The use of neoadjuvant systemic therapy in the treatment of breast cancer patients is increasing beyond the scope of locally advanced disease. Imaging provides important information in assessing ...response to therapy as a complement to conventional tumor measurements via physical examination. The purpose of this article is to discuss the advantages and limitations of current assessment methods, as well as review functional and molecular imaging approaches being investigated as emerging techniques for evaluating neoadjuvant therapy response for patients with primary breast cancer.
RSNA, 2017.
Historically, breast magnetic resonance imaging (MRI) was not considered an effective modality in the evaluation of ductal carcinoma in situ (DCIS). Over the past decade this has changed, with ...studies demonstrating that MRI is the most sensitive imaging tool for detection of all grades of DCIS. It has been suggested that not only is breast MRI the most sensitive imaging tool for detection but it may also detect the most clinically relevant DCIS lesions. The role and outcomes of MRI in the preoperative setting for patients with DCIS remains controversial; however, several studies have shown benefit in the preoperative evaluation of extent of disease as well as predicting an underlying invasive component. The most common presentation of DCIS on MRI is nonmass enhancement (NME) in a linear or segmental distribution pattern. Maximizing breast MRI spatial resolution is therefore beneficial, given the frequent presentation of DCIS as NME on MRI. Emerging MRI techniques, such as diffusion‐weighted imaging (DWI), have shown promising potential to discriminate DCIS from benign and invasive lesions. Future opportunities including advanced imaging visual techniques, radiomics/radiogenomics, and machine learning / artificial intelligence may also be applicable to the detection and treatment of DCIS.
Level of Evidence: 3
Technical Efficacy Stage: 3
J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2020;52:697–709.
The practice of breast imaging has transitioned through a wide variety of technologic advances from the early days of direct-exposure film mammography to xeromammography to screen-film mammography to ...the current era of full-field digital mammography and digital breast tomosynthesis. Along with these technologic advances, organized screening, federal regulations based on the Mammography Quality Standards Act, and the development of the American College of Radiology Breast Imaging Reporting and Data System have helped to shape the specialty of breast imaging. With the development of breast ultrasonography and breast magnetic resonance imaging, both complementary to mammography, additional algorithms for diagnostic workup and screening high-risk subgroups of women have emerged. A substantial part of breast imaging practice these days also involves breast interventional procedures-both percutaneous biopsy to obtain tissue diagnosis and localization procedures to guide surgical excision. This article reviews the evolution of breast imaging starting from a historical perspective and progressing to the present day.
Conventional breast MRI is highly sensitive for cancer detection but prompts some false positives. We performed a prospective, multicenter study to determine whether apparent diffusion coefficients ...(ADCs) from diffusion-weighted imaging (DWI) can decrease MRI false positives.
A total of 107 women with MRI-detected BI-RADS 3, 4, or 5 lesions were enrolled from March 2014 to April 2015. ADCs were measured both centrally and at participating sites. ROC analysis was employed to assess diagnostic performance of centrally measured ADCs and identify optimal ADC thresholds to reduce unnecessary biopsies. Lesion reference standard was based on either definitive biopsy result or at least 337 days of follow-up after the initial MRI procedure.
Of 107 women enrolled, 67 patients (median age 49, range 24-75 years) with 81 lesions with confirmed reference standard (28 malignant, 53 benign) and evaluable DWI were analyzed. Sixty-seven of 81 lesions were BI-RADS 4 (
= 63) or 5 (
= 4) and recommended for biopsy. Malignancies exhibited lower mean in centrally measured ADCs (mm
/s) than benign lesions 1.21 × 10
vs.1.47 × 10
;
< 0.0001; area under ROC curve = 0.75; 95% confidence interval (CI) 0.65-0.84. In centralized analysis, application of an ADC threshold (1.53 × 10
mm
/s) lowered the biopsy rate by 20.9% (14/67; 95% CI, 11.2%-31.2%) without affecting sensitivity. Application of a more conservative threshold (1.68 × 10
mm
/s) to site-measured ADCs reduced the biopsy rate by 26.2% (16/61) but missed three cancers.
DWI can reclassify a substantial fraction of suspicious breast MRI findings as benign and thereby decrease unnecessary biopsies. ADC thresholds identified in this trial should be validated in future phase III studies.
Background
Quantitative diffusion‐weighted imaging (DWI) MRI is a promising technique for cancer characterization and treatment monitoring. Knowledge of the reproducibility of DWI metrics in breast ...tumors is necessary to apply DWI as a clinical biomarker.
Purpose
To evaluate the repeatability and reproducibility of breast tumor apparent diffusion coefficient (ADC) in a multi‐institution clinical trial setting, using standardized DWI protocols and quality assurance (QA) procedures.
Study Type
Prospective.
Subjects
In all, 89 women from nine institutions undergoing neoadjuvant chemotherapy for invasive breast cancer.
Field Strength/Sequence
DWI was acquired before and after patient repositioning using a four b‐value, single‐shot echo‐planar sequence at 1.5T or 3.0T.
Assessment
A QA procedure by trained operators assessed artifacts, fat suppression, and signal‐to‐noise ratio, and determine study analyzability. Mean tumor ADC was measured via manual segmentation of the multislice tumor region referencing DWI and contrast‐enhanced images. Twenty cases were evaluated multiple times to assess intra‐ and interoperator variability. Segmentation similarity was assessed via the Sørenson–Dice similarity coefficient.
Statistical Tests
Repeatability and reproducibility were evaluated using within‐subject coefficient of variation (wCV), intraclass correlation coefficient (ICC), agreement index (AI), and repeatability coefficient (RC). Correlations were measured by Pearson's correlation coefficients.
Results
In all, 71 cases (80%) passed QA evaluation: 44 at 1.5T, 27 at 3.0T; 60 pretreatment, 11 after 3 weeks of taxane‐based treatment. ADC repeatability was excellent: wCV = 4.8% (95% confidence interval CI 4.0, 5.7%), ICC = 0.97 (95% CI 0.95, 0.98), AI = 0.83 (95% CI 0.76, 0.87), and RC = 0.16 * 10−3 mm2/sec (95% CI 0.13, 0.19). The results were similar across field strengths and timepoint subgroups. Reproducibility was excellent: interreader ICC = 0.92 (95% CI 0.80, 0.97) and intrareader ICC = 0.91 (95% CI 0.78, 0.96).
Data Conclusion
Breast tumor ADC can be measured with excellent repeatability and reproducibility in a multi‐institution setting using a standardized protocol and QA procedure. Improvements to DWI image quality could reduce loss of data in clinical trials.
Level of Evidence: 2
Technical Efficacy: Stage 1
J. Magn. Reson. Imaging 2019;49:1617–1628.
The purpose of this study is to evaluate a nonradioactive inducible magnetic seed system (Magseed, Endomag) for preoperative localization of nonpalpable breast lesions.
All of the 73 seeds placed in ...the first 4 months of clinical use were successfully placed and all were successfully retrieved intraoperatively. The mean time from seed placement to surgery was 3 days. Early clinical experience suggests that Magseed is an effective and accurate means of preoperative breast lesion localization.
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