A Machine Learning-Based Unenhanced Radiomics Approach to Distinguishing Between Benign and Malignant Breast Lesions Using T2-Weighted and Diffusion-Weighted MRI

BACKGROUND

Breast MRI has been recommended as supplemental screening tool to mammography and breast ultrasound of breast cancer by international guidelines, but its long examination time and use of contrast material remains concerning.

PURPOSE

To develop an unenhanced radiomics model with using non-gadolinium based sequences for detecting breast cancer based on T2-weighted (T2W) and diffusion-weighted (DW) MRI.

STUDY TYPE

Retrospective analysis followed by retrospective and prospective cohorts study.

POPULATION

1760 patients: Of these, 1293 for model construction (n = 775 for training and 518 for validation). The remaining patients for model testing in internal retrospective (n = 167), internal prospective (n = 188), and external retrospective (n = 112) cohorts.

FIELD STRENGTH/SEQUENCE

3.0T MR scanners from two institution. T2WI, DWI, and first contrast-enhanced T1-weighted sequence.

ASSESSMENT

AUCs in distinguishing breast cancer were compared between combined model with gadolinium agent sequence and unenhanced model. Subsequently, the AUCs in testing cohorts of unenhanced model was compared with two radiologists' diagnosis for this research. Finally, patient subgroup analysis in testing cohorts was performed based on clinical subgroups and different types of malignancies.

STATISTICAL TESTS

Mann-Whitney U test, Kruskal-Wallis H test, chi-square test, weighted kappa test, and DeLong's test.

RESULTS

The unenhanced radiomics model performed best under Gaussian process (GP) classifiers (AUC: training, 0.893; validation, 0.848) compared to support vector machine (SVM) and logistic, showing favorable prediction in testing cohorts (AUCs, 0.818-0.840). The AUCs for the unenhanced radiomics model were not statistically different in five cohorts from those of the combined radiomics model (P, 0.317-0.816), as well as the two radiologists (P, 0.181-0.918). The unenhanced radiomics model was least successful in identifying ductal carcinoma in situ, whereas did not show statistical significance in other subgroups.

DATA CONCLUSION

An unenhanced radiomics model based on T2WI and DWI has comparable diagnostic accuracy to the combined model using the gadolinium agent.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 2.

Analysis of the Value of Quantitative Features in Multimodal MRI Images to Construct a Radio-Omics Model for Breast Cancer Diagnosis

Objective

To analyze the diagnostic value of quantitative features in multimodal magnetic resonance imaging (MRI) images to construct a radio-omics model for breast cancer.

Methods

Ninety-five patients with breast-related diseases from January 2020 to January 2021 were grouped into the benign group (n=57) and malignant group (n=38) according to the pathological findings. All cases were randomized as the training group (n=66) and validation group (n=29) in a 7:3 ratio based on the examination time. All subjects were examined by T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), dynamic contrast enhancement (DCE), and apparent diffusion coefficient (ADC) multimodality MRI. The MRI findings were analyzed against pathological findings. A diagnostic breast cancer radiomics model was constructed. The diagnostic efficacy of the model in the validation group was analyzed, and the diagnostic efficacy was analyzed via the ROC curve.

Results

Fibroadenoma accounted for 49.12% of benign breast diseases, and invasive ductal carcinoma accounted for 73.68% of malignant breast diseases. The sensitivity of T1WI, T2WI, DWI, ADC, and DCE in diagnosing breast cancer was 61.14%, 66.67%, 73.30%, 78.95%, and 85.96%, using the four-fold table method. The area under the curves (AUCs) of T1WI, T2WI, DWI, ADC, and DCE for diagnosing breast cancer were 0.715, 0.769, 0.785, 0.835, and 0.792, respectively. The AUCs of plain scan, diffuse, enhanced, plain scan + diffuse, plain scan + enhanced, enhanced + diffuse, and plain scan + enhanced + diffuse for diagnosing breast cancer were 0.746, 0.798, 0.816, 0.839, 0.890, 0.906, and 0.927, respectively.

Conclusion

The construction of a radio-omics model by quantitative features in multimodal MRI images was valuable in the diagnosis of breast cancer. The value of radio-omics models such as plain scan + enhanced + diffuse was higher than the other models in diagnosing breast cancer and could be widely applied in clinical practice.

Ultrasound as a Method for Early Diagnosis of Breast Pathology

INTRODUCTION

Ultrasound is a non-invasive, low-cost technique that does not use ionising radiation and provides a "real-time" image, and for these reasons, this method is ideal in several situations.

PURPOSE

To demonstrate breast ultrasound evaluation as a first-line diagnostic method and to evaluate the variation of breast characteristics with age.

MATERIAL AND METHODS

A total of 105 women with a mean age of 30 years participated and were divided into three age groups: 18-39, 40-59, and 60-79 years, excluding participants subject to mastectomy. After completing the informed consent, all participants answered personal and sociodemographic questions, such as personal and family history, menstrual cycle, pregnancy, ultrasound, and mammography, among others. They were then submitted to a bilateral breast ultrasound examination. Subsequently, all the images and their data were analysed, and a technical report of the examination was given to all the participants.

RESULTS

A total of 105 women with a mean age of 30 years participated, 58 of whom underwent the examination for the first time. In 31, changes (of which only 7 were known) were diagnosed. It was verified that, according to age group, the density of the breast stroma varied; older women have less breast density.

CONCLUSIONS

Ultrasound is a good method for breast evaluation and can be considered important for the early evaluation of breast pathology and follow-up of the pathology.

Abbreviated Breast MRI: Our Two-Year Initial Experience

OBJECTIVE

The aim of this study was to retrospectively evaluate and present our two-year experience with abbreviated breast MRI at our academic institution as a screening tool to identify primary breast cancers.

METHODS

Employing eight specialty trained breast radiologists, studies were interpreted using the BI-RADS MRI lexicon in this IRB-approved retrospective study. The protocol utilized T1-weighted, fat-saturated, pre- and post-contrast, short  T1 inversion recovery images, and was completed within 10 minutes. Abbreviated breast MRI was offered to asymptomatic women of all breast densities, whose ages ranged from 24 to 90 years. Statistical analysis was performed for comparative data utilizing estimated odds ratios.

RESULTS

Of 1338 patients that met inclusion criteria, 83% (1111/1338) were BI-RADS 1 or 2, 9.0% (121/1338) were BI-RADS 3, and 8% (106/1338) were categorized as either BI-RADS 4 or 5 with recommended biopsy. Biopsy of BI-RADS 4 and 5 categorized patients yielded 15 cancers for a positive predictive value (PPV) 2 of 14.2% and a PPV3 of 18.5%, with 76% (81/106) of patients undergoing the recommended biopsy. An additional cancer was detected in a BI-RADS 3 finding. All cancers detected were in women with heterogeneously dense or extremely dense breasts. Therefore, 16 cancers were detected, yielding a cancer detection rate of 12.0 per 1000. Over the next 12 to 24 months, no interval cancers were detected.

CONCLUSION

Abbreviated breast MRI demonstrates a higher cancer detection rate compared with mammography only and may provide a supplemental screening method to detect breast cancers in patients with varying risk factors.

Implementation of abbreviated breast MRI in diagnostic and screening settings

BACKGROUND

Abbreviated magnetic resonance imaging (MRI) includes fewer sequences than standard MRI, which could be utilized for breast cancer detection.

PURPOSE

To evaluate the diagnostic accuracy of abbreviated MRI protocol in screening and diagnostic settings.

MATERIAL AND METHODS

All women with screening and diagnostic (problem-solving and preoperative staging) MRI examination were recruited from 2017 to 2020. Two expert radiologists assessed designed abbreviated protocol (fat-saturated T1-weighted [T1W] pre-contrast and two first fat-saturated T1W post-contrast series with reconstruction of their subtraction) including maximum intensity projection (MIP) and then evaluated standard protocol of breast MRI. Associated findings, including axillary lymphadenopathy and invasion to nipple, skin, or pectoralis muscle were also evaluated. The concordance rate of abbreviated with standard protocol in screening and diagnostic settings were also compared, based on BI-RADS classification. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive value were calculated.

RESULTS

A total of 108 (26.5%) of 408 patients (mean age = 43 ± 9 years) were classified as BI-RADS 4-5 and considered positive findings based on suspicious enhancement (mass or non-mass enhancement). Compared to standard protocol, abbreviated protocol revealed >98% accuracy in the diagnostic setting as well as 100% accuracy in the screening setting. Concordance rates in screening and diagnostic settings were 99.6% and 98.1%, respectively. There was no discordance between abbreviated and standard protocol in the evaluation of associated findings.

CONCLUSION

Abbreviated MRI protocol possesses substantial diagnostic accuracy in both screening and diagnostic settings. Additional information provided by standard protocol might not require for cancer detection.

Abbreviated Breast MRI Utilization: A Survey of the Society of Breast Imaging

OBJECTIVE

To survey Society of Breast Imaging (SBI) membership on their use of abbreviated breast MRI to understand variability in practice patterns.

METHODS

A survey was developed by the SBI Patient Care and Delivery committee for distribution to SBI membership in July and August 2021. Eighteen questions queried practice demographics and then abbreviated breast MRI practices regarding initial adoption, scheduling and finances, MRI protocols, and interpretations. Comparisons between responses were made by practice demographics.

RESULTS

There were 321 respondents (response rate: 15.3%), of whom 25% (81/321) currently offer and 26% (84/321) plan to offer abbreviated breast MRI. Practices in the South (37/107, 35%) and Midwest (22/70, 31%) were more likely to offer abbreviated MRI (P = 0.005). Practices adopted many strategies to raise awareness, most directed at referring providers. The mean charge to patients was $414, and only 6% of practices offer financial support. The median time slot for studies is 20 minutes, with only 15% of practices using block scheduling of consecutive breast MRIs. Regarding MRI protocols, 64% (37/58) of respondents included only a single first-pass post-contrast sequence, and 90% (52/58) included T2-weighted sequences. Patient eligibility was highly varied, and a majority of respondents (37/58, 64%) do not provide any recommendations for screening intervals in non-high-risk women.

CONCLUSION

Abbreviated breast MRI utilization is growing rapidly, and practices are applying a variety of strategies to facilitate adoption. Although there is notable variability in patient eligibility, follow-up intervals, and costs, there is some agreement regarding abbreviated breast MRI protocols.

Financial and medicolegal implications of focused/fast abdominopelvic MRI exams

PURPOSE

Abbreviated MRI offers significant advantages in terms of MRI throughput, patient tolerance and expediency, and is being utilized for a variety of abdominopelvic imaging applications. However questions abound with respect to financial and medicolegal treatment of these relatively new protocols.

METHODS

A review of the relevant literature was performed.

RESULTS

There is no Current Procedural Terminology code for a "limited" MRI study, but it may not be appropriate to bill an abbreviated study the same as a more comprehensive study. With respect to medicolegal concerns, the risk of liability when missing or misinterpreting medically significant findings due to use of an abbreviated scan will turn on whether abbreviated MRI has become the standard of care.

CONCLUSION

In light of these ambiguities, it would behoove abdominopelvic imagers to advocate for their professional and subspecialty organizations to issue practice parameters/guidelines with respect to the utilization of abbreviated MRI protocols, and for the subspecialty to bill these abbreviated scans at objectively reasonable rates.

Implementation of Abbreviated Breast MRI for Screening: AJR Expert Panel Narrative Review

Abbreviated breast MRI (AB-MRI) is being rapidly adopted to harness the high sensitivity of screening MRI while addressing issues related to access, cost, and workflow. The successful implementation of an ABI-MRI program requires collaboration across administrative, operational, financial, technical, and clinical providers. Institutions must be thoughtful in defining AB-MRI patient eligibility and providing recommendations for screening intervals, as existing practices are heterogeneous. Similarly, there is no universally accepted AB-MRI protocol, though guiding principles should harmonize abbreviated and full protocols while being mindful of scan duration and table time. The interpretation of AB-MRI will be a new experience for many radiologists and may require a phased rollout as well as a careful audit of performance metrics over time to ensure benchmark metrics are achieved. AB-MRI finances, which are driven by patient self-payment, will require buy-in from hospital administration with the recognition that downstream revenues will be needed to support initial costs. Finally, successful startup of an AB-MRI program requires active engagement with the larger community of patients and referring providers. As AB-MRI becomes more widely accepted and available, best practices and community standards will continue to evolve to ensure high quality patient care.

Abbreviated MR Imaging for Breast Cancer

Breast MR imaging is the most sensitive imaging method for the detection of breast cancer and detects more aggressive malignancies than mammography and ultrasound examination. Despite these advantages, breast MR imaging has low use rates for breast cancer screening. Abbreviated breast MR imaging, in which a limited number of breast imaging sequences are obtained, has been proposed as a way to solve cost and patient tolerance issues while preserving the high cancer detection rate of breast MR imaging. This review discusses abbreviated breast MR imaging, including protocols, multicenter clinical trial results, clinical workflow implementation challenges, and future directions.

Abbreviated Protocol Breast MRI

OBJECTIVE. Patients with dense breast tissue are seeking supplemental screening because of the limited sensitivity of mammography. Abbreviated protocol (AP) breast MRI is attractive because it offers a higher cancer detection rate, shorter scan time, and lower cost than full MRI. This article explores the issues of balancing the benefits of AP MRI with safety concerns about gadolinium-based contrast agents, lack of standardization of protocols and field strengths, potential decrease in performance metrics, and potential for overdiagnosis. CONCLUSION. Important questions need to be addressed before AP MRI can be used routinely for breast cancer screening. Evidence is lacking from well-designed prospective trials that can confirm the accuracy and efficacy of AP MRI are comparable with those of other breast imaging modalities. Determining which patients benefit most from AP MRI will help shape future screening guidelines.

Abbreviated Breast MRI: Road to Clinical Implementation

Breast MRI offers high sensitivity for breast cancer detection, with preferential detection of high-grade invasive cancers when compared to mammography and ultrasound. Despite the clear benefits of breast MRI in cancer screening, its cost, patient tolerance, and low utilization remain key issues. Abbreviated breast MRI, in which only a select number of sequences and postcontrast imaging are acquired, exploits the high sensitivity of breast MRI while reducing table time and reading time to maximize availability, patient tolerance, and accessibility. Worldwide studies of varying patient populations have demonstrated that the comparable diagnostic accuracy of abbreviated breast MRI is comparable to a full diagnostic protocol, highlighting the emerging role of abbreviated MRI screening in patients with an intermediate and high lifetime risk of breast cancer. The purpose of this review is to summarize the background and current literature relating to abbreviated MRI, highlight various protocols utilized in current multicenter clinical trials, describe workflow and clinical implementation issues, and discuss the future of abbreviated protocols, including advanced MRI techniques.

Breast MRI: Is Faster Better?

OBJECTIVE. Fast breast MRI protocols have the same sensitivity as conventional protocols, but their specificity is variable and can be inadequate. An ultrafast sequence provides early enhancement of lesion characteristics that optimize the characterization of the fast protocol, increasing positive predictive values without increasing time. CONCLUSION. These new abbreviated protocols could constitute a viable screening tool both for women at high risk of breast cancer and for those at intermediate risk with high breast density.