MRI
Dynamic contrast-enhanced MRI mammography is a technique that has been widely studied over the last decade, particularly as a screening modality for young women with a high risk for familial breast cancer and women with dense breasts (Figure 3A-D). Its use as an adjunct to routine screening imaging to clarify inconclusive or suspicious findings is gaining popularity, and to more accurately size tumors where clinical and mammogram or ultrasonography breast findings have disparity. The overall NPV for breast MRI is 84.5%.[39] It has a high PPV and high NPV to differentiate surgical scarring from recurrence.[40,41] The largest body of evidence to date is its value in screening high-risk younger women. Multiple prospective studies have evaluated the role of MRI in high-risk patients, and concluded that diagnosis of breast cancer in this group is improved by use of MRI, with a sensitivity of 79-98%.[42] The American Cancer Society guidelines recommend that MRI and mammography should be used for annual screening of all women who have a BRCA mutation or lifetime risk of 20-25% or more.[43]
Breast MRI showing a malignant lesion in the right breast. (A) MRI breast T2 coronal image showing lesion in right breast. (B) Postcontrast subtraction image (15 min) showing enhancing malignant lesion in posteromedial region of the right breast. (C) Postcontrast subtraction image (65 min) showing right breast posteromedial malignant lesion extending to chest wall. (D) Type 3, time-intensity MRI curve showing rapid peak wash in and wash out, which is typical of a malignant lesion.
MRI is also used to look for breast malignancy in patients with an unknown primary who have negative conventional breast imaging,[44] and in patients with locally advanced breast cancer undergoing neo-adjuvant treatment, where MRI can be used to identify responders: the earliest sign of response is change of enhancement kinetics, which precedes change in tumor morphology by weeks.[45] It is also useful to detect residual disease burden after completion of chemotherapy.[46] It is also the method of choice to detect local recurrence of breast cancer and to estimate residual malignancy in the breast after wide local excision where margins of resection are considered inadequate.[47]
Patients with breast implants always pose a challenge for imaging, and MRI can delineate cancer obscured by the implant. MRI is also the method of choice in the evaluation of the augmented breast, with very high accuracy in assessment of implant integrity and in cancer detection.[48]
Breast MRI is, at present, the most accurate breast imaging available, with a NPV of 99.8%. It correlates better with histological tumor size and may be superior to mammography for demonstrating intraductal tumor extension.[49,50] False-positive rates and call backs can be reduced by timing the study during days 7-10 of the menstrual cycle.
A recent study did show that, for selected patients, preoperative breast MRI can improve overall management by correctly identifying women who have occult contralateral malignancy and multifocal occult cancers.[51]
MRI has exceptional sensitivity for detection of breast cancer and is able to show lesions not depicted on other screening modalities. It is now increasingly being used as a complementary tool in the diagnosis and management of breast cancer.
Future Oncol. 2008;4(4):501-503. © 2008 Future Medicine Ltd.
Cite this: New Diagnostic Techniques for Breast Cancer Detection - Medscape - Aug 01, 2008.
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