Magnetic resonance imaging of breast cancer: clinical indications and breast MRI reporting system

Predictive models and biomarkers for survival in stage III breast cancer: a review of clinical applications and future directions

Stage III breast cancer, characterized by locally advanced tumors and potential regional lymph node involvement, presents a formidable challenge to both patients and healthcare professionals. Accurate prediction of survival outcomes is crucial for guiding treatment decisions and optimizing patient care. This publication explores the potential clinical utility of predictive tools, encompassing genetic markers, imaging techniques, and clinical parameters, to improve survival outcome predictions in stage III breast cancer. Multimodal approaches, integrating these tools, hold the promise of delivering more precise and personalized predictions. Despite the inherent challenges, such as data standardization and genetic heterogeneity, the future offers opportunities for refinement, driven by precision medicine, artificial intelligence, and global collaboration. The goal is to empower healthcare providers to make informed treatment decisions, ultimately leading to improved survival outcomes and a brighter horizon for individuals facing this challenging disease.

The Influence of Data-Driven Compressed Sensing Reconstruction on Quantitative Pharmacokinetic Analysis in Breast DCE MRI

Radial acquisition with MOCCO reconstruction has been previously proposed for high spatial and temporal resolution breast DCE imaging. In this work, we characterize MOCCO across a wide range of temporal contrast enhancement in a digital reference object (DRO). Time-resolved radial data was simulated using a DRO with lesions in different PK parameters. The under sampled data were reconstructed at 5 s temporal resolution using the data-driven low-rank temporal model for MOCCO, compressed sensing with temporal total variation (CS-TV) and more conventional low-rank reconstruction (PCB). Our results demonstrated that MOCCO was able to recover curves with K^trans values ranging from 0.01 to 0.8 min⁻¹ and fixed V_e = 0.3, where the fitted results are within a 10% bias error range. MOCCO reconstruction showed less impact on the selection of different temporal models than conventional low-rank reconstruction and the greater error was observed with PCB. CS-TV showed overall underestimation in both K^trans and V_e. For the Monte-Carlo simulations, MOCCO was found to provide the most accurate reconstruction results for curves with intermediate lesion kinetics in the presence of noise. Initial in vivo experiences are reported in one patient volunteer. Overall, MOCCO was able to provide reconstructed time-series data that resulted in a more accurate measurement of PK parameters than PCB and CS-TV.

A Discrete Dipole Approximation Solver Based on the COCG-FFT Algorithm and Its Application to Microwave Breast Imaging

We introduce the discrete dipole approximation (DDA) for efficiently calculating the two-dimensional electric field distribution for our microwave tomographic breast imaging system. For iterative inverse problems such as microwave tomography, the forward field computation is the time limiting step. In this paper, the two-dimensional algorithm is derived and formulated such that the iterative conjugate orthogonal conjugate gradient (COCG) method can be used for efficiently solving the forward problem. We have also optimized the matrix-vector multiplication step by formulating the problem such that the nondiagonal portion of the matrix used to compute the dipole moments is block-Toeplitz. The computation costs for multiplying the block matrices times a vector can be dramatically accelerated by expanding each Toeplitz matrix to a circulant matrix for which the convolution theorem is applied for fast computation utilizing the fast Fourier transform (FFT). The results demonstrate that this formulation is accurate and efficient. In this work, the computation times for the direct solvers, the iterative solver (COCG), and the iterative solver using the fast Fourier transform (COCG-FFT) are compared with the best performance achieved using the iterative solver (COCG-FFT) in C++. Utilizing this formulation provides a computationally efficient building block for developing a low cost and fast breast imaging system to serve under-resourced populations.

Convolutional neural network for breast cancer diagnosis using diffuse optical tomography

We have developed a computer-aided diagnosis system based on a convolutional neural network that aims to classify breast mass lesions in optical tomographic images obtained using a diffuse optical tomography system, which is suitable for repeated measurements in mass screening. Sixty-three optical tomographic images were collected from women with dense breasts, and a dataset of 1260 2D gray scale images sliced from these 3D images was built. After image preprocessing and normalization, we tested the network on this dataset and obtained 0.80 specificity, 0.95 sensitivity, 90.2% accuracy, and 0.94 area under the receiver operating characteristic curve (AUC). Furthermore, a data augmentation method was implemented to alleviate the imbalance between benign and malignant samples in the dataset. The sensitivity, specificity, accuracy, and AUC of the classification on the augmented dataset were 0.88, 0.96, 93.3%, and 0.95, respectively.

Accuracy of diffusion kurtosis imaging in characterization of breast lesions

OBJECTIVE

The aim of this study was to evaluate the accuracy of diffusion kurtosis in the characterization and differentiation of breast lesions.

METHODS

49 females with 53 breast lesions underwent breast MRI. The MRI magnetic field is 1.5 T, and the protocol is standard MRI sequences, dynamic sequences pre- and post-contrast agent administration and diffusion images. Diffusion kurtosis imaging (DKI) was applied as part of our standard breast MRΙ protocol. Two experienced radiologists on breast MRI, blinded to the final diagnosis, reviewed the parametric maps and placed a volume of interest on all slices including each lesion. Kurtosis [K apparent (K_app)] and corrected apparent diffusion coefficient [D apparent (D_app)] median values were then calculated from the whole-lesion histogram analysis. Receiver-operating characteristic analysis was used to determine the most effective cut-off values for the differentiation between benign and malignant pathologies. Histological analysis of the breast lesions was performed, and further comparative analysis of the results was performed to investigate the accuracy of the method.

RESULTS

Benign (n = 19) and malignant lesions (n = 34) had mean diameters of 20.8 mm (10.1-31.5 mm) and 26.4 mm (10.5-42.3 mm), respectively. The lowest and the highest kurtosis values (K_app) of malignant lesions were significantly higher than those of benign lesions. A cut-off of 0.71 provided specificity of 93.7% and sensitivity 97.1%, and the area under the curve (AUC) was 0.976 (p < 0.0001). The lowest and the highest D_app values of malignant lesions were lower than those of benign lesions. A cut-off value of 1.57 × 10^-3 mm² s^-1 provided specificity of 93.7% and sensitivity of 91.2% with AUC of 0.949 (p < 0.0001).

CONCLUSION

DKI is an accurate additional tool for the characterization and differentiation of breast lesions with high K_app and D_app sensitivity and specificity rates. Advances in knowledge: DKI is able to distinguish benign from malignant breast pathologies. DKI increases the specificity of breast MRI.

Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra

In this paper, we report a compact and ultra-wide band antenna on a flexible substrate using the 5-(4-(perfluorohexyl)phenyl)thiophene-2-carbaldehyde compound for microwave imaging. In contrast to other microwave based imaging systems, such as an array of 16 antennas, we proposed a bi-static radar based imaging system consisting of two omnidirectional antennas, which reduces complexity and the overall dimension. The proposed compact antennas are 20 × 14 mm² and designed for operating at frequencies from 4 to 6 GHz. To allow for implantation into a bra, the electromagnetic performances of the antennas must be considered in bending conditions. In comparison with the recently reported flexible antennas, we demonstrated both electromagnetic performance and imaging reconstruction for bending conditions. For the proof of concept, the electromagnetic performances both at flat and bending conditions have been verified using a homogeneous multilayer model of the human breast phantom. Our results demonstrate that the antenna, even at bending conditions, exhibits an excellent omni-directional radiation pattern with an average efficiency above 70% and average gain above 1 dBi, within the operational frequency band. The comprehensive aim of the realized antenna is to design a biodegradable and wearable antenna-based bra for early breast cancer detection in the future.

Whole-lesion apparent diffusion coefficient (ADC) metrics as a marker of breast tumour characterization-comparison between ADC value and ADC entropy

OBJECTIVE

To prospectively assess the role of whole-lesion apparent diffusion coefficient (ADC) metrics in the characterization of breast tumours by comparing ADC value with ADC entropy.

METHODS

49 patients with 53 breast lesions underwent phased-array breast coil 1.5-T MRI. Two radiologists experienced in breast MRI, blinded to the final diagnosis, reviewed the ADC maps and placed a volume of interest on all slices including each lesion on the ADC map to obtain whole-lesion mean ADC value and ADC entropy. The mean ADC value and ADC entropy in benign and malignant lesions were compared by the Mann-Whitney U-test. Receiver-operating characteristic analysis was performed to assess the sensitivity and specificity of the two variables in the characterization of the breast lesions.

RESULTS

The benign (n = 19) and malignant lesions (n = 34) had mean diameters of 20.8 mm (10.1-31.5 mm) and 26.4 mm (10.5-42.3 mm), respectively. The mean ADC value of the malignant lesions was significantly lower than that of the benign ones (0.87 × 10^-3 vs 1.49 × 10^-3 mm² s^-1; p < 0.0001). Malignant ADC entropy was higher than benign entropy, without reaching levels of statistical significance (5.4 vs 5.0; p = 0.064). At a mean ADC cut-off value of 1.16 × 10^-3 mm² s^-1, the sensitivity and specificity for diagnosing malignancy became optimal (97.1% and 93.7, respectively) with an area under the curve (AUC) of 0.975. With regard to ADC entropy, the sensitivity and specificity at a cut-off of 5.18 were 67.6 and 68.7%, respectively, with an AUC of 0.664.

CONCLUSION

Whole-lesion mean ADC could be a helpful index in the characterization of suspicious breast lesions, with higher sensitivity and specificity than ADC entropy. Advances in knowledge: Two separate parameters of the whole-lesion histogram were compared for their diagnostic accuracy in characterizing breast lesions. Mean ADC was found to be able to characterize breast lesions, whereas entropy proved to be unable to differentiate benign from malignant breast lesions. It is, however, likely that entropy may distinguish these two groups if a larger cohort were used, or the fact that this may be influenced by the molecular subtypes of breast cancers included.

Pharmacokinetic Parameters Analyzed from MR Contrast Enhancement Kinetics of Multiple Malignant and Benign Breast Lesions Detected in the Same Patients

Ninety-nine patients with confirmed breast cancer were reviewed to identify patients who had two confirmed malignant lesions of identical pathology (Group-1, N=17), and patients who had one malignant lesion and the second benign lesion (Group-2, N=8). Contrast enhancement kinetics from every lesion was measured and analyzed using three different models to obtain fitting parameters related to up-slope, enhancement amplitude, and wash-out, including Model-1: modified Tofts model ( vp, Ktrans, kep), Model-2: standard Tofts model ( Ktrans, kep), and Model-3: a 3-parameter heuristic model ( Tc, A, C). By analyzing lesions from same patients, the differences in whole body hemodynamics thus the blood kinetics could be controlled. Two questions were addressed in this study: i) What is the association between pharmacokinetic parameters analyzed from multiple cancers of identical pathology in same patients?; and ii) What is the difference between secondary malignant lesions and secondary benign lesions with reference to the primary cancer? All three models could fit the enhancement kinetics satisfactorily. Regardless of the analysis model the parameter obtained from the primary cancer and the secondary cancer showed significant correlations. In comparison between Group-1 and Group-2 subjects, the wash-out parameter kep in Models-1 and 2 could significantly differentiate benign from malignant lesions, but not the magnitude parameters, Ktrans in Model-2 or the parameter A in Model-3. If analyzed using appropriate models the early up-slope parameters, vp in Model-1 and Tc in Model-3, might be able to distinguish between benign and malignant lesions. When more data are available a reference database can be established with the method described in this study, and from which to determine the likelihood of malignancy for each incidental lesion found in preoperative MRI, with reference to the primary cancer.

Subcategorization of Suspicious Breast Lesions (BI-RADS Category 4) According to MRI Criteria: Role of Dynamic Contrast-Enhanced and Diffusion-Weighted Imaging

OBJECTIVE

The purposes of this study were to investigate whether dynamic contrast-enhanced MRI is adequate for subcategorization of suspicious lesions (BI-RADS category 4) and to evaluate whether use of DWI improves diagnostic performance.

MATERIALS AND METHODS

The study group was composed of 103 suspicious lesions found in 83 subjects. Patient ages and lesion sizes were compiled, and two radiologists reanalyzed the images; subcategorized the findings as BI-RADS 4A, 4B, or 4C; and calculated apparent diffusion coefficient (ADC) values. The stratified variables were tested by univariate analysis and inserted in two multivariate predictive models, which were used to generate ROC curves and compare AUCs. Positive predictive values (PPVs) for each subcategory and ADC level were calculated, and interobserver agreement was tested.

RESULTS

Forty-four (42.7%) suspicious findings proved malignant. Except for age (p = 0.08), all stratified predictor variables were significant in univariate analyses (p < 0.01). Logistic regression models did not differ substantially after comparison of the ROC curves (p = 0.09), but the one including ADC values was slightly better: AUC of 0.89 (95% CI, 0.82-0.95) against AUC of 0.85 (95% CI, 0.78-0.93). PPV increased progressively in each BI-RADS 4 subcategory (4A, 0.15; 4B, 0.37; 4C, 0.84). ADC values of 1.10 × 10(-3) mm(2)/s or less had the second highest PPV (0.77). Interobserver agreement was substantial at a kappa value of 0.80 (95% CI, 0.70-0.90; p < 0.01).

CONCLUSION

Risk stratification of suspicious lesions (BI-RADS category 4) can be satisfactorily performed with DCE-MRI and slightly improved when DWI is introduced.

A new quantitative image analysis method for improving breast cancer diagnosis using DCE-MRI examinations

PURPOSE

To investigate the feasibility of applying a new quantitative image analysis method to improve breast cancer diagnosis performance using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) by integrating background parenchymal enhancement (BPE) features into the decision making process.

METHODS

A dataset involving 115 DCE-MRI examinations was used in this study. Each examination depicts one identified suspicious breast tumor. Among them, 75 cases were verified as malignant and 40 were benign by the biopsy results. A computer-aided detection scheme was applied to segment breast regions and the suspicious tumor depicted on the sequentially scanned MR images of each case. We then computed 18 kinetic features in which 6 were computed from the segmented breast tumor and 12 were BPE features from the background parenchymal regions (excluding the tumor). Support vector machine (SVM) based statistical learning classifiers were trained and optimized using different combinations of features that were computed either from tumor only or from both tumor and BPE. Each SVM was tested using a leave-one-case-out validation method and assessed using an area under the receiver operating characteristic curve (AUC).

RESULTS

When using kinetic features computed from tumors only, the maximum AUC is 0.865 ± 0.035. After fusing with the BPE features, AUC increased to 0.919 ± 0.029. At 90% specificity, the tumor classification sensitivity increased by 13.2%.

CONCLUSIONS

The proposed quantitative BPE features provide valuable supplementary information to the kinetic features of breast tumors in DCE-MRI. Their addition to computer-aided diagnosis methodologies could improve breast cancer diagnosis based on DCE-MRI examinations.

Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends.

Breast magnetic resonance imaging: management of an enhancing focus

An enhancing focus is a commonly encountered type of lesion on breast magnetic resonance (MR) imaging. No set criteria for appropriate management are available. Often management of these lesions depends on the interpreting radiologist, with varying recommendations for biopsy, short-term follow-up, or routine surveillance. This article reviews published studies in order to develop a strategy for the management of enhancing foci identified on breast MR imaging.

Review of electromagnetic techniques for breast cancer detection

Breast cancer is anticipated to be responsible for almost 40,000 deaths in the USA in 2011. The current clinical detection techniques suffer from limitations which motivated researchers to investigate alternative modalities for the early detection of breast cancer. This paper focuses on reviewing the main electromagnetic techniques for breast cancer detection. More specifically, this work reviews the cutting edge research in microwave imaging, electrical impedance tomography, diffuse optical tomography, microwave radiometry, biomagnetic detection, biopotential detection, and magnetic resonance imaging (MRI). The goal of this paper is to provide biomedical researchers with an in-depth review that includes all main electromagnetic techniques in the literature and the latest progress in each of these techniques.

Diagnostic value of breast proton magnetic resonance spectroscopy at 1.5T in different histopathological types

The purpose of this study was to investigate the usefulness of quantitative proton magnetic resonance spectroscopy (¹H-MRS) for characterizing breast lesions at 1.5T, and to evaluate the diagnostic performance of in vivo breast ¹H-MRS using receiver operating characteristics (ROC) analysis. 112 patients (99 malignant and 13 benign tumors) who were scanned with the MRI/MRS protocol were included in this study. Choline-containing compounds (tCho) levels were measured and compared with histological findings. The measured tCho levels in this work had range of 0.08–9.99 mmol/kg from 65 (66%) of 99 patients with malignant tumors. Of the 13 benign lesions, ¹H-MRS detected one as false positive, with tCho level of 0.66 mmol/kg. The optimal tCho level cutoff point that yielded the highest accuracy was found to be >0.0 mmol/kg. The resulting sensitivity was 66% and specificity 92% for distinguishing benign from malignant lesions. The tCho levels were found to be higher in invasive cancer compared to ductal carcinoma in situ or benign lesions, possibly associated with more aggressive behavior or faster cell replication in invasive cancer. Quantitative in vivo   ¹H-MRS may provide useful information for characterizing histopatholoigical types in breast cancer.

The added value of quantitative multi-voxel MR spectroscopy in breast magnetic resonance imaging

Objective

To determine whether quantitative multivoxel MRS improves the accuracy of MRI in the assessment of breast lesions.

Methods

Twenty-five consecutive patients with 26 breast lesions ≥1 cm assessed as BI-RADS 3 or 4 with mammography underwent quantitative multivoxel MRS and contrast-enhanced MRI. The choline (Cho) concentration was calculated using the unsuppressed water signal as a concentration reference. ROC analysis established the diagnostic accuracy of MRI and MRS in the assessment of breast lesions.

Results

Respective Cho concentrations in 26 breast lesions re-classified by MRI as BI-RADS 2 (n = 5), 3 (n = 8), 4 (n = 5) and 5 (n = 8) were 1.16 ± 0.43 (mean ± SD), 1.43 ± 0.47, 2.98 ± 2.15 and 4.94 ± 3.10 mM. Two BI-RADS 3 lesions and all BI-RADS 4 and 5 lesions were malignant on histopathology and had Cho concentrations between 1.7 and 11.8 mM (4.03 ± 2.72 SD), which were significantly higher (P = 0.01) than that in the 11 benign lesions (0.4–1.5 mM; 1.19 ± 0.33 SD). Furthermore, Cho concentrations in the benign and malignant breast lesions in BI-RADS 3 category differed (P = 0.01). The accuracy of combined multivoxel MRS/breast MRI BI-RADS re-classification (AUC = 1.00) exceeded that of MRI alone (AUC = 0.96 ± 0.03).

Conclusions

These preliminary data indicate that multivoxel MRS improves the accuracy of MRI when using a Cho concentration cut-off ≤1.5 mM for benign lesions.

Key Points

• Quantitative multivoxel MR spectroscopy can improve the accuracy of contrast-enhanced breast MRI.

• Multivoxel-MRS can differentiate breast lesions by using the highest Cho-concentration.

• Multivoxel-MRS can exclude patients with benign breast lesions from further invasive diagnostic procedures.

Optimal timing of breast MRI examinations for premenopausal women who do not have a normal menstrual cycle

OBJECTIVE

The objective of this article is to describe a method for timing breast MRI examinations corresponding to the follicular phase of the menstrual cycle in premenopausal women without cyclical menses, thereby reducing the number of false-positive findings and nondiagnostic examinations.

CONCLUSION

Serum progesterone concentrations corresponding to the follicular phase of a normal menstrual cycle can aid in optimal scheduling of breast MRI examinations for premenopausal women who lack cyclical menses.

[Breast MRI--histologic correlation for ductal carcinoma in situ]

OBJECTIVE

To evaluate the concordance between the breast MRI findings and the histologic findings for the size and extension of pure ductal carcinoma in situ (DCIS) and to compare this concordance with that of conventional techniques (mammography and ultrasonography).

MATERIAL AND METHODS

This is a retrospective study of consecutive patients diagnosed with DCIS after percutaneous biopsy. We estimated Lin's coefficient of concordance for the histologic findings with each of the three techniques. We also assessed concordance using Bland-Altman graphs. Finally, we determined the impact of the MRI findings on the surgical management of patients with DCIS.

RESULTS

A total of 32 patients were included in the study. Concordance between imaging and histology on tumor size was higher for MRI (0.78; 95%CI, 0.62-0.87) than for mammography (0.43; 95%CI, 0.19-0.62) or for ultrasonography (0.27; 95%CI, 0.09-0.43). MRI overestimated the size of DCIS by a mean of 3 mm, whereas mammography and ultrasonography underestimated it by 9 mm and 18 mm, respectively. MRI detected multifocality and multicentricity (7 cases) better than mammography (3) or ultrasonography (0). The MRI findings correctly changed the surgical management in six patients.

CONCLUSION

Breast MRI is better than conventional techniques for the evaluation of the size of DCIS. Breast MRI also detects more cases of multifocality and multicentricity. We recommend that all patients diagnosed with DCIS (especially those with dense breasts) undergo breast MRI prior to surgery.

Significance of breast lesion descriptors in the ACR BI-RADS MRI lexicon

In recent years, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has altered the clinical management for women with breast cancer. In March 2007, the American Cancer Society (ACS) issued a new guideline recommending annual MRI screening for high-risk women. This guideline is expected to substantially increase the number of women each year who receive breast MRI. The diagnosis of breast MRI involves the description of morphological and enhancement kinetics features. To standardize the communication language, the Breast Imaging Reporting and Data System (BI-RADS) MRI lexicon was developed by the American College of Radiology (ACR). In this article, the authors will review various appearances of breast lesions on MRI by using the standardized terms of the ACR BI-RADS MRI lexicon. The purpose is to familiarize all medical professionals with the breast MRI lexicon because the use of this imaging modality is rapidly growing in the field of breast disease. By using this common language, a comprehensive analysis of both morphological and kinetic features used in image interpretation will help radiologists and other clinicians to communicate more clearly and consistently. This may, in turn, help physicians and patients to jointly select an appropriate management protocol for each patient's clinical situation.

Characterization of breast lesions with CE-MR multimodal morphological and kinetic analysis: comparison with conventional mammography and high-resolution ultrasound

OBJECTIVE

Evaluation of the diagnostic value of magnetic resonance mammography and comparison with conventional mammography and ultrasonography in cases of women with suspicious breast lesions.

SUBJECTS AND METHODS

Sixty-nine women (age range 39-68 years) with 78 focal breast lesions were examined with mammography, ultrasonography and dynamic magnetic resonance mammography. The lesions were classified according to the Breast Imaging Reporting and Data System (BI-RADS) lexicon of the American College of Radiology for each diagnostic method. Histological reports were available after biopsy or surgical excision of the lesions.

RESULTS

Pathological examination confirmed that 53 lesions were malignant and 25 benign. Conventional mammography estimated a total of 59/78 lesions as malignant with 44 true positive lesions, ultrasonography estimated a total of 50/78 lesions as malignant with 44 true positive lesions and magnetic resonance mammography estimated a total of 66/78 lesions as malignant with 52 true positive lesions. Sensitivity and specificity of magnetic resonance mammography in the diagnosis of malignancy was 98.1% and 44%, of conventional mammography 83% and 40% and of ultrasonography 83% and 76%. Negative predictive value for magnetic resonance mammography was 91.7%, for ultrasonography 67.9% and for mammography 52.6% for malignancies.

CONCLUSION

Magnetic resonance mammography has the highest negative predictive value compared with mammography and ultrasound in cases of suspicious breast lesions. The combination of morphologic and enhancement criteria can improve the diagnostic capability of magnetic resonance mammography (MRM) in breast lesion characterization.

The role of diffusion-weighted imaging and the apparent diffusion coefficient (ADC) values for breast tumors

Objective

We wanted to evaluate the role of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) for detecting breast tumors, as compared with the T1- and T2-weighted images.

Materials and Methods

Forty-one female patients underwent breast MRI, and this included the T1-, T2-, DWI and dynamic contrast-enhanced images. Sixty-five enhancing lesions were detected on the dynamic contrast-enhanced images and we used this as a reference image for detecting tumor. Fifty-six breast lesions were detected on DWI and the histological diagnoses were as follows: 43 invasive ductal carcinomas, one mucinous carcinoma, one mixed infiltrative and mucinous carcinoma, seven ductal carcinomas in situ (DCIS), and four benign tumors. First, we compared the detectability of breast lesions on DWI with that of the T1- and T2-weighted images. We then compared the ADCs of the malignant and benign breast lesions to the ADCs of the normal fibroglandular tissue.

Results

Fifty-six lesions were detected via DWI (detectability of 86.2%). The detectabilities of breast lesions on the T1- and T2-weighted imaging were 61.5% (40/65) and 75.4% (49/65), respectively. The mean ADCs of the invasive ductal carcinoma (0.89 ± 0.18 × 10^-3mm²/second) and DCIS (1.17 ± 0.18 × 10^-3mm²/second) are significantly lower than those of the benign lesions (1.41 ± 0.56 × 10^-3mm²/second) and the normal fibroglandular tissue (1.51 ± 0.29 × 10^-3mm²/second).

Conclusion

DWI has a high sensitivity for detecting breast tumors, and especially for detecting malignant breast tumors. DWI was an effective imaging technique for detecting breast lesions, as compared to using the T1- and T2-weighted images.

MRI-directed, wire-localized breast excisions: incidence of malignancy and recommendations for pathologic evaluation

Magnetic resonance imaging (MRI) has an evolving role in the evaluation of breast lesions and is currently being used for the screening of high-risk patients (eg, women with a personal or family history of breast cancer), for the evaluation of extent of disease in patients with a current diagnosis of cancer, and for patients with suspicious, but indeterminate, findings by other imaging modalities. If a suspicious lesion detected by MRI is not well visualized by another method, an MRI-directed core biopsy or breast excision may be performed. MRI cannot be used to verify the lesion in the specimen because MRI lesion detection is dependent on uptake of gadolinium after intravenous injection. Accordingly, these breast excisions present unique challenges to pathologists. The purpose of this report is to define the surgical pathology issues involved in processing MRI-localized excisions. Retrospective review of 85 consecutive MRI-directed breast excisions from 77 patients was performed. Malignant lesions were present in 20 (24%) of 85 excisions, including 10 cases of invasive carcinoma (median size, 0.4 cm), 9 cases of ductal carcinoma in situ, and 1 case of lymphoma. Most of the malignancies (85% or 17/20) had no associated gross finding and only 5 (25%) of 20 of these malignancies were associated with a definite finding on the specimen radiograph. This study demonstrates that gross examination and specimen radiography do not identify most of the malignancies in MRI-localized biopsies and, therefore, optimal processing requires complete microscopic examination of these specimens.

Cancer yield of probably benign breast MR examinations

PURPOSE

To evaluate the cancer yield, frequency of use, and follow-up compliance of breast MR examinations assessed as "probably benign."

MATERIALS AND METHODS

We retrospectively reviewed our MR database of 809 consecutive examinations between January 2003 and June 2004. We identified all examinations that ultimately received an MR breast imaging reporting and data system (BI-RADS) 3 assessment and recommendation for a short-interval follow-up MR with or without an antecedent targeted ultrasound. The clinical indication for breast MR, date of the follow-up examination, follow-up assessment, and any pathology findings through June 2005 were collected from clinical records and radiology and pathology reports. Frequency of BI-RADS 3 use, follow-up compliance, and cancer yield were calculated.

RESULTS

A total of 160 out of 809 (20%) examinations comprise the study population. A total of 100 out of 160 (63%) women returned for the recommended follow-up MR, in which three out of 100 (3%) were upgraded to BI-RADS 4 with biopsy recommended. One patient underwent biopsy and the result was benign. A total of seven out of 160 (4%) underwent mastectomy in lieu of MR for known cancer elsewhere in the breast. One out of seven mastectomy specimens contained malignancy that corresponded to the probably benign finding, resulting in a cancer yield of one out of 160 (0.6%).

CONCLUSION

Our data suggest that follow-up MR is a valid alternative to biopsy for MR BI-RADS 3 lesions.

Breast imaging and reporting data system (BIRADS): magnetic resonance imaging

This article reviews the technical aspects and interpretation criteria in breast MR imaging based on the first edition of breast imaging and reporting data system (BIRADS) published by the American College of Radiology (ACR) in 2003. In a second article, practical cases will be proposed for training the readers. The major aims of using this lexicon are: first to use a logical and standardized description of MR lesions, secondly to obtain a structured MR report with a clear final impression (BIRADS assessment categories), and thirdly to help comparison between different clinical studies based on similar breast MRI terminology.

The diagnostic impact of contrast-enhanced MRI in management of breast disease

For effective use, the diagnostic impact of contrast-enhanced breast MRI (CE MRI) needs to be quantified. This is a retrospective study of 441 women who have undergone CE MRI of the breast from 1 July 1997 to 25 March 2002. Indications for CE MRI studies were diagnostic in 176, monitoring chemotherapy in 126 and study of MRI screening for breast cancer (MARIBS) cases in 139. CE MRI results were confusing or incorrect in 6% of the diagnostic group, 13% of the chemotherapy group and 9% of the MARIBS group. In 18 of 38 of these cases CE MRI stimulated further tests to clarify a clinical query. CE MRI resulted in an increase in confidence or change in clinical plan in 46% of the diagnostic group, 72% of the chemotherapy group and 80% of the MARIBS group. In 44 of 283 of these, CE MRI caused a beneficial change in the clinical plan based on conventional radiology. CE MRI results in a positive diagnostic impact above conventional imaging in a clinically important proportion of patients, but gives some false calls in a smaller proportion (8.6%).

Breast MR Imaging Lexicon Updated

The American College of Radiology Breast Imaging and Reporting Data System MR imaging lexicon incorporates morphologic and kinetic features of lesions identified on breast MR imaging. This brief article is aimed at introducing this material and should not be used as a definitive guide. Because the breast MR imaging lexicon is a work in progress, there are many areas that need exploring and better characterization. It is hoped that the radiologist uses the terms and concepts presented here as a template to which future lexicon terminology can be added.

Promising techniques for breast cancer detection, diagnosis, and staging using non-ionizing radiation imaging techniques

Traditional imaging for the diagnosis and staging of breast cancer has relied on the tissue morphology of cancers in the background of normal patterns of fibroglandular breast tissue. X-ray mammography and ultrasound have been the primary modalities for the diagnosis and the work-up of breast cancer. New modalities have been validated including magnetic resonance imaging (MRI) and positron emission tomography (PET). New pulse sequences in MRI combined with contrast enhancement kinetic perfusion curves have greatly enhanced detection of mammographically occult cancers. New modalities on the horizon include optical imaging, exploiting again the differential perfusion properties of cancers in a background of normal glandular tissue. Even more specificity can be ach eved with the addition of ductal or intravenous introduction of optical probes specific to tumor associated antigens such as the HER-2/neu receptor in aggressive breast cancers. Quantum dots and other fluorescent dyes coupled to peptides or other probes will greatly enhance our ability to detect cancers earlier and without ionizing radiation.

[Breast MRI in invasive lobular carcinoma: diagnosis and staging]

PURPOSE

To assess the use of breast MRI for the diagnosis and staging of invasive lobular carcinoma and its impact on surgical management.

MATERIALS AND METHODS

Retrospective study of 35 invasive lobular carcinoma, histologically diagnosed in 34 patients who underwent clinical exam, mammography, ultrasonography and magnetic resonance imaging.

RESULTS

Enhancement at MRI was seen for all 35 cancers. It was focal for 24 patients, regional for 10 and diffuse for 1. The kinetic of the enhancement was characteristic of malignancy for 33 patients. For 11 patients the MRI staging was positive, finding 8 news cancers. For 3 patients MRI lead to biopsy of benign lesions but improved the surgical management in the 8 cases of new cancers: wider excision for 3 cases, planned breast conservation converted to mastectomy in 3 cases and excision of contralateral lesion in 2 cases.

CONCLUSION

Breast MRI is useful in diagnosis, staging and surgical management of invasive lobular breast carcinoma.

Rates of reexcision for breast cancer after magnetic resonance imaging-guided bracket wire localization

BACKGROUND

We performed this study to determine rates of close or transected cancer margins after magnetic resonance imaging-guided bracket wire localization for nonpalpable breast lesions.

STUDY DESIGN

Of 243 women undergoing MRI-guided wire localizations, 26 had MRI bracket wire localization to excise either a known cancer (n = 19) or a suspicious MRI-detected lesion (n = 7). We reviewed patient age, preoperative diagnosis, operative intent, mammographic breast density, MRI lesion size, MRI enhancement curve and morphology, MRI Breast Imaging Reporting and Data System (BI-RADS) assessment code, number of bracket wires, and pathology size. We analyzed these findings for their relationship to obtaining clear margins at first operative excision.

RESULTS

Twenty-one of 26 (81%) patients had cancer. Of 21 patients with cancer, 12 (57%) had negative margins at first excision and 9 (43%) had close/transected margins. MRI size > or = 4 cm was associated with a higher reexcision rate (7 of 9, 78%) than those < 4 cm (2 of 12, 17%) (p = 0.009). MRI BI-RADS score, enhancement curve, morphology, and preoperative core biopsy demonstrating ductal carcinoma in situ (DCIS) were not predictive of reexcision. The average number of wires used for bracketing increased with lesion size, but was not associated with improved outcomes. On pathology, cancer size was smaller in patients with negative margins (12 patients, 1.2 cm) than in those with close/transected margins (9 patients, 4.6 cm) (p < 0.001). Reexcision was based on close/transected margins involving DCIS alone (6, 67%), infiltrating ductal carcinoma and DCIS (2, 22%), or infiltrating ductal carcinoma alone (1, 11%). Reexcision pathology demonstrated DCIS (3, 33%), no residual cancer (5, 55%), and 1 patient was lost to followup (1, 11%). Interestingly, cancer patients who required reexcision were younger (p = 0.022), but breast density was not associated with reexcision.

CONCLUSIONS

To our knowledge, this is the first report of MRI-guided bracket wire localization. Patients with MRI-detected lesions less than 4 cm had clear margins at first excision; larger MRI-detected lesions were more likely to have close/transected margins. Reexcision was often because of DCIS and was the only pathology found at reexcision, perhaps because MRI is more sensitive for detecting invasive carcinoma than DCIS.

Frequency of malignancy in lesions classified as probably benign after dynamic contrast-enhanced breast MRI examination

PURPOSE

To determine the chance of malignancy in lesions classified as "probably benign" by dynamic magnetic resonance imaging (MRI), in a heterogeneous population.

MATERIALS AND METHODS

Reports from 473 patients, from March 1994 to March 2002, who underwent breast MRI were retrospectively reviewed. A total of 79 patients (17%) had lesions classified as probably benign after the MRI, which required further imaging follow-up. We evaluated subsequent MRI, mammographic reports, and clinical follow-up in these patients and established the frequency of malignancy in this group.

RESULTS

MRI classified probably benign lesion were diagnosed in 79 women because of focal or diffuse mild enhancement and benign dynamic enhancement curves in the area of the mammographic abnormality, or because of the presence of microcalcifications on the mammogram, or because of incidental enhancing lesions. Two-year radiographic and/or clinical follow-up was available in 68 women. On follow-up, four women (6%) were diagnosed with cancer between 14 and 18 months after the initial MRI.

CONCLUSION

Patients with a lesion assessed as probably benign by dynamic contrast enhanced MRI have a higher chance of malignancy than patients with probably benign lesions (Breast Imaging Reporting and Data System category 3, BI-RADS 3) seen on mammography. These patients should be informed of the increased risk of cancer and be given the option of biopsy or close follow-up.

Diagnostic accuracy of mammography, clinical examination, US, and MR imaging in preoperative assessment of breast cancer

PURPOSE

To prospectively assess accuracy of mammography, clinical examination, ultrasonography (US), and magnetic resonance (MR) imaging in preoperative assessment of local extent of breast cancer.

MATERIALS AND METHODS

Institutional review board approval and informed patient consent were obtained. Results of bilateral mammography, US, and contrast-enhanced MR imaging were analyzed from 111 consecutive women with known or suspected invasive breast cancer. Results were correlated with histopathologic findings.

RESULTS

Analysis included 177 malignant foci in 121 cancerous breasts, of which 89 (50%) foci were palpable. Median size of 139 invasive foci was 18 mm (range, 2-107 mm). Mammographic sensitivity decreased from 100% in fatty breasts to 45% in extremely dense breasts. Mammographic sensitivity was highest for invasive ductal carcinoma (IDC) in 89 of 110 (81%) cases versus 10 of 29 (34%) cases of invasive lobular carcinoma (ILC) (P < .001) and 21 of 38 (55%) cases of ductal carcinoma in situ (DCIS) (P < .01). US showed higher sensitivity than did mammography for IDC, depicting 104 of 110 (94%) cases, and for ILC, depicting 25 of 29 (86%) cases (P < .01 for each). US showed higher sensitivity for invasive cancer than DCIS (18 of 38 [47%], P < .001). MR showed higher sensitivity than did mammography for all tumor types (P < .01) and higher sensitivity than did US for DCIS (P < .001), depicting 105 of 110 (95%) cases of IDC, 28 of 29 (96%) cases of ILC, and 34 of 38 (89%) cases of DCIS. In anticipation of conservation or no surgery after mammography and clinical examination in 96 breasts, additional tumor (which altered surgical approach) was present in 30. Additional tumor was depicted in 17 of 96 (18%) breasts at US and in 29 of 96 (30%) at MR, though extent was now overestimated in 12 of 96 (12%) at US and 20 of 96 (21%) at MR imaging. After combined mammography, clinical examination, and US, MR depicted additional tumor in another 12 of 96 (12%) breasts and led to overestimation of extent in another six (6%); US showed no detection benefit after MR imaging. Bilateral cancer was present in 10 of 111 (9%) patients; contralateral tumor was depicted mammographically in six and with both US and MR in an additional three. One contralateral cancer was demonstrated only clinically.

CONCLUSION

In nonfatty breasts, US and MR imaging were more sensitive than mammography for invasive cancer, but both MR imaging and US involved risk of overestimation of tumor extent. Combined mammography, clinical examination, and MR imaging were more sensitive than any other individual test or combination of tests.

Contrast-enhanced MR imaging of breast lesions and effect on treatment

PURPOSE

To assess the value of local staging with preoperative magnetic resonance imaging (MRI) in patients with suspect breast lesions and the effect on therapeutic approach.

MATERIALS AND METHODS

Two hundred and four consecutive women with suspect breast lesions on clinical examination (CE) and/or mammography (MX) and/or ultrasound (US) underwent preoperative contrast-enhanced MRI. Detection of multifocal, multicentric and bilateral breast cancer by all three imaging modalities was evaluated. Results of preoperative breast MRI were discussed with the treating surgeons. The type of therapeutic change after preoperative MRI was marked on a questionnaire (none, additional fine needle aspiration, core biopsy, open biopsy, wider excision, mastectomy) and considered 'necessary' or 'unnecessary' using final histopathological results as gold standard.

RESULTS

In 170 patients, breast cancer was diagnosed. MRI detected 96% of multifocal disease and 95% of multicentric disease, whereas MX depicted 37 and 18%, and US 41 and 9% of them, respectively. All bilateral breast cancers were seen on MRI; both MX and US detected 56%. Findings of more extensive disease and unsuspected multiple breast cancer foci identified on MRI only, changed the therapeutic approach correctly in 30.6% of breast cancer patients. Nine unnecessary wider excisions and three unnecessary FNA/core biopsies were performed because MRI overestimated the number or size of malignant lesions.

CONCLUSION

Preoperative breast MRI is an important adjunct to conventional imaging in the loco-regional staging of breast cancer and a useful tool in treatment planning.

Correlation of dynamic contrast enhancement MRI parameters with microvessel density and VEGF for assessment of angiogenesis in breast cancer

PURPOSE

To investigate the association between parameters obtained from dynamic contrast enhanced MRI (DCE-MRI) of breast cancer using different analysis approaches, as well as their correlation with angiogenesis biomarkers (vascular endothelial growth factor and vessel density).

MATERIALS AND METHODS

DCE-MRI results were obtained from 105 patients with breast cancer (108 lesions). Three analysis methods were applied: 1) whole tumor analysis, 2) regional hot-spot analysis, and 3) intratumor pixel-by-pixel analysis. Early enhancement intensities and fitted pharmacokinetic parameters were studied. Paraffin blocks of 71 surgically resected specimens were analyzed by immunohistochemical staining to measure microvessel counts (with CD31) and vascular endothelial growth factor (VEGF) expression levels.

RESULTS

MRI parameters obtained from the three analysis methods showed significant correlations (P < 0.0001), but a substantial dispersion from the linear regression line was noted (r = 0.72-0.97). The entire region of interest (ROI) vs. pixel population analyses had a significantly higher association compared to the entire ROI vs. hot-spot analyses. Cancer specimens with high VEGF expression had significantly higher CD31 microvessel densities than did specimens with low VEGF levels (P < 0.005). No significant association was found between MRI parameters obtained from the three analysis strategies and IHC based measurements of angiogenesis.

CONCLUSION

A consistent analysis strategy was important in the DCE-MRI study. In this series, none of these strategies yielded results for MRI based quantitation of tumor vascularity that were associated with IHC based measurements. Therefore, different analyses could not account for the lack of association.

Counseling the at risk patient in the BRCA1 and BRCA2 Era

The 5-year experience since the identification of the BRCA1 and BRCA2 genes has shown that genetic evaluation and testing can increase understanding of cancer risks for individuals with a personal or family history of early onset breast cancer and ovarian cancer. However, testing needs to be undertaken in a clinical setting where pretest counseling, including likelihood of identifying a mutation and risks and benefits of the process are provided. Identifying women who carry mutations in either BRCA1 or BRCA2 has implications for prevention, screening and treatment of these cancers.

Breast cancer imaging with MRI

Breast MRI is an emerging technology that may revolutionize our management of women with known or suspected breast cancer. MRI examinations should be interpreted with an awareness of the pitfalls and artifacts that can affect on image evaluation. Development of an MRI lexicon will assist by providing standardized terminology that may improve our understanding of the positive predictive value of different MRI features. To date, breast MRI has proven most useful in patients with proven breast cancer to assess for multifocal/multicentric disease, chest wall involvement, chemotherapy response, or tumor recurrence or to identify the primary site in patients with occult breast cancer. Further work is necessary to assess the utility of breast MRI in other settings, such as screening of women at high risk for breast cancer.

Observer variability and applicability of BI-RADS terminology for breast MR imaging: invasive carcinomas as focal masses

OBJECTIVE

The purpose of this study was to assess whether the descriptive terminology and final assessment categories of the Breast Imaging Reporting and Data System (BI-RADS) lexicon can be used for breast carcinomas detected on MR imaging and to assess the inter- and intraobserver variabilities in the use of the descriptors and final assessment categories.

MATERIALS AND METHODS

In 82 patients, 101 masses, including 68 infiltrating carcinomas and 33 benign lesions, were interpreted independently by four radiologists and described by BI-RADS terminology with respect to mass shape and margin and BI-RADS final assessment categories. The enhancement pattern of the mass was also reported. In addition, two radiologists interpreted each case twice to evaluate intraobserver variability. The final case set for analysis was the 68 infiltrating carcinomas.

RESULTS

Most of the infiltrating carcinomas were described as irregular, spiculated, and heterogeneously enhancing masses. The final impression of the 68 carcinomas was BI-RADS category 5 (highly suggestive of malignancy) in 41 (61%), category 4 (suspicious abnormality) in 24 (35%), and category 3 (probably benign) in three (4%). Enhancement pattern was heterogeneous in 40 (59%), homogeneous in 14 (21%), and rim in 14 (21%). Interobserver agreement was moderate for mass margin, shape, enhancement, and final assessment category.

CONCLUSION

This study suggests that the mammographic BI-RADS lexicon with some modifications may be applied to describe the features of infiltrating carcinoma seen on breast MR imaging.

Illustrated breast MR lexicon

A group of international breast MRI experts is currently working on a definitive lexicon for breast MRI that will incorporate both morphologic and kinetic features of lesions identified on breast MRI. The work to develop the lexicon is supported currently by the American College of Radiology (ACR). This article is aimed at introducing this material and should not be used as a definitive guide as the breast MRI lexicon is a work in progress. It is hoped that radiologists will use the terms and concepts presented here as a template to which future lexicon terminology can be added.