6 min readBreast MRI: Will it Lead to an End in Surgeries?
What is the benefit of a breast MRI? Why use breast MRI and not a mammogram? These are some of the questions that face many patients when they are asked to undergo a breast MRI. Thus, it is very important to understand this procedure from the patient’s perspective to bring out its utility in the best possible manner.
The cells in our bodies have life as we all do. They are born, grow, age and die just like we do. This cellular life plan is controlled by our DNA and programs every cell to do what it is supposed to do. Sometimes, damage to the DNA structure causes cells to grow and divide uncontrollably and not die. These cells are called tumour cells. Not all tumour cells are cancerous – some are benign. It is the malignant tumours that we refer to when we talk about cancer. Malignant cells spread both locally (invading local anatomy) and distantly (termed “metastasis”).
To understand breast cancer, it is essential to understand breast anatomy. The breast is composed of two dominant tissues: glandular and fat. The glandular tissue is designed for milk production. Within the glandular tissue are two structures: lobules where milk is made and ducts where milk is transported to the nipple. There are two kinds of breast cancer: lobular and ductal. 90 % of breast cancers form in duct cells and 10% in lobule cells. These are very different cancers, but they are both called “breast cancer”.
Breast cancer occurs in phases: starting from normal ductal anatomy to typical ductal hyperplasia to atypical ductal hyperplasia (abnormal cell growth) to ductal carcinoma in situ (abnormal cell growth causing duct obstruction and formation of microcalicifications) and finally leading to invasive ductal carcinoma (cells disrupt the ductal lining and invade locally and sometimes distantly). All breast cancers go through these phases which can occur over years or months. Breast cancer cells may remain localized for many years and may never become important to the patient. Sometimes, for unknown reasons, some become “invasive” and begin to travel away from where they started. This is when they become very important to detect and remove while they are still locally invasive.
The chance of cure is extremely high if breast cancer is diagnosed when it is local or has just become invasive. It is when it goes all through the body that cure becomes difficult. Thus, breast cancer should be removed completely and early in order to prevent “metastasis” and increase the chance of cure.
Breast cancer is the second highest cause of cancer death and the second most common cancer in women. Right now, there are over two million women who have been treated for breast cancer. It is estimated that in 2008, more than 200,000 women will be diagnosed and more than 40,000 will die of the disease. Statistics suggest that one in eight women will develop breast cancer in their lifetimes and one in 33 will only die of it. Lowering this death rate can only be achieved with the right treatment plan, making an informed choice right from the diagnosis through to final treatment.
The detection of breast cancer starts from observation of the breasts and self examination. In the case of the patient suspecting a physical abnormality, a clinical examination by a doctor is needed. If the doctor suspects a deviation, the patient is asked to undergo the first level of breast imaging: mammography.
The next step after detection is diagnosis. Where a screening mammogram detects an abnormality, the patient goes to the next step of mammography which is called diagnostic mammography. In the diagnostic mammography, additional views with compression and different projections are taken to analyze the anatomy of the breasts. The anatomical analysis of the breast helps the doctor decide whether a breast ultrasound is required or not. Also, biopsies and laboratory tests are required in some cases.
There are three types of biopsy: core, stereo and surgical biopsy.
Core biopsy consists of drawing the core cells from the suspected mass with the help of a needle. The cells are then sent to the lab to determine whether they are cancerous. This is one of the most common forms of biopsy and is done to confirm cancer one is not sure of.
The second form of biopsy is stereo biopsy. Stereo biopsy is done when mass but indeterminate calcifications are detected. This is done with special equipment for probably benign or suspicious lesions.
Surgical biopsy is done by putting a wire into the suspicious mass. The reason for the wire is to guide the surgeon during the surgery to mark the cancerous tissue. This biopsy is also called lumpectomy because a large lump of the cells is taken out. The next step after lumpectomy is staging of the cancer. This is done by laboratory tests and local exams, which include clinical exams or MRI. Also, it is necessary to find if the cancer has spread or is localized to the breast. This can be done by sentinel node, Bone Scan, CAT scan, PET scan and MRI.
The next step is cancer treatment which includes therapy which is decided after the cancer is staged. The patient might need surgery which may be a lumpectomy, partial mastectomy, simple, radical mastectomy or modified radical. Chemotherapy could be conventional, neo-adjuvant, adjuvant or hormonal. The other method of treatment is through irradiation. One might need a combination of different treatments once the disease is accurately staged. The newest therapy is mammosite, where a small catheter is laid out in the bed where tumour has been taken out by lumpectomy. The crater is radiated to kill the residual tumour. This is a breakthrough technology which is localized and painless.
Given the above, where does breast MRI come into play? Breast MRI is already used in screening, diagnosis and staging, and there are hopes of it being used in therapy as well. In future, breast MRI is predicted to end all the unnecessary surgeries and biopsies. Breast MRI can help create planes and projections out of the breast image, create colour codes and do volumetric analysis. This helps the radiologist determine the size of the tumour and what is required for a cure. Breast MRI prevents compression and allows bilateral positioning, which helps to screen both breasts at the same time. The procedure might take from 15 minutes to 30 minutes.
Breast MRI is currently performed under specific conditions. In the case of Breast Cancer (BRCA) gene positive patients where one breast has already been biopsied, the other breast may be screened for an abnormality. Breast MRI also plays an integral part in staging. It allows the extent of tumour in a biopsied breast to be examined to see if the cancer has spread to the shoulder or back, and to exclude multifocal or bilateral tumours. This method is also important in diagnosis. The recurrence of breast cancer after treatment can be discovered using breast MRI, particularly the tumour response to chemotherapy. The scan can determine whether the tumour has shrunk or re-grown.
For breast MRI enhancement, a small dye contrast called gadolinium is injected into the forearm. This is not the same as CT contrast, and does not cause flush, warmth or nausea. It is a thousand fold safer and requires a much smaller amount than CT contrast. During the procedure, the patient is injected with the contrast and enhancement pattern over time is observed every minute. The slices or sections of the breast in different planes – “coronal” “sagittal” and “axial” – are taken. 15 million graphs are taken in a breast MRI.
Special tools are required to study the MRI, as 15 million points cannot be reviewed in few minutes without advanced techniques. Computer Aided Detection (CAD) is one of the tools which analyses all the points and highlights the ones which should be reviewed. The curves help to point out and identify tumours which are malignant, benign or suspicious.
The hope of MRI is to take mammography results and increase their specificity. This method of detection also decreases pain and suffering, as only patients who really need invasive staging end up having a biopsy.
Breast MRI gives very good results in women with dense breasts and fibrocystic breast changes which sometimes lead to unnecessary biopsies. Fibrocystic breast change is a very common breast problem and it confounds the ability to see the normal breasts by mammography and other methods. Cancer can also be detected in women with breast implants with the Breast MRI method.
MRI also works very well in preoperative staging and also helps distinguish between invasive and non-invasive tumours. Treatments such as lumpectomies or mastectomies can be decided upon with appropriate staging, which is possible using breast MRI. Some countries are already making good use of breast MRI. In Germany, before any surgery is performed, whether conservative or a mastectomy, a breast MRI is required to be done.
This method of diagnosis has a bright future. MR spectroscopy of the breast will also be possible in a few years, allowing small virtual boxes to be put on tumours to analyze their histology and chemical make up. This would effectively be a virtual biopsy. The current false positive in breast MRI of 18% would be brought down by MR spectroscopy. This should also lead to a point where doctors would be able to detect the tumour and vaporize or ablate it at the same time. This means that, ultimately, breast MRI will remove the need for surgery in many patients.