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Mammography is the process of using low-dose X-rays (usually around 0.7 mSv) to examine the human breast. It is used to look for different types of tumors and cysts. Mammography has been proven to reduce mortality from breast cancer. No other imaging technique has been shown to reduce risk, but self-breast examination (SBE) and physician examination are essential parts of regular breast care. In some countries routine (annual to five-yearly) mammography of older women is encouraged as a screening method to diagnose early breast cancer. Screening mammograms were first proven to save lives in research published by Sam Shapiro, Philip Strax and Louis Venet in 1966. Image File history File links Mammogram. ...
Image File history File links Mammogram. ...
In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...
The sievert (symbol: Sv) is the SI derived unit of dose equivalent. ...
A pregnant womans breasts. ...
Tumor (American English) or tumour (British English) originally means swelling, and is sometimes still used with that meaning. ...
A cyst is a closed sac having a distinct membrane and developing abnormally in a cavity or structure of the body. ...
Breast cancer is cancer of breast tissue. ...
Philip Strax (1909-1999) was a radiologist who pioneered the use of mammography to screen for early breast cancer. ...
Like all x-rays, mammograms use doses of ionizing radiation to create this image. Radiologists then analyze the image for any abnormal growths. Despite continuous improvements and innovations, mammography has garnered a sizable opposition in the medical community because of an error rate that is still high and the amount of harmful radiation used in the procedure. (Gofinan) It is normal to use longer wavelength X-rays (typically Mo-K) than those used for radiography of bones. Radiation hazard symbol. ...
The wavelength is the distance between repeating units of a wave pattern. ...
Radiography is the creation of images by exposing a photographic film or other image receptor to X-rays. ...
Grays Anatomy illustration of a human femur. ...
At this time, mammography is still the modality of choice for screening for early breast cancer. It is the gold-standard which other imaging tests are compared with. CT has no real role in diagnosing breast cancer at the present. Ultrasound, Ductography, and Magnetic Resonance are adjuncts to mammography. Ultrasound is typically used for further evaluation of masses found on mammography or palpable masses not seen on mammograms. Ductograms are useful for evaluation of bloody nipple discharge when the mammogram is non-diagnostic. MRI can be useful for further evaluation of questionable findings, or sometimes for pre-surgical evaluation to look for additional lesions. Breast cancer is cancer of breast tissue. ...
This article does not cite its references or sources. ...
A fetus in its mothers womb, viewed in a sonogram (brightness scan) A fetus, aged 29 weeks, in a 3D ultrasound Ultrasound is sound with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz). ...
This article or section does not cite its references or sources. ...
Mammography has a false-negative (missed cancer) rate of at least 10 percent. This is partly due to dense tissues obscuring the cancer and the fact that the appearance of cancer on mammograms has a large overlap with the appearance of normal tissues.
[edit] Procedure During the procedure, the breast is compressed by a dedicated mammography machine, in order to even out the tissue, increase image quality, and to hold the breast still (preventing motion blur). Both front and side images of the breast are taken. Deodorant, talcum powder or lotion may show up on the X-ray as calcium spots, and women are discouraged from applying these on the day of their investigation. Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ...
This amusement ride moved during the exposure. ...
Roll-on deodorant Deodorants are cosmetic substances applied to the body, most frequently the armpits, to reduce the body odor caused by the bacterial breakdown of perspiration. ...
Talc block Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. ...
A lotion is a low- to medium-viscosity medicated or non-medicated topical preparation intended for application to unbroken skin. ...
General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ...
Until some years ago, mammography was typically performed with screen-film cassettes. Now, mammography is undergoing transition to digital detectors. This progress is some years later than in general radiology. This is due to several factors:
- the higher resolution demands in mammography,
- significantly increased expense of the equipment,
- the fact that digital mammography has never been shown to be superior to film-screen mammography for the diagnosis of breast cancer.
As of 2005, only a small percentage of facilities have digital mammography. 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...
[edit] "Work-up" process In the past several years, the "work-up" process has become quite formalized. It generally consists of screening mammography, diagnostic mammography, and biopsy when necessary. After a screening mammogram, some women may have areas of concern which can't be resolved with only the information available from the screening mammogram. They would then be called back for a "diagnostic mammogram". This phrase essentially means a problem-solving mammogram. During this session, the radiologist will be monitoring each of the additional films as they are taken to determine the cause of the abnormal appearance. Ultrasound is often used at this point, as well. A biopsy (in Greek: bios = life and opsy = look/appearance) is a medical test involving the removal of cells or tissues for examination. ...
A fetus in its mothers womb, viewed in a sonogram (brightness scan) A fetus, aged 29 weeks, in a 3D ultrasound Ultrasound is sound with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz). ...
Generally the cause of the unusual appearance is found to be benign. If the cause cannot be determined to be benign with sufficient certainty, a biopsy will be recommended. The biopsy procedure will be used to obtain actual tissue from the site for the pathologist to examine microscopically to determine the precise cause of the abnormality. In the past, biopsies were most frequently done in surgery, under local or general anesthesia. The majority are now done with needles using either ultrasound or mammographic guidance to be sure that the area of concern is the area that is biopsied. Benign can refer to any medical condition which, untreated or with symptomatic therapy, will not become life-threatening. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
Anesthesia or anaesthesia (see spelling differences) has traditionally meant the process of blocking the perception of pain and other sensations. ...
One study shows that needle biopsies of liver malignancies rarely increase the likelihood that cancer will spread, and has not been found to occur with breast needle biopsies.[1]
[edit] Results
 Normal (left) versus cancerous (right) mammography image. Often women are quite distressed to be called back for a diagnostic mammogram. Most of these recalls will be false positive results. It helps to know these approximate statistics: of every 1,000 US women who are screened, about 7% (70) will be called back for a diagnostic session. About 10 of these will be referred for a biopsy, the remaining 60 are found to be of benign cause. Of the 10 referred for biopsy, about 3.5 will have a cancer, and 6.5 will not. Of the 3.5 who do have cancer, about 2 have a low stage cancer that will be essentially cured after treatment. Image File history File links Mammo_breast_cancer. ...
Image File history File links Mammo_breast_cancer. ...
Scientists recognize two different sorts of error:[1] Statistical error: the difference between a computed, estimated, or measured value and the true, specified, or theoretically correct value (see errors and residuals in statistics) that is caused by random, and inherently unpredictable fluctuations in the measurement apparatus. ...
It is important to note that while mammography is the only screening method which has been shown to actually save lives, it is not perfect. Estimates of the numbers of cancers missed by mammography are usually around 10-20%. This means that of the 350 per 100,000 women who currently have a breast cancer, about 35-70 will not be seen by mammography. Reasons for not seeing the cancer include observer error, but more frequently it is due to the fact that the cancer is hidden by other dense tissue in the breast and even after retrospective review of the mammogram, cannot be seen. Furthermore, one form of breast cancer, lobular cancer, has a growth pattern that produces shadows on the mammogram which are indistinguishable from normal breast tissue.
Computer-assisted analysis is being tested to decrease the number of cases of cancer that are missed in mammograms. In one test, a computer identified 71% of the cases of cancer that had been missed by physicians. However, the computer also flagged twice as many non-cancerous masses than the physicians did. In a second study of a larger set of mammograms, a computer recommended six biopsies that physicians did not. All six turned out to be cancers that would have been missed. (Destounis, et al., 2004)
While data is accumulating suggesting that CAD can find a few additional cancers, this should be put in perspective. The additional find rate was 20%, thus in a group of 1000 women who will have about 4 cancers, CAD may help find an additional 0.8. The types of additional cancers that may be found are likely to be early and small. As of 2006, there has been no data to show that finding these additional cancers will have any effect on survival rate. Some feel that these cancers are likely to be found at the next screening, still at a curable stage, and therefore it remains to be proven whether CAD will be eventually found to have any effect on patient outcome.
[edit] False positives The goal of any screening procedure is to examine a large population of patients and find the small number most likely to have a serious condition. These patients are then referred for further, usually more invasive, testing. Thus a sreening exam is not intended to be definitive, it is intended to have a high sensitivity so as to not miss any cancers. The cost of this high sensitivity is a relatively large number of results that would be regarded as suspicious in patients without disease. This is true of mammography. The patients called back for further testing from a screening session (about 7%) are sometimes referred to as "false positives", implying an error. In fact, it is essential to call back many healthy patients for further testing in order to capture as many cases of cancer as possible, and these call backs should not be regarded as errors. (see above: "results")
[edit] False Negatives At the same time, mammograms also have a rate of missed tumors, or "false negatives." Accurate data regarding the number of false negatives is very difficult to obtain, simply because we cannot perform mastectomies on every woman who has had a mammogram to determine the false negative rate accurately. Estimates of the false negative rate depend on close follow-up of a large number of patients for many years. This is difficult in practice, because many women do not return for regular mammography making it impossible to know if they ever developed a cancer. Dr. Samuel S. Epstein, in his book, The Politics Of Cancer, claims that in women ages 40 to 49, one in four instances of cancer is missed at each mammography. Researchers have found that breast tissue is denser among younger women, making it difficult to detect tumors. For this reason, false negatives are twice as likely to occur in premenopausal mammograms. (Prate). In medicine, mastectomy is the medical term for the surgical removal of one or both breasts, partially or completely. ...
The importance of these missed cancers is not clear, particularly if the woman is getting yearly mammograms. Research on a closely related situation has shown that small cancers which are not acted upon immediately, but are observed over periods of even several years, will have good outcomes. A group of 3184 women had mammograms which were formally classified as "probably benign". This classification is for patients who are not clearly normal, but have some area of minor concern. This results, not in the patient being biopsied, but having early follow up mammography every 6 months for three years to guarantee no change. Of these 3184 women, 17 (0.5%) did have cancers. Most importantly, when the diagnosis was finally made, they were all still stage 0 or 1, the earliest stages. Five years after treatment, none of these 17 women had evidence of recurrence. Thus, small early cancers, even though not acted on immediately, were still entirely curable. (Sickles, AJR, 179:463-468, 1991).
Regardless of the precise number of false negatives, it is very clear that even if some tumors are missed, lives are saved when they are found. Women need to understand that a negative mammogram is not a perfect guarantee that there is no breast cancer present, but it is the best method we have available currently.
[edit] Spread of Cancer One study shows that needle biopsies may increase the likelihood that cancer will spread, if indeed the tumor is malignant. However, that study was about pancreatic cells and went on to talk about liver cells. Breast tissue is not discussed.[2]
The risk of radiation is apparently higher among younger women. The NCI released evidence that, among women under 35, mammography could cause 75 cases of breast cancer for every 15 it identifies. (Prate did not give a source for this statement).
Another Canadian study found a 52 percent increase in breast cancer mortality in young women given annual mammograms. (Prate did not give a source for this statement. It did not come from Miller, AB, et al. in 1992 or 2002). [3]
Dr. Samuel Epstein also claims that pregnant women exposed to radiation could endanger their fetus. He advises against mammography during pregnancy because "the future risks of leukemia to your unborn child, not to mention birth defects, are just not worth it." HI CAMOIN thIS IS YOUR FRIEND CJ Leukemia (leukaemia in British English) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation of blood cells, usually white blood cells (leukocytes). ...
While the number of deaths caused by breast cancer has decreased, the incidence of breast cancer is still rising. Since 1940, the incidence of breast cancer has risen by one to two percent every year. Between 1973 and 1991, the incidence of breast cancer in females over 65 rose nearly 40 percent in the United States. (That's when mammography was starting to be used and calcifications could be seen for the first time. Hence the increase in the diagnosis of DCIS by technological advances. Some proponents of thermography incorrectly cite a study allegedly in Lancet from 1995 saying mammography caused the DCIS. There is no study in Lancet that year that said that. They copied it wrong from Goldberg and didn't bother to verify the comments by Ernster, et al, (JAMA 1996) that said it was the technology that allowed for finding the DCIS.)
Some researchers attribute this increase to better detection technologies; i.e., as the number of women screened for breast cancer rises, so does the number of reported cases. Other analysts say the correlation between mammographic screening and increases in breast cancer is much more ominous, suggesting radiation exposure is responsible for the growing number of cases. While the matter is still being debated, Professor Sandra Steingraber offers ways to navigate these statistics. According to Steingraber, the rise in breast cancer predates the introduction of mammograms as a common diagnostic tool. In addition, the groups of women in whom breast cancer incidence is ascending most swiftly -- black people and the elderly -- are also least likely to get regular mammograms.
The majority of health experts agree that the risk of breast cancer for women under 35 is not high enough to warrant the risk of radiation exposure. For this reason, and because the radiation sensitivity of the breast in women under 35 is possibly greater than in older women, most radiologists will not perform screening mammography in women under 40. However, if there is a significant risk of cancer in a particular patient (BRCA posiitve, very positive family history, palpable mass), mammography may still be important. Often, the radiologist will try to avoid mammography, by using ultrasound, or MRI imaging.
Similarly, the risk of breast cancer to women over 55 very clearly justifies the risk of mammograms. The statistics about mammography and women between the ages of 40 and 55 are the most contentious. A 1992 Canadian National Breast Cancer Study showed that mammography had no positive effect on mortality for women between the ages of 40 and 50. In fact, the study seemed to suggest that women in that age group are more likely to die of breast cancer when screened regularly. (check the study and see if you think 10 women out of 25,000+ in each arm is cause to confuse the average reader with that statement.)[4] This study, however, is the only study to find this result. The study's critics pointed out that there were very serious design flaws in the study that invalidated these results. While screening between 40 and 50 is still controversial, the preponderence of the evidence indicates that there is some small benefit in terms of early detection. Currently, the American Cancer Society and the American College of Radiology encourage mammograms every two years for women ages 40 to 49. Trying to settle this debate, a 1997 consensus panel appointed by the NIH was unable to come to a conclusion as to whether there was definite benefit between the ages of 40 and 50. The panel advised women to weigh the risks with their doctors and decide for themselves. (Prate) The American Cancer Society (ACS) is a medical organization with a corporate attitude in the United States. ...
[edit] Alternatives to Mammography While the cost of Mammography is relatively low, its sensitivity is not ideal, with reports listing the range from 45% to about 90% depending on factors such as the density of the breast. Neither is the X-ray based technology completely benign, as noted above. Therefore there is considerable ongoing research into the use of alternative technologies.
One approach, 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 intravascular injection of a contrast agent (Gadolinium DTPA). The pre-contrast images are "subtracted" from the post-contrast images, and 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. The available literature suggests that the sensitivity of contrast-enhanced breast MRI is considerably higher than that of either radiographic mammography or ultrasound, and is generally reported to be in excess of 95% (though not all reported studies have been as encouraging...) The specificity (the confidence that a lesion is cancerous, and not a false positive) is only fair, thus a positive finding by MRI should not be interpreted as a definitive diagnosis. The reports of 4271 breast MRIs from eight large scale clinical trials were reviewed recently by CD Lehman. Overall the sensitivity ranged from 71% to 100% in these reports, however the call-back rates were low at 10% and the risk of having a benign biopsy was reported at 5%, a significant improvement over mammography.
Several medical instrument vendors have entered this arena with breast MRI solutions. One company, Aurora Systems, stands out as being the only manufacturer to make a breast-dedicated unit and as the exclusive patent holder of certain solutions to fat signal suppression that appear to be more or less essential. Siemens, General Electric and Philips Medical, the leading manufacturers of MRI instruments, each offer breast MRI products or add-ons and several third party companies (e.g., MRI Devices/IGC) offer aftermarket products to enable breast MRI on conventional MRI instruments.
[edit] References - Destounis SV, DiNitto P, Logan-Young W, Bonaccio E, Zuley ML, Willison KM (2004). "Can computer-aided detection with double reading of screening mammograms help decrease the false-negative rate? Initial experience". Radiology 232 (2): 578-84. PMID 15229350.
- Shapiro S, Strax P, Venet L (1966). "Evaluation of Periodic Breast Cancer Screening With Mammography". Journal of the American Medical Association (JAMA) 195(9): 111.
- Lehman CD (2006). ""Role of MRI in screening women at high risk for breast cancer"". Journal of Magnetic Resonance Imaging 24 (5): "964-70. PMID 17036340.
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