An octreotide scan – also known as somatostatin receptor scintigraphy (SRS) – may be used to detect certain neuroendocrine cancer cells in the body. The test requires multiple scans, usually taken over 2 days.
On the first day, you will receive an injection that contains a very small amount of a radioactive substance called an octreotide tracer.
Octreotide is a drug very similar to somatostatin. Neuroendocrine cells with somatostatin receptors on their surface will attract and attach to the octreotide tracer.
Later that day, the first set of scans will be taken to look for areas in the body that have picked up this tracer, which may indicate where certain neuroendocrine cancer cells are located. Further octreotide scans will usually be taken over the next 24 to 48 hours to produce more detailed pictures.
A bone scintigraphy scan is an imaging test that uses a very small amount of a radioactive substance to determine if NET cancer has spread to the bones from another part of the body.
Usually the entire body is scanned during a bone scan procedure. If the results show bone damage that may be caused by cancer, then more diagnostic NET tests may be necessary. These may include a CT scan, an MRI scan, or taking a biopsy.
A MIBG scan is another imaging test that can be carried out to find the location of NETs in the body, but it is used less often than an octreotide scan.
It works by injecting a substance called an isotope into your veins. The MIBG scan is named after the chemical ‘iodine-131-metaiodobenzylguanidine’ or MIBG for short, to which the isotope is attached.
After it is injected, the isotope travels around the body and sticks to any abnormal areas in the body. Several hours or days later the body is scanned with a gamma camera to look for areas that have picked up the isotope.
This allows doctors to identify and pinpoint any areas of abnormality, including certain types of NETs.
A PET scan is a unique type of imaging test that allows doctors to see how the organs and tissues inside your body are actually functioning. This scan involves injecting a very small dose of a radioactive chemical, called a tracer, into the vein of your arm.
PET scans can detect and record the energy given off by the tracer in your cells. Detailed, three-dimensional images from the PET scan are then produced through a computer. A PET scan is usually used in combination with a CT scan to build up a picture of the size, location and status of NETs.
Certain types of radioactive tracers can be used in PET scans to detect particular types of NETs:
F-DOPA is an abbreviation for 18F-dihydroxy-phenylalanine, which is the radioactive tracer for this type of PET scan. This tracer is highly sensitive for detecting the primary tumour of a neuroendocrine cancer, and secondary tumours (metastases), where the disease has spread.
FDG is an abbreviation for fluorodeoxyglucose, which is the tracer injected for this type of PET scan. A PET scan is used to identify the presence of a metabolically active tumour within the body.
Gallium-68 is a radioactive tracer attached to octreotide. It is injected into the body and can be used to identify specific neuroendocrine cancer cells during a PET scan.
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