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Breast Cancer


Figure 5: False-positive Finding on Enhanced Magnetic Resonance Imaging


AB determine the local extent, tumour size and location,11,13,27,37–48 which


means a better indication of the most suitable therapy, better evaluation of heterogeneous or extremely dense breasts,3,29,52,53


high


sensitivity for the detection of additional foci of occult cancer,3,11,13,27,29– 31,37–53


which imparts a new approach to possible therapies (see Figures


1–3) and its capacity to evaluate post-chemotherapy changes13,14,16,17 (see Figure 4). The most important disadvantage is its low specificity (50–70%),11,23,27,29,37


Magnetic resonance imaging (MRI) of a 49-year-old patient with palpable nodule in the left breast and a suspicious lesion in the mammogram (not shown). A and B: Post-gadolinium MRI, maximum-intensity projection (MIP) axial reconstruction, grey-scale (A) and colour- coded maps (B), show multiple lesions in the left breast (white arrows) and a suspicious microlobulated enhancing mass in the right (pink arrow), suggestive of bilateral carcinoma. The histology was locally advanced multicentric carcinoma in the left breast (poorly differentiated infiltrative ductal carcinoma) and fibroadenoma in the right breast. The treatment decided on was left mastectomy with lymphadenectomy.


Paget’s disease. Irrespective of whether the clinical team routinely uses pre-operative MRI, women who are newly diagnosed with breast cancer should always be informed of the potential risks and benefits of pre-operative MRI, and radiologists should always remember that the results of MRI should be interpreted by taking into account clinical breast examination, mammography and sonography and should be verified by percutaneous biopsy.47


According to this, MR guidance


for needle biopsy and pre-surgical localisation should be available or potentially accessible if pre-operative MRI is to be implemented, as lesions detected only on MRI are not infrequent.47,56,57


but is extremely variable (37–97%) depending on the technique used, parameters and interpretation criteria.3,37,23


An


Normal breast parenchyma can enhance symmetrically or with a nodular pattern, particularly in pre-menopausal women, which limits the role of MRI by causing false-positives (see Figure 5). In order to decrease the probability of detecting false-positives, MRI should be performed during the first few days of the menstrual cycle (days five to fifteen), because the parenchymatous enhancement is less intense in this period.3,23,24


unexpected enhancement of lesions occurs on 16–29% of breast MRI.23


Several lesions can simulate breast cancer in MRI,


including benign injuries such as fibroadenomas (see Figure 5), papillomas, lymphatic nodules, high-risk injuries such as lobar carcinoma in situ, atypical ductal hyperplasia, atypical lobular hyperplasia and a miscellaneous group that includes fibrocystic changes, adenosis, sclerosis, ductal hyperplasia and fibrosis.23,24 Therefore, it is extremely important to always obtain a biopsy before changing the treatment approach after the detection of a lesion in a pre-surgical staging MRI.3,24,29,56


Other limitations of breast MRI are lower sensitivity for ductal carcinoma in situ50


variable between 60 and 90%,27 different series), high cost, limited availability50


and 40 and 100%24 and, in particular, the


lack of availability of MRI-compatible biopsy equipment.3,4,11,47,54,55 Summary


Triple Assessment versus Mammography and Ultrasound in Breast Cancer Evaluation The main advantages of breast MRI for the evaluation of breast cancer are: greater accuracy than mammography and ultrasound to


28


than for invasive tumours (which is extremely 50 and 80%3


in


The most important disadvantage of breast MRI and the most controversial point in its use for breast cancer staging is its low specificity, which is between 50 and 70% in the majority of the literature,11,23,27,29,37


which means that in breast cancer staging all suspicious MRI-detected lesions must always be biopsied before changing therapy.3,24,29,56


In any case, there are subgroups of patients


who profit the most from MRI staging: women with ductal carcinoma in situ, those with infiltrating lobular carcinoma, patients who are going to be treated with neoadjuvant chemotherapy, patients with Paget’s disease or those with dense breasts who are going to undergo modified radical mastectomy.15


A clear understanding of the valid indications and selection criteria for using breast MRI appropriately12


is fundamental,


and clear communication to patients about the limits of MRI should be established due to the possibility of false-positive findings.58


Future Directions


which means that all additional foci diagnosed with MRI have no real impact on survival and recurrence rates, with an increased false-positive rate and unnecessary surgery.34,35 published meta-analysis,35


The impact of the use of breast MRI on survival and recurrence rates in breast cancer is not well established. Some authors report that the multicentric foci of multifocal carcinomas detected on MRI could have been properly treated with radiotherapy and chemotherapy after surgery,54,59–61


In a recently the percentage of additional foci detected


in MRI and the percentage of patients with a change in surgical planning due to those findings was 7.8–33.3%. A modified radical mastectomy was executed instead of conservative surgery in 8.1% of patients with malignant lesions and 1.1% of patients with false-positives. Extension of conservative surgery was carried out in 11.3% of patients with additional carcinoma foci and 5.3% of patients with benign lesions. The same authors concluded in a posterior study that MRI adds unnecessary surgery and does not demonstrate a better survival rate.33


An important fact in all these discussions is


that in breast divisions that integrate all imaging techniques (mammography, ultrasonography and MRI) and interventional procedures, the rate of incorrect change in the therapy is low, at 3.8%.62


Radiologists should never forget that in breast cancer screening the combination of mammography, ultrasonography, clinical examination and MRI is more sensitive than any other individual test or combination of tests.7


This indicates that integration of MRI into the work-up as an additional imaging technique in pre-surgical staging of breast cancer is mostly beneficial.


Concerning the re-operation rate, Pengel et al.32 recently published


the first randomised clinical trial to compare patients staged with MRI versus patients who did not undergo MRI for staging. In the first group the re-operation rate was 13.8%, and in the second, 19.1%. The authors concluded that MRI does not significantly affect the re-operation rate but decreases ductal carcinoma in situ with a positive margin rate. The most recent publication, which covered the Comparative Effectiveness of MRI in Breast Cancer study (COMICE), a randomised controlled trial, confirmed that the addition of MRI to conventional triple assessment is not significantly associated with a reduced re-operation rate, so may be


EUROPEAN ONCOLOGY & HAEMATOLOGY


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