An octreotide scan, also known as somatostatin receptor scintigraphy, is a non-invasive test used to evaluate the body for the presence of neuroendocrine tumor cells. This test is performed in a Nuclear Medicine department, which is a branch of radiology that uses radioactive materials to diagnose or treat diseases.
Neuroendocrine tumors originate from neuroendocrine cells, which are found throughout the body. As a result, neuroendocrine tumors can be found in many areas of the body, including the brain, thyroid, lungs and GI tract. Many neuroendocrine tumors have receptors on their surface for a compound called somatastatin. When an octreotide scan is performed, these receptors are targeted so that neuroendocrine tumor cells can be seen on the scan.
Because octreotide scans are highly specialized and require radioactive material to be performed, they are not performed in all centers.
What is this test used for?
This test is used to look for the presence of neuroendocrine cells throughout the body.
This scan may be used as part of an initial evaluation for a neuroendocrine cancer to visualize the primary tumor as well as evaluate for tumor cells that have spread, or metastasized.
How is this test performed?
An IV is placed and an injection of octreotide with radioactive material attached to it (called "radiolabeled"), is given. The amount of radiation used is very small.
Octreotide is a drug very similar to somatostatin. Cells with somatostatin receptors on their surface will attract and attach to the radiolabeled octreotide. The radioactive material emits a low dose of radiation that can be seen with a special scanner (similar to a CT scan).
About 4 hours after the injection, the patient will undergo a scan to look for cells that have taken up the octreotide.
The patient will lie flat for approximately 1-2 hours on a table, with a camera taking pictures above and below them. The scan evaluates the entire body.
The test requires multiple scans. The first set of scans are performed on the day of the injection. A CT Scan may also be performed to create a 3D image of the body. The patient will return the next day for additional scans.
The scanner's computer processes the images, creating a figure of the patient. Any areas with increased uptake show up as a bright spot on the image.
How do I prepare for an octreotide scan?
If you taking octreotide or somatostatin, you may need to stop the medication prior to the scan. You should discuss this with your physician.
If you are pregnant or nursing a baby, you should notify your doctor prior to the scan.
How do I interpret the results of an octreotide scan report?
Following the scan, the images are processed by a computer and interpreted by a nuclear medicine physician. A report is created for the ordering medical professional.
In general, the report states the patient's name, date of birth, and indication (reason for the octreotide scan) at the top of the report. Radiology reports follow a standard outline, regardless of where they are obtained. Radiologists report both normal and abnormal findings in a very systematic approach. For this reason, it is very important to discuss the results with your doctor.
The first paragraph typically includes the specific technical information involved in obtaining the scan (i.e. how much radiolabeled octreotide was given, whether the whole body was scanned, etc).
The middle paragraphs generally begin the description of findings, both normal and abnormal. Because reports are generated for other medical professionals, the terminology is often medically oriented and can be difficult to interpret.
Following the detailed interpretation above, an impression generally follows. This is a summary of the findings, often generated to answer the question posed by the ordering physician.