A gallium scan is performed to detect the presence, location, and size of lymphoma; to detect chronic infections and abscesses; to differentiate malignant from benign lesions; and to determine the extent of invasion of known malignancies. The entire body is scanned looking for lymph node involvement. For both adult and pediatric patients, this scan is used to help stage bronchogenic cancer, Hodgkin lymphomas, and non-Hodgkin lymphomas. Gallium images may also be used to record tumor regression after radiation or chemotherapy. The radionuclide used in this study is gallium citrate (⁶⁷Ga).

The underlying mechanism for the uptake of ⁶⁷Ga is not well understood. Uptake in some neoplasms may depend on the presence of transferrin receptors in tumor cells, but this is only speculation. Once ⁶⁷Ga enters a tissue, it remains there until radioactive decay dissipates the isotope. Medical centers that have PET/CT scanners have seen a major reduction in gallium scans because of PET/CT superior tumor imaging ability.

1. Laxatives, suppositories, or tap water enemas are often ordered before the scan. The patient may eat breakfast on the day of the scan.

2. Inject the radionuclide 24–96 hours before imaging.

3. Have the patient lie quietly without moving during the imaging procedure. Take anterior and posterior views of the entire body.

4. Additional imaging may be done at 24-hour intervals to differentiate normal bowel activity from pathologic concentrations.

5. See Chapter 1 guidelines for safe, effective, informed intratest care.

1. Abnormal gallium concentration usually implies the existence of underlying pathology:

   1. Malignancy, especially lung and testes

   2. Mesothelioma

   3. Stages of lymphoma, Hodgkin disease, melanoma, hepatoma, soft tissue sarcoma, primary tumor of bone or cartilage, neuroblastoma, and leukemia

   4. Abscesses

   5. Tuberculosis

   6. Thrombosis

   7. Abscessed sarcoidosis

   8. Chronic infection

   9. Interstitial pulmonary fibrosis

2. Further diagnostic studies usually are performed to distinguish benign from malignant lesions.

3. Tumor uptake of ⁶⁷Ga varies with tumor type, among persons with tumors of the same histologic type, and even among tumor sites of a given patient.

4. Tumor uptake of ⁶⁷Ga may be significantly reduced after effective treatment.

5. Although ¹¹¹In-labeled leukocyte imaging is more specific for acute abscess localization, a gallium scan may be used as a multipurpose screening procedure for chronic infection.

Pretest Patient Care

1. Explain the purpose, procedure, benefits, and risks of a gallium scan.

2. Usually no change in eating habits is required before testing. However, some departments request that patients eat a low-residue lunch and a clear-liquid supper the day before the examination.

3. See standard NMI pretest precautions.

4. The usual preparation includes oral laxatives taken on the night before the first scanning session and again on the night before each scanning session. Enemas or suppositories may also be given. These preparations clear normal gallium activity from the bowel.

5. Actual imaging time is 45–90 minutes per session.

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

1. A negative study cannot definitely rule out the presence of disease. (The rate of false-negative results in gallium studies is 40%.)

2. It is difficult to detect a single, solitary nodule (e.g., adenocarcinoma). Lesions smaller than 2 cm can be detected. Tumors near the liver are difficult to detect, and interpretation of iliac nodes is difficult.

3. Because gallium does collect in the bowel, there may be an abnormal concentration in the lower abdomen. For this reason, laxatives and enemas may be ordered.

4. Degeneration or necrosis of tumor and use of antineoplastic drugs immediately before imaging cause false-negative results.

Normal

No evidence of tumor-type activity or infection