Mammography

Mammography is the process of using low-dose X-rays to examine the human breast. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses, architectural distortion and/or microcalcifications. Mammography reduces mortality from breast cancer. No other imaging technique has been shown to reduce the death rate, but breast self-examination (BSE) and physician examination are considered part of regular breast care.m

Mammography does not find all cancers. This is partly due to dense tissues obscuring the cancer and the fact that the appearance of cancer on mammograms may overlap with the appearance of normal tissues.

Mammography also finds many abnormalities that are not cancer. Women may be understandably distressed to be called back for a diagnostic mammogram. Most of these recalls will not be cancer, but radiologists would rather be “safe-than-sorry,” so try not to worry if you’re called back for extra pictures. Some women even need a needle biopsy to determine whether cancer is present, or not. These are done usually with either ultrasound or mammogram guidance. Local anaesthetic (freezing) is given first. It stings about the same, or less, than the sting when blood is taken from the arm. Once the freezing is in, only dull pressure is felt. So a needle biopsy is only slightly “more glamorous” than a blood test!

A mammogram is a quick and easy X-ray of the breast done in complete privacy by a specially trained female technologist.

m2Often women are quite distressed to be called back for a diagnostic mammogram. Most of these recalls will be false positive results.
m3A mammogram is a quick and easy X-ray of the breast done in complete privacy by a specially trained female technologist.

 

Who interprets the results and how do I get them?

A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you. You will also be notified of the results by the mammography facility.

What are the benefits vs. risks?

 

Benefits

  • • Imaging of the breast improves a physician's ability to detect small tumors. When cancers are small, the woman has more treatment options and a cure is more likely.

Risks

  • Five percent to 10 percent of screening mammograms require more testing such as additional mammograms or ultrasound, etc. Most of these tests turn out to be not cancer. If there is an abnormal finding, a follow-up or biopsy may be recommended.
  • The risk of the radiation from a mammogram actually causing a breast cancer is negligible. The doses used are very small. It’s estimated that out of a million mammograms performed, that theoretically, one cancer might be caused. The data from the BC Screening Mammography Program show that women who have mammograms have over 40% fewer deaths from breast cancer than women who do not have mammograms, so even if there’s a theoretical risk of one cancer being caused (per million mammograms), the risk of dying from it is less. In other words, the benefit far outweighs the potential risk.

Mammograms are the most important tool doctors have, not only to screen for breast cancer, but also to diagnose, evaluate, and follow people who’ve had breast cancer. They are safe and reasonably accurate, and have been in use for over 50 years.

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The Procedure

The technologist will position your breast, one at a time, between the compression paddle and the film holder or detector. She will pull your breast as far as possible into the machine, so all the breast tissue is visible on the film. Try to relax and allow her to position you. If you’re tense, the examination won’t be as good. You will feel pressure on your breast as it is squeezed by the compression paddle. Some women with sensitive breasts may experience discomfort. If this is the case, schedule the procedure when your breasts are least tender. Try not to schedule your appointment during the week before your menstrual period. Some women find that if they gradually wean themselves off caffeine (coffee, tea, colas and chocolate) for a few weeks before the test, that the discomfort is less. Be sure to inform the technologist if pain occurs as compression is increased. If discomfort is significant, less compression will be used. The compression will only be uncomfortable for a few seconds. It will automatically release as soon as the exposure is made.

Other Breast Imaging Tests

Research into the use of complementary technologies is ongoing. Ultrasound is typically used for further evaluation of masses found on mammography or palpable masses (feelable lumps). Breast lumps are broadly categorized into fluid-filled (cysts) and lumps made of tissue (solid) and ultrasound is very accurate at distinguishing between the two. Some solid lumps can be confidently diagnosed as not cancer on ultrasound. When this is not the case, an ultrasound guided needle biopsy can get tissue for the pathologist to look at under the microscope, to make a definite diagnosis. Cysts can be left alone. If a cyst becomes tender, it can be drained easily. Contrast enhanced magnetic resonance imaging (MRI), has shown substantial progress. In this method, the breast is scanned in an MRI device before and after the intravenous injection of a contrast agent (Gadolinium DTPA). Any areas that have increased blood flow are seen as bright spots on a dark background. Since breast cancers generally have an increased blood supply, the contrast agent causes these lesions to "light up" on the images. Not all areas that “light up” are cancer, and some cancers don’t show on MRI. MRI can be useful for further evaluation of questionable findings as well as for pre-surgical staging in patients with known breast cancer to detect any additional lesions that might change the surgical approach, for instance: from breast-conserving lumpectomy to mastectomy. The sensitivity of contrast-enhanced breast MRI is considerably higher than that of either mammography or ultrasound and is generally reported to be in excess of 95%. The specificity is only fair, thus a positive finding by MRI might not be cancer, and additional tests, including needle biopsy, might be required. MRI is time-consuming and expensive, so is not recommended for screening, except for women at very high risk of developing breast cancer. Currently, this includes women who have had genetic testing, and are known to be carriers of one of the breast cancer genes. Ductograms are used in some institutions for evaluation of bloody nipple discharge when the mammogram is non-diagnostic. It involves inserting a thin tube into the opening of the duct, and injecting a fluid that shows up on a mammogram. It can demonstrate a growth in the duct, even if the growth is too small to show up on a mammogram or ultrasound. New procedures, including breast tomosynthesis offer other benefits. Tomosynthesis is an application of digital mammography, that takes pictures of the breast tissue in slices, that can be viewed by the radiologist as a video clip. By negating the effect of overlapping tissue that is unavoidable in regular mammograms, it has the potential to reduce the number of false positives, and false negatives.

Minimizing Radiation Exposure

Special care is taken during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection councils continually review and update the technique standards used by radiology professionals. State-of-the-art x-ray systems have tightly controlled x-ray beams with significant filtration and dose control methods to minimize stray or scatter radiation. This ensures that those parts of a patient's body not being imaged receive minimal radiation exposure.