Norm of Octreotide Scan (Somatostatin-Receptor Scintigraphy)
Physiologic tracer uptake demonstrates normal size, shape, and position of liver, spleen, bladder, and kidney.
Usage of Octreotide Scan (Somatostatin-Receptor Scintigraphy)
Location and diagnosis of primary and metastatic cancers arising from the neuroendocrine system that express somatostatin receptors, such as carcinoid tumors, gastrinomas of pancreas and duodenum, thymoma, thymic carcinoma, pheochromocytoma, pituitary adenomas (growth hormone, TSH tumors), islet cell tumors (insulinoma, glucagonoma), neuroblastoma, small cell carcinoma of the lung, paragangliomas, medullary carcinoma of thyroid, meningioma, astrocytoma, lymphoma, Merkel cell tumor, and breast cancer; staging of Hodgkin's disease; may help in client selection for clinical trials using somatostatin analogs in the treatment of neuroendocrine cancers.
Description of Octreotide Scan (Somatostatin-Receptor Scintigraphy)
An octreotide scan is a nuclear medicine scan of the whole body after injection of a radioactive tracer, [111In-DTPA-D-Phe]octreotide or [123I-Thy3]octreotide, for the purpose of detecting areas of increased uptake by somatostatin-receptor tumors. The octreotide tracer is a somatostatin analog. Various organs and tumors uptake the tracer at varying degrees. The tracer radiation is emitted as gamma rays and is detected by gamma cameras. A series of images are taken from various angles around the client and compiled by single-photon emission computed tomography (SPECT). Cross-sectional and three-dimensional imaging can be accomplished. A series of scans are conducted at 4 and 24 hours following injection of radioisotope. Additional scans may be done.
Professional Considerations of Octreotide Scan (Somatostatin-Receptor Scintigraphy)
Consent form IS required.
Octreotide may produce severe hypoglycemia in clients with insulinomas. An intravenous line is recommended for clients with suspected insulinomas for the administration of glucose solution as needed.
Women who are breast-feeding.
During pregnancy, risks of cumulative radiation exposure to the fetus from this and other previous or future imaging studies must be weighed against the benefits of the procedure. Although formal limits for client exposure are relative to this risk:benefit comparison, the United States Nuclear Regulatory Commission requires that the cumulative dose equivalent to an embryo/ fetus from occupational exposure not exceed 0.5 rem (5 mSv). Radiation dosage to the fetus is proportional to the distance of the anatomy studied from the abdomen and decreases as pregnancy progresses. For pregnant clients, consult the radiologist/ radiology department to obtain estimated fetal radiation exposure from this procedure.
- See Client and Family Teaching.
- Octreotide acetate therapy should be discontinued 24–48 hours before the scan, while monitoring client for signs of withdrawal.
- Jewelry and metal objects should be removed before scanning.
- A bowel prep such as GoLYTELY (Colyte) or MagCitrate (magnesium citrate) may be recommended for the evening of the injection, before the 24-hour scan.
- The client should be well hydrated.
- Intravenous radioactive tracer is administered 3½ to 4 hours before the first scan.
- The client should drink two glasses of water immediately following the injection and continue to increase fluid intake for the next 2 days.
- The client is placed in a supine position and the whole body is scanned with a gamma camera.
- A bowel prep such as GoLYTELY (Colyte) or MagCitrate (magnesium citrate) may be recommended for the evening of day 1.
- Repeat scan will be done 24 hours later.
- Repeat scans may be done on days 3 and 4.
- Continue to maintain hydration throughout test period.
Client and Family Teaching
- Fasting is NOT required for this test.
- You may feel a warm sensation when the radioisotope is injected into your vein.
- The level of radiation exposure to is low and not associated with any significant risks.
- You will need to lie still on a hard table during the procedure.
- Each scan takes 1–2 hours and is painless.
- Drink plenty of fluids during the 2 days following the injection of the isotope.
Factors That Affect Results
- Reduced sensitivity of octreotide imaging may occur in clients receiving therapeutic doses of octreotide acetate (Sandostatin) therapy.
- The radioisotope tracer is primarily excreted by the kidney. Studies have not been conducted in clients with poor renal function. It is not known if octreotide can be removed by dialysis.
- The physical half-life of [111In-DTPA-D-Phe]octreotide is 2.8 days.
- The scan is often used to identify tumors unrevealed by CT or MRI scans.
- Uptake of the octreotide tracer may indicate the client is a candidate for octreotide injections to treat the cancer.
- Health care professionals working in a nuclear medicine area must follow federal standards set by the Nuclear Regulatory Commission. These standards include precautions for handling the radioactive material and monitoring of potential radiation exposure.