may be possible to diagnose breast cancer more effectively in the early stages.

Impact of preoperative magnetic resonance imaging on surgery and eligibility for intraoperative radiotherapy in early breast cancer

We looked at the usefulness of magnetic resonance imaging (MRI) in decision-making and surgical management of patients selected for intraoperative radiotherapy (IORT). We also compared lesion size measurements in different modalities (ultrasound (US), mammogram (MMG), MRI) against pathological size as the gold standard. 63 patients eligible for IORT based on clinical and imaging criteria over a 34-month period were enrolled. All had MMG and US, while 42 had additional preoperative MRI for locoregional preoperative staging. Imaging findings and pathological size concordances were analysed across the three modalities. MRI changed the surgical management of 5 patients (11.9%) whereby breast-conserving surgery (BCS) and IORT was cancelled due to detection of satellite lesion, tumor size exceeding 30mm and detection of axillary nodal metastases. Ten of 42 patients (23.8%) who underwent preoperative MRI were subjected to additional external beam radiotherapy (EBRT); 7 due to lymphovascular invasion (LVI), 2 due to involved margins, and 1 due to axillary lymph node metastatic carcinoma detected in the surgical specimen. Five of 21 (23.8%) patients without prior MRI were subjected to additional EBRT post-surgery; 3 had LVI and 2 had involved margins. The rest underwent BCS and IORT as planned. MRI and MMG show better imaging-pathological size correlation. Significant increase in the mean 'waiting time' were seen in the MRI group (34.1 days) compared to the conventional imaging group (24.4 days). MRI is a useful adjunct to conventional imaging and impacts decision making in IORT. It is also the best imaging modality to determine the actual tumour size.

Development and validation of a deep learning model for breast lesion segmentation and characterization in multiparametric MRI

Importance

The utilization of artificial intelligence for the differentiation of benign and malignant breast lesions in multiparametric MRI (mpMRI) assists radiologists to improve diagnostic performance.

Objectives

To develop an automated deep learning model for breast lesion segmentation and characterization and to evaluate the characterization performance of AI models and radiologists.

Materials and methods

For lesion segmentation, 2,823 patients were used for the training, validation, and testing of the VNet-based segmentation models, and the average Dice similarity coefficient (DSC) between the manual segmentation by radiologists and the mask generated by VNet was calculated. For lesion characterization, 3,303 female patients with 3,607 pathologically confirmed lesions (2,213 malignant and 1,394 benign lesions) were used for the three ResNet-based characterization models (two single-input and one multi-input models). Histopathology was used as the diagnostic criterion standard to assess the characterization performance of the AI models and the BI-RADS categorized by the radiologists, in terms of sensitivity, specificity, accuracy, and the area under the receiver operating characteristic curve (AUC). An additional 123 patients with 136 lesions (81 malignant and 55 benign lesions) from another institution were available for external testing.

Results

Of the 5,811 patients included in the study, the mean age was 46.14 (range 11–89) years. In the segmentation task, a DSC of 0.860 was obtained between the VNet-generated mask and manual segmentation by radiologists. In the characterization task, the AUCs of the multi-input and the other two single-input models were 0.927, 0.821, and 0.795, respectively. Compared to the single-input DWI or DCE model, the multi-input DCE and DWI model obtained a significant increase in sensitivity, specificity, and accuracy (0.831 vs. 0.772/0.776, 0.874 vs. 0.630/0.709, 0.846 vs. 0.721/0.752). Furthermore, the specificity of the multi-input model was higher than that of the radiologists, whether using BI-RADS category 3 or 4 as a cutoff point (0.874 vs. 0.404/0.841), and the accuracy was intermediate between the two assessment methods (0.846 vs. 0.773/0.882). For the external testing, the performance of the three models remained robust with AUCs of 0.812, 0.831, and 0.885, respectively.

Conclusions

Combining DCE with DWI was superior to applying a single sequence for breast lesion characterization. The deep learning computer-aided diagnosis (CADx) model we developed significantly improved specificity and achieved comparable accuracy to the radiologists with promise for clinical application to provide preliminary diagnoses.

A simplified scoring protocol to improve diagnostic accuracy with the breast imaging reporting and data system in breast magnetic resonance imaging

BACKGROUND

The breast imaging reporting and data system (BI-RADS) lexicon provides a standardized terminology for describing leision characteristics but does not provide defined rules for converting specific imaging features into diagnostic categories. The inter-reader agreement of the BI-RADS is moderate. In this study, we explored the use of a simplified protocol and scoring system for BI-RADS categorization which integrates the morphologic features (MF), kinetic time-intensity curve (TIC), and apparent diffusion coefficient (ADC) values with equal weights, with a view to providing a convenient and practical method for breast magnetic resonance imaging (MRI) and improving the inter-reader agreement and diagnostic performance of BI-RADS.

METHODS

This cross-sectional, retrospective, single-center study included 879 patients with 898 histopathologically verified lesions who underwent an MRI scan on a 3.0 Tesla GE Discovery 750 MRI scanner between January 1, 2017, and June 30, 2020. The BI-RADS categorization of the studied lesions was assessed according to the sum of the assigned scores (the presence of malignant MF, lower ADC, and suspicious TIC each warranted a score of +1). Total scores of +2 and +3 were classified as category 5, scores of +1 were classified as category 4, and scores of +0 but with other lesions of interest were classified as category 3. The receiver operating characteristic (ROC) curves were plotted, and the sensitivity, specificity, and accuracy of this categorization were investigated to assess its efficacy and its consistency with pathology.

RESULTS

There were 472 malignant, 104 risk, and 322 benign lesions. Our simplified scoring protocol had high diagnostic accuracy, with an area under curve (AUC) value of 0.896. In terms of the borderline effect of pathological risk and category 4 lesions, our results showed that when risk lesions were classified together with malignant ones, the AUC value improved (0.876 vs. 0.844 and 0.909 vs. 0.900). When category 4 and 5 lesions were classified as malignant, the specificity, accuracy, and AUC value decreased (82.3% vs. 93.2%, 89.3% vs. 90.2%, and 0.876 vs. 0.909, respectively). Therefore, to improve the diagnostic accuracy of the protocol for BI-RADS categorization, only category 5 lesions should be considered to be malignant.

CONCLUSIONS

Our simplified scoring protocol that integrates MF, TIC, and ADC values with equal weights for BI-RADS categorization could improve both the diagnostic performance of the protocol for BI-RADS categorization in clinical practice and the understanding of the benign-risk-malignant breast diseases.

The clinical impact of MRI on surgical planning for patients with in-breast tumor recurrence

OBJECTIVE

The objective of this study was to evaluate the clinical utility of breast MRI for patients with known in-breast tumor recurrence (IBTR). The aim was to determine if the addition of breast MRI altered surgical approach or multidisciplinary management. Previous studies have focused on using breast MRI for surgical planning for index breast cancers (BC) or detecting IBTR. However, the clinical impact of obtaining MRI in the setting of known IBTR has not been evaluated.

METHODS

A single-institution retrospective chart review was performed to compare surgical approach and multidisciplinary management for patients diagnosed with isolated IBTR who did and did not undergo breast MRI following IBTR diagnosis.

RESULTS

IBTR was identified in 69 patients, 46% of whom underwent MRI. There was no difference in the operative approach (p = 0.14) for IBTR patients who did and did not undergo breast MRI Additionally, there was no difference in multidisciplinary care, treatment order, metastatic disease identification, or mortality between cohorts. A relatively small subgroup of patients (n = 3) required change in surgical plan based on MRI results. Patients proceeding with surgery first who also underwent breast MRI experienced a significantly longer time to surgical intervention (p = 0.03).

CONCLUSION

Breast MRI following IBTR diagnosis infrequently impacted clinical management, including surgical approach and multidisciplinary care. MRI for local disease assessment at the time of IBTR should be used selectively based on clinical concern.

Contrast-enhanced spectral mammography (CESM)-guided breast biopsy as an alternative to MRI-guided biopsy

Objective:

Contrast-enhanced spectral mammography (CESM) breast biopsy has been recently introduced into clinical practice. This short communication describes the technique and potential as an alternative to MRI-guided biopsy.

Methods and materials:

An additional abnormality was detected on a breast MRI examination in a patient with lobular carcinoma. The lesion was occult on conventional mammography, tomosynthesis and ultrasound and required histological diagnosis. Traditionally, this would have necessitated an MRI-guided breast biopsy, but was performed under CESM guidance.

Results:

A diagnostic CESM study was performed to ensure the lesion visibility with CESM and then targeted under CESM guidance. A limited diagnostic study, CESM scout and paired images for stereotactic targeting were obtained within a 10 min window following a single injection of iodinated contrast agent. The time from positioning in the biopsy device to releasing compression after biopsy and marker clip placement was 15 min. The biopsy confirmed the presence of multifocal breast cancer.

Conclusion:

CESM-guided breast biopsy is a new technique that can be successfully used as an alternative to MRI-guided breast biopsy.

Advances in knowledge:

CESM-guided biopsy can be used to sample breast lesions which remain occult on standard mammography and ultrasound.

Perioperative magnetic resonance imaging in breast cancer care: Distinct adoption trajectories among physician patient-sharing networks

BACKGROUND

Despite no proven benefit in clinical outcomes, perioperative magnetic resonance imaging (MRI) was rapidly adopted into breast cancer care in the 2000's, offering a prime opportunity for assessing factors influencing overutilization of unproven technology.

OBJECTIVES

To examine variation among physician patient-sharing networks in their trajectory of adopting perioperative MRI for breast cancer surgery and compare the characteristics of patients, providers, and mastectomy use in physician networks that had different adoption trajectories.

METHODS AND FINDINGS

Using the Surveillance, Epidemiology, and End Results-Medicare database in 2004-2009, we identified 147 physician patient-sharing networks (caring for 26,886 patients with stage I-III breast cancer). After adjusting for patient clinical risk factors, we calculated risk-adjusted rate of perioperative MRI use for each physician network in 2004-2005, 2006-2007, and 2008-2009, respectively. Based on the risk-adjusted rate, we identified three distinct trajectories of adopting perioperative MRI among physician networks: 1) low adoption (risk-adjusted rate of perioperative MRI increased from 2.8% in 2004-2005 to 14.8% in 2008-2009), 2) medium adoption (8.8% to 45.1%), and 3) high adoption (33.0% to 71.7%). Physician networks in the higher adoption trajectory tended to have a larger proportion of cancer specialists, more patients with high income, and fewer patients who were Black. After adjusting for patients' clinical risk factors, the proportion of patients undergoing mastectomy decreased from 41.1% in 2004-2005 to 38.5% in 2008-2009 among those in physician networks with low MRI adoption, but increased from 27.0% to 31.4% among those in physician networks with high MRI adoption (p = 0.03 for the interaction term between trajectory group and time).

CONCLUSIONS

Physician patient-sharing networks varied in their trajectory of adopting perioperative MRI. These distinct trajectories were associated with the composition of patients and providers in the networks, and had important implications for patterns of mastectomy use.

Current and Future Directions of Breast MRI

Magnetic resonance imaging (MRI) is the most sensitive exam for detecting breast cancer. The American College of Radiology recommends women with 20% or greater lifetime risk of developing breast cancer be screened annually with MRI. However, other high-risk populations would also benefit. Hartmann et al. reported women with atypical hyperplasia have nearly a 30% incidence of breast cancer at 25-year follow-up. Women with dense breast tissue have up to a 4-fold increased risk of breast cancer when compared to average-risk women; their cancers are more likely to be mammographically occult. Because multiple cohorts of women are at high risk for developing breast cancer, there has been a movement to develop an abbreviated MRI (abMRI) protocol to expand the availability of MRI screening. Studies on abMRI effectiveness have been promising, with Weinstein et al. demonstrating a cancer detection rate of 27.4/1000 in women with dense breasts after a negative digital breast tomosynthesis. Breast MRI is also used to evaluate the extent of disease as part of preoperative assessment in women with newly diagnosed breast cancer, and to assess a patient's response to neoadjuvant chemotherapy. This paper aims to explore the current uses of MRI and propose future indications and directions.

Impact of pre-operative breast magnetic resonance imaging on contralateral synchronous and metachronous breast cancer detection-A case control comparison study with 1468 primary operable breast cancer patients with mean follow-up of 102 months

Background

Women with unilateral breast cancer are at an increased risk for the development of contralateral breast cancers. We hypothesis that combined breast MRI would detect more contralateral synchronous breast cancer than conventional imaging alone, and resulted in less contralateral metachronous breast cancer during follow-up.

Methods

We retrospectively collected two groups of breast cancer patients diagnosed from 2009 to 2013 for evaluating the effectiveness and value of adding pre-operative breast MRI to conventional breast images (mammography and sonography) for detection of contralateral synchronous breast cancer. The new metachronous contralateral breast cancer diagnosed during follow-up was prospectively evaluated and compared.

Results

Group A (n = 733) comprised patients who underwent conventional preoperative imaging and group B (n = 735) combined with MRI were enrolled and compared. Seventy (9.5%) of the group B patients were found to have contralateral lesions detected by breast MRI, and 65.7% of these lesions only visible with MRI. The positive predictive value of breast MRI detected contralateral lesions was 48.8%. With the addition of breast MRI to conventional imaging studies, more surgical excisions were performed in contralateral breasts (6% (44/735) versus 1.4% (10/733), P< 0.01), more synchronous contralateral breast cancer detected (2.9% (21/735) versus 1.1% (8/733), P = 0.02), and resulted in numerical less (2.2% (16/714) versus 3% (22/725), p = 0.3) metachronous contralateral breast cancer during a mean follow-up of 102 months.

Conclusions

Our study provides useful estimates of the pre-operative breast MRI for the increased detection of contralateral synchronous breast cancer and less subsequent contralateral metachronous breast cancer.

Are we choosing wisely? Drivers of preoperative MRI use in breast cancer patients

INTRODUCTION

Factors contributing to the use of preoperative MRI remain poorly understood.

METHODS

Data from a randomized controlled trial of stage 0-3 breast cancer patients undergoing breast conserving surgery between 2016 and 2018 were analyzed.

RESULTS

Of the 396 patients in this trial, 32.6% had a preoperative MRI. Patient age, race, ethnicity, tumor histology, and use of neoadjuvant therapy were significant predictors of MRI use. On multivariate analysis, younger patients with invasive lobular tumors were more likely to have a preoperative MRI. Rates also varied significantly by individual surgeon (p < 0.001); in particular, female surgeons (39.9% vs. 24.0% for male surgeons, p = 0.001) and those in community practice (58.9% vs. 14.2% for academic, p < 0.001) were more likely to order preoperative MRI. Rates declined over the two years of the study, particularly among female surgeons.

CONCLUSIONS

Preoperative MRI varies with patient age and tumor histology; however, there remains variability by individual surgeon.

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.

Simultaneous FAPI PET/MRI Targeting the Fibroblast-Activation Protein for Breast Cancer

Background Integrated PET/MRI is a promising modality for breast assessment. The most frequently used tracer, fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG), is applied for whole-body staging in advanced breast cancer but has limited accuracy in evaluating primary breast lesions. The fibroblast-activation protein (FAP) is abundantly expressed in invasive breast cancer. FAP-directed PET tracers have recently become available, but results in primary breast tumors remain lacking. Purpose To evaluate the use of FAP inhibitor (FAPI) breast PET/MRI in assessing breast lesions and of FAPI whole-body scanning for lymph node (LN) and distant staging using the ligand gallium 68 (⁶⁸Ga)-FAPI-46. Materials and Methods In women with histologically confirmed invasive breast cancer, all primary ⁶⁸Ga-FAPI-46 breast and whole-body PET/MRI and PET/CT examinations conducted at the authors' center between October 2019 and December 2020 were retrospectively analyzed. MRI lesion characteristics and standardized uptake values (SUVs) were quantified with dedicated software. Mann-Whitney U tests were used to compare tumor SUVs across different tumor types. The Pearson correlation coefficient was calculated between SUV and measures of MRI morphologic characteristics. Results Nineteen women (mean age, 49 years ± 9 [standard deviation]) were evaluated-18 to complement initial staging and one for restaging after therapy for distant metastases. Strong tracer accumulation was observed in all 18 untreated primary breast malignancies (mean maximum SUV [SUV_max] = 13.9 [range, 7.9-29.9]; median lesion diameter = 26 mm [range, 9-155 mm]), resulting in clear tumor delineation across different gradings, receptors, and histologic types. All preoperatively verified LN metastases in 13 women showed strong tracer accumulation (mean SUV_max= 12.2 [range, 3.3-22.4]; mean diameter = 21 mm [range, 14-35 mm]). Tracer uptake established or supported extra-axillary LN involvement in seven women and affected therapy decisions in three women. Conclusion This retrospective analysis indicates use of ⁶⁸Ga fibroblast-activation protein inhibitor tracers for breast cancer diagnosis and staging. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Mankoff and Sellmyer in this issue.

Which Patients With Newly Diagnosed Breast Cancer Benefit From Preoperative Magnetic Resonance Imaging?

Objective

The aim of this study was to identify the effectiveness and selective applications of preoperative magnetic resonance imaging (MRI) by investigating clinicopathologic factors of the index tumor with or without false lesions on MRI.

Summary of background data

Preoperative MRI is commonly performed in patients with newly diagnosed breast cancer, but its clinical significance is unclear.

Methods

A total of 103 breast cancer patients who had undergone MRI or ultrasound followed by mastectomy were included in this retrospective investigation of pathologic, clinical, and imaging findings.

Results

MRI showed 29 false-positive lesions in 57 patients, 5 false-negative lesions in 5 patients, and 69 true-positive lesions in 103 patients. More false lesions on MRI were found in patients with more lesions on ultrasound, small-sized index tumors on ultrasound, or early-stage cancer. The sensitivity of MRI and ultrasound were 96.5% and 92.3% (P = 0.119), respectively, and the positive predictive value of them were 71.5% and 72.5% (P = 0.828), respectively.

Conclusions

Preoperative MRI is more useful in patients with newly diagnosed breast cancer who have large-sized or more advanced cancers or fewer lesions on ultrasound.

Accuracy of contrast-enhanced spectral mammography compared with MRI for invasive breast cancers: Prospective study in population of predominantly underrepresented minorities

OBJECTIVES

This prospective study compares contrast-enhanced spectral mammography (CESM) with contrast-enhanced breast MRI in assessing the extent of newly diagnosed breast cancer in a multiethnic cohort.

METHODS

This study includes 41 patients with invasive breast cancer detected by mammography or conventional ultrasound imaging from May 2017 to March 2020. CESM and MRI scans were performed prior to any treatment. Results are compared with each other and to histopathology. Detection of the malignant lesion was assessed by sensitivity, specificity, PPV, NPV. Consistency of malignant tumor size measurement was compared between modalities using Intraclass Correlation Coefficient (ICC).

RESULTS

In a multiethnic cohort with over 65% Hispanic and African-American women, the sensitivity of detecting malignant lesions for CESM is 93.1% (77.23%, 99.15%) and MRI is 96.55% (82.24%, 99.91%). The PPV for CESM 96.43% (81.65%, 99.91%) is better compared to MRI 82.35% (65.47%, 93.24%). CESM is as effective as MRI in evaluating index cancers and multifocal/multicentric/contralateral disease. CESM has greater specificity and PPV since MRI tends to overcall benign lesions. There is a good agreement of tumor size between CESM to surgery and MRI to surgery with ICC of 0.85 (95% CI 0.69, 0.93) and 0.87 (95% CI 0.74, 0.94), respectively. There is good agreement of malignancy detection between CESM and MRI with Kappa of 0.74 (95% CI 0.52, 0.95).

CONCLUSIONS

CESM is an effective imaging modality for evaluating the extent of disease in newly diagnosed invasive breast cancers and a good alternative to MRI in a multiethnic population.

Diagnostic value of mammography for accompanying non-mass enhancement on preoperative breast MRI

BACKGROUND

Successful surgical treatment for localized breast cancer can depend on accurate diagnosis for accompanying non-mass enhancement (NME) on preoperative breast magnetic resonance imaging (MRI).

PURPOSE

To evaluate the diagnostic value of mammography for accompanying NME adjacent to index cancer on preoperative breast MRI.

MATERIAL AND METHODS

Among 569 consecutive patients who underwent preoperative breast MRI from January 2016 to August 2018 for ultrasound-guided biopsy-proven breast cancer, 471 patients who underwent initial mammography and subsequent surgery were finally included. Two radiologists retrospectively reviewed preoperative MRI findings of the 471 patients and detected accompanying NME adjacent to index cancer. MRI, mammography, and histopathology findings of the accompanying NME were evaluated using Pearson's chi-square test, Mann-Whitney U test, and logistic regression analysis. The area under the receiver operating characteristic curve (AUC) of MRI and combined MRI and mammography was calculated in differentiating benign from malignant accompanying NME. The reference standard was surgical pathologic findings.

RESULTS

MRI revealed 93 accompanying NME lesions in 92 (19.5%) of the 471 patients, showing 55 (59.1%) malignant and 38 (40.9%) benign lesions. On multivariate analysis, malignant NME lesions were more associated with mammography-positive findings (P = 0.000), clumped or clustered ring internal enhancement (P = 0.015), and extensive intraductal component presence of index tumor (P = 0.007) compared with benign lesions. The AUC increased after correlation with mammography showing 0.649 (95% confidence interval [CI] 0.533-0.765) for MRI and 0.833 (95% CI 0.747-0.919) for combined MRI and mammography.

CONCLUSION

Mammography is valuable in predicting malignancy for accompanying NME on preoperative breast MRI.

Comparison of the sensitivity of mammography, ultrasound, magnetic resonance imaging and combinations of these imaging modalities for the detection of small (≤2 cm) breast cancer

The aim of this study was to compare the sensitivity of mammography (MG), ultrasound (US), magnetic resonance imaging (MRI), and combinations of these imaging modalities for the detection of small (≤2 cm) breast cancer and to evaluate the benefit of preoperative breast MRI after performing conventional imaging techniques for small breast cancer.This was an observational retrospective review of 475 patients with pathologically confirmed breast cancer. We reviewed the medical records; assessed the preoperative reports of MG, US, and MRI; and categorized them as benign features (BI-RADS 1-3) or malignant features (BI-RADS 4 or 5). The criterion standard for detection was the pathologic assessment of the surgical specimen. The sensitivities of the different techniques were compared using the McNemar test.Among the 475 women, the sensitivity of MG was significantly greater in patients with low breast density than in those with high breast density (84.5% vs 65.8%, P < .001). US had higher sensitivity than MG (P < .001), and the combination of MG + US showed better sensitivity than MG or US alone (P < .001). Further addition of MRI to the combination of MG and US statistically contributed to the sensitivity yield (from 93.3% to 98.2%; P < .001) but did not significantly increase the mastectomy rate (from 48.2% to 49.3%; P = .177).MG has limited diagnostic sensitivity in patients with small breast cancer, especially in those with dense breast tissue. US is better than MG at detecting small breast cancer, regardless of breast density. The addition of MRI to MG and US could increase sensitivity without increasing the mastectomy rate. This study suggests performing MRI routinely on the basis of MG and US for small (≤2 cm) breast cancer.

Prediction of the number of metastatic axillary lymph nodes in breast cancer by radiomic signature based on dynamic contrast-enhanced MRI

BACKGROUND

The number of metastatic axillary lymph nodes (ALNs) play a crucial role in the staging, prognosis and therapy of patients with breast cancer.

PURPOSE

To predict the number of metastatic ALNs in breast cancer via radiomics.

MATERIAL AND METHODS

We enrolled 197 patients with breast cancer who underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). A total of 3386 radiomic features were extracted from the early- and delayed-phase subtraction images. To classify the number of metastatic ALNs, logistic regression was used to develop a radiomic signature and nomogram.

RESULTS

The radiomic signature were constructed to distinguish the N₀ group from the N₊ (metastatic ALNs ≥ 1) group, which yielded area under the curve (AUC) values of 0.82 and 0.81 in the training and test group, respectively. Based on the radiomic signature and BI-RADS category, a nomogram was further developed and showed excellent predictive performance with AUC values of 0.85 and 0.89 in the training and test groups, respectively. Another radiomic signature was constructed to distinguish the N₁ (1-3 ALNs) group from the N_2-3 (≥4 metastatic ALNs) group and showed encouraging performance with AUC values of 0.94 and 0.84 in training and test group, respectively.

CONCLUSIONS

We developed a nomogram and a radiomic signature that can be used to predict ALN metastasis and distinguish the N₁ from the N_2-3 group. Both nomogram and radiomic signature may be potential tools to assist clinicians in assessing ALN metastasis in patients with breast cancer.