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Breast Cancer


Figure 4: Chemotherapy Response Evaluation with Magnetic Resonance Imaging


AB


in the surgical piece (excluding false-positives of biopsy). In these patients, MRI is useful for locating the tumour. When there is malignancy after resection of a supposed benign lesion, MRI should be performed for re-staging and detection of additional foci or multicentric or contralateral cancer. Post-surgical MRI should always be performed in the first two weeks after the excision, because later granulation tissue can cause false-positives.15


CD E FG H


Concerning lesions of uncertain malignant potential or B3 (Nottingham classification after percutaneous biopsy), which include radial scars, papillary lesions, lobular carcinoma in situ, atypical lobular hyperplasia, flat epithelial atypia and atypical ductal hyperplasia, there is no scientific evidence concerning the use of MRI for the detection of concomitant malignant lesions.20


The American


nevertheless other guides recommend performing breast MRI annually in patients with lobular carcinoma in situ.22


A–F: Pre-chemotherapy magnetic resonance imaging (MRI) in a 36-year-old woman with a palpable lesion in the left breast that has grown. Maximum-intensity projection (MIP) axial reconstructions and gray-scale (A) and colour-coded maps (B) show a spiculated enhancing mass (large arrow) in the upper lateral quadrant of the left breast. Closer to the skin, another smaller enhancing lesion (small arrow) is seen. Important enhancement in the surrounding parenchyma is also noted. Fine-needle aspiration cytology (FNAC) was positive for carcinoma. Unenhanced (C), post-gadolinium (D) and subtraction images (E) of the left breast show an irregular mass (arrow) with peripheral enhancement and a type III enhancement curve in the dynamic study (F). Biopsy (pre-chemotherapy): poorly differentiated infiltrating ductal carcinoma (G3). G–H: MRI post-chemotherapy. Post- gadolinium axial image: grey-scale (G) and colour-coded maps (H). No areas of pathological enhancement are noted. No suspicious images are observed. Histology: no tumour found in the piece of quadrantectomy post-chemotherapy. There were eight negative lymph nodes and partial fibrosis in two other lymphatic nodules, which could correspond to complete regression of metastatic foci. The treatment decided on was quadrantectomy with lymphadenectomy and radiotherapy.


Stavros et al., applying strict echographic criteria of benignancy obtained a sensitivity of ultrasound for depicting malignancy of 98.4%.6


Magnetic Resonance Imaging Indications


Breast magnetic resonance imaging (MRI) is the most sensitive additional diagnostic method, with sensitivity values ranging between 89 and 100%,3,11


complementary procedure to mammography.12


and is developing widespread acceptance as a MRI is indicated for


chemotherapy response evaluation13,14 (see Figure 4), high-risk patient


screening (still controversial), primary tumour detection in patients with metastatic lymph nodes of unknown origin and detection of breast implant rupture.15


There are different opinions regarding the


accuracy of MRI for the evaluation of chemotherapy response: some authors refer to overestimation of the residual tumour13,14 to underestimation and false-negatives.16,17


and others There is controversy about


the use of MRI for the evaluation of microcalcifications: some studies advise against MRI in this situation, while others propose the technique to avoid unnecessary biopsies.18


In any case, MRI is useful for pre-surgical staging of a possible ductal carcinoma in situ.15 Findings and Interpretation


Breast MRI has similar sensitivity and specificity to galactography and a higher negative predictive value for the detection of intraductal lesions in women with nipple discharge, with the advantage that it is a non-invasive technique.19


Special cases are those consisting of residual tumour after resection, with positive macroscopic tumour margins or no evidence of cancer


26


Breast MRI should be read by a suitable expert, which is not the case at the majority of institutions. Images should be evaluated in a workstation as mentioned, completing post-processing that includes the subtraction and quantification of the enhancement.23


Post-processing of the images is performed in a workstation by an expert radiologist, who also carries out the subtraction and quantification of the enhancement. The most representative reformatted images are sent to the picture archiving and communication system (PACS) and a hard copy is attached to the report for the patient.


Cancer Society does not recommend follow-up with MRI in these patients;21


The utility of MRI for screening high-risk patients and for the staging of breast cancer, and its impact on clinical management, will be discussed later.


Technique


Some authors recommend bilateral whole breast ultrasound in pre-operative evaluation of patients with breast cancer.9,10


Multiple breast MRI protocols are described in the literature. Most of the studies are carried out with a high-field magnet (1.0–1.5T) using specific breast surface superficial coils. In general, the study includes both breasts, especially in pre-surgical staging and post-surgical evaluation. Patients are laid down in the prone position and paramagnetic intravenous contrast is almost always administered using an injection pump (0.1–0.2mmol/kg at a rate of 2ml/second, followed by 15–20ml of saline solution at the same rate). The acquisition plane is axial or coronal for bilateral studies, although sagittal images can also be useful.23


Our protocol includes axial and coronal T2-weighted sequences with and without fat saturation (FS), which are particularly useful


for the characterisation of certain lesions (cysts) and to evaluate


post-surgical changes. Subsequently, dynamic T1-weighted sequences with high temporary and spatial resolution are acquired in the axial plane before and after the administration of a gadolinium chelate. These last sequences are the essential base of breast MRI. Fat suppression images can also be obtained by post-processing (subtraction) techniques.23


We administer 0.1mmol/kg of intravenous gadolinium chelate and use dedicated breast surface coils.


A great


variety of morphological and dynamic criteria is used to evaluate suspicious findings. The American College of Radiology (ACR) has developed the lexicon BI-RADS–MRI to homogenise the language used


EUROPEAN ONCOLOGY & HAEMATOLOGY


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