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Introduction ⬇

A mammogram, also known as mammography or breast x-ray, is an x-ray that provides visualization of the soft tissue of the breast to detect small abnormalities that could suggest a malignancy or benign disease. Its primary use is to screen for and discover cancers that escape detection by other means such as palpation. Typically, lesions less than 1 cm cannot be detected by routine clinical or self-examinations. Although the average breast cancer has likely been present for some time before it reaches the clinically palpable 1-cm size, the prognosis for cure is excellent if detected in this preclinical or presymptomatic phase.

The low-energy x-ray beam used for this procedure is applied to a tightly restricted area and consequently does not produce significant radiation exposure to other areas of the body. Therefore, it is quite acceptable from a radiation safety standpoint to recommend routine screenings. Diagnosis by mammography is based on the x-ray appearance of gross anatomic structures. Benign lesions tend to push breast tissue aside as they expand, whereas malignant lesions may invade surrounding breast tissue. Although false-negative and false-positive readings can occur, a mammogram is highly accurate.

Most breast lumps are not malignant; many are benign cysts. For women older than 40 years, the benefits of using low-dose mammography to find early, curable cancers outweigh possible risks from radiation exposure (Table 10.6).

The American College of Radiology (ACR) accredits mammography machines, and the U.S. Food and Drug Administration (FDA) certifies mammographic facilities. To earn accreditation, mammograms must be performed by specially trained and credentialed radiographers, and the resulting images must be interpreted by radiologists who meet criteria for continuing education in mammography. Additionally, the ACR has stringent standards for equipment, image quality, and radiation dose. Health insurers, including Medicare, require mammographic services to be performed at an accredited institution. The FDA has approved certain digital systems to record breast anatomy electronically.

  1. To detect clinically nonpalpable breast cancer in women aged 45 years and older (per the American Cancer Society), younger women at high risk, or those with a history of breast cancer

  2. When signs and symptoms of breast cancer are present

    1. Skin changes (e.g., “orange peel” skin associated with inflammatory-type cancer)

    2. Nipple or skin retraction

    3. Nipple discharge or erosion

  3. Breast pain

  4. “Lumpy” breast; multiple masses or nodules

  5. Pendulous breasts that are difficult to examine manually

  6. Survey of opposite breast after mastectomy

  7. Patients at risk for having breast cancer (e.g., family history of breast cancer)

  8. Adenocarcinoma of undetermined origin

  9. Previous breast biopsy

  10. Tissue samples removed from the breast may be imaged using detailed mammography techniques

  11. Follow-up studies for questionable mammographic images

Procedure ⬆ ⬇

  1. Mammogram

    1. Perform mammograms with the person in an upright position, preferably standing. Make accommodations for patients using wheelchairs.

    2. Expose the breast. Elevate the inframammary fold to its maximum height. Lift onto a cassette or digital plate to the level of the inferior surface of the patient’s breast. Adjust the breast tissue by hand, smoothing out all skin folds and wrinkles. Lower a movable paddle onto the breast, rigorously compressing the breast tissue.

    3. Make an x-ray exposure quickly and immediately lift the compression.

    4. Take two views (craniocaudal and mediolateral oblique) of each breast.

    5. Before the x-ray examination, the technologist visually observes and manually palpates the breasts.

    6. Tell the patient that the complete examination takes about 30 minutes.

    7. Follow guidelines in Chapter 1 for safe, effective, informed intratest care.

  2. X-ray–guided biopsy (stereotactic technique)

    1. Administer a local anesthetic agent.

    2. Have the patient lie on the abdomen, allowing the breast to protrude through an opening in a special table.

    3. Take two stereo view mammograms, allowing precise positioning of the biopsy needle.

    4. Insert the needle into the breast at precise locations using sterile lacerations. Take multiple core tissue samples because tumors have both benign and malignant areas. In vacuum-assisted biopsy procedure, a probe is inserted directly into the suspicious area, and tissue is gently vacuumed out for subsequent analysis.

    5. Cleanse the breast and apply a sterile dressing.

  3. Needle x-ray localization and surgical biopsy

    1. Administer a local anesthetic agent.

    2. Insert a needle that holds a fine wire, clip, or biodegradable marker into the breast tissue, using stereotactic or sonographic guidance. When the needle point is at the tip of the lesion, the device is released. It stays there until the surgeon, guided by the wire, removes a specimen of the abnormal tissue.

Clinical Alert

  1. Computer software (computer-assisted diagnosis) scans the image and notes suspicious areas that a radiologist could miss, thus acting as a second opinion.

  2. Many radiologists double-read all mammograms.

  3. Comparison with prior mammograms is very important. Consequently, patients are advised to have all mammograms performed at the same facility or retrieve prior mammograms and bring them along when having a new study performed.

  4. Mammographic examination of augmented breasts requires additional views that add to procedure time. The presence of implants should be communicated to the radiology department when scheduling the procedure.

Clinical Implications ⬆ ⬇

Abnormal mammogram findings reveal the following conditions:

  1. Breast mass

    1. Benign breast masses (e.g., cysts, fibroadenomas) are usually round and well demarcated.

    2. Malignant breast masses are often irregularly shaped with extensions into adjacent tissue, generally with an increased number of blood vessels (Figure 10.1).

    3. When a mass is detected, additional studies are performed to help differentiate the nature of the mass. These studies may include the following:

      1. Special x-ray magnification views of the area in question

      2. Spot compression views performed using a paddle that isolates the suspicious tissue (Figure 10.2)

      3. Ultrasound of the area to help differentiate a cystic (fluid-filled) mass from a solid 
lesion

  2. Calcifications present in the malignant mass (duct carcinoma) or in adjacent tissue (lobular carcinoma) are described as innumerable punctuate calcifications resembling fine grains of salt or rodlike calcifications that appear thin, branching, and curvilinear. Macrocalcifications (large mineral deposits) generally represent benign degenerative processes. Microcalcifications (less than 1/50 inch) are of more concern and require close examination.

  3. The likelihood of malignancy increases with a greater number of calcifications in a cluster. However, a cluster with as few as three calcifications, particularly if they are irregular in shape or size, can occur in cancer.

  4. Typical parenchymal patterns are as follows:

    1. N1: normal

    2. P1: mild duct prominence on less than one-fourth of the breast

    3. P2: marked duct prominence

    4. DY: dysplasia (some diagnosticians believe that the person who exhibits dysplasia is 22 times more likely to develop breast cancer than the person with normal results)

  5. Findings of breast cancer when contrast is injected are associated with extravasation of contrast, filling defects, obstruction, or irregular narrowing of ducts (Chart 10.1).

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain the purpose, procedure, benefits, and risks of mammograms. Mammography is the single best method for detecting breast cancer while it is still in a curable stage. Warn the patient that some discomfort is to be expected when the breast is compressed.

  2. Assess pregnancy status of female patients. If positive, advise radiology department.

  3. Instruct the patient not to apply deodorant, perfume, powders, or ointment to the underarm or chest area on the day of the examination. Residue from these preparations can obscure optimal visualization.

  4. Tell the patient to remove all clothing and jewelry from the upper body. Provide the patient with the appropriate covering.

  5. Suggest that patients who have painful breasts refrain from caffeinated foods and beverages (e.g., coffee, tea, cola, chocolate, some over-the-counter medications, and most antiasthmatic medication) for up to 2 weeks before testing.

  6. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. If a biopsy is necessary, see procedures for biopsy using x-ray technology.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Clinical Alert

  1. A mammogram detects abnormalities that could warn of cancer. The actual diagnosis is made by biopsy.

  2. Several methods can be used to provide a breast tissue sample necessary for cancer diagnosis. These include core needle biopsy, surgical biopsy, and vacuum-assisted biopsy. Any of these methods can utilize either x-ray mammography or ultrasound for image guidance.

Reference Values ⬆

Normal

Essentially normal breast tissue: calcification, if present, should be evenly distributed; normal ducts with gradual narrowing ductal system branches