Role of MRI in Screening, Diagnosis and Management of Breast Cancer
Mammography and ultrasound has an established role in breast cancer screening and detection. Most cancer(s) can be detected, sized and staged with conventional mammograms and thorough ultrasound evaluation. However the advent of MRI and its role in management of breast disease is ever increasing.
In Australia facilities performing and reporting breast cases are not widespread, unlike general radiology. Specialist Radiologists who perform and report the studies are limited. It is therefore important to send a patient to a centre where Breast MRI is routinely performed.
MRI serves in the role of screening, diagnosis and management of breast cancer primarily as an adjunct to conventional methods of mammogram and ultrasound.
MRI is useful in:
- Screening of high risk individuals with or without BRC1 or BRC2 mutations;
- Patients who had childhood cancers such as chest Lymphoma and mediastinal radiation (these patients are at a higher risk of developing breast cancer);
- Patients with extremely dense breasts where there is high index of concern but are mammographically and sonographically occult for disease;
- Pre-operative planning and staging of extensive or multifocal disease;
- Evaluation for residual disease in cases of positive margins or early disease recurrence in scar;
- Staging and assessing the response to chemotherapy; and
- MRI guided techniques (vacuum assisted core biopsies for lesions not visible on mammogram or ultrasound).
Benefits of MRI:
- Does not involve ionizing radiation, therefore can be a screening tool used in young women with high risk and dense breasts;
- Ability to show abnormality is not lessened by dense breast tissue (as may be the case for some mammograms in dense breasts); and
- MRI is the best method to evaluate the breasts of women with implants (and the integrity of the implant) as implants can obscure breast tissue. Although, it is important to note that not all microcalcifications can be seen with MRI, in these cases performing a mammogram is also required.
Limitations of MRI:
- Cannot be used in pregnant patients as the contrast agent (Gadolinium) cannot be given;
- Patients who have renal failure due to inability to give contrast (possible contra- indication);
- Patients who suffer from claustrophobia; and
- Cost considerations as patients must meet the pre-requisites to attract the Medicare rebate.
MRI in Diagnosis and Staging:
Some studies show that MRI may be better at identifying multifocal and multicentric disease, particularly for some DCIS and lobular cancers.
MRI is useful in patients with axillary lymphadenopathy due to occult disease. It is also useful in detecting cancer or early changes in the contralateral breast.
MRI is more sensitive than ultrasound or CT scan to assess the lymph node involvement in the mediastinum and axilla- thus helping staging.
Silicone implant rupture can have detection rates of 99% with MRI. It is a challenge to detect early cancer in an augmented breast, particularly with rupture, because carcinomatous change may be misinterpreted as silicone mastopathy or nodularity, skin retraction or nipple inversion.
MRI allows objective assessment of response to chemotherapy and assessment of reduction or residual tumour size and restaging of the axilla.
MRI is now an established tool in our armament for diagnosis and management of breast cancer.
Its limitations of high sensitivity and cost mean in Australia we only use it for select cases.
The judicious use of MRI leads to better management of screening high risk patients, better outcomes in the work up of disease and reduced morbidity and mortality to provide the patient with the best surgical and medical option the first time.