Mammography: Additional Projections

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American Society of Radiologic Technologists self-directed essentialeducation LEARNING

Mammography: Additional Projections

Marty Ronish, PhD

This article describes After reading the information presented, the reader should be able to: additional positions for  Identify the major anatomical structures of the female breast. diagnostic mammography,  Specify at least 3 reasons for taking additional projections. the procedures and  Define terms specific to mammography. reasons for each view  Determine which supplemental views best demonstrate specific areas of interest. and problem-solving  List in correct order the steps for positioning each supplemental view.  tips. Additional views in Identify the appropriate uses of a BB.  Determine the proper positioning for breasts that have implants. mammography can help to  Tell from the localization map which projection helps localize a lesion. better demonstrate lesions and visualize more breast tissue. hen the 2 standard screening comes from day-to-day experience. The projections demonstrate a mammographer must be resourceful and lesion needing further study, creative to find whatever position or angle Wor when the initial screening produces the best possible image. does not show enough breast tissue, further imaging is required. This course Anatomy explains additional views that enable the The mammographer must understand mammographer and radiologist to visual- the anatomy of the breast to position and ize more breast tissue, see tissue from a compress the breast properly. The image different angle, magnify small areas, dif- should show as much tissue as possible. ferentiate lesions from dense tissue, and Expert processing and dedicated equip- detect any irregularities. ment cannot be effective if positioning is If additional views are indicated, the poor. At worst, such mistakes can yield a mammographer should explain to the false negative, and important pathologies patient that the need for extra films does might be missed.1 not necessarily mean there is a problem; The base of the breast extends from the the extra views show breast tissue in more second to the sixth rib in the midclavicu- detail. When additional views reveal a lar line over the pectoralis major muscle. problem, the mammographer provides The glandular tissue always spreads far- empathy and support to the patient and ther than the gross outline of the breast. A works closely with the radiologist. long, tongue-like process of breast tissue, Practicing mammographers know an the axillary appendage or tail of Spence, academic explanation of additional views extends from the main mass up the ante- is no substitute for the understanding that rior axillary line toward and even into the

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and extralobular ducts), leading into lobules. Lobules are made up of intralobular ducts, terminal ducts (ductules) and, during lactation, several small saccular glands, or acini, which are the milk-producing units of the breast. The lobule is the functional unit of the mammary gland. Every glandular lobe is divided into 20 to 40 lobules, each about 1mm to 2 mm in diameter. Standard terminology designates the lobule and the duct leading into it as the terminal ductal lobular unit (TDLU).1,2,3 On a mammographic image the TDLUs appear as tiny overlapping densities. Most lesions, benign or malignant, appear in these tissues. During pregnancy and lactation, the terminal ducts and acini, which start out as buds during puberty,4 increase in number and size. Mammograms are taken during this period only if the patient experiences symp- toms, and then only after the breast has been emptied of milk for a clearer image.2 After lactation ceases, lobules and small ducts atrophy and gradually are replaced by fat. Because fat is more radiolucent than glandular tissue, mammographic images of postlactating women tend to appear less dense. This is important because any growth or new tissue in these glandular regions can indicate the presence of malignancy.2 Why Take Additional Views? Telling a patient that additional films are necessary can cause a great deal of worry and anxiety. Nevertheless, the reasons for taking additional projec- Figure 1. Anatomy of the breast. Illustration by Yvonne Walston, MA, tions are important. By taking the time to explain these CMI., ©1995 Creative Imagery Inc. Albuquerque, NM. reasons, the mammographer or radiologist can alleviate some of the fear while also educating the patient. The radiologist will request additional views if the axilla. This glandular tissue is of considerable impor- standard projections fail to show a portion of the breast tance, because it is a common site of benign or malignant tissue. Additional films may be necessary if the patient abnormalities that often are mistaken for pathology of is large-breasted or obese, very small-breasted, kyphotic, the axillary lymph nodes. On mammograms, the axillary barrel-chested, male, has breast tissue extending far into tail of breast tissue usually is seen best in the mediolat- the axilla, or has had a mastectomy, lumpectomy, pace- eral oblique projection. maker, chest surgery, or implants. Histologically, the female breast has 15 to 20 lobes of Sometimes overlapping tissue in the breast appears glandular tissue with associated ducts, called the lactifer- on film as a suspicious-looking mass. This mass may ous ducts, extending to orifices at the nipple (see Figure show up on 1 standard view but not the other, so the 1). Each lactiferous duct enlarges immediately behind radiologist will request additional images to determine the areola to form a lactiferous sinus, in which milk and whether it is a radiographic distortion or a true mass. other secretions can accumulate. Beyond the lactiferous Overlap also can obscure the clarity of tissues behind sinuses the ducts branch and rebranch (the excretory it; an underlying lesion may be overlooked when it is

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