MR Imaging for Surveillance of Women at High Familial Risk for Breast Cancer

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.

On a fractional order calculus model in diffusion weighted breast imaging to differentiate between malignant and benign breast lesions detected on X-ray screening mammography

OBJECTIVE

To evaluate a fractional order calculus (FROC) model in diffusion weighted imaging to differentiate between malignant and benign breast lesions in breast cancer screening work-up using recently introduced parameters (βFROC, DFROC and μFROC).

MATERIALS AND METHODS

This retrospective analysis within a prospective IRB-approved study included 51 participants (mean 58.4 years) after written informed consent. All patients had suspicious screening mammograms and indication for biopsy. Prior to biopsy, full diagnostic contrast-enhanced MRI examination was acquired including diffusion-weighted-imaging (DWI, b = 0,100,750,1500 s/mm2). Conventional apparent diffusion coefficient Dapp and FROC parameters (βFROC, DFROC and μFROC) as suggested further indicators of diffusivity components were measured in benign and malignant lesions. Receiver operating characteristics (ROC) were calculated to evaluate the diagnostic performance of the parameters.

RESULTS

29/51 patients histopathologically revealed malignant lesions. The analysis revealed an AUC for Dapp of 0.89 (95% CI 0.80-0.98). For FROC derived parameters, AUC was 0.75 (0.60-0.89) for DFROC, 0.59 (0.43-0.75) for βFROC and 0.59 (0.42-0.77) for μFROC. Comparison of the AUC curves revealed a significantly higher AUC of Dapp compared to the FROC parameters DFROC (p = 0.009), βFROC (p = 0.003) and μFROC (p = 0.001).

CONCLUSION

In contrast to recent description in brain tumors, the apparent diffusion coefficient Dapp showed a significantly higher AUC than the recently proposed FROC parameters βFROC, DFROC and μFROC for differentiating between malignant and benign breast lesions. This might be related to the intrinsic high heterogeneity within breast tissue or to the lower maximal b-value used in our study.

The Changing World of Breast Cancer: A Radiologist's Perspective

Compared with other fields of medicine, there is hardly an area that has seen such fast development as the world of breast cancer. Indeed, the way we treat breast cancer has changed fundamentally over the past decades. Breast imaging has always been an integral part of this change, and it undergoes constant adjustment to new ways of thinking. This relates not only to the technical tools we use for diagnosing breast cancer but also to the way diagnostic information is used to guide treatment. There is a constant change of concepts for and attitudes toward breast cancer, and a constant flux of new ideas, new treatment approaches, and new insights into the molecular and biological behavior of this disease. Clinical breast radiologists and even more so, clinician scientists, interested in breast imaging need to keep abreast with this rapidly changing world. Diagnostic or treatment approaches that are considered useful today may be abandoned tomorrow. Approaches that seem irrelevant or far too extravagant today may prove clinically useful and adequate next year. Radiologists must constantly question what they do, and align their clinical aims and research objectives with the changing needs of contemporary breast oncology. Moreover, knowledge about the past helps better understand present debates and controversies. Accordingly, in this article, we provide an overview on the evolution of breast imaging and breast cancer treatment, describe current areas of research, and offer an outlook regarding the years to come.

Independent value of image fusion in unenhanced breast MRI using diffusion-weighted and morphological T2-weighted images for lesion characterization in patients with recently detected BI-RADS 4/5 x-ray mammography findings

OBJECTIVES

The aim of this study was to evaluate the accuracy and applicability of solitarily reading fused image series of T2-weighted and high-b-value diffusion-weighted sequences for lesion characterization as compared to sequential or combined image analysis of these unenhanced sequences and to contrast- enhanced breast MRI.

METHODS

This IRB-approved study included 50 female participants with suspicious breast lesions detected in screening X-ray mammograms, all of which provided written informed consent. Prior to biopsy, all women underwent MRI including diffusion-weighted imaging (DWIBS, b = 1500s/mm²). Images were analyzed as follows: prospective image fusion of DWIBS and T2-weighted images (FU), side-by-side analysis of DWIBS and T2-weighted series (CO), combination of the first two methods (CO+FU), and full contrast-enhanced diagnostic protocol (FDP). Diagnostic indices, confidence, and image quality of the protocols were compared by two blinded readers.

RESULTS

Reading the CO+FU (accuracy 0.92; NPV 96.1 %; PPV 87.6 %) and the CO series (0.90; 96.1 %; 83.7 %) provided a diagnostic performance similar to the FDP (0.95; 96.1 %; 91.3 %; p > 0.05). FU reading alone significantly reduced the diagnostic accuracy (0.82; 93.3 %; 73.4 %; p = 0.023).

CONCLUSIONS

MR evaluation of suspicious BI-RADS 4 and 5 lesions detected on mammography by using a non-contrast-enhanced T2-weighted and DWIBS sequence protocol is most accurate if MR images were read using the CO+FU protocol.

KEY POINTS

• Unenhanced breast MRI with additional DWIBS/T2w-image fusion allows reliable lesion characterization. • Abbreviated reading of fused DWIBS/T2w-images alone decreases diagnostic confidence and accuracy. • Reading fused DWIBS/T2w-images as the sole diagnostic method should be avoided.

The Changing World of Breast Cancer: A Radiologist's Perspective

Compared with other fields of medicine, there is hardly an area that has seen such fast development as the world of breast cancer. Indeed, the way we treat breast cancer has changed fundamentally over the past decades. Breast imaging has always been an integral part of this change, and it undergoes constant adjustment to new ways of thinking. This relates not only to the technical tools we use for diagnosing breast cancer but also to the way diagnostic information is used to guide treatment. There is a constant change of concepts for and attitudes toward breast cancer, and a constant flux of new ideas, new treatment approaches, and new insights into the molecular and biological behavior of this disease. Clinical breast radiologists and even more so, clinician scientists, interested in breast imaging need to keep abreast with this rapidly changing world. Diagnostic or treatment approaches that are considered useful today may be abandoned tomorrow. Approaches that seem irrelevant or far too extravagant today may prove clinically useful and adequate next year. Radiologists must constantly question what they do, and align their clinical aims and research objectives with the changing needs of contemporary breast oncology. Moreover, knowledge about the past helps better understand present debates and controversies. Accordingly, in this article, we provide an overview on the evolution of breast imaging and breast cancer treatment, describe current areas of research, and offer an outlook regarding the years to come.

Introduction of an automated user-independent quantitative volumetric magnetic resonance imaging breast density measurement system using the Dixon sequence: comparison with mammographic breast density assessment

OBJECTIVES

The purposes of this study were to introduce and assess an automated user-independent quantitative volumetric (AUQV) breast density (BD) measurement system on the basis of magnetic resonance imaging (MRI) using the Dixon technique as well as to compare it with qualitative and quantitative mammographic (MG) BD measurements.

MATERIALS AND METHODS

Forty-three women with normal mammogram results (Breast Imaging Reporting and Data System 1) were included in this institutional review board-approved prospective study. All participants were subjected to BD assessment with MRI using the following sequence with the Dixon technique (echo time/echo time, 6 milliseconds/2.45 milliseconds/2.67 milliseconds; 1-mm isotropic; 3 minutes 38 seconds). To test the reproducibility, a second MRI after patient repositioning was performed. The AUQV magnetic resonance (MR) BD measurement system automatically calculated percentage (%) BD. The qualitative BD assessment was performed using the American College of Radiology Breast Imaging Reporting and Data System BD categories. Quantitative BD was estimated semiautomatically using the thresholding technique Cumulus4. Appropriate statistical tests were used to assess the agreement between the AUQV MR measurements and to compare them with qualitative and quantitative MG BD estimations.

RESULTS

The AUQV MR BD measurements were successfully performed in all 43 women. There was a nearly perfect agreement of AUQV MR BD measurements between the 2 MR examinations for % BD (P < 0.001; intraclass correlation coefficient, 0.998) with no significant differences (P = 0.384). The AUQV MR BD measurements were significantly lower than quantitative and qualitative MG BD assessment (P < 0.001).

CONCLUSIONS

The AUQV MR BD measurement system allows a fully automated, user-independent, robust, reproducible, as well as radiation- and compression-free volumetric quantitative BD assessment through different levels of BD. The AUQV MR BD measurements were significantly lower than the currently used qualitative and quantitative MG-based approaches, implying that the current assessment might overestimate breast density with MG.

Poly Implant Prothèse (PIP) incidence of rupture: a retrospective MR analysis in 64 patients

AIM OF THE STUDY

The purpose of this retrospective study was to describe the magnetic resonance imaging (MRI) features of Poly Implant Prothèse (PIP) hydrogel implants in a group of 64 patients and to assess the incidence of rupture, compared to other clinical trials.

MATERIAL AND METHODS

In this double-center study, we retrospectively reviewed the data sets of 64 consecutive patients (mean age, 43±9 years, age range, 27-65 years), who underwent breast MRI examinations, between January 2008 and October 2013, with suspected implant rupture on the basis of clinical assessment or after conventional imaging examination (either mammography or ultrasound). All patients had undergone breast operation with bilateral textured cohesive gel PIP implant insertion for aesthetic reasons. The mean time after operation was 8 years (range, 6-14 years). No patients reported history of direct trauma to their implants.

RESULTS

At the time of clinical examination, 41 patients were asymptomatic, 16 complained of breast tenderness and 7 had clinical evidence of rupture. Normal findings were observed in 15 patients. In 26 patients there were signs of mild collapse, with associated not significant peri-capsular fluid collections and no evidence of implant rupture; in 23 patients there was suggestion of implant rupture, according to breast MRI leading to an indication for surgery. In particular, 14 patients showed intra-capsular rupture, with associated evidence of the linguine sign in all cases; the keyhole sign and the droplet signs were observed in 6 cases. In 9 patients there was evidence of extra-capsular rupture, with presence of axillary collections (siliconomas) in 7 cases and peri-prosthetic and mediastinal cavity siliconomas, in 5 cases.

CONCLUSIONS

The results of this double center retrospective study, confirm the higher incidence (36%) of prosthesis rupture observed with the PIP implants, compared to other breast implants.

Dynamic contrast-enhanced MRI texture analysis for pretreatment prediction of clinical and pathological response to neoadjuvant chemotherapy in patients with locally advanced breast cancer

The aim of this study was to investigate the potential of texture analysis, applied to dynamic contrast-enhanced MRI (DCE-MRI), to predict the clinical and pathological response to neoadjuvant chemotherapy (NAC) in patients with locally advanced breast cancer (LABC) before NAC is started. Fifty-eight patients with LABC were classified on the basis of their clinical response according to the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines after four cycles of NAC, and according to their pathological response after surgery. T1 -weighted DCE-MRI with a temporal resolution of 1 min was acquired on a 3-T Siemens Trio scanner using a dedicated four-channel breast coil before the onset of treatment. Each lesion was segmented semi-automatically using the 2-min post-contrast subtracted image. Sixteen texture features were obtained at each non-subtracted post-contrast time point using a gray level co-occurrence matrix. Appropriate statistical analyses were performed and false discovery rate-based q values were reported to correct for multiple comparisons. Statistically significant results were found at 1-3 min post-contrast for various texture features for the prediction of both the clinical and pathological response. In particular, eight texture features were found to be statistically significant at 2 min post-contrast, the most significant feature yielding an area under the curve (AUC) of 0.77 for response prediction for stable disease versus complete responders after four cycles of NAC. In addition, four texture features were found to be significant at the same time point, with an AUC of 0.69 for response prediction using the most significant feature for classification based on the pathological response. Our results suggest that texture analysis could provide clinicians with additional information to increase the accuracy of prediction of an individual response before NAC is started.

Let's go out of the breast: prevalence of extra-mammary findings and their characterization on breast MRI

PURPOSE

The aim of this study is to assess the prevalence, the site and the nature of extra-mammary findings on breast magnetic resonance imaging (MRI) and to determine its accuracy in the characterization of the discovered lesions.

MATERIALS AND METHODS

A retrospective review of 308 female patients (mean age 50 ± 20) who underwent breast MRI with 1.5T device was performed. 125 out of 308 (40.5%) had a positive personal history of breast cancer (pre-operative n=80; follow-up n=45), while the remaining 183 without history of breast cancer (high familiar risk for breast cancer n=80; dense breast n=103). All incidental findings were characterized by means of additional imaging (US; Bone scintigraphy-MRI; CT-PET-CT).

RESULTS

59 incidental findings were found in 53/308 (17%) examined patients. 9/59 incidental findings (15%) were confirmed to be malignant while the remaining 50/59 (84%) benign. The most common site was the liver (33/59; 55.8%), followed by the lung (6/59; 10.1%), bone (6/59; 10.1%), diaphragm (6/59; 10.1%) spleen (3/59; 5%), kidney (2/59; 3.4%), gall bladder (1/5; 1.5%), ascending aorta (1/59; 1.5%), thyroid (1/59; 1.5%). The incidence of malignant incidental findings resulted to be higher in the group of patients with personal breast cancer (36%) than in the other one (8%). By comparing MRI findings with the additional definitive imaging tools, breast MRI allowed a correct diagnosis in 58/59 cases with a diagnostic accuracy value of 98%.

CONCLUSION

Incidental extramammary findings on breast MRI are common. Benign lesions represent the most frequent findings, however malignant ones need to be searched especially in patients with personal history of breast cancer because they could influence the clinical patient management. Breast MRI can characterize incidental findings with high accuracy value.

Small masses on breast MR: is biopsy necessary?

RATIONALE AND OBJECTIVES

To evaluate outcome of magnetic resonance (MR)-detected biopsied breast lesions ≤5 mm by correlating imaging characteristics with pathology.

METHODS AND MATERIALS

Institutional review board-approved retrospective review of 565 lesions biopsied with MR guidance between March 2004 and February 2009 found 68 lesions ≤5 mm in 61 patients. Lesions evaluated were those prospectively recommended for biopsy based on clinical setting, suspicious lesion morphology, and kinetics. Two study radiologists, blinded to final pathology, reviewed MR exams recording patient age, exam indication (staging, surveillance, diagnostic, or follow-up), mass location, size, morphology, T2-weighted signal, and kinetics. Chart review provided final pathology.

RESULTS

Of 68 masses ≤5 mm, 14 (20.6%) were malignant. Of 32 <5 mm, 32 (28.1%) were malignant. Of 14 malignancies, 7 (50%) were in patients with recently diagnosed breast cancer, 6 in the same breast, of which 4 (66.7%) were in same quadrant. Higher likelihood of malignancy based on proximity to known cancer was statistically significant (P = .01). No significant difference in proportion of malignancies was found based on age, T2-weighted signal, morphology, or kinetics.

CONCLUSION

For MR-detected biopsied masses, the positive predictive value for malignancy of those ≤5 mm was 20.6%. The highest prevalence of cancers was in the same quadrant as a newly diagnosed breast cancer. The decision to biopsy small masses should be based on carefully assessed MR features, and in the context of exam indication, not solely on size.

[Role of imaging in the diagnostic and therapeutic algorithms of breast cancer]

Early diagnosis and prevention have the most significant effect on overall disease specific outcome; 90% of all breast cancer cases could be cured if diagnosed early and treated accurately. As for all diagnostic methods the most important requirement for diagnostic imaging is to detect breast cancer in its early stage, and to determine accurate tumor staging, in order to select the appropriate therapy. Its role is to monitor the effectiveness of therapy, to follow up patients reliably for early detection of recurrent disease. The spectrum of radiological imaging methods in breast cancer became broader in the past two decades; imaging that provides functional or metabolic data and whole body information such as CT, MRI and PET-CT are now available besides common X-ray and ultrasound mammography. The MRI is getting more and more important for the detection and characterization of breast cancer. Multimodal imaging techniques provide more accurate analysis, which is confirmed by increasing statistics authentically, but none of the imaging methods was specific enough to provide histological diagnosis. However, imaging-guided biopsies enable precise histological or cytological confirmation.

Bilateral prophylactic mastectomy in Swedish women at high risk of breast cancer: a national survey

BACKGROUND/OBJECTIVE

This study attempted a national inventory of all bilateral prophylactic mastectomies performed in Sweden between 1995 and 2005 in high-risk women without a previous breast malignancy. The primary aim was to investigate the breast cancer incidence after surgery. Secondary aims were to describe the preoperative risk assessment, operation techniques, complications, histopathological findings, and regional differences.

METHODS

Geneticists, oncologists and surgeons performing prophylactic breast surgery were asked to identify all women eligible for inclusion in their region. The medical records were reviewed in each region and the data were analyzed centrally. The BOADICEA risk assessment model was used to calculate the number of expected/prevented breast cancers during the follow-up period.

RESULTS

A total of 223 women operated on in 8 hospitals were identified. During a mean follow-up of 6.6 years, no primary breast cancer was observed compared with 12 expected cases. However, 1 woman succumbed 9 years post mastectomy to widespread adenocarcinoma of uncertain origin. Median age at operation was 40 years. A total of 58% were BRCA1/2 mutation carriers. All but 3 women underwent breast reconstruction, 208 with implants and 12 with autologous tissue. Four small, unifocal, invasive cancers and 4 ductal carcinoma in situ were found in the mastectomy specimens. The incidence of nonbreast related complications was low (3%). Implant loss due to infection/necrosis occurred in 21 women (10%) but a majority received a new implant later. In total, 64% of the women underwent at least 1unanticipated secondary operation.

CONCLUSIONS

Bilateral prophylactic mastectomy is safe and efficacious in reducing future breast cancer in asymptomatic women at high risk. Unanticipated reoperations are common. Given the small number of patients centralization seems justified.

Magnetic resonance imaging--guided breast interventions

The use of breast magnetic resonance imaging (MRI) for screening, diagnosis, staging, and management of breast cancer is rapidly increasing. MRI is highly sensitive for the detection of benign and malignant abnormalities that are occult to physical examination, ultrasound, and mammography. However, the specificity of MRI is moderate. These attributes necessitate methods for MR-guided tissue sampling to determine the histology of MRI detected lesions. This article will review appropriate peer-reviewed data and currently accepted methods for MR-guided tissue sampling. A detailed step-by-step technique for vacuum-assisted MR-guided breast biopsy is included. We also review emerging data for percutaneous and transcutaneous MR-guided breast interventions such as tissue ablation for benign and malignant disease.