Breast imaging: basics

High-risk women with a genetic predisposition will develop breast cancer not only more frequently but also at a much younger age than average-risk women. Traditional population-based mammography screening programs aiming primarily at postmenopausal women are therefore not sufficient as surveillance for these women. Contrast-enhanced breast MRI with its high sensitivity independent of breast density has been shown to be the ideal screening tool for young premenopausal high-risk women. Depending on the age and risk constellation of the individual patient, this can be supplemented by mammography and/or tailored second-look ultrasound. To be effective, high-risk multimodality screening should be offered annually starting at age 25 to 30. However, even annual multimodality screening with MRI may not be sufficient in BRCA1-mutation carriers to detect a sufficiently large proportion of cancers in a curable stage, and risk-reducing mastectomy may be considered as a viable alternative in these patients. Whereas age-specific breast cancer incidence is fairly well established for BRCA1/2 mutation carriers, breast cancer risk prediction in high-risk patients without such a mutation is much more difficult, and substantial variations in calculated risk exist between the currently available models. This is of great importance, as accurate breast cancer risk prediction is vital for correctly tailoring the high-risk screening program. If the observed breast cancer incidence in the screened population is too low, the positive predictive value will decline to unacceptable levels and screening will become ineffective.

The nipple-areolar complex lesions deserve particular consideration. They are a group of entities that arise in this specific area. It may be affected by normal variations in embryologic development and breast maturation. Besides, abnormal processes can be found, and benign and malignant pathology can be seen in this region. Eczema, mastitis, abscesses, adenomas, papillomas and duct ectasia should be considered as benign processes. On the opposite, Paget disease, in situ carcinoma, invasive carcinoma and lymphoma should be included as malignant processes. The radiologist should be aware of the clinical manifestations of these entities (inversion, retraction, palpable mass, nipple discharge, skin changes etc..) We should also keep in mind the different radiological findings and their peculiarities. We should be aware of the different imaging techniques and which of them is better for reaching a specific diagnosis. Mammography, ultrasound, galactography, ductoscopy and MRI can be useful in the diagnosis of these lesions. A multimodal diagnosis is required, and a multidisciplinary approach is recommended to correct treatment.

Over the last three decades, magnetic resonance imaging (MRI) has dramatically entered the clinical field of detection and management of breast cancer (BC). Thanks to the introduction of contrast-enhanced (CE) sequences it gained very high sensitivity and intrinsic multiparametric nature. A modern, robust protocol is essentially composed of an unenhanced T2-weighted sequence; T1-weighted sequences acquired before and after intravenous administration of gadolinium-based contrast agent (GBCA) at a dose of 0.1 mmoL/kg/body weight; and diffusion-weighted imaging (DWI). A fat suppression with fat saturation, inversion recovery or alternatively, Dixon method, should be added to T1w and/or T2w scans. Non-uniform magnetic field and patient motion may reduce image quality potentially rendering an image or study non-diagnostic. Artefacts in breast MRI may be grouped under two broad categories: patient-related such as positioning, motion, and susceptibility and technical artefacts such as wraparound, chemical shift, and misregistration. Radiologists should be aware of and identify common artefacts to minimise potential negative effects on image interpretation and patient experience. Close attention must be played to injection of contrast material, the timing of the examination, lymph node evaluation, extra-mammary findings and kinetic assessment for avoiding pitfalls that can make interpretation of breast MR images challenging and lead to misdiagnosis. Recognising pitfalls associated with breast MR imaging is necessary for appropriate and accurate interpretation. Finally, empathic patient management has been reported as the most important factor in the overall quality of the examination.

Mammography is the gold standard for breast cancer detection both in the symptomatic and screening population. This talk will first review the anatomy of the breast in relation to mammographic appearances, allowing accurate interpretation of imaging findings. The importance of mammographic technique will be discussed, highlighting the importance of both compression and positioning of the breast for detection of malignancy. The use of additional mammographic views will be reviewed with case examples, and important artefacts will be covered. Finally, the use of mammography in screening will be covered, with European recommendations for high-quality screening and recommendations for radiology practice. The controversy about the use of mammographic screening regarding reduction in mortality and overdiagnosis and overtreatment will also be discussed.

The breast composition and appearance of benign diseases and breast cancer at mammography, ultrasound and MRI will be discussed by the presentation of a correctly structured report of the imaging and interventional procedures. Personal and family history impacts the decisions made during an exam and should be reported. Description of the density according to ACR BI-RADS® lexicon (a,b,c,d) indicates the mammographic (Mx) sensitivity. Description of all Mx abnormalities (asymmetry, mass lesion, architectural distortion and microcalcifications) includes position, size, distance to the nipple, relation to other lesions in the breast. Palpable mass and/or Mx abnormality are investigated with ultrasound (US) of the whole breast and axillary (level 1,2,3) region. The US report includes breast composition, location, description of shape, margins, size of the lesion and evaluation of the lymph nodes(LN), and comparison with previous exams. Depending on the suspiciousness and type of lesion, additional core-needle or vacuum-assisted (ultrasound, stereotactic, MRI guided) biopsies need to be done (assessment categories BI-RADS®lexicon). If needed the lesion(s) should be marked with a clip. The three main indications of the additional use of breast magnetic resonance imaging (MRI) are the pre-operative extent of disease evaluation in the ipsilateral and contralateral breast (i.e. lobular carcinoma, dense breast, young women, discordant Mx/US information), neo-adjuvant therapy evaluation, screening of gene mutation carriers. An assessment report integrating the findings on MX, US, MRI and the second look US, is preferred. Communication with the referring physician and surgeon on the radio-pathological results and eventually use pre-operative localisation technique is advised.

The MIPA study aimed at verifying the impact of preoperative breast MRI. Up to November 2018, over 7,000 patients were recruited in 30 centres. Data from 2,425 patients were: 1,201 (49.5%) received MRI, 1,224 (50.5%) did not. Of these 1,224 MRIs, 210 (17%) were performed for screening (4%) or diagnostic purposes (13%). Of 1,014 MRIs performed as preoperative studies, 59% were ordered by radiologists alone, 32% by surgeons alone; radiologist and surgeons were involved in 68% and 40% of cases, respectively. Mastectomy rate planned at mammography/ultrasound was 185/1,201 (15.4%) in the no-MRI-group, 245/1,224 (20.0%) in the MRI-group (p<0.001). In the MRI group, 21 additional mastectomies (1.7%) were planned after MRI, while 25 patients planned with mastectomy shifted to conservative surgery (CS). Of the 1,004 patients planned for CS before MRI, MRI did not change surgery in 733 (73%), while prompting a wider CS in 143 (12.5%), a less extensive CS in 128 (12.7%). Mastectomy rate was 192/1,201 (16%) in no-MRI-group and 257/1,224 (21%) in MRI-group (p<0.001). Per-patient reoperation rate for close/positive margins were 135/1009 (13.4%) and 80/967 (8%), respectively (p<0.001). Most mastectomies were already planned at mammography/ultrasound, using MRI as a confirmation tool, contributing in determining a lower reoperation rate in women undergoing MRI. Additional mastectomies were compensated by mastectomies shifted to CS and CS surgery was modified by MRI according to disease extent, balancing increased and decreased tissue removal. No increase in tissue removal has been determined by MRI.

1. To describe MRI biomarkers for breast cancer. 2. To understand the value of biomarkers in clinical practice. 3. To know the new possibilities for the future. Biomarkers - Diagnostic Biomarker - Detection or confirmation of a disease - Risk Biomarker - Identifies women at increased risk of breast cancer - Predictive Biomarker - How is the therapy working? - Prognostic Biomarker (needed more) - Identify cancer aggressiveness relates to patient outcome - MRI BPE. Native fibroglandular tissue will demonstrate variable enhancement patterns and levels of enhancement on breast MRI. The enhancement of the existing underlying fibroglandular tissue has been termed background parenchymal enhancement. As background parenchymal enhancement is related to vascular flow, it has been proposed that this may represent an imaging biomarker of the underlying proliferation of fibroglandular tissue. Investigations have shown that there is an extremely strong association between BPE and risk of breast cancer, at least a strong as the association between mammographic density and breast cancer. As with breast density and distribution of breast parenchyma on mammography, it appears that the background parenchymal enhancement of breast MRI is also extremely variable and women have different patterns and intensity of background parenchymal enhancement. In fact, it has been observed that not all mammographically dense breasts demonstrate increased background parenchymal enhancement. Therefore, it is possible that MRI can further stratify women at high risk for developing breast cancer on the basis of background parenchymal enhancement.

Early diagnosis improves the survival of women with breast cancer. Mammographic screening improves early diagnosis of breast cancer. And yet, there appears to be room for improvement. Major shortcomings of mammographic screening are overdiagnosis of prognostically unimportant cancer, as well as underdiagnosis of cancers that are indeed relevant. Failure to detect biologically relevant breast cancer with mammographic screening is driven by host-related factors, i.e. breast tissue density, but also tumour-related factors: Biologically relevant cancers may exhibit imaging features that renders them indistinguishable from normal or benign breast tissue on mammography. These cancers will then progress to become the advanced-stage interval cancers observed in women undergoing mammographic screening. Since breast cancer continues to represent a major cause of cancer death in women, the search for improved breast cancer screening method continues. Abbreviated breast MRI has been proposed for this purpose because it will greatly reduce the cost associated with this method, due to a greatly reduced magnet time (down to 3 minutes), but especially also due to a greatly abridged image interpretation time, i.e. radiologist reading time. This lecture will review the current evidence and presents the EA1141 trial designed to investigate the utility of abbreviated breast MRI for screening average-risk women with dense breast tissue.

Mammographic screening is beneficial to the population. Apart from a reduction in mortality less intense treatment is often possible due to the fact that the tumour burden is lower compared to a non-screening situation. Despite these advantages screening also creates inevitable harm to women. It is the challenge to balance the benefits and harms in order to optimise a screening program. Compared to FFDM tomosynthesis has advantages and disadvantages regarding recall, detection and clinical outcome. The differences between FFDM and tomosynthesis in a screening environment will be highlighted. Errors in screening are inevitable. The main errors are false-positives and false-negative results. The reasons for these errors, consequences for women and possible solutions will be discussed.

The sensitivity and specificity of mammography are limited in highly fibroglandular /dense breasts. Digital mammography provides increased sensitivity in young women and those with moderately dense breasts, and digital three-dimensional mammography (Tomosynthesis) promises further improvement. For women with the densest breasts, however, radiography is unlikely to be the optimum solution. MRI, although not affected by breast density, is expensive and access is often limited. Ultrasonography is attractive for breast cancer screening because, likewise, it is not impaired by breast density, and it avoids the use of ionising radiation and the need for breast compression. Nevertheless, enthusiasm for the use of ultrasonography has been limited because its specificity has been much lower than that of mammography, but technical developments have given rise to sharper, more informative images. These improvements foster the use of ultrasound particular in those women with higher breast density. Different trials have been preformed, and promising results have been reported.