Scintimammography, also known as breast-specific gamma imaging and molecular breast imaging, is an NMI test that is often used in cases of indeterminate mammography or a breast abnormality. Other indications for performing scintimammography include follow-up to surgery, biopsy, radiation therapy, or chemotherapy because it is more specific than x-ray mammography and may differentiate between benign and malignant lesions.
Lymphoscintigraphy is an NMI test used to detect any axillary lymph node involvement from breast cancer and decreases the number of unnecessary breast biopsies. Sentinel and satellite node identification and staging in early breast cancer using lymphoscintigraphy and intraoperative gamma node and tissue biopsy show micrometastasis more frequently than standard dissection. Lymphoscintigraphy assesses the lymphatic drainage of tumors.
Scintimammography
Inject the radiopharmaceutical intravenously in the arm opposite from the breast of concern.
Have the patient lie prone on a special table with a cut-out section that allows the breasts to hang through the table unobstructed.
Place the patient in the supine position with the arms raised for obtaining images of the axillary lymph nodes.
Although the total patient time is approximately 45–60 minutes, the actual scan time is only 25–30 minutes.
For sentinel node identification, see Chapter 11 for a complete discussion of the procedure.
Remember that an optional SPECT examination may be requested by the nuclear medicine physician. This examination may take an additional 30–40 minutes.
See Chapter 1 guidelines for safe, effective, informed intratest care.
Lymphoscintigraphy
Special positioning is required. (See sentinel node evaluation in Chapter 11.)
The tracer is injected by intradermal method for melanoma evaluation or subcutaneously for breast cancer evaluation. Massage after injection for at least 30 seconds, moving the breast to optimally clear the overlying soft tissue.
Images are obtained immediately and 2–4 hours after injection.
Sentinel lymph node (SLN) identification may also be performed to evaluate metastatic spread of cancer to penis, vulva, uterus, head, and neck.
Scintimammography
Abnormal increased focal uptake is found in cases of a fibroadenoma and adenocarcinoma.
Nonuniform increased diffuse uptake of activity is associated with fibrous dysplasia, which may be unilateral or bilateral.
Several areas of increased focal uptake are often seen in cases of multifocal breast cancer.
In patients with a breast prosthesis, a focal decrease in activity is observed in relation to the size and shape of the prosthesis.
Axillary metastasis is detected as focal areas of increased uptake in the axillary nodes.
This scan is used to evaluate radiation therapy and chemotherapy.
Lymphoscintigraphy
Abnormal nodes show leaks into adjacent tissue, a blush around the affected node, and unusual collateral lymph drainage pathways.
The first lymph node to drain the tumor invariably contains the tumor.
It has been found that there are more than one lymphatic channels draining the tumor, and that there are one, two, or three SLNs as well as satellite nodes.
Micrometastasis of biopsied tissue is found more frequently than standard axillary node dissection.
Pretest Patient Care
Explain the purpose, procedure, benefits, and risks of NMI. See Chapter 11 for more information on sentinel node biopsy.
Have the patient remove all clothing and jewelry from the waist up. The patient wears a hospital gown with the opening of the gown in the front. There are no dietary or medication restrictions.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
See standard NMI pretest precautions.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed. Counsel appropriately about need for further tests (e.g., biopsy and possible immediate surgery).
Refer to standard NMI posttest precautions.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.
There should not be any other detectable amount of radioactivity in the patient.
The patient should be lying supine for the injection of the radiopharmaceutical agent (for scintimammography) to prevent a “streaking” artifact found on the resulting image in the breast region, which corresponds to the arm that received the injection.
To eliminate a false-positive appearance, the patient should be injected on the side opposite of a known lymphatic lesion. If the patient is known to have bilateral breast cancer, a foot vein may be used for injection.
Extravasation of the radiopharmaceutical agent can result in hot spots of radioactivity in the location of the axillary lymph nodes.